L4610- Really excessive blow-by

[rutwad]

Kubota L4610 has approx 900 hrs. Lots of white smoke and oily residue coming from valve cover vent line. Starts shortly after running. Air filters clean, engine runs fine. Could this be something simple, or engine trouble?

 

[kuboman]

Kubota L4610 has approx 900 hrs. Lots of white smoke and oily residue coming from valve cover vent line. Starts shortly after running. Air filters clean, engine runs fine. Could this be something simple, or engine trouble?

Not likely very simple. Head gasket or cracked head or cracked block or..........sorry not good news

 

[brain55]

From the breather tube, I'm guessing dusted motor. I would check the intake hose, clamps, intake manifold, or gaskets after I did a compression test. Rarely do Kubotas have this type of issue that is a factory defect. In the 12 years I spent as a mechanic in Kubota dealerships I saw 2 engine failures that were Kubota's fault. Only one with symptoms like yours. It was a failed intake gasket. I have also done engine rebuilds on engines with as few as 80 hours because the owner never checked the air filter. Typically if this was a head gasket, head, or block issue you would have white smoke coming out of the exhaust. Before I got too carried away with guessing, I would do a compression test and a cylinder leakage test.

Brian

 

[Egon]

Before I got too carried away with guessing, I would do a compression test and a cylinder leakage test.

That would sure help finding the problem.:thumbsup:

 

[rutwad]

Doesn't sound good. At least I have some ideas to start looking. Thanks.

I noticed pretty heavy black smoke coming from the exhaust when I first cranked it.

 

[rutwad]

I need a non-technical explanation to help me understand. The vent tube is connected to the valve cover. Isn't there typically oil with the valves? Why would it not smoke under normal conditions?

If the rings were bad allowing compression to escape into the crankcase, is there a place that it could vent?

 

[Egon]

If the rings were bad allowing compression to escape into the crankcase, is there a place that it could vent?

Yes, back up the oil galleries and up to the valve covers.

 

[rutwad]

:thumbsup: easy enough

THANKS!