Gas smell in oil

[pmschmitt]

440 big block just changing oil and noticed the oil smells strongly of gas. Car runs good when operating main issue is hot start problems. Car also had a lot of condensation /black soot that comes out of the tail pipes.

I have not replaced the fuel pump since purchase 3 years ago. Does this sound like leaky fuel pump into block? Is that possible. What other reasons could the oil have the strong gas smell? Or is this just typica of big block mopar?

 

[Badvert65]

You have a bad fuel pump.
Replace it and change your oil and filter.

 

[Big_John]

All your messing around trying to start the car is probably the cause.

 

[pmschmitt]

Thank you for your help!

 

[Zymurgy]

I had a '78 T-Bird that the mechanical fuel pump fail, there was so much gas in the oil, that it ran out like water. Some how I didn't catch anything on fire or ruin anything.

 

[73Coupe]

Same thing happened to me a few year ago with my flathead Dodge 6 - a seemingly good fuel pump was slowly leaking into the crankcase - I didn't catch it until it was too late. Had the same sooty tailpipe. Rod bearings and cylinder walls were toast!
Change the pump and oil before driving it anymore.

 

[OneEyed]

Geez, Sounds like id better replace mine too! Glad I stopped by today

 

[saylor]

blockoff plate + elec FP and this will never happen again.

but ya +1 what ^^ they said - your oil aint oily when it has gas in it, so nothing is getting oiled properly. will kill engine fastly.

try not to die -

saylor

 

[pomonamissel]

here in calif the gas sucks big time , it boils off out of the carb bowl and fills the intake track full of hot fueled air , which makes itself to the rings and washes the cylinders down after each drive , thats what is happening to my oil . we have to restrict the heat going under the carb , blocking the heat transfor port is a good way , but you will need to go with an electric choke on the carb , and for cooler weather we used the water hot plate from the fords back in the 60-70 used on square bore carbs it ran motor coolant under the carb for a pre-heater to keep the fuel atomized better . if hood clearance is an issue i've used just muti gaskets n spacer plates to keep the heat out of the carb as well . hope you can see the spacers under this carb set up .

 

[OneEyed]

How do you know which size or style of electric fuel pump?

 

[Big_John]

A lot of these responses say to replace the pump and absolutely none of them are telling you how to check the pump first. While it's possible that a leak will pump gas into your oil, you've also had multiple starting problems that have most likely flooded the cylinders with gas. That can cause the problem you describe. Depending on the sensitivity of your nose, it can be a little gas, or a lot. I can't smell it over the internet... LOL!

So... If I were you, rather than throwing parts at the car, I would check pressure and volume on the pump. A tear in the pump diaphragm won't get smaller and will cause you to have some of the starting issues you've had.... and yes, maybe even leak some gas back in the oil.

So... diagnose the problem first. If nothing else, this is a really good chance to learn a little more with just a few bucks spent on a vacuum/fuel pump tester. Everyone with an old car should have one of these in their tool box anyway. $16 Fuel Pump and Vacuum Tester

Rather than me explaining it, here's a good explanation of how to check it. Common Classic Car Fuel Pump Problems

 

[Big_John]

blockoff plate + elec FP and this will never happen again.

try not to die -

saylor

If you do that, install a crash sensor to shut the pump off if you go on your head. IIRC, I think you may be able to get one from a junk Crown Vic pretty easy and cheap. Here's a new one for reference, but Google is your friend.

https://www.summitracing.com/parts/rfw-cr92

 

[pomonamissel]

has anyone that issues with the cam lobe and push rod that pumps the mech pump arm . on my 440 67 and 8's i had issues with the pump not working correctly as well as not enough pressure . one we dismantled had the push rod pend over on the cam side , shorting it enough to loss the pumping action totally , my 383's don't have any issues .

 

[Big_John]

has anyone that issues with the cam lobe and push rod that pumps the mech pump arm . on my 440 67 and 8's i had issues with the pump not working correctly as well as not enough pressure . one we dismantled had the push rod pend over on the cam side , shorting it enough to loss the pumping action totally , my 383's don't have any issues .

That seems to be a common problem. I've never experienced it myself, but I believe it's usually due to a replacement rod.

 

[moper]

I just replaced the pump on my Imperial. Same thing. Won't start, oil smells like fuel and is thin...

 

[Ironwolf]

OMG !!!!1 Does that bring back some painful memories for me,,,,

In my younger days back in the early 80's I totally rebuilt my 318 and to save a few bucks I reinstalled the old fuel pump. About a week or two later my oil idiot light would intermittently start to flicker after coming to a stop or slowing down coming off of the highway, I checked the dipstick levels and it and seemed fine on several occasions. Until one day I checked it after hearing the engine sounding like a typewriter, my dad asked does the oil smell like gas ? OH YES IT DID !!! and man oh man was the inside of the engine clean of all and any oil when I took it apart again.. Then I replaced that engine with a low mileage 1977 318 Cordoba engine, What an expensive lesson to learn that ended up to be.

 

[bluefury361]

Forget the electric pump, bad idea. You don't even know if it is the pump.
Perhaps flooding conditions at the carb due to a high float level, excessive "pumping" of the gas pedal, misadjusted choke. These are all more likely then the fuel pump, and installing an electric pump may aggravate the problem. A good mechanical pump is the best application for a big block with carb.