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Symptom: My ca 10 yr old riding mower (Craftsman w B&S engine) turns over (barely) once or twice and stops before anything major happens (no firing, etc.) - it feels as if the compression is "stronger" than the starter.

Had this problem before (6 months ago), so I exchanged the solenoid, starter and battery (not all at once), played with lubrication (external) and starter fluid. Eventually I got the engine to start and run. I undid all changes except the battery - so old solenoid, old starter, new battery (4/12) and used the mower over the summer. I had the problem (or a temporary version of it) on occasion, but always managed to start eventually. I kept the battery on a trickle charger in between uses and the mower in a closed in shed.

For a few weeks now, the problem has reoccurred and I cannot get it to work anymore. Here is what I checked:
- Battery fully charged (per charger, as well as measured)
- Ground connections (solenoid & battery) are good (took all off, cleaned, reattached and measured)
- Removed air filter to remove intake resistance
- Removed plug:
. o starter spins engine freely (and gas-air-mix puffs out nicely as well)
. o Checked spark (have spark)
. o Removed valve cover: everything looks straight & clean, clicking away
. o Battery during cranking (with plug out) measures only 10.8V

FYI, the old battery measured okay, so did the first replacement in spring, but neither worked. This is the 2nd new one (returned the first and got a new one in April after only a week) and this one somehow worked (still not convinced it was merely the battery, though).

So with the voltage during crank, I hear you saying, " get a new battery " but given that I did this twice and this one is only 6 months old (and I kept charged throughout the year), I wonder if something else is wrong

I also set the charger to crank assist but to no avail (does not turn better/at all at that point). (and I am scared I fry my starter or charger this way, so I only did this very briefly)
And, I tried jumping the mower with my car but despite constant 13V (+) in the system, the symptoms remain: One turn and the starter seems too weak to go any further.

Could the starter have been my problem all along and it just miraculously recovered over the summer?

I could use some advice here before I replace the starter again (kind of a hassle), plus it's the last thing I can think off ... am I overlooking something completely?

thanks a bunch

I've been going through some electrical issues on my B&S engine lately and found this manual/guide:

https://dl.dropbox.com/u/464376/sma...18-46 Riding Mower/alternator_replacement.pdf

It's got all kinds of values as to what resistance, amperage and voltage should be for the starter, alternator and all that good stuff. It's possible your starter has high resistance or something. Maybe that manual will help you test the starter.

When you had the valve cover off did you see things that looked similar to this picture?

SandBur has you on the right path. I'll bet that the valve clearance needs to be readjusted. Post the engine model numbers and we will give you the clearance spec. If you also post the engine series, (Vanguard, Intek, etc) I will try to post where you can down load a repair manual.

SandburRanch said:

When you had the valve cover off did you see things that looked similar to this picture?

Click to expand...

Yes - while I am not sure about the exact contours of the head, the rockers, springs, pushrod and overall composition looks right on the money (same style and all).

Rivets said:

SandBur has you on the right path. I'll bet that the valve clearance needs to be readjusted. Post the engine model numbers and we will give you the clearance spec. If you also post the engine series, (Vanguard, Intek, etc) I will try to post where you can down load a repair manual.

Click to expand...

It's a CRAFTSMAN Model #917270732 42 LAWN TRACTOR with a BRIGGS&STRATTON Model #311707-0132-E3 ENGINE. (at least I always believed it was)

Thanks.

natenkiki2004 said:

I've been going through some electrical issues on my B&S engine lately and found this manual/guide:

https://dl.dropbox.com/u/464376/sma...18-46 Riding Mower/alternator_replacement.pdf

It's got all kinds of values as to what resistance, amperage and voltage should be for the starter, alternator and all that good stuff. It's possible your starter has high resistance or something. Maybe that manual will help you test the starter.

Click to expand...

Cool - I'll look through it and see if I get new ideas - much appreciated!

Since it's a OHV engine, it's really (REALLY) easy to adjust the valves and it would be worthwhile doing even if it doesn't solve your issue.

I have a specs chart for various engines here:
https://dl.dropbox.com/u/464376/small_engine/Briggs & Stratton Engine Specs Chart.pdf
(Dropbox is down right now, check it out later)
It looks like yours is the last one under "OHV Single Cylinder".

For the actual adjustment, I enjoy watching this guy on YouTube:
( HOW TO ADJUST VALVES) FIX HARD TO START Lawn Tractor with OHV Briggs Engine- MUST SEE- Part 2/2 - YouTube

Holy Cow ... the 1st part of that video is my last three weeks on film - exeactly what I've been batteling with - I will definitely adjust the gap over the weekend and see what happens.

Dropbox is indeed still down ... should I just go with the video and start at 40 thou and work my way up from there?

Thanks so much (... getting excited here ...)

No problem :thumbsup: Dropbox should be back up now but if it's not for you, then here's the values you need:

Intake Valve: .003-.005"
Exhaust Valve: .005-.007"

Remember to do it with the engine cold. If my thinking is right, the exhaust one should have a much larger gap compared to those values which would cause the exhaust to not leave the engine. I could be wrong though.

Have you checked the water in the battery? Being on a constant trickle charger, and I assume unlike a car, it is unregulated, the battery emits a small amount of hydrogen gas/water vapor through the vent holes in the battery caps. I only charge a battery when it is low and @ 2amps. A low battery can still show 12v, but the amps are not enough for good cranking.

One of these two manuals should contain your engine.

http://dl.dropbox.com/u/12502267/B&S Service Manuals/03_272144VanguardTwinCylinderOHV.pdf

http://dl.dropbox.com/u/12502267/B&S Service Manuals/05_273521TwinCylinderOHV.pdf

I mentioned earlier that I'm going through some electrical problems on my mower as well and today I did some measurements to get an insight on what's going on. I won't bloat up this thread with my findings but someone, somewhere (doesn't look like this thread but I thought it was) posted this:

https://dl.dropbox.com/u/464376/sma...18-46 Riding Mower/MTD Electrical Testing.pdf

It's a document by MTD that shows the ins and outs of their 700 series electrical system. About 1/2 way through, it starts talking about voltage drop and this will apply for any mower. It shows you how to test for bad grounds, cables, solenoid and switches by bypassing them with a multimeter and whatever value you get on the multimeter shows you how much electricity is bypassing and thus how much you're losing due to resistance from bad connections or corrosion or whatever.

Also, I looked up rebuilding a starter motor and it seems really cheap and easy. You can get a new bottom plate that contains the contacts and brushes for about $20 (at least in my case). Beyond that, all you need are basic tools, a piece of sandpaper and a pinch of general purpose grease:
How to rebuild a Briggs and Stratton starter motor (replacing bottom end cap assembly) - YouTube

I'm not sure how old your mower is but mine's 18 years and I don't want to forever be chasing electrical gremlins so I'm going to redo a fair bit of the electrical. New gold plated ring terminals (after sanding/wire brushing the metal) soldered directly on overkill gauge wire (4AWG for starter & solenoid, 14AWG for anything else). Also using dielectric grease on all contacts. Soldering will eliminate over half the connections and create less areas that corrosion can cause problems down the road. Again, it's overkill but I enjoy the work knowing that I won't ever have to second guess the electrical system except maybe the battery in a few years.


This is a lot of info but hopefully your answer lies somewhere in this thread. Lotta documents to read

natenkiki2004 said:

No problem :thumbsup: Dropbox should be back up now but if it's not for you, then here's the values you need:

Intake Valve: .003-.005"
Exhaust Valve: .005-.007"

Remember to do it with the engine cold. If my thinking is right, the exhaust one should have a much larger gap compared to those values which would cause the exhaust to not leave the engine. I could be wrong though.

Click to expand...

Okay I did the adjustments (upper/intake: 0.004; lower/exhaust: 0.005) and lo and behold, it started spinning (not great, but better than not at all). Despite some help with starter fluid, it would not start, though, and the battery got weak after a few attempts. So I closed the gap on the exhaust a bit further (0.003), sanded the plug a bit for better spark and checked the oil. The oil looked a bit used (blackish, but still partially translucent), but more importantly, it was a good bit low. Given my impatience at this point and the fact that I did an oil change in spring I simply added about 10 oz to fill the oil to just above min, recharged the battery and gave it another try.

I fired up and ran smooth. (Yeah!!!)

I took the choke out and ran it for a while (10 sec) with the valve cover off. While expecting a bit of oil spray, all the sudden there was a stream of oil (a chocolaty goo - picture 1) running out of the front. I could not see where exactly, but I believe for the lower pushrod. I assume that is not normal - the stream was too much to look normal to me anyway, so I cut the engine, and did what I should have done in the first place: Removed the dipstick and did a complete oil change. The oil drained rather slowly, I thought (slow but steady stream), but maybe that is normal ...

Oddly, though, the oil came out all bubbly (aerated - picture 2) I am no expert, but could it be that with pressure building up in the engine and me running it without the cover allowed both air into the system and a pressure differential that forced the oil out through the pushrod guide?

Anyway, I cleaned up the mess, fill with fresh oil, checked the spark plug gap (which was at almost 0.035", so I adjusted it to 0.03" and closed the valve cover. I crossed my fingers and gave it another shot. It started, ran smooth, purred like a kitten and developed no leaks during the next 1/2 acre of mowing ... at least after I could see through the smoke from oil burn-oo on the exhaust ;-).

I'd say, that did the trick. :thumbsup:

Thanks to everyone who piched in with ideas, support and links ... you guys rock!

chance123 said:

Have you checked the water in the battery? Being on a constant trickle charger, and I assume unlike a car, it is unregulated, the battery emits a small amount of hydrogen gas/water vapor through the vent holes in the battery caps. I only charge a battery when it is low and @ 2amps. A low battery can still show 12v, but the amps are not enough for good cranking.

Click to expand...

Good point - I didn't do a hydrometer check (because I don't have one, nor do I know where to get one ...), but eyeballing it looks okay.

Rivets said:

One of these two manuals should contain your engine.

http://dl.dropbox.com/u/12502267/B&S Service Manuals/03_272144VanguardTwinCylinderOHV.pdf

http://dl.dropbox.com/u/12502267/B&S Service Manuals/05_273521TwinCylinderOHV.pdf

Click to expand...

Awesome - thanks.

natenkiki2004 said:

I mentioned earlier that I'm going through some electrical problems on my mower as well and today I did some measurements to get an insight on what's going on. I won't bloat up this thread with my findings but someone, somewhere (doesn't look like this thread but I thought it was) posted this:

https://dl.dropbox.com/u/464376/sma...18-46 Riding Mower/MTD Electrical Testing.pdf

It's a document by MTD that shows the ins and outs of their 700 series electrical system. About 1/2 way through, it starts talking about voltage drop and this will apply for any mower. It shows you how to test for bad grounds, cables, solenoid and switches by bypassing them with a multimeter and whatever value you get on the multimeter shows you how much electricity is bypassing and thus how much you're losing due to resistance from bad connections or corrosion or whatever.

Also, I looked up rebuilding a starter motor and it seems really cheap and easy. You can get a new bottom plate that contains the contacts and brushes for about $20 (at least in my case). Beyond that, all you need are basic tools, a piece of sandpaper and a pinch of general purpose grease:
How to rebuild a Briggs and Stratton starter motor (replacing bottom end cap assembly) - YouTube

I'm not sure how old your mower is but mine's 18 years and I don't want to forever be chasing electrical gremlins so I'm going to redo a fair bit of the electrical. New gold plated ring terminals (after sanding/wire brushing the metal) soldered directly on overkill gauge wire (4AWG for starter & solenoid, 14AWG for anything else). Also using dielectric grease on all contacts. Soldering will eliminate over half the connections and create less areas that corrosion can cause problems down the road. Again, it's overkill but I enjoy the work knowing that I won't ever have to second guess the electrical system except maybe the battery in a few years.


This is a lot of info but hopefully your answer lies somewhere in this thread. Lotta documents to read

Click to expand...

Excellent - I'll add that to my library ... next trouble shooting will start with these docs in my backpocket! :thumbsup:

Good to hear you got it going again!

If you have the exhaust valve set at .00, you will have problems down the road. That clearance is to small and will become even less as the valve heats up and expands. Air bubbles in the oil were caused by running with the valve cover off.

Rivets said:

If you have the exhaust valve set at .00, you will have problems down the road. That clearance is to small and will become even less as the valve heats up and expands. Air bubbles in the oil were caused by running with the valve cover off.

Click to expand...

+1 You will end up burning that valve

Rivets said:

If you have the exhaust valve set at .00, you will have problems down the road. That clearance is to small and will become even less as the valve heats up and expands. Air bubbles in the oil were caused by running with the valve cover off.

Click to expand...

Thanks for confirming my bubble-assumption.

I have the exhaust valve at .03 (not .00) ... do you still think that is too tight and I need to back it out a bit again? (sniff ... but it ran so good - and I ran it for about 1 hr, mowing)

Yes its a little too tight for (exhaust)
Valve Clearance Intake .003 .005
Valve Clearance Exhaust .005 .007

EngineMan said:

Yes its a little too tight for (exhaust)
Valve Clearance Intake .003 .005
Valve Clearance Exhaust .005 .007

Click to expand...

Okay, I'm out of town for two weeks, but when I get back, I'll do just that ... thanks again for all the advice.

This has been a very informative thread but I need some information to clear my ignorance. On the youtube valve clearance setting, it mentioned top dead center check. I know what his is but don't know how check. Any simple expalnations?

Jeep Man said:

This has been a very informative thread but I need some information to clear my ignorance. On the youtube valve clearance setting, it mentioned top dead center check. I know what his is but don't know how check. Any simple expalnations?

Click to expand...

A safe rule of thumb for me is to go a tad "past" TDC. In that way you know for certain that the lifters/pushrods are on the low side of the cams.

Thanks Chance123, I appreciate the reply.

Jeep Man said:

This has been a very informative thread but I need some information to clear my ignorance. On the youtube valve clearance setting, it mentioned top dead center check. I know what his is but don't know how check. Any simple expalnations?

Click to expand...

In a four-stroke engine, top dead center (TDC) is the point in the cycle right between the compression and the the power stroke. At that point, the intake and exhausts valves are closed and the piston is the closest to them (simplified).

In a single cylinder engine, to find TDC you could just turn the engine and watch all valves close, and right before the exhaust valve opens again, stop and turn back a tad. ...

If you've watched the YouTube video and liked it, I suggest, also checking out his 1st part of the video which shows how to do this with the help of a screwdriver in the sparkplup-hole (tells you the piston is up) ... just be carefull now to damage your piston/cylinder (easy does it):

Part 1 of the Video

Hope this helps ...

Just a quick note that some engines, and I can't remember which ones, but when you are exactly at TDC, the auto compression release could still be a little engaged and is why I find it best to go a little past TDC just to be sure the valves are "completely" closed. You are on the low side of the cam from a tad past TDC to the bottom of that stroke, so you have a lot of tolerance and no need to be that precise as long as you are within that down stroke

chance123 said:

Just a quick note that some engines, and I can't remember which ones, but when you are exactly at TDC, the auto compression release could still be a little engaged and is why I find it best to go a little past TDC just to be sure the valves are "completely" closed. You are on the low side of the cam from a tad past TDC to the bottom of that stroke, so you have a lot of tolerance and no need to be that precise as long as you are within that down stroke

Click to expand...

I haven't watched video mentioned by Hauker yet but I intend to. I was thinking earlier if I put a dowel or pencil through the spark hole and watch for limit of extension, I should be able to get a close TDC.
The closing of valves, I hadn't thought of. Thanks to all for the info.