Gas In Crankcase

irvanm · Posted: Wed May 27, 2015 10:19 am Post subject: Gas In Crankcase

I just bought a 65 VW and it has some gas in the oil. I tried search but haven't been able to find what the causes might be, any help appreciated.

Tim Donahoe · Posted: Wed May 27, 2015 10:31 am Post subject:

Fuel pump diaphragm is leaking? If so, replace the fuel pump. Or the fuel pump may be pushing way too much pressure. If so, do a pressure check to see if you're at 2.5 to 3 lbs.

Carburetor float is leaking, or the inlet valve is weak. If so, take the carburetor apart and check.

Someone did a recent compression check and kept yanking on the throttle arm like it was a slot machine while doing the test and pumping a lot of fuel into engine (not likelly, but possible).

Tim
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nlorntson · Posted: Wed May 27, 2015 10:32 am Post subject:

The fuel pump is the likely culprit. The diaphragm tears and lets fuel travel into the crankcase.

Replace the fuel pump and change the oil before you run the engine again.

Danwvw · Posted: Wed May 27, 2015 10:53 am Post subject:

My 1967 would do that but only when it was really cold out. I think they can suck the fuel up the emulsion tube inside the Solex Carb when the choke is fully closed. The only real solution I found was to make sure all the stock air-cleaner and pre-heat was in place and when it was below zero to only fill the gas tank 1/2 full and to make sure the engine was warmed up a little before driving it. But still sometimes it would happen. But yeah, I would also check the float in the carb it could be bad and of course the fuel pump diaphragm. Change the oil every time it happens too.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

hitest · Posted: Wed May 27, 2015 2:36 pm Post subject:

There's a ton of info on the previous 23 threads- search "fuel in oil"
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grandpa pete · Posted: Wed May 27, 2015 3:35 pm Post subject:

You will never have that problem with an electric pump

Mr gasket ; the red one , autozone $45
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irvanm · Posted: Wed May 27, 2015 4:45 pm Post subject:

Thanks, I don't know if this tie holding the choke lever might be related? I looked in a catalog for fuel pumps and they show for 66 up, I don't know if mine is right or not.

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rcroane · Posted: Wed May 27, 2015 5:12 pm Post subject:

Could it be that you are running at constant fast idle with the cam tied in that position and this would cause flooding and gas in the crankcase?
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'65 Sunroof Bug

Danwvw · Posted: Thu May 28, 2015 9:01 am Post subject:

KTPhil · Posted: Thu May 28, 2015 9:47 am Post subject:

Search the "fuel in oil" threads and you will find some mention of rebuild (diaphragm) kits for your pump. The choke problem is almost surely unrelated.

60ragtop · Posted: Thu May 28, 2015 10:06 am Post subject:

Why do you think having the choke rigged so it stays on all the time would not have anything to do with gas in the oil? Please explain your reasoning with us so we can all learn something new today.
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sjbartnik · Posted: Thu May 28, 2015 10:54 am Post subject:

sjbartnik · Posted: Thu May 28, 2015 11:00 am Post subject:

Gas in the oil has many possible causes:

1) leaking fuel pump diaphragm
2) fuel pump pressure too high, overpowering carb needle valve
3) faulty carb needle valve or float
4) excessively rich mixture.

Before you go looking into the hard stuff, fix the stupid easy stuff. Having the choke zip-tied on all the time is definitely stupid and definitely easy to fix.

With full choke on all the time you will be getting an excessively rich mixture. Some of that extra fuel will not vaporize or will condense in the intake, will wash the oil off your cylinder walls, will get past the rings, and get into the crankcase and mix with the oil. So fix that first.

Then find the guy who put that zip-tie on and punch him in the face.
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nlorntson · Posted: Thu May 28, 2015 11:11 am Post subject:

Danwvw · Posted: Thu May 28, 2015 12:52 pm Post subject:

nlorntson"The only way fuel could enter the crankcase via the carb is if raw fuel made it down the manifold, into the head and past the rings. He'd have much bigger problems if that were the case"
And this is exactly what is happening or did happen. There is plenty of manifold vacuum to suck pure fuel into the engine and it will run that way until it warms up and floods. If the car is started and driven that way a block or two it would probably have a quart of gas in the oil after that. If you catch it it probably won't hurt the engine though. It's amazing how much gas in the oil they will take. Mine got so bad that it would not rev up. The Mix of oil and gas will just splash out. It's got to be pretty cold out for this to happen though. But tying that choke closed like that it would at least pump gas into the oil when cranking the engine over even if it was too rich to start.
I see something missing in this photo:

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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

irvanm · Posted: Thu May 28, 2015 4:12 pm Post subject:

is it the missing hose from the air cleaner to the tin or is it something else, if something else I would appreciate knowing what. Thanks

rcroane · Posted: Thu May 28, 2015 4:23 pm Post subject:

The missing hose is the pre heat tube. WW sells them. It goes from the oil bath cleaner, through the hole in the tin, and connects to a pre heat pipe/tube attached to the engine. Here's a picture of the pipe not attached to the car. Yours may be missing....they often are, but you should be able to locate one if it is.

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'65 Sunroof Bug

nlorntson · Posted: Thu May 28, 2015 4:27 pm Post subject:

rcroane · Posted: Thu May 28, 2015 4:33 pm Post subject:

And here's a picture of the pre-heat tube connection on my '65......

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'65 Sunroof Bug

60ragtop · Posted: Thu May 28, 2015 5:25 pm Post subject:


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