Edmunds Answers



  • zaken1 09/05/08 11:57 pm PST

    When engine oil smells like gas, it usually is the result of excess fuel getting into the oil. On carbureted engines, this typically comes from a leak in the fuel pump diaphragm. It also can be caused by an automatic choke that does not open completely, by a brass carburetor float that has developed a leak and become heavy with gasoline, by a plastic carburetor float that has become porous and is now heavy with gasoline, by excessively rich carburetor jetting, or from an idle mixture adjustment that is too rich.

    Fuel injected engines are less likely to get excess gas in their oil; but it can happen if the fuel pressure regulator is defective or is set for too high a pressure, or if the exhaust oxygen sensor has failed or been disconnected.

    If an engine is used exclusively for short trips, and thus does not get warm enough to vaporize the small amounts of fuel which accumulate in the oil during normal operation; this will eventually lead to the oil smelling like gas. That is why it is recommended to change the oil much more often, if a vehicle is used mostly for short trips.

    I hope this helps!!!

  • tony78 09/06/08 1:18 am PST

    I think zaken is trying to tell you that excessive " blow-by " that is getting past the piston rings when the engine is cold,,is fuel vapor that is accumulating in your oil.

  • karjunkie 09/06/08 7:54 am PST

    Given it is a 1971 VW Beetle, I suspect the problem is worn piston rings rather than your valve guides. Run a compression check on all cylinders. If any cylinder is below 120 psi, your engine will need new piston rings and possibly a rebore depending on the severity of the wear. Since your engine is air cooled with bolt on cylinders you can remove the cylinders easily. A good reading 160+ psi per cylinder. I doubt it is a fuel pump problem as a 1971 bug uses a mechanical low pressure fuel pump and carburettor.

  • MrShift@Edmunds 09/06/08 10:59 am PST

    Probably blow-by through worn piston rings. If you had serious gasoline dilution of the oil from a bad carburetor, your engine would have blown up already. VW engines of this era need rebuilds every 60,000 miles. The best thing to do is just buy a rebuilt engine through a VW specialty engine rebuilder. They are cheap and have a warranty. A compression test may tell you what you need to know but sometimes compression tests can fool you with regards to worn oil rings (because the compression ring on top can still be fairly good). The best test for this sort of thing is a Cylinder Leakdown Test which any competent shop can perform for you.

    Another simple test is to read your dipstick. If your oil level is HIGHER than it should be, that's gasoline intrusion. If it's lower and lower as you drive, that's worn piston rings and blow-by.


Top Oil Experts View More

Rank Leader Points
1. MrShift@Edmunds 1215
2. karjunkie 1110
3. zaken1 555
4. texases 495
5. Stever@Edmunds 465
6. 0patience 365
7. coolrunning 200