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LawnMower Man...Mmmm Hmmmm

Chief Brody

Chief Brody

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I like some biscits and mustard...ummm hmmmm...

I am getting gasoline in my oil and oil is blowing out the muffler on my riding lawnmower...
Any small engine guys? stuck valve? what could it be?
 
It's a 12 hp Briggs & Stratton on a Toro 12-32
 
weird thing is when I drain the gas out of the oil and put new oil in, it runs great while I mow the yard...no smoke at all...then when I stop it, it won't start up again...motor is hard to turn over like the pistons are scalded...

If it were the rings, wouldn't it still smoke like crazy?
 
How often does the gas fill the crankcase? Do you use a fuel shutoff before the carb? Ive had that problem with 2 cylinder John Deere tractors when the needle and seat would wear out.

Now I shut the fuel off regardless when not in use.
 
79rustyk10 said:
How often does the gas fill the crankcase? Do you use a fuel shutoff before the carb? Ive had that problem with 2 cylinder John Deere tractors when the needle and seat would wear out.

Now I shut the fuel off regardless when not in use.
Click to expand...

It fills up with gas in about an hour...about the amount of time it takes me to mow the yard...last three times I mowed, I had to change the oil...it's thin as gas...
 
I put Seafoam and slick 50 in hoping that would unstick it...but it didn't
 
And it still runs correctly?

Maybe get a manual, and do a compression test. Or even pull the head off and see what happens when you turn it over.

The only thing I can think of for the oil out the muffler is blow by, unless it only does it after being dilluted by the fuel. And I dont know how gas could dillute the oil that fast and the thing still run.
 
79rustyk10 said:
And it still runs correctly?

Maybe get a manual, and do a compression test. Or even pull the head off and see what happens when you turn it over.

The only thing I can think of for the oil out the muffler is blow by, unless it only does it after being dilluted by the fuel. And I dont know how gas could dillute the oil that fast and the thing still run.
Click to expand...

Yeah...once I change the oil it is great while I mow the yard...come next week try to start it up...it won't..change oil...great again...
where would you put this shut-off valve?
 
what does small engine rebuild cost these days?
 
I realize its nighttime, but just in case....SHUT IT OFF!!

The bigger Briggs engines use a compression driven fuel pump.
The diaphragm is busted, never a good thing........And the pump is pumping gas into the crankcase.

The gas dilutes the oil, causing bearing damage, ring damage, and incidentally blow-by.

Either follow the fuel line from the carb back toward the tank, or from the tank to the carb.

Its the hockey puck looking thing.

Most of them are hockey puck looking. But it will either be mounted on the engine, or have a hose going to the block with a fuel line in and one out.
 
Fordum said:
The bigger Briggs engines use a compression driven fuel pump.
The diaphragm is busted, never a good thing........And the pump is pumping gas into the crankcase.

Either follow the fuel line from the carb back toward the tank, or from the tank to the carb.
Its the hockey puck looking thing.
Most of them are hockey puck looking. But it will either be mounted on the engine, or have a hose going to the block with a fuel line in and one out.
Click to expand...

My engine is 20 years old...you think it still has that compression driven fuel pump?
 
First one I can remember seeing was on a 1963 Johnson outboard. It was mounted directly to the engine over a hole.

Those type pumps have been around a while...

I think the Briggs on my Snapper is 26 years old, and its got one. Also the Briggs on my mower................:D
 
Oh, and if you can navigate that site, its got pretty good prices on parts and engines. There is another site for complete engines I like, but I'll have to look for it.....
 
Fordum said:
First one I can remember seeing was on a 1963 Johnson outboard. It was mounted directly to the engine over a hole.

Those type pumps have been around a while...

I think the Briggs on my Snapper is 26 years old, and its got one. Also the Briggs on my mower................:D
Click to expand...

I am looking at an exploded view on PartsTree.com and I still don't see it...
 
You might not find it on an engine parts view. While it is an engine part, the engine does not necessarily have to have it to run.

If the mower or whatever its mounted on has a gravity feed tank it might not have one.
But if it has a remote tank, even if its above the carb, it probably will.
So it is usually lumped in with mower parts, not Briggs parts.
 
I don't see it...the fuel line goes direct from the fuel tank, around the front of the engine and hooks to the carburetor...
 
Yeah, I checked the Toro section, and it looks like they didn't put one on that model. 12hp may not be big enough. Mines an 18hp.

In that case, sounds like your float is leaking..........CRAP, no it isn't. Let me check the diagram again. I bet the carb has a build in pump also running off the compression. Some of them did.

You can tell by the, usually, right angle hose going to the engine and a squarish plate on the side of the carb held on by 4 screws.

Let me check that site again.......
 
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