Gasoline in Oil
 

My son's '01 S40 that he bought used is getting gas in the oil. The engine runs great. No sign of running rich but there is a distinct gas smell in the oil even after an oil change. This car only has 60K miles and I think it sat for a while. I imagine an injector may not be sealing properly or could be leaking through the evap system. The car is getting a P0442 code. We did replace the gas cap which had a cracked gasket and cleaned the gas fill surface.

Any clues why the gas in the oil?
Thanks
Stan

A few thoughts - could be a leaky fuel injector or a faulty fuel pressure regulator, could be the vacuum line into the evap canister which are letting gas leak into the cylinders on shut down. Do you have longer than normal cranking on start up (fuel pressure regulator) or see a puff of black smoke on first start up (leaky injector)? Do you tend to have short drives (ie not enough to allow the oil to fully heat)? Any signs of a clogged PCV oil trap (glove test, smoke from dip stick etc)? For the fuel pressure regulator, a quick test would be to start the car then shut off (to pressurize the rail), then pull the vacuum line off that goes from the bottom of the regulator to the intake to see if any gas is dripping back into the intake. After that you could do a compression test (wet/dry) to rule out rings. Also read up on the J-tube problem S70s and S80s have...Not sure if its the same design for the S40s but in short there's a small vacuum line component that fails all the way back at the canister.

The car starts up immediately with no black smoke. Idles very smooth. There is likely an issue with a leaky evap line, hence the P0442.

I don't know the history of the car but I have a feeling that it sat for a long time. With 60K miles in 15 years, this thing wasn't driven much. Injectors may have gotten gummed up. I suppose rings could have gotten sticky.

I didn't see a pressure regulator on the fuel rail. There looks to be a pressure sensor (FPS). It may be like my V50 there the pressure is regulated by the fuel pump based on the FPS. I let the car sit over night and the rail was still pressurized. I'll have to find a vacuum diagram to see where fuel can get through to the crank case.

on the Gen1 S40 the fuel pressure regulator is at the end of the rail (ie #4 cylinder) over by/under the throttle cable spool cover. It press fits into the rail with an o-ring - just follow the fuel line. Under the unit is an s shaped vacuum line. That's the line you'd want to pull off to see if its dripping fuel. With that said, looking for a leaky evap line is probably a more likely diagnosis, but checking the regulator for a leak takes about 5 minutes to do so no pain in eliminating the possibility.

Just to follow up... The oil seems fine now with no gasoline smell. It could have been multiple factors. The car gets driven longer and more often now, which should help evaporate any accumulated gasoline in the oil. Also, I replaced the spark plugs which, not only were Autolite, but also the gap was way out of spec at over 0.09 in vs the proper 0.03 in recommended. They did not look worn but were sooty. I installed Volvo plugs with proper gaps.

By the way, I did check the fuel pressure regulator and there was no leak from the vac line. Thanks for the tip.

Stan

geez, I'm surprised it even sparks at .09! you probably had a unburnt fuel in the cylinders when the engine was cold pushing past the rings (too much gas can wash off the oil on the rings). Autolite plugs will work fine (particularly the copper cores) but getting the gap right was key for you. .030" or .75mm is the spec but anything in the .028 to .032 should be good - some of us older folk remember when you;d gap down in the winter and gap up in the summer. Cars with ECTs don't need to bother. Also a reminder to only torque the plugs to 20ft-lbs- which is hand tighten to bottom the plug, then add about 1/4 turn.

These were the Autolite Platinum. I was really surprised that the car ran as well as it did with the wide gaps. It does run better with the new plugs and proper gap.