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Can a governor spring cause smoking?

#1

C

cuckoochris

Sorry I don't have many detalis about the engine, it's a Brigg's 11hp in an old Murray riding mower. The governor spring was broken off at the lever, so I put a bend on it and re-attached it. Ran ok but it did lose a little power under heavy load and started blowing blue smoke. The smoking was kind of random, but it seemed to do it the worst when there was a heavier load. Is there any chance it could be the spring? Thanks!


#2

sgkent

sgkent

Blue smoke is oil by bypassing the rings or valve guides, sometimes coming from a passage in a head gasket depending on the head. The spring helps maintain the engine RPM. What I would wonder is if the spring finally fatigued itself to death, how old is the engine and how many hours on it? How well has it been maintained? When was the last oil change? What is the level of the oil now? If high, is there gasoline in it? Is it possible it was smoking for a long time and you never noticed it until something else broke and took your attention to it? White smoke is usually coolant on a water cooled engine.


#3

B

bertsmobile1

Shortening the governor spring means that the engine will run slower simple as that Simply got it wrong.
yes it makes the engine run faster
The spring rate is balance against the force generated by the internal governor.
REst removed because it was irrevelent


#4

C

clfrank13

bertsmobile1 said:
Shortening the governor spring means that the engine will run slower simple as that
The spring rate is balance against the force generated by the internal governor.
Running slower should not cause smoking unless it is so slow that the engine is overheating and thus thinning the oil
Running slower can end up with the engine running on the left side of peak torque so the power drops off proportional to the engine speed.
FWIW
Peak torque on a mower engine will be from 2800 rpm to 3200 rpm ( depending upon the actual engine )
Mowe engines run from 3200 rpm to 3600 rpm
The theory behind this is as you load the engine and the revs drop, the torque increases allowing the engine to overcome the extra load and resume running at noraml speed .
Click to expand...
Shortening the governor spring will make the engine run faster - not slower. Assuming you are shortening AND aren't also stretching it before reassembling it to create less resistance.


#5

Farmer Jean

Farmer Jean

When you put a bend on it and re-attached it you effectively made the engine rev a little higher than it was. When you add more load it revs even higher than it used to.

If the engine wasn't having issues with the gov spring off, but is having issues with it on, it's likely a slightly to moderately worn engine in the piston/rings dept. Give it a carb tuneup and oil change too and see if that helps before you blame it all on the spring :)


#6

C

cuckoochris

Thanks for the responses! Didn't want to write a book about the situation yesterday, so I kept it short. It's my dad's mower, a few weeks ago my brother went to cut the grass and noticed that there was gas leaking through the carb. I have no idea how long it was like that. It may have been used all last year like that. I fixed the carb and drained the oil/gas out and put in fresh oil. When I pulled the carb off I noticed that the spring wasn't connected to the governor, so I just put hook in it and reattached it. So the spring is effectively shorter that it was. I started it up yesterday and started to mow, first time I've used it. That's when it started putting out clouds of blue smoke. It sounds like the spring shouldn't have anything to do with the smoking, so I guess I'll have to look elsewhere. The mower looks like this if anyone is familiar with it and knows how old it is. Thanks again for the help!

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#7

sgkent

sgkent

if you laid it on the side to drain or work on it oil may have gotten into the exhaust. Also make sure you did not overfill it, and that gasoline is not leaking from the carb into the intake manifold when it sits, and diluting the oil with gasoline. That is a risk if you rebuilt the carb.


#8

F

Forest#2

Can you post up a model number and serial number on that old Murray?

The reason I ask is I have one and cannot locate any info.

Not knowing the engine model, type and code.
On yours make sure that the oil has not become contaminated with gas again and if was ran with contaminated gas before it may smoke for awhile. Use a straight 30w oil and do not overfill. Also add a gas petcock and inline red briggs filter. If it just briefly puffs blue smoke every once in awhile and still runs ok just keep using it. Could even be the breather valve sticking shut.


#9

C

cuckoochris

sgkent said:
if you laid it on the side to drain or work on it oil may have gotten into the exhaust. Also make sure you did not overfill it, and that gasoline is not leaking from the carb into the intake manifold when it sits, and diluting the oil with gasoline. That is a risk if you rebuilt the carb.
Click to expand...
It's a tractor, so I didn't lay it on its side. I did lift up one side to try and get all of the gas out of the engine (exhaust/muffler was up), probably 45 degrees max. It is not overfilled with oil. I'll get some pics the next time I'm at my mom's. Is anyone familiar with the model in the pic I posted before? I didn't see an OHV cover like other engines I've worked on. I'm wondering if this could be pre-ohv? Either that or I just need to pull off the covers around the engine. I'll dig into it more and try to give more specifics when I get back there to investigate more. Thanks!


#10

F

Forest#2

You asked: I'm wondering if this could be pre OHV?


Probably pre OHV.

Being a Briggs 11 hp probably single cylinder L-Head, (valves in head) and the model type code will be on the air cowling tag.
If it's a OHV the info will be stamped into the top of the valve cover.
You do need to pull the air shroud and clean the engine fins. If the fins are clogged the engine will overheat and may pop out a valve seat. You can use a air compressor or a leaf blower for cleaning. Good idea to give the engine a cleaning quite often.

Look under the seat for a complete tractor model number and if found post it? I have one that I cannot find tractor model info so as to look for parts? I have a good engine for it but not going to install unless I can find a IPL for parts.

When you find the engine info you can search on-line for the CORRECT governor spring. Pay attention to the code number when looking for a governor spring. Not knowing the model number you may have incresed the engine rpm's on a old engine, plus if the sump oil was contaminated with gas it's still getting some gas fumes in the crankcase as it gets hot. Make sure the new oil is not getting thinned out with gas Sometimes them old Briggs engines won't smoke as much if the oil level is down about 1/8 inch on the dip stick. (they want to naturally seek a little bit lower level than completely full)
Also if that is a L-head single cylinder engine keep a heads up when working on the carb and handle it carefully. Some of them old two piece flo jet GOOD carbs are pricy and hard to find. (good low priced ones are rare as hens teeth)

If you have to pull the carb for a good cleaning here is a good reference link for small engine carb repair:
https://outdoorpowerinfo.com/repairs/


#11

C

cuckoochris

Forest#2 said:
You asked: I'm wondering if this could be pre OHV?


Probably pre OHV.

Being a Briggs 11 hp probably single cylinder L-Head, (valves in head) and the model type code will be on the air cowling tag.
If it's a OHV the info will be stamped into the top of the valve cover.
You do need to pull the air shroud and clean the engine fins. If the fins are clogged the engine will overheat and may pop out a valve seat. You can use a air compressor or a leaf blower for cleaning. Good idea to give the engine a cleaning quite often.

Look under the seat for a complete tractor model number and if found post it? I have one that I cannot find tractor model info so as to look for parts? I have a good engine for it but not going to install unless I can find a IPL for parts.

When you find the engine info you can search on-line for the CORRECT governor spring. Pay attention to the code number when looking for a governor spring. Not knowing the model number you may have incresed the engine rpm's on a old engine, plus if the sump oil was contaminated with gas it's still getting some gas fumes in the crankcase as it gets hot. Make sure the new oil is not getting thinned out with gas Sometimes them old Briggs engines won't smoke as much if the oil level is down about 1/8 inch on the dip stick. (they want to naturally seek a little bit lower level than completely full)
Also if that is a L-head single cylinder engine keep a heads up when working on the carb and handle it carefully. Some of them old two piece flo jet GOOD carbs are pricy and hard to find. (good low priced ones are rare as hens teeth)

If you have to pull the carb for a good cleaning here is a good reference link for small engine carb repair:
https://outdoorpowerinfo.com/repairs/
Click to expand...
Great info, thank you!!! Based on some of the responses it probably doesn't have over head valves, so a blown head gasket is out of the question as a reason for the smoking. I'm just trying to narrow things down for the next time I go and look at it. I think my plan is going to be to change the oil again to hopefully get more of the gas out. Then fill it with fresh oil, a little on the lighter side and give it another try. I'll also look at taking the covers off and cleaning out anything that might be making it overheat. Thanks again!!


#12

J

judy0320

for a mower that age I would run 20w50 motor oil. I run that motor oil in all of the engines that are in my fleet of greens mowers, bunker rakes and out front rotary mowers. One thing that you could do is when you finish mowing, take the engine down and install a set of chrome rings and replace your upper and lower seal.


#13

F

Freddie21

cuckoochris said:
Thanks for the responses! Didn't want to write a book about the situation yesterday, so I kept it short. It's my dad's mower, a few weeks ago my brother went to cut the grass and noticed that there was gas leaking through the carb. I have no idea how long it was like that. It may have been used all last year like that. I fixed the carb and drained the oil/gas out and put in fresh oil. When I pulled the carb off I noticed that the spring wasn't connected to the governor, so I just put hook in it and reattached it. So the spring is effectively shorter that it was. I started it up yesterday and started to mow, first time I've used it. That's when it started putting out clouds of blue smoke. It sounds like the spring shouldn't have anything to do with the smoking, so I guess I'll have to look elsewhere. The mower looks like this if anyone is familiar with it and knows how old it is. Thanks again for the help!
Click to expand...
Hey Cuckochris, you mentioned red Briggs fuel filter. Is it required on a Briggs or can paper filters be used, I do think the paper filters are finer micron in size.


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