Fuel in the crankcase?

[arch252]

I picked up a JD LX255 for parts but noticed the engine had compression so I figured I'd take a shot at it. Almost all of me engine repair work has been with horizontal shaft engines, and mostly older ones at that so my experience with larger vertical shaft engines is quite limited. I have no experience with Kohler engines. This JD has a 15 hp Kohler, Model CV15S, Spec # 41571, Family: SKH426U1G2RB.

The engine would start using starter fluid and would stay running (barely, and rough at that) with continuous spray of starter fluid but it smoked terribly and would eventually die. I figured I had a carb fuel delivery issue and a blown head gasket. So I finally got the OHV and head removed, much more difficult than an old horizontal Briggs! When I removed the head I noticed a mix of gas and oil running a steady stream out of the valve rod openings. Since my experience with these engines is limited I didn't know if that much oil should be coming out of there but the fuel in the oil was very concerning. I didn't see any significant defects in the head gasket. The cylinder head was good, valves looked good, cylinder bore was spotless. I drained the oil and it was obvious there was a lot of gas mixed in the oil.

Without tearing this engine down any further at this point, can someone tell me what I am likely dealing with? I wondering if it's worth going any further.

 

[clay45]

What is the chance the tank was filled with an oil-gas mix by mistake?

 

[arch252]

I doubt that happened but how would that explain fuel in the crankcase?

 

[bt3]

For small engines, gas in the oil is usually one of two things.

Most common, a stuck needle valve in the carb allowing gas to pour unchecked into the combustion chamber, where it seeps past the piston and into the crankcase. Usually when the engine is not running. Many recommend a fuel line shutoff be put in line to stop this if you can't easily or quickly correct this problem in the carb.

Much less common, severely worn piston rings allowing some fuel to enter the crankcase.

There may be other issues with that engine I am not aware of, but these are the common causes of gas in crankcase oil that I have been exposed to. Whatever the case, it is obviously not a good thing to have gas in your crankcase oil. You need to address this, as you are doing, and remedy the situation quickly. Don't allow the engine to run with gas in the crankcase.


Good luck.

 

[SeniorCitizen]

If the carburetor has a brass float check it for gasoline inside the float. They don't float too well in that condition and it leaves the needle valve open for gas to run where ever it likes and sometimes into the crank case.

 

[arch252]

Good info, I've dealt with those leaking floats before but with a horizontal engine it doesn't cause these issues. I'll rebuild the carb and put on a new head gasket and see what happens. I'm trying to avoid opening the crankcase.

On a good note, at least the crankcase is clean, that old oil had so much gas in it that it ran out like water.

 

[Fish]

I just called up the blowup of your engine, and it has a mechanical fuel pump which could easily be your culprit!!!

 

[bt3]

I just called up the blowup of your engine, and it has a mechanical fuel pump which could easily be your culprit!!!

DING DING DING! Nice Catch! Yes, OP, absolutely. Had no ideal there was a fuel pump involved.

 

[arch252]

This makes sense, the people told me that they had the fuel filter replaced but that didn't fix it so they parked it. It may have fixed the problem but if they never dumped the bad oil it wouldn't a time right. That makes sense. Might not be a carb issue at all. I'll still give the carb a good makeover since I have it off and we'll see what happens. Thanks folks!

 

[clay45]

Man, I don't even know what I thought I read.


:ashamed: