Oil smells like gasoline

[Jordan S.]

I'm getting ready to put my 70 back on the road. Only drove around the block previously before a brake overhaul 1 1/2 yrs ago swelled into a front end/cooling system restoration. Anyway, I just drained the old oil (remaining from prior owner who claimed to have changed it just prior to sale to me) and it smells of gasoline.

Should I be concerned? Is this a sign of an impending fuel pump failure? If fuel did get into the oil, could this have caused any damage? The car ran well when I test drove it although it was a short/ slow drive because of the brakes. Could the smell just be normal? Your comments and suggestions are appreciated.

[Harry S.]

Re: Oil smells like gasoline

Jordan, gas in the oil is a precursor to a catastrophic failure. Find the leak as soon as you can before the engine goes from together to apart.

[Clem Z.]

Re: Oil smells like gasoline

I'm getting ready to put my 70 back on the road. Only drove around the block previously before a brake overhaul 1 1/2 yrs ago swelled into a front end/cooling system restoration. Anyway, I just drained the old oil (remaining from prior owner who claimed to have changed it just prior to sale to me) and it smells of gasoline.

Should I be concerned? Is this a sign of an impending fuel pump failure? If fuel did get into the oil, could this have caused any damage? The car ran well when I test drove it although it was a short/ slow drive because of the brakes. Could the smell just be normal? Your comments and suggestions are appreciated.

could be the fuel pump or a carb leaking down

[Jean C.]

Re: Oil smells like gasoline

Jordan, a leaking carb can cause hydraulic lock when attempting to start the car and result in a bent connecting rod, a piston contacting the crank weights, lots of unusual noise. Been there. Better find the problem asap.
Best regards

[Jordan S.]

Re: Oil smells like gasoline

So I removed the fuel pump. I did see some liquid intially come out from around the "arm" presumably due to a leaking diaphragm. I tried filling the lower reservoir and turning the pump upside down...no definite leak.

The pump looks original and I'll replace it anyway (but keep the original for later rebuild?)

How would I know if I have a "carb leak"? What diagnostic procedure could I do? I plan to remove all the spark plugs and check the cylinders for accumulated gasoline prior to cranking/ startup. Any other precautions to prevent "hyraulic lock"?

[Jeffrey B.]

Re: Oil smells like gasoline

Jordan,

A faulty power valve in the carb will also cause hydraulic lock.

[Duke W.]

Re: Oil smells like gasoline

"Faulty power valve" only applies if it's a Holley. The OP did not specify the engine or carburetor, which he should have done.

Check for fuel drip at the discharge nozzles after shutdown. Fuel drip is likely if hot starts are hard, and the cause is either too high float level or a leaky needle/seat.

[Jordan S.]

Re: Oil smells like gasoline

Thanks for the replys.

My car is a 70 454 with the original Q-jet/ original block/ 46K miles but looks to have sat for a long while. I'll install the new fuel pump later this week and do a little reading on Q-jet adjustment. I have read on another forum advice to "drop the oil pan and check the bearings" if the oil was contaminated with fuel. I will eventually be doing a complete engine rebuild but wasn't planning on it until I got some mileage on the car. Any urgent need to check bearings now given my plan for an eventual rebuild anyway?

[Duke W.]

Re: Oil smells like gasoline

I see no cause for concern.

With only 46K miles I doubt if a rebuild is necessary, but you should run compression and leakdown tests to determine internal engine health and document the rate of oil consumption.

Beyond this a "major tuneup" that might include a carb and dist. overhaul might be in order along with a thorough inspection of the fuel system for deposit buildup/corrosion.

I'm not sure if the '70 LS-5 had the new LS-6 type dual valve springs or the old spring/damper design. (Clem and Joe L. probably do.) If so, you should consider replacing the valvesprings with the new LS-6 type. You can buy them from Federal Mogul.

There was a major discussion on this issue a few months ago. You should search for it to get up to speed on big block valve spring issues.

[Joe C.]

Re: Oil smells like gasoline

So I removed the fuel pump. I did see some liquid intially come out from around the "arm" presumably due to a leaking diaphragm. I tried filling the lower reservoir and turning the pump upside down...no definite leak.

The pump looks original and I'll replace it anyway (but keep the original for later rebuild?)

How would I know if I have a "carb leak"? What diagnostic procedure could I do? I plan to remove all the spark plugs and check the cylinders for accumulated gasoline prior to cranking/ startup. Any other precautions to prevent "hyraulic lock"?

That's not necessarily so! A small amount of motor oil normally seeps thru the pushrod bore and into the space between the pump and the cavity behind it. A small to moderate amount of oil in this area is normal, and serves to lubricate the friction surfaces of the arm/pivot/pushrod. If you had a good amount of fuel behind the pump, then that would be another matter.
If the pump was supplying anywhere from about 4-7 psi @ idle, then the chances are that the diaphragm is intact.
Since the pump is already off the engine, the only way to verify now, is to see whether BOTH sides of the pump will hold (about) 8 PSI.

Joe

[Stuart F.]

Re: Oil smells like gasoline

I would think the first place to look at on any Vette with a QJ is the carb. QJ's are infamous for sinking floats and/or leaky jet well plugs. Early 70's were specially prone to these problems, so much so that they made rubber plugs cut to fit in the chamber under the jet wells. I can't count on how many of those I fixed for people.

Stu fox

[Jordan S.]

Re: Oil smells like gasoline

I would think the first place to look at on any Vette with a QJ is the carb. QJ's are infamous for sinking floats and/or leaky jet well plugs. Early 70's were specially prone to these problems, so much so that they made rubber plugs cut to fit in the chamber under the jet wells. I can't count on how many of those I fixed for people.

Stu fox

Thanks for the info. Can you recommend a good reference to learn about the Q-jet. Can anyone recommend a good Q-jet rebuilder in the New York Metro Area?