Will there always be SOME gas in the intake manifold??

[54Illinois]

I have been messing with this gas in the manifold issue for a while...after much research, it looks like the gas was being "spit" into the intake when the gas pedal was pushed down from a complete stop, or from turning a corner etc. The accelerator pump linkage was readjusted to stop the bogging down, but when the day is over, I open the throttle very slowly, I still see a small amount of gas setting there.

Is this the norm??

[Rusty O'Toole]

There shouldn't be, after the motor warms up. If you went for a drive long enough to get up to operating temp, the manifold should be dry. If you only started the motor and let it idle for a few minutes maybe there could be some gas hanging around. Especially if the heat riser is not working.

When you say a small amount do you mean the surface is damp or it's sloshing around down there?

[Mark D]

When the ignition switch is turned off the motor spins to a stop. The last few revolutions of the motor have enough vacuum and compression to clear the manifold of un-burnt gas vapor.

[54Illinois]

Maybe about a teaspoon puddled in there now. I will say the car only idled for about 5 minutes.

[Mark D]

That would lead me to look at the carburetor. It may be dropping gas into the manifold. Has the carb been rebuilt? Is the float set correctly? Just listing some things I'd look into.

[Plymouthy Adams]

unfortunately this problem is now in about three threads and hard to keep up with...if memory serve me correct this is also the second rebuilt carb placed on the vehicle and the fuel pump pressure is within specs..

[Rusty O'Toole]

If the motor was started and run for 5 minutes with the choke on there could very well be a little unburned gas in the manifold. Nothing to worry about.

[54Illinois]

I see your point Tim, but I did not want to retread from the other posts...just curious if there will always be some gas in the intake manifold.

Is this possibly normal? Does anyone ever look? The only reason I found out this issue is I had gas in my oil.

[greg g]

How is it you are seeing gas in the manifold??? If the engine is not running and you open the trottle to look down the carb, you will by doing so actuate the accelerator pump, squirting fluid fuel into the carb and it will puddle there. If you keep doing this the puddle will grow till it evaporates or you start the engine.

Other than that I do not understand what problem you could be describing.

[54Illinois]

Greg, I was taking the carb off the manifold after every test to avoid that. You are probably right though, I would imagine a little would get by upon removal.

[Rusty O'Toole]

Gas dilution of the oil was common on cars with carburetors, under certain conditions. Short trips that did not allow the engine to completely warm up especially in winter. With the choke on, excess gas could get past the rings into the crank case.

This was especially prevalent on old flathead engines. They had such massive iron castings that it could take at least 15 or 20 miles of driving to get them completely up to operating temperature.

The solution was to change oil more frequently in winter if the car was used for stop and go driving.

So, if your car is not on the road and has merely been started, moved around or run for a few minutes at a time it could be completely normal.

On the other hand it could also be a defective carburetor, for example a soggy float, leaky needle valve, etc. I don't know when your carb was rebuilt last but could be due for one.

This is one of those cases where you need to use your own judgement or have some old mechanic look at the car. Sorry it is not possible to be more specific without seeing the car.

[54Illinois]

Drove the car about 50 miles today. Mainly city driving. Ran several errands, start car, stop car etc. Upon parking her in the garage I smelled gas. I checked the oil, faint smell of gas. Pulled the oil filler cap, could smell fumes in the block. Before checking the carb, I rolled up some paper towel to catch any gas possibly squirted into the manifold. I saw a little puddle, black in color.

I just wonder if the fumes from the manifold are drifting into the oil?

[greg g]

Have you checked the condition and proper operation of you needle and seat and or your float level. Have you changed your oil??? Gas doesn't lubricat very well.

[54Illinois]

Everything appears normal with the carb. I just checked a while ago, and the manifold was "wet" but not puddled. The oil on the dipstick is normal looking, and not frothy like it was before when I had gas in the oil. I wonder if it is possible if there is still gas left over from the original contamination?

[Don Coatney]

Drove the car about 50 miles today. Mainly city driving. Ran several errands, start car, stop car etc. Upon parking her in the garage I smelled gas. I checked the oil, faint smell of gas. Pulled the oil filler cap, could smell fumes in the block. Before checking the carb, I rolled up some paper towel to catch any gas possibly squirted into the manifold. I saw a little puddle, black in color.

I just wonder if the fumes from the manifold are drifting into the oil?

If you drove 50 miles and there was no miss-firing nor plug fouling then I do not believe you have a problem.