fuel in crankcase

[clutch07182]

i got an oil change today(ive had car running for two days now runs real shitty) and they told me there is fuel in the crankcase. is there a common cause of this or do i need to have a diagnostic run thanks

[ecp48]

You haven't said which Z or if it is a Z you are driving.

The answer would be different depending on the year and carbs or FI.

Get back to us with some answers.

[clutch07182]

well i sold the car but im helping the guy fix it. its a 1981 280zx non turbo. were ripping apart the engine and doing a valve job and piston rings

[beandip]

If you have had fuel in the oil , It would be a vary good idea to check the crank journals. The gasoline in the oil can deminish the lubercating of the oil and damage the berings . Another thing if you dont hone the cylinders the rings may not seat , and the engine will be a oil burner . Have you miked the cylinders for taper ?

[sblake01]

You haven't said which Z or if it is a Z you are driving.

The answer would be different depending on the year and carbs or FI.

Get back to us with some answers.

Not sure if I get that. Fuel in the crankcase is never a good thing. Remember John Candy's car in 'Uncle Buck'?

[ecp48]

clutch07182,

With a fuel injected car the cause could be a leaking injector. When you shut off the engine the fuel system maintains the working pressure for some time. If an injector is leaking, raw fuel will be entering one of the cylinders and leaking past the rings to enter into the sump after the car has stopped.

Did any of the cylinders have a heavy coating of black in the head or piston top, indicative of a cylinder running rich?

You could also have a leaking fuel pressure regulator, where the diaphragm has ruptured and raw fuel is being sucked into the intake through the vaccum line.

[sblake01]

Okay, I stand enlightened. But surely that leaking fuel injector or leaking pressure regulator would show symptoms that would cause me to repair it before it caused more serious damage like washing the oil from the bearings, sooting up the cylinder, etc. I'm trying to recall if you (clutch07182) are the guy that replaced the fuel pressure regulator. If so, you can rule that out assuming that you replaced it with a new or known working fpr. If you have a fuel pressure guage, install it between the fuel filter and the fuel rail and run the car. It should show somwhere between 35-37 psi. (the FSM says 36.3) When you shut it off it should hold that pressure. If not, something is leaking.

[clutch07182]

thanks for all your help guys my compueter has been down for a while and i wasnt able to see it. i have the car back as mine (guys check was no good) and ive been driving the car fine for about 2 weeks now. it went through a set of plat plugs in liek 3 days but i put some cheap arse ones in and it has been running fine seince. seemed liek it may have been sitting for quite a while.it not really burning oil anymore that i can tell but it does have some other problems. like no o2 sensor or bung (header conversion from a stupid previous owner) and i need to hollow out erm i mean replace that cat. other than that its in really good shape im gonna do a full fluid swap soon and replace the clutch(bad throw out berring) but yeah thanks for all the help.

also if anyone could refer me to a place near austin texas to get work or parts that would be greatly apretiated thanks again all.