Kawasaki blowing smoke intermittenly, burning oil

arch252 · Aug 14, 2016

17hp FC540V single cylinder Kawasaki on a JD 325. Bought the mower, did some general maintenance along with a lot of carb work. I've had the head off, cleaned the carbon off the piston head and valves, wasn't too bad. Cylinder was nice and smooth. Metal head gasket looked fine so i did not replace. No signs of any leaks.

Mowed with it yesterday for a little more than an hour, ran great, no problems at all. No smoke at all. Started it today and it smoked A LOT. That cleared out completely in about a minute. Mowed for about 30 minutes when suddenly a LARGE puff of blue smoke, obviously oil burning. It was so bad I was waiting for the head gasket to go but it didn't. It blew the smoke out for about two seconds then stopped. It started repeating that every 30 seconds to one minute. Still ran just fine but when it blew out smoke it was a lot of smoke. No noticeable loss of power.

So where should I start? Does this sound like a head gasket? Rings? Something else?

577jersey · Aug 14, 2016

I had an old FC420 v motor that would blow smoke every minute then clear up,,what was happening was there was oil getting pushed through the breather into the air filter,,then the carb would suck it in and it would smoke...I never found out why the breather was dumping a few drops of oil into the carb every minute,maybe some sort of breather valve is bad??
The oil level was normal..my fix was to reroute the breather line into a small container and plug up the breather hole on the air box...I would dump the oil out of the canister back into the crankcase every other lawn cutting or so...worked great and ran it for years that way,,the motor still runs great!!

Im sure its a simple fix though,,just never figured it out.

Tom

arch252 · Aug 14, 2016

Thanks Tom. Symptoms sound the same. Hopefully someone can explain what might be going on.

577jersey · Aug 14, 2016

arch252 said:
Thanks Tom. Symptoms sound the same. Hopefully someone can explain what might be going on.

Yes sir no problem,,Just do a test and remove the breather hose from the air filter box,,just let it hang down and put some duct tape over the nipple on the air box,,if the smoke stops and you see oil dripping from the hose you found your problem...I believe there is a valve for the breather under the valve cover that might need replacement,,its a small reed valve if If my memory serves me well.

Good luck!!

Tom

arch252 · Aug 14, 2016

So that is definitely the source of the burned oil. There is a lot of oil coming into the breather through the tube. I am familiar with that reed valve inside the valve cover.

Question is: Is it just that the reed valve is allowing oil to get past it or is there another problem causing excessive oil into the valve cover? Is this a sign of worn rings, faulty head gasket, worn valve stem guides or seals, or something else? I'm wishing it was just that reed valve but something is telling me it won't be that simple.

bertsmobile1 · Aug 14, 2016

All of the above. Singularly or all together.
No way to diagnose properly without full disassembly.
Usually worn out rings will blow smoke continually.
However so will a very bad head gasket.

So start with the head & head gasket.

What we did not alert you to is to check the oil.
If the oil is thin and has a gassy smell or is overfull then you have a problem with fuel seeping into the crankcase and thinning the oil.

arch252 · Aug 14, 2016

Oil was not thin and did not smell of gas. Oil level was on the lower end of the normal range. The head gasket won't be bad, I'll start there and hope for the best. Thanks Bert!

577jersey · Aug 14, 2016

Like I said,,I ran that 420v for years commercially after this happened and it never burned another drop,,i did have to empty the little plastic can into the crankcase every few hours though but the machine still made me a boat load of $$.

This issue started happening after the mower was 6ft under water in a flood for 2 days...Kawasaki makes one tough engine,,thats for certain!!

Keep us posted bro.

Tom

mhavanti · Aug 17, 2016

Something that happens quite often in a piston powered engine is the rings align or become closely aligned that extra compression gets into the crankcase, thus the blowby is carrying liquids (engine oil) into the breather hose leading into the breather.

Bert is absolutely correct, disassembly of the block may bring about the rest of this story.

If you find the rings closely aligned then try the below:

If the rings are in good shape, nice and square, plenty of tension, cylinder is in good shape, place the rings at 180 degree away from each other. Begin at the bottom oil ring, then second compression, then first compression rings. Slide it back together and run the crap out of it because you probably found and fixed it.

577jersey · Aug 17, 2016

I always wondered how rings stay in their proper clocked position after so many hours of run time...

Kawasaki blowing smoke intermittenly, burning oil

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