I acquired a 1984 Dodge D 100 pick up with a 318 and automatic transmission that has been sitting for years. Even though it has a seized caliper I was able to drive it from Where is the tow truck dropped it off In the yard onto my carport. There is some gasoline in the engine oil. I sprayed stabil fogging oil in the spark plug holes and squirted them liberally with Marvel mystery oil. I let them set up a couple days, turned the engine over a couple times and put in new spark plugs. I started the motor and let it run for a minute, and it sounded good. Of course there is a bunch of white smoke Until all that oil treatment is burned off.My next move is to change the oil. I'm wondering if I should go ahead and replace the mechanical fuel pump for good measure. I'm just trying to think of ways fuel can get in the oil. At some point I will need to deal with the Brake caliper (Hopefully just a slide pin). I just don't want to start throwing money into this truck until I am confident the engine is OK.
I'm just trying to think of ways fuel can get in the oil.
I don't think gas can contaminate oil via the mechanical fuel pump. Rebuild the carburetor. Lord knows when the last time it was rebuilt. Engines that are running way too rich (more fuel than air is termed running rich) will contaminate the engine oil, and the carb brings all of it together.
I have a '79 Pontiac Catalina and its fuel pump lasted for 42 years before it gave up the ghost. Unfortunately, I was a good ways from home when it happened. The AAA guy chuckled when he got to my car. That Pontiac took up the entire length of the flat bed truck. Haha.
@justin-shepherd Thanks Justin! It seems like if the fuel pump was worn, rusted and compromised, it could leak in there with the lever, but your advice seems pretty solid. I did go ahead and soak it real good in carb cleaner when I did the plugs, wires, cap and rotor.
You're welcome. The fuel pump on that car is basically a diaphragm pump. The pumping action is controlled by the camshaft in the engine via an extra lobe. When I got around to taking mine off and replacing it, the old pump sounded like a rubber chicken when I'd try to manually cycle it. Haha.
As @justin-shepherd says the most likely way you have gas getting into the oil is due to a leaky carb. Sounds like carb rebuild time. However if the fuel pump diaphragm is cracked that will let gas into the oil as well.
If the fuel pump is working OK and not leaking I would just leave it. The Chinesium mechanical fuel pumps sold today tend to be of horrendously bad quality. On AMC forums I've seen reports of them failing in days. (AMC used the same type of mechanical pumps.) Some say the GMB brand pumps made in Korea are OK but I have not tried one of those myself. If your old pump is rebuildable (held together with screws instead of crimped) that might be something to consider.
Another possibility that some have taken is to install an electric pump and a blockoff plate where the old mechanical pump was mounted. However to do this right you'd want to wire in an impact switch to cut off the fuel pump in the event of an accident.
@chucktobias thanks for chiming in. I have a carburetor rebuild kit ready to pull the trigger. The only experience I've had with a leaky carburetor, it was leaking outside the engine. This one of course is dry as a bone on the outside. I can't really see any leaks outside the fuel pump either.Is there a way to diagnose this definitively before I start throwing parts on it?
All you can do for the carb is physical examination. Could be as simple as a leaking needle valve or as bad as the carb body cracked or warped. (It is over 40 years old after all.) For the pump you could try pouring some gas into the inlet side and see if it leaks into the engine side when moving the pump arm.