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Intek 40 Series Pushrod Length vs Adjustment Range

#1

D

Dave_C

Lawn mower has a B&S Intek V-twin 19HP
Model 407777
Type 0137 E1
Code 980422YG

Does anyone know what the spec is for the pushrod length?

It overheated, valve guide slipped, bent one or more pushrods. I got the pushrod part #s, 690981 (steel, exhaust), and 690982 (aluminum, intake).

I was sent a generic kit labeled CT160 (or CTM160, something like that), which is supposed to be the above two part #s but compared to a bent steel exhaust rod that was pulled, the new pushrods look about 1.5mm shorter.

I checked the engine service manual # 273521 and it doesn't spec the pushrod length.

Is there an acceptable range of length that can be adjusted for, is something 1.5mm shorter likely to work okay? I'd just throw it in and try to adjust it but the mower is at my mother's place and I'd like to have viable parts when I get there.


#2

Craftsman Garage

Craftsman Garage

Pretty sure that when you adjust the valves, it will compensate for it being shorter


#3

D

Dave_C

Yes I know there is some adjustment as I'd adjusted it previously when it burped trying to start it (a few years ago, I did not cause this, lol), but I don't know, if after a couple+ decades of wear (maybe around 600 hrs), if 1.5mm shorter is outside a reasonable expectation of adjustment range.


#4

Tiger Small Engine

Tiger Small Engine

Dave_C said:
Yes I know there is some adjustment as I'd adjusted it previously when it burped trying to start it (a few years ago, I did not cause this, lol), but I don't know, if after a couple+ decades of wear (maybe around 600 hrs), if 1.5mm shorter is outside a reasonable expectation of adjustment range.
Click to expand...
Are you changing the cylinder that overheated and pushed the valve guide? Did you thoroughly clean the top of engine and cooling fins from debris after it overheated? This mower is 25 years old and has been around the block a time or two.


#5

StarTech

StarTech

The old 690981 which supersedes to 597785 is 6.275" (159.385 mm) in length per my caliper.


#6

D

Dave_C

StarTech said:
The old 690981 which supersedes to 597785 is 6.275" (159.385 mm) in length per my caliper.
Click to expand...
Thanks! I was just reminded that my caliper is only 6", so I had to extrapolate, after beating the old bent pushrod close to straight.

That gives me old pushrod length 159.25mm, two new steel 157.75mm, and oddly the two aluminum are different lengths from each other, about 157.25mm and 158.25mm... gotta luv quality control!


#7

D

Dave_C

Tiger Small Engine said:
Are you changing the cylinder that overheated and pushed the valve guide? Did you thoroughly clean the top of engine and cooling fins from debris after it overheated? This mower is 25 years old and has been around the block a time or two.
Click to expand...
Changing the cylinder? You mean a new head? I was hoping to just replace the pushrods, dremel a groove on the valve guide while it's sticking out, that would end up just below the level of the head, put some high-temp red loctite on, pound the guide back down and stake it in.

Yes there was a lot of grass muck built up and that has already been cleaned off. I also considered pulling the head, then tapping it and using a set screw as I've seen Taryl and others do on youtube videos, but still trying to decide.


#8

StarTech

StarTech

Dave_C said:
Thanks! I was just reminded that my caliper is only 6", so I had to extrapolate, after beating the old bent pushrod close to straight.

That gives me old pushrod length 159.25mm, two new steel 157.75mm, and oddly the two aluminum are different lengths from each other, about 157.25mm and 158.25mm... gotta luv quality control!
Click to expand...
Just out of curiosity are these from Briggs or are they after market? IF form Briggs it does sounds like a quality control issue as Briggs in the past has always been good but ever since the they went bankrupt and the financial investment company took them over I do suspect a lot more items are coming from China.

Also note the 796632 and 796633 cylinder heads have been superseded a few times. They even at one time came as a set for half the price but quickly changed that back to individual heads out of China. Current heads are 84001918 (#1) and 84001919 (#2) and they are not a stock item from Briggs direct. IE slow boat from China.


#9

Tiger Small Engine

Tiger Small Engine

Dave_C said:
Changing the cylinder? You mean a new head? I was hoping to just replace the pushrods, dremel a groove on the valve guide while it's sticking out, that would end up just below the level of the head, put some high-temp red loctite on, pound the guide back down and stake it in.

Yes there was a lot of grass muck built up and that has already been cleaned off. I also considered pulling the head, then tapping it and using a set screw as I've seen Taryl and others do on youtube videos, but still trying to decide.
Click to expand...
If you cut a groove in valve guide, insert a c-clip into the groove so it stays put. Make sure it is at correct depth of course. You can red Loctite it and peen it also.


#10

StarTech

StarTech

As a professional shop I don't do this to my customers. I warranty my workmanship and if the repair don't hold it bites me in the anus.

Beside grinding on the cast iron valve guide will weaken it. Another option I have heard of is to pull the head drive the guide back in place and spot weld the guide inside the valve chamber as these guides are usually pushed out. Even that I don't recommend. But it is the OP's engine and he can take the risks if he wants to as he can always repair it again if it fails again or replace it. Just note there is no replacement guides.

BTW any beating on the valve guide usually means it will need reaming to correct size.


#11

Tiger Small Engine

Tiger Small Engine

StarTech said:
As a professional shop I don't do this to my customers. I warranty my workmanship and if the repair don't hold it bites me in the anus.

Beside grinding on the cast iron valve guide will weaken it. Another option I have heard of is to pull the head drive the guide back in place and spot weld the guide inside the valve chamber as these guides are usually pushed out. Even that I don't recommend. But it is the OP's engine and he can take the risks if he wants to as he can always repair it again if it fails again or replace it. Just note there is no replacement guides.

BTW any beating on the valve guide usually means it will need reaming to correct size.
Click to expand...
I don’t do this repair this way either for a customer. It is a new cylinder head, clean top of engine of debris, etc.


#12

D

Dave_C

StarTech said:
Just out of curiosity are these from Briggs or are they after market?
Also note the 796632 and 796633 cylinder heads have been superseded a few times. They even at one time came as a set for half the price but quickly changed that back to individual heads out of China. Current heads are 84001918 (#1) and 84001919 (#2) and they are not a stock item from Briggs direct. IE slow boat from China.
Click to expand...

The pushrods were aftermarket. I noticed the new part #'s, supposedly improved with a lip so the valve guide can't slip up. I looked around and they seem to be going for about $190 and up, each. If my repair attempts don't work, and don't result in trashing the engine internally, then I'll end up getting the 84001918 as it is cylinder #1 with the slipped valve guide. Cylinder #2 looked to be okay still.


#13

D

Dave_C

Tiger Small Engine said:
If you cut a groove in valve guide, insert a c-clip into the groove so it stays put. Make sure it is at correct depth of course. You can red Loctite it and peen it also.
Click to expand...

There seems to be some difference of opinion where these valve guides are supposed to sit. Some state that they only stick up out of the rocker arm side of the head by 1/8" or so, and have some area sticking out the other end, which might be enough clearance for a c-clip, but other people state that the back of the valve guide is supposed to be flush with the head and stick out a bit further than 1/8", which seems more consistent with pics I've seen of new heads.

If I'm taking the head off anyway, I plan to tap a hole and put in one or more set screws. For now I am considering trying just the loctite threadocker and staking it, seeing if that holds up long enough to get the fall leaves mowed up as there are a ton of them accumulating while the mower is down. I suppose someone could be hired to mow a time or two to get rid of the leaves but they're not even close to done falling yet. In this climate the grass is no longer growing till around late March.


#14

D

Dave_C

StarTech said:
As a professional shop I don't do this to my customers. I warranty my workmanship and if the repair don't hold it bites me in the anus.

Beside grinding on the cast iron valve guide will weaken it. Another option I have heard of is to pull the head drive the guide back in place and spot weld the guide inside the valve chamber as these guides are usually pushed out. Even that I don't recommend. But it is the OP's engine and he can take the risks if he wants to as he can always repair it again if it fails again or replace it. Just note there is no replacement guides.

BTW any beating on the valve guide usually means it will need reaming to correct size.
Click to expand...

Okay but as a shop, what would you charge to put the new head on, and presumably clean it out since it is likely brought in with nothing done yet? I figure that's at least a $450 service with parts, right? The mower isn't worth more than that, is a (roughly) circa 1999 Scotts aka Murray, which works fine besides the engine but isn't long term investment worthy. A new head at $190-ish is about the limit. If the other head also needed replaced, it would blow the budget to replace them both.

Grinding on the cast iron valve guide? I'd just put a groove in it for peening around that, to have some purchase on it, or a dimple for a set screw. It looks steel (shiny silver), doesn't look like it would be easy to weaken it. If loctite and staking it, then a set screw doesn't keep it still, I may find some welder to do that. I think the main issue with a set screw will be whether the loctite threadlocker stays set up at the head temperature. It's rated for 450F but since this is a side load, might not slip without it doing its job.

I found yet another alternative which is a machined washer that sits over the casting, under the spring. Here's a video example:



#15

Craftsman Garage

Craftsman Garage

Well, you get what you pay for. If you want your engine to actually run good, do yourself a favor and get Briggs Oem.


#16

S

slomo

Moral of this story is CLEAN YOUR COOLING FINS. Swear this has been posted on here buy one of us. (y):D


#17

D

Dave_C

slomo said:
Moral of this story is CLEAN YOUR COOLING FINS. Swear this has been posted on here buy one of us. (y):D
Click to expand...

Yeah the problem in this case was that I'd always used a leaf blower all over the mower, which gave the false impression that nothing was building up anywhere since I couldn't see the buildup on the heads.


#18

StarTech

StarTech

And Mice, Mud Dabbers, and Jenny Wrens are quick to build nests. And mice loves chewing wires and hoses too.

What a lot of people don't understand when trying to stay cheap is how much it costs to have someone else mow their lawns. I had a couple to complain about my repair estimates until they checked out having someone else to mow their lawns. They quickly had me to repair their old mowers. And last year I had one customer that thought $750 was too much to repair a JD mower that they were abusing but was willing to spend $3500 on a new mower because they could get it on credit.


#19

Tiger Small Engine

Tiger Small Engine

Dave_C said:
Okay but as a shop, what would you charge to put the new head on, and presumably clean it out since it is likely brought in with nothing done yet? I figure that's at least a $450 service with parts, right? The mower isn't worth more than that, is a (roughly) circa 1999 Scotts aka Murray, which works fine besides the engine but isn't long term investment worthy. A new head at $190-ish is about the limit. If the other head also needed replaced, it would blow the budget to replace them both.

Grinding on the cast iron valve guide? I'd just put a groove in it for peening around that, to have some purchase on it, or a dimple for a set screw. It looks steel (shiny silver), doesn't look like it would be easy to weaken it. If loctite and staking it, then a set screw doesn't keep it still, I may find some welder to do that. I think the main issue with a set screw will be whether the loctite threadlocker stays set up at the head temperature. It's rated for 450F but since this is a side load, might not slip without it doing its job.

I found yet another alternative which is a machined washer that sits over the casting, under the spring. Here's a video example:

Click to expand...
Technically, by the service manual, the mower shroud is supposed to be removed once a year and the engine and cooling fins checked for debris, to avoid overheating.

Paying $450-$550 to remove and replace a cylinder head, head gasket, decarbon, and set valves, etc. on a mower that is worth $450-$550 is a judgment call. A new bottom of the line basic riding mower is $2000. Mower probably needs a tune up also and there are sometimes other small issues. The cost keeps rising. One thing I will say is that going through all that work and “just seeing if it can get through the end of the season “ seems rather short sided. Cut a groove, Loctite it, put in a set screw, and peen it. Throw the kitchen sink at it.


#20

S

slomo

Tiger Small Engine said:
Technically, by the service manual, the mower shroud is supposed to be removed once a year and the engine and cooling fins checked for debris, to avoid overheating.
Click to expand...
So true so true. On every air cooled engine out there.

More often if bagging or scalping. Some riding baggers can dump grass up high and get sucked into the shroud. And when you empty said bags it pours out all over the engine.


#21

D

Dave_C

Before this engine popped out the valve guide, it had plenty of power for mowing.

Should the valves for just this one head be lapped while the head is off, or will this potentially be worse, causing a difference in compression between this cylinder and the other cylinder which won't get the valves lapped?

I realize that best practices would mean lapping valves for both heads, but I'm running out of time, need to get all the work done on the same visit. If all the leaves get too much rain or snow, they're going to mat down and can't be mow-mulched away.


#22

Tiger Small Engine

Tiger Small Engine

Dave_C said:
Before this engine popped out the valve guide, it had plenty of power for mowing.

Should the valves for just this one head be lapped while the head is off, or will this potentially be worse, causing a difference in compression between this cylinder and the other cylinder which won't get the valves lapped?

I realize that best practices would mean lapping valves for both heads, but I'm running out of time, need to get all the work done on the same visit. If all the leaves get too much rain or snow, they're going to mat down and can't be mow-mulched away.
Click to expand...
Always do visual inspection, lap valves, de-carbon valves, cylinder head, and piston head, and check head for level with feeler gauge on glass. Don’t worry about other cylinder unless it is a problem. Perform compression test to compare two cylinders once work is complete.


#23

D

Dave_C

How do you do a compression test on these? I was under the impression that they have a compression release mechanism that's active while cranking, till running higher than a certain RPM. That won't impact the reading?


#24

StarTech

StarTech

Dave_C said:
How do you do a compression test on these? I was under the impression that they have a compression release mechanism that's active while cranking, till running higher than a certain RPM. That won't impact the reading?
Click to expand...
This why you do leak down tests and better yet the modified leak down test when an OHV engine is involved. With low pressure leak down tester you can test all of cylinder condition from TDC to BDC. The tester I have test at 12-15 psi to get full scale readings; therefore I can hand hold the flywheel and can rotate through the TDC to BDC cycle while watching the leak down percentage needle. Also paying attention the air is leaking out in case of a bad valve seal or a blown head gasket.

While using this modified test I found several engines with lower cylinder damage that would have no shown up on a standard leak down test.


#25

Tiger Small Engine

Tiger Small Engine

Dave_C said:
How do you do a compression test on these? I was under the impression that they have a compression release mechanism that's active while cranking, till running higher than a certain RPM. That won't impact the reading?
Click to expand...
Yes, the compression release will affect a compression test reading. You are looking for at least 60-70 psi on a twin cylinder with compression release. You are also looking for 10% or less differential between the two cylinders. I sometimes do a leak down test also, depending upon the situation.


#26

kbowley

kbowley

I have seen and repaired this issue countless times in my shop from mice building nests beneath the cooling shroud. Buy a new head, gasket kit, and pushrods if you want it fixed properly. You can try driving the guide back down with a correct-size socket, but it won't last. A new head will be around two hundred, pushrods, twenty-five, and a gasket kit around twenty-five. It isn't a hard job, just a bit time-consuming removing everything to get it done. For me, roughly 2.5 hours of labor. For me to do it for someone runs around four hundred to four fifty, including an oil change.


#27

justin@justintime

justin@justintime

I enjoy reading the back and forth on this stuff. Quickly as a shop do it the right way and this only due to save our bum from lack of service and neglect. As a shop for myself that changes his oil uses API rated CH-4 cj-4 or CK-4 oil 20w-50 and cleans his cooling fins id drive the pin in ream the guide and recut my seats and face my valves but I also have the 600 dollars or so in neway tools to do that. As a DIY you don't wanna pay a shop or a head, slam it in do it by feel and do as you please. It'll work just no crystal ball as to how long. Engines are engines they are all the same and they all need to meet the same requirements in order to run 14.7 figure out that number and all engines will be easier to work on heat and friction are the enemy. Your weed Wacker and your Ferrari both need 14.7


#28

P

Peva

Dave_C said:
Okay but as a shop, what would you charge to put the new head on, and presumably clean it out since it is likely brought in with nothing done yet? I figure that's at least a $450 service with parts, right? The mower isn't worth more than that, is a (roughly) circa 1999 Scotts aka Murray, which works fine besides the engine but isn't long term investment worthy. A new head at $190-ish is about the limit. If the other head also needed replaced, it would blow the budget to replace them both.

Grinding on the cast iron valve guide? I'd just put a groove in it for peening around that, to have some purchase on it, or a dimple for a set screw. It looks steel (shiny silver), doesn't look like it would be easy to weaken it. If loctite and staking it, then a set screw doesn't keep it still, I may find some welder to do that. I think the main issue with a set screw will be whether the loctite threadlocker stays set up at the head temperature. It's rated for 450F but since this is a side load, might not slip without it doing its job.

I found yet another alternative which is a machined washer that sits over the casting, under the spring. Here's a video example:

Click to expand...
That step washer is a clean solution. I was wondering if one or both ends of the spring should be ground shorter to equal the thickness of the part of the washer that it's resting on so the spring is compressed as designed. Or is that over-thinking it?


#29

P

Peva

justin@justintime said:
I enjoy reading the back and forth on this stuff. Quickly as a shop do it the right way and this only due to save our bum from lack of service and neglect. As a shop for myself that changes his oil uses API rated CH-4 cj-4 or CK-4 oil 20w-50 and cleans his cooling fins id drive the pin in ream the guide and recut my seats and face my valves but I also have the 600 dollars or so in neway tools to do that. As a DIY you don't wanna pay a shop or a head, slam it in do it by feel and do as you please. It'll work just no crystal ball as to how long. Engines are engines they are all the same and they all need to meet the same requirements in order to run 14.7 figure out that number and all engines will be easier to work on heat and friction are the enemy. Your weed Wacker and your Ferrari both need 14.7
Click to expand...
I was getting ready to show my ignorance and ask what "14.7" had to do with anything - tried to guess what it might be.

Started thinking: Standard ambient air pressure is 14.7 psi. But that can't be it. Suddenly the words "stoichiometric" and "O2 sensors" popped info my mind from years ago - so I internet-searched those terms, and - voilà! - 14.7:1 is the ideal stoichiometric air-fuel ratio.

The mind us a terrible thing! 😱 😄


#30

justin@justintime

justin@justintime

Peva said:
That step washer is a clean solution. I was wondering if one or both ends of the spring should be ground shorter to equal the thickness of the part of the washer that it's resting on so the spring is compressed as designed. Or is that over-thinking it?
Click to expand...
💯 Infact from what I can tell I'm the only one that's ever heard of valve spring shims. Again engines are engines there's an odd misconception small engines are in a different category. Yes you want the spring compressed they even last longer that way. Now it is just a small engine yes it will run no it will probably not be a noticeable difference. When I cut valves seats I shim springs on my engines but not so much on customers as I fear faster damage would result in going to far and again it's a small engine cost is the issue not function. These guys getting 6 and 7 grand in RPM achieve this mainly due to (amongst others) heavier springs to reduce "valve float" without the heavy springs they fall on their face at about 4500rpm. The last thing I would do is trim the guide. Pound it in, peen it in, run a drill bit through by hand and wrap a piece of fine grit sandpaper to a stiff piece of wire and hone the guide take a scotch Brite pad to your stem and adjust your valves to spec. The smaller side of spec as you've gone past break in period your 1.5mm will not affect your overall valve lift as your taking it up on the adjuster only way to loose valve lift would be taking the cam lobes down or loose clearances
. Shim the spring if you feel the need I see no need as you haven't changed anything.


#31

G

gregboggess

Dave_C said:
Lawn mower has a B&S Intek V-twin 19HP
Model 407777
Type 0137 E1
Code 980422YG

Does anyone know what the spec is for the pushrod length?

It overheated, valve guide slipped, bent one or more pushrods. I got the pushrod part #s, 690981 (steel, exhaust), and 690982 (aluminum, intake).

I was sent a generic kit labeled CT160 (or CTM160, something like that), which is supposed to be the above two part #s but compared to a bent steel exhaust rod that was pulled, the new pushrods look about 1.5mm shorter.

I checked the engine service manual # 273521 and it doesn't spec the pushrod length.

Is there an acceptable range of length that can be adjusted for, is something 1.5mm shorter likely to work okay? I'd just throw it in and try to adjust it but the mower is at my mother's place and I'd like to have viable parts when I get there.
Click to expand...
There is 25.4 mm to an inch, so are you saying they are 1 1/2 inches shorter?


#32

P

Peva

justin@justintime said:
💯 Infact from what I can tell I'm the only one that's ever heard of valve spring shims. Again engines are engines there's an odd misconception small engines are in a different category. Yes you want the spring compressed they even last longer that way. Now it is just a small engine yes it will run no it will probably not be a noticeable difference. When I cut valves seats I shim springs on my engines but not so much on customers as I fear faster damage would result in going to far and again it's a small engine cost is the issue not function. These guys getting 6 and 7 grand in RPM achieve this mainly due to (amongst others) heavier springs to reduce "valve float" without the heavy springs they fall on their face at about 4500rpm. The last thing I would do is trim the guide. Pound it in, peen it in, run a drill bit through by hand and wrap a piece of fine grit sandpaper to a stiff piece of wire and hone the guide take a scotch Brite pad to your stem and adjust your valves to spec. The smaller side of spec as you've gone past break in period your 1.5mm will not affect your overall valve lift as your taking it up on the adjuster only way to loose valve lift would be taking the cam lobes down or loose clearances
. Shim the spring if you feel the need I see no need as you haven't changed anything.
Click to expand...
I was only meaning that if you put the step washer in to retain the valve guide, the bottom end of the washer acts as a shim for the spring. Depending on how thick you make that inadvertent-new-spring-shim part of the washer, you could be over-compressing the spring, which may shorten it's life (could yield/weaken or break).

Again - I may be overthinking it. But if you make it 1/16" thick or more, perhaps that would become a spring life factor. Perhaps OK if maybe 1/32 or 3/64" thick. Anyway, with me being OCD, if I were doing it, I would grind the end(s) of the spring to remove maybe 0.01" shy of whatever that thickness is - ounce of prevention kind of thing.


#33

P

Peva

gregboggess said:
There is 25.4 mm to an inch, so are you saying they are 1 1/2 inches shorter?
Click to expand...
I think you had a brain fart,

1.5mm = 0.060"


#34

D

Dave_C

I haven't completed the repair yet but got a lot done. Cleaned fins, removed/cleaned head, checked flatness, lapped valves, decarboned valves/stems, drove valve guide out, tapped a hole in side of head and dimpled an adjacent spot on the valve guide, ground a notch in the valve guide near the rocker arm facing end, put it back in with some Permatex high heat red threadlocker on it, and on a set screw and now that's curing. Also staked the head aluminum around the top of the valve guide.

I already had a generic gasket kit, bought years ago when the exhaust manifold bolts came out, and one of the gaskets was lost. Upon checking it, and having the head off to compare, I now realize that the new head gasket has a little bit (maybe 4mm, I didn't measure it) larger cylinder bore hole, but has just as much coverage of the machined areas on the cylinder and head, and bolt holes line up. Since it's larger rather than smaller, it's probably going to work, right? I mean in theory it might reduce the compression a (tiny?) amount but hopefully not a problematic amount.

It also means I will be trying to reuse the exhaust manifold gaskets since I'd already used those out of this gasket kit, and if they don't seal well enough, can come back later and replace those without having to take off many additional parts for access.

Something occurred to me, that by lapping the valves, I regained at least a fraction of a millimeter in how high the valve stem sits in the head, which places the rocker arm that amount lower on the pushrod end, making up at least a little of the difference in pushrod length which was the issue that started this topic. We'll see, and if at some point in the future the guide pushes back out, I'll be sure to update the topic with that info.


#35

O

outdoorpowermike

Dave_C said:
Lawn mower has a B&S Intek V-twin 19HP
Model 407777
Type 0137 E1
Code 980422YG

Does anyone know what the spec is for the pushrod length?

It overheated, valve guide slipped, bent one or more pushrods. I got the pushrod part #s, 690981 (steel, exhaust), and 690982 (aluminum, intake).

I was sent a generic kit labeled CT160 (or CTM160, something like that), which is supposed to be the above two part #s but compared to a bent steel exhaust rod that was pulled, the new pushrods look about 1.5mm shorter.

I checked the engine service manual # 273521 and it doesn't spec the pushrod length.

Is there an acceptable range of length that can be adjusted for, is something 1.5mm shorter likely to work okay? I'd just throw it in and try to adjust it but the mower is at my mother's place and I'd like to have viable parts when I get there.
Click to expand...


#36

D

Dave_C

Peva said:
I was only meaning that if you put the step washer in to retain the valve guide, the bottom end of the washer acts as a shim for the spring. Depending on how thick you make that inadvertent-new-spring-shim part of the washer, you could be over-compressing the spring, which may shorten it's life (could yield/weaken or break).

Again - I may be overthinking it. But if you make it 1/16" thick or more, perhaps that would become a spring life factor. Perhaps OK if maybe 1/32 or 3/64" thick. Anyway, with me being OCD, if I were doing it, I would grind the end(s) of the spring to remove maybe 0.01" shy of whatever that thickness is - ounce of prevention kind of thing.
Click to expand...

I'm not sure how that would work out because of the way they designed the spring. The last coil on both ends is flattened, like they had already machined off some material or pressed it that way, so there might not be enough left to remove even 1/16th more material. "Maybe", 1/32" on both ends would work, but I'd still wonder if that would weaken the spring more than extra compression from adding a washer - if it came to that.

I'm not set up to make my own washers and have no idea what the fellow in the video, or someone else would charge to make them, and forgot to get dimensional measurements needed for such a washer while I had the head apart... which I could still do but for now, I'm hoping the washer(s) won't be needed.


#37

D

Dave_C

outdoorpowermike said:
(seemed to want to know the pushrod length)
Click to expand...

StarTech said:
The old 690981 (pushrod) which supersedes to 597785 is 6.275" (159.385 mm) in length per my caliper.
Click to expand...


#38

R

RevB

Dave_C said:
Thanks! I was just reminded that my caliper is only 6", so I had to extrapolate, after beating the old bent pushrod close to straight.

That gives me old pushrod length 159.25mm, two new steel 157.75mm, and oddly the two aluminum are different lengths from each other, about 157.25mm and 158.25mm... gotta luv quality control!
Click to expand...
Could make your own. 4130 tube isn't that much nor is 6061 AL. You already have the ends. Can't be that hard. Give B&S a call and talk to tech about what the specs say.


#39

D

Dave_C

RevB said:
Could make your own. 4130 tube isn't that much nor is 6061 AL. You already have the ends. Can't be that hard. Give B&S a call and talk to tech about what the specs say.
Click to expand...

Where can you get small quantities of metals at a delivered price that is cheaper than a couple of pushrods? If the ones I have don't work because there isn't enough adjustment in the rocker arm screws, I can just order the genuine B&S pushrods, or see if a local John Deere or whoever dealer might happen to have some in stock.


#40

T

TobyU

I don't know why this would really be a concern or it could be prevented by making sure you buy the Briggs & Stratton brand part number that comes back to that engine.
I wouldn't buy an aftermarket push rod for these.
When they come out of a sealed Briggs & Stratton package with the correct part number on them or one of the new numbers because Briggs always changes their part numbers at least once and usually twice but they're all the same part, this should be a non-issue.

It seems most of these of the same series or model use the same push rods.
You can take almost any of the 31 series engines and interchange the push rods as you can do the same with a 33 and those probably the same as the 31 but I'd have to pull a couple to look. Lol
All of the twins mostly if not all completely use the same push rods too when you're talking about the 41 series or one particular series like that.


#41

T

TobyU

Dave_C said:
Where can you get small quantities of metals at a delivered price that is cheaper than a couple of pushrods? If the ones I have don't work because there isn't enough adjustment in the rocker arm screws, I can just order the genuine B&S pushrods, or see if a local John Deere or whoever dealer might happen to have some in stock.
Click to expand...
This is what I first thought of and recommended in my first post, I didn't read all of the entries..
You should be able to order from eBay or Amazon and if they say the brand name is Briggs & Stratton and they show a picture of the package then hopefully it will be a brand name OEM when it comes in.
Unfortunately some things are bad online about this as they do it with belts too.
I will not put an aftermarket belt on a machine because they never last as long and half the time they don't even fit right or work right whether it be not engaging properly or disengaging.
It simply isn't worth it for the few extra dollars you save.

I say the same about push rods.


#42

kbowley

kbowley

While all these suggestions are interesting, they are not the correct way to fix it and prevent issues down the road. God lord, man, just buy the correct OEM parts and fix it right.


#43

D

Dave_C

kbowley said:
While all these suggestions are interesting, they are not the correct way to fix it and prevent issues down the road. God lord, man, just buy the correct OEM parts and fix it right.
Click to expand...

I can appreciate your position on this, when a customer is paying more for labor than parts, and you want to minimize come-backs, but I am very much about replacing/refurbishing down at the discrete component level of what actually failed and reusing the rest, whether it be a furnace, car, washing machine, computer power supply, whatever.

Often that saves equipment down-time and repair time too, but in this case I trade a little time for the learning experience, and the valve guide might just pop right back out, I accept that, but it was a pretty tight fit going back in, plus the additional measures taken, so I have hopes.

Plus it saves me money, creates less waste in landfills and from mining/manufacturing/distribution of goods that "may" not need replaced, though at this point, if it ends up needing a new head, it'll get one.


#44

kbowley

kbowley

Dave_C said:
I can appreciate your position on this, when a customer is paying more for labor than parts, and you want to minimize come-backs, but I am very much about replacing/refurbishing down at the discrete component level of what actually failed and reusing the rest, whether it be a furnace, car, washing machine, computer power supply, whatever.

Often that saves equipment down-time and repair time too, but in this case I trade a little time for the learning experience, and the valve guide might just pop right back out, I accept that, but it was a pretty tight fit going back in, plus the additional measures taken, so I have hopes.

Plus it saves me money, creates less waste in landfills and from mining/manufacturing/distribution of goods that "may" not need replaced, though at this point, if it ends up needing a new head, it'll get one.
Click to expand...
I respect your position, and in my 45 years of doing this, I have driven many valve guides back in as well as peened in many fallen-out valve seats. Sometimes they last forever, other times one mow. My respectful point is that you are not paying for labor, and the head replacement is much easier than your current path, and it will be fixed right. Going through the hassle of having to remove the head once again if it fails is a PITA. However, if it doesn't overheat again, it may be fine.


#45

D

Dave_C

So when you guys pull a head on the B&S Intek V-Twins, do you take off the intake manifold too?

I tried to skip that step, just unbolted cyl #1 head from the intake and left the intake in place. I got it off fine that way, but putting it back on, was a challenge... might've been because I had a generic gasket kit and the intake gasket was thicker than stock, but I could not get the head on the guide pins, seated down on the cylinder, nor even off it a little, and coax the intake gasket into place.

What I ended up having to do is torque the head bolt that sits inside the valve cover, most of the way to get enough clearance, then loosen it a little and wiggle around the head quite a bit while pushing on the intake gasket with a screwdriver to nudge it over, then once that was bolted on, loosened back up the head bolt I'd put in and then put in and torqued the rest of the head bolts in the right sequenced stages. I was surprised that this part of the repair would be where it took longer than anticipated.

Those shorter pushrods, there was barely enough adjustment available on the rocker arm screws to accommodate them, but there was and got most of it back together, had to replace a fuel line that didn't like being bent after ~25 yrs, started it up and it seemed to run good, but I didn't run it for long nor mow with all the covers and front end off the mower.

Not sure if I have a head gasket leak, or an exhaust gasket leak (I'd reused the exhaust manifold gaskets because they had been taken out of this gasket kit previously), or if with the shroud off and the mower not moving, I'm just not accustomed to where the exhaust would go as it looked like a little smoke coming from an unusual location on (or near) the repaired cylinder, but it was hard to tell for sure, and wasn't running rough at all.

I stopped at a couple auto parts stores to get a loaner compression tester or leak down tester but both were out of them. Might call around to check for one at a few more stores, or just break down and buy one on Amazon.

This topic has exceeded it's original purpose which was to figure out whether generic aftermarket, shorter pushrods would work. The answer to that is, yes in my case with the amount of wear my engine has, yes, 1.5mm shorter will barely work. Would I buy the generics again instead of OEM B&S pushrods? No.


#46

D

Dave_C

I ran the engine for a few minutes and checked the rocker arm to valve stem clearances again, after having set them to 0.005" previously, and the clearance grew so they were adjusted to 0.005" again. Rest of mower was put back together but it's been raining every day and lawn staying wet, so didn't get the chance to try to mulch-mow up the leaves yet.


#47

A

Auto Doc's

Teryl fixes all has some good ideas, but he also has the tools and experience to modify components as needed.

I recommend you get a used head and lap in the valves and replace the valve seals. Also take the time to resurface the head using a section of flat tempered glass and some 400-grit sandpaper.

Make sure all cooling fins are cleaned out well and keep them clean. Pressed in valve guides move due to severe overheating and poor oil maintenance.

The 1.5mm length difference is an allowable difference that can be adjusted out.


#48

D

Dave_C

^ I considered a used head but then thought, what is stopping anyone from taking a head that had this problem, cleaning it up and (only) tapping the valve guide back in, and then selling it? I'd be no better off than I started.

If ALL the heads with the new part #, are the redesigned ones with the lip to keep the valve guides from moving, then I'd have more assurance, but for now, I'll see how long my *fixed* head holds up. The mower is 100% put back together and just waiting for the lawn to dry out before mowing again.


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