Briggs & Stratton 20 hp Intek burning oil

Zane S.

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Good day all,

I recently picked up a John Deere L120 with a 20 horspower Briggs & Stratton Intek (V twin). When I picked it up, the mower didn't run but would crank, I put in fresh fuel, new spark plugs, new oil and a new oil filter. The mower ran after that but very rough. I determined the carburetor was dirty and cleaned it. The mower started right up and ran well on full choke but will die if you try to remove the choke. I guess I missed something in the carburetor so I will have to reclean it. When I pulled the plastic cover off initially, the area between the V was cover in oil and dirt build up but I initially paid it no attention as I assumed it had never been cleaned or someone spilled oil on it at some point.

However, the mower smokes pretty heavily and the smoke is white/blue in color. I have ran it for about 45 minutes and the smoke never went away and it burned off oil in that time. I don't have fuel mixing with the oil so I think my float assembly is ok. However, when I run it with out the air filter I can see smoke coming from the intake, I assume that it is from the valve breather line. When the motor is running, the smoke is wisked away quite forcefully by air flow but when I kill the engine a cloud of smoke lingers in the intake.

I pulled the spark plugs wires from one side and then the other and both sides seem to run equally smooth. The right side is the one that smokes. I assume that because the two sides run equally well, my piston rings should be ok or else one side would suffer from decreased compression. This leads me to believe that I have a blown head gasket on the right cylinder. Would a blown head gasket cause oil to discharge on to the exterior of the engine block and carburetor?

Would anyone be able to confirm this or suggest anything I may have missed? I would like to have the parts in hand before I tear the engine down to prevent any for objects entering the engine during down time waiting for parts. I know it is hard to say for sure without investigating visually but I am trying to put together and educated guess to prevent further damage.

Thank you in advance for the help and please let me know if there are any questions I can answer.

- Zane
 
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Yes a bad gasket can do that. Also it causes pressure in the crankcase. If you take the oil dip stick out you will see it rise up from there.
A carb that runs on choke only is not good for the engine at all. A passage is clogged somewhere. Is it the single carb or the dual carb ??
 

bertsmobile1

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Cheap and nasty check for a head gasket is to run the engine for 10 minutes , turn it off, wait a minute the remove the dip stick.
Smoke signals = blown head gasket.
Between the vylinders is also the breather.
A blocked breather will also cause the engine to smoke.
A bad oil scraper ring will make no difference to the compression or the short term running but will cause the engine to smoke although this will usually load up the plug.
 

Zane S.

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Yes a bad gasket can do that. Also it causes pressure in the crankcase. If you take the oil dip stick out you will see it rise up from there.
A carb that runs on choke only is not good for the engine at all. A passage is clogged somewhere. Is it the single carb or the dual carb ??

It is dual carb, I cleaned it once but apparently not as thoroughly as I thought. I used carburetor cleaner with a straw and blew out all the holes or so I thought. Next time I will be more thorough.
 

Zane S.

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Cheap and nasty check for a head gasket is to run the engine for 10 minutes , turn it off, wait a minute the remove the dip stick.
Smoke signals = blown head gasket.
Between the vylinders is also the breather.
A blocked breather will also cause the engine to smoke.
A bad oil scraper ring will make no difference to the compression or the short term running but will cause the engine to smoke although this will usually load up the plug.

Good to know. When I pulled the old plugs, they weren't bad at all, I replaced them just for the sake of a tune up. I went ahead and ordered a head gasket kit so hopefully when it gets here I will tear into it and there will be one that needs replacing.

Thanks!
 
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