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So, I have been maintaining my engine fine for 5 years. This season for whatever reason, I spaced and didn't bother. I was doing some fall cleanup today when I noticed a "burning rubber" smell. It went away and about 30 minutes later, I heard some grinding noise in the engine, then the noise went away. After shutting the engine down, the tractor shook a little. I let the engine cool, checked the oil, which was low. I added some fresh oil and re-started the engine. It sounded "rough" and shutting it sown again gave the tractor a shake.

I was able to bring the tractor in the garage under it's own power. I'm worried that I seized something up and whatever part it is, broke inside the engine.

I'm looking at buying a new engine (bummer, my engine only had 110 hours on it and it's clean all around) or attempting to repair this engine.

I have a little experience with engines, but nothing serious. I can adjust valve clearances, replace gaskets and rebuild carbs, but nothing overly mechanical.

Do you guys think spending $650 on a new engine (I am certain I can take the old one out and put a new one in myself) is worth it, or would I save money by taking the engine to a shop? Is there something quick I can inspect by taking the valve covers off, with the engine still in the tractor?

I want to finish my fall cleanup and smack myself on the head for neglecting something so simple... I really don't need a $650 bill

Thanks for any advice.

BTW: Engine Info on Sticker is: 6BSXS.7242VF 276480 Briggs and Stratton 20 hp V-Twin

I had a simular deal with my '92 18hp Kohler M18S Magnum in my GT 1862 cub cadet. I had changed the oil/filter. Mowed for a hour and the engine seemed/smelled hot. Brought it to a idle and it had a double peck. Shut it off and let it cool. Fired it up and no pecking. I did this twice. Peck when hot and ran fine when cool.
Finally felt the remote oil filter and it was cool with a hot engine. My brand new Wix oil filter wasn't circulating oil.

Bought and installed a Kohler oil filter and put fresh oil in. No more double pecking sounds. The engine has mowed all summer in 100-110 degree heat.

Just more fodder to ponder. Dump the old oil and filter for some new.

WELCOME to LMF....

You say it was low on oil & you added some....
How low was it? How much did you add?

Without knowing what is wrong... I would not be thinking of replacing the engine, or even be sure the problem is the engine...
Check the belt driven things first.... :smile:KennyV

Hey Guys,

I checked it not long after shutting engine down, so very low at least. I'm sure some oil was returning to the sump as I checked the dipstick. I have no idea how it drained out in the first place.

I replaced about 2/3 of a quart so far.

What I DID notice is that:

I pulled off one of the valve covers, the two rods (piston rods?) were straight and true. One of the valve adjustment arms was tight, the other wiggles a bit, probably normal...) Anyway, I run the engine for 3 minutes and notice that one valve cover is hot, while the other is cool...

Wondering if oil is getting into one valve cover and not the other... weird.

I might just run the motor for a while doing chores and see if the other valve cover ever gets warm. If not, could this mean the cylinder is stuck?

Thanks!

There is a potability that one cylinder is not firing... Could be an ignition, compression, fuel delivery problem??? Is the exhaust port getting hot on Both cylinders?
If it's running on 1 cylinder it Will shake a Lot...
The valve push rods you see should move as you turn the engine... a valve "could" be stuck open, check the compression on each cylinder and post back... :smile:KennyV

KennyV said:

There is a potability that one cylinder is not firing... Could be an ignition, compression, fuel delivery problem??? Is the exhaust port getting hot on Both cylinders?
If it's running on 1 cylinder it Will shake a Lot...
The valve push rods you see should move as you turn the engine... a valve "could" be stuck open, check the compression on each cylinder and post back... :smile:KennyV

Click to expand...

Hi Kenny,

pardon my ignorance, but how do I check compression? Is there some kind of tool/gauge to measure it?

The exhaust port is warm, but I think it is due to it being co-connected to the muffler with the other exhaust port and it's cast iron...

anyway, I'll remove the other valve cover and turn the engine to see if the valves move and report back asap

UPDATE

So, I had a little time today to look.

I opened the other valve cover and the rocker arms are freely moving when I turn the engine, guess that's good news.

I pulled both spark plugs, one (the "bad" cylinder) had a little oil or gas on it, the other was dry. I wiped both off with a brush and swapped them. The tractor only starts on one cylinder (left-hand one if facing from seating position). I swapped out the (coil?) that the spark plug wires are attached to... same thing, only left-hand cylinder will start tractor.

The right-hand cylinder valve cover has the fuel pump tube attached to it, I am assuming the valves pull some kind of vacuum to move the fuel to the carb... that must be working obviously.

So, I'm left to pull the carb? I don't see where the fuel goes into each cylinder, perhaps inside the cast iron manifold attached to the carb?

That looks like a more demanding job for the weekend...

Anyone have thoughts on why only one cylinder is firing? Any electrical test points I can check?

I cannot find a service manual for this model either, guess that is sold at a John Deere dealer...

Thanks for all your help so far.

Have you checked compression yet?
& is there actually a spark at the plug on the cylinder that's not firing?
:smile:KennyV
Just remembered you asked about a compression tester, ...Here is a short clip on youtube: http://www.youtube.com/watch?v=X_tbksFYhl4... small engine testing will be the same. you just need to compare your two cylinder readings.

OK, I will get a compression tool kit and report back Friday!

Great Link Kenny, I learned a lot.

timmyd said:

UPDATE

So, I had a little time today to look.

I opened the other valve cover and the rocker arms are freely moving when I turn the engine, guess that's good news.

I pulled both spark plugs, one (the "bad" cylinder) had a little oil or gas on it, the other was dry. I wiped both off with a brush and swapped them. The tractor only starts on one cylinder (left-hand one if facing from seating position). I swapped out the (coil?) that the spark plug wires are attached to... same thing, only left-hand cylinder will start tractor.

The right-hand cylinder valve cover has the fuel pump tube attached to it, I am assuming the valves pull some kind of vacuum to move the fuel to the carb... that must be working obviously.

So, I'm left to pull the carb? I don't see where the fuel goes into each cylinder, perhaps inside the cast iron manifold attached to the carb?

That looks like a more demanding job for the weekend...

Anyone have thoughts on why only one cylinder is firing? Any electrical test points I can check?

I cannot find a service manual for this model either, guess that is sold at a John Deere dealer...

Thanks for all your help so far.

Click to expand...

I really don't think it is your carb because the same carb feeds both cylinders. Is the spark plug wet on the non-firing cylinder? When you rotate the engine, do you see both push rods moving their full travel? I mention this because "if" you have a valve that is stuck partially open, "then" attempt to adjust your valve clearence, in effect, what will happen is the rocker arm will push the valve too far and possibly into the piston. A comp test will reveal a lot.

OK,

Good news, spark on non-firing cylinder.

Bad News:
1. plug keeps getting fouled with oil and gas
2. I bought a compression tester. 0psi on "bad" cylinder and 100psi on running cylinder, this was a dry test only. No point in a wet test if I have zero pounds?

So, I'm searching for an answer so I don't have to pull the head off the engine. I'm not a mechanic!

It looks like a stuck valve (maybe that was that grinding noise, the valve is broken?) or head gasket.

Anyway, should I attempt to use the tractor to do my chores, or is this a big no no (I bet it can't be good)

If I have to pull the engine (I can), it's going to cost me at least $300 at a machine shop to diagnose and fix... for twice the money, I can just order a new engine and replace it myself. Leaving me with a spare to tinker with and learn...

I'm hoping there is some solution in the middle! so, if you guys have any thoughts, I'd appreciate them!

Thanks a bunch.

Tim

When you swap the plugs from one side to the other is it the same side that does not fire.
My 20hp was only running on one side yesterday was just a bad plug

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Carscw said:

When you swap the plugs from one side to the other is it the same side that does not fire.
My 20hp was only running on one side yesterday was just a bad plug

Sent from my iPhone using LMF

Click to expand...

Yeah, same side every time, tried that... it didn't work

I'm doing my fall cleanup anyway, worse that can happen, I spend $600 on a new motor. It's really lost some power obviously, but getting the job done so far.

Once done, I don't use the tractor in winter, I have a separate snow machine, so I'll have nearly 5 months to look at the engine.

I say run it hard till it blows then get a new one

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Once you find No compression on a cylinder there is no reason to look further... You have found the problem.
The reason there is no compression is located In that cylinder.
Valves Not moving, (rocker stuck/broken or bent push rod or cam problem) piston rings broke or hole in piston. Head gasket problem....
You will have to look into that cylinder.
With that piston in a compression stroke, You could put compressed air into the spark plug hole, then check at the carburetor, muffler and the oil fill... it will give you a place to start looking. :smile:KennyV