there's gas in my oil

[JMACK]

Hi everyone, I was running my "76 B the other night in the garage and noticed a slight drop in oil pressure, from about 80 to 50 pounds at idle. I shut the motor down and checked the oil level, when I removed the dip stick I could smell a strong odor of gas. I wasn't sure what this meant and thought it best to change the oil, well, when I pulled the drain plug I was quite suprised that instead of black old oil I saw, brownish thin liquid, more than six qrts worth. I spoke to a friend who said my needle valve was bad and excess fuel was being dumped into the crank case, is he correct? How should I corredt this? What precaustions do I need to take before I restart my engine? Thanks MACK

 

[piman]

Hello Jmack,
does your 'B' have a mechanical fuel pump, if so it could be that the diaphragm is leaking fuel directly into the crankcase.
By the way, that oil pressure sounds far too high.
Normal running pressure should be about 50 psi above 2,000 rpm.

Alec

 

[JMACK]

Alec, Thanks for getting back so quick. The fuel pump is electric, I've noticed the contacts clicking when I turn the key on, is correct? Someone told me, if this happens every time I turn the key on this could be an indication of fuel leaking "somewhere" what do you think? JMACK

 

[aeronca65t]

You should definitely fix thais problem ASAP. Gas in the engine oil can cause rapid wear of your internal engine parts.
The most likely source of a problem like this is a sticking float valve in the carb. I'm surprised that you haven't mentioned that the car is creating a lot of black smoke or running extremley rough (due to an overly rich mixture).
At any rate, carb repair of this sort isn't that expensive so you should get it done straight away.
You're sure it's gas, right? (and not anti-freeze from a head gasket problem)

 

[aerog]

I'm not sure how the fuel pump can be suspect - it's mounted at the fuel tank and pumps forward. A certain amount of "clicking" is normal if the car's been sitting awhile - but if you switch the ignition on and it keeps clacking away you might have a leak.

If you have a bad needle/float valve and it's letting fuel pour out of the carb (which, if your pump constantly runs might be a good clue). I can see a cylinder possibly loading up and diluting the oil, but two quarts seems like an awful lot.

Normal idling oil pressure is 10-25lb, running pressure 50-80lb by the way.*


* From the official MGB shop manuals

[ 04-16-2004: Message edited by: aerog ]</p>

 

[Guest]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by JMACK:
Hi everyone, I was running my "76 B the other night in the garage and noticed a slight drop in oil pressure, from about 80 to 50 pounds at idle. I shut the motor down and checked the oil level, when I removed the dip stick I could smell a strong odor of gas. I wasn't sure what this meant and thought it best to change the oil, well, when I pulled the drain plug I was quite suprised that instead of black old oil I saw, brownish thin liquid, more than six qrts worth. I spoke to a friend who said my needle valve was bad and excess fuel was being dumped into the crank case, is he correct? How should I corredt this? What precaustions do I need to take before I restart my engine? Thanks MACK<hr></blockquote>

I find it very hard to believe that all that gas is getting into your oil from the carbs and the car still running. 6 quarts is an awful lot of gas. Are you sure its gas? Is the car parked ever anywhere where someone could tamper with it and vandalize it by puting the gas in the oil. As I grew up there were some kids that would do such a thing.

The fuel pump will click a couple of clicks when you first turn the key but should stop. If it keeps running, there is a leak somewhere.

Maybe there is water in the oil and you have two problems. A gas leak thus the strong odor and water in the oil indicating a head gaskit bad.

I think we need more info on how the engine is running. Is it running fine, is it smoking (black smoke out the exhaust, Are bubbles coming up in the radiator at idle, is there oil in the water, how is the compression, to just name a few.

Bob

 

[JTB]

Have a 69, never re-built engine that runs at 40-50 lbs at idle and 70-80 lbs at speed. From what I can tell there is a fairly wide acceptable operating range per Piman's post. Whatever it is absolutely...the change is troubling, naturally, and must be due to the oil thinning. Wish I could add something intelligent about the next step. Shouldn't the carb overflow tubes take excess off? I am not very knowledgeable about carbs (yet...heh,heh). It does seem like a heck of a lot in that period of time.

 

[JMACK]

Hi everyone, thanks for all the help, here are some answers to the questions asked. No oil in the antifreeze, it's a fine shade of green, the car runs great(in the garage that is, I am not "on the road yet"}, no black smoke, very slight hint of white, blue type smoke, but very "fumey" exhaust smelling, no chance of tampering, the car is locked in my garage and compression is about 90-92lbs on all four, looked at the plugs while doing the comp. test all the plugs seem to have some dry black carbon, I'm using Autolite 63's. Thanks again for all the help. J MACK

 

[Jim 67B]

black plugs mean you are running rich. The compression looks way to low. Check the compression both dry and wet and see if there is a difference.

 

[JMACK]

Jim 67B, Thanks for answering, I went back out and rechecked the compression, I forgot to use the adapter with the O rings for a tight seal, I only did a dry test and the comp pressure was 122 on all four, I hope that sounds better!! Next you said I'm running rich, how do I adjust? I have the SU tool for that adjustment, do I turn clockwise or counter-clockwise? Or something else? Thanks, John

 

[aeronca65t]

Your compression sounds OK. The adjustment tool you have (I guess) is the wrench that turns the main jet (under the carb). Your main jet can be turned CW (looking up from under the carb) to make it leaner (less rich). Truthfully, the car should be fully warmed up...if you're not really driving the car at this point, wait until you have a chance to drive it for a bit before doing this.
I would change the oil again and keep and eye on the level. You could also tap on the float chamber (while the engine is running) with a small wrench...this can "unstick" a stuck-float needle.
You mentioned the SU tool, so I'm assuming your car has SU carbs (normally that year doesn't). One of the best Brit carb sites I've seen is here:

https://www.teglerizer.com/sucarbs/techtip6.htm

[ 04-16-2004: Message edited by: aeronca65t ]</p>

 

[GTsRFine]

I think your floats are stuck/sticking open. The float bowl overflows may not have been correctly hooked up when the SUs were back-fitted to your 76 MG.
Is your fuel pump the stock SU pump? If not, it may be pumping at too high of a pressure which would overpower the float bowl needles.

 

[GTsRFine]

Let me hurry to Add:
Don't run the engine until you get this fixed!!!
You will destroy the bearings , followed shortly by the rings.

 

[Guest]

I've had some more thoughts on this problem. Isn't the 76 a single Zenith carb? I have dual HIF4's and the hose from the oil separater splits and goes to both carbs. What if on yours the hose from there got put on the bowl overflow by mistake and the needles are leaking as said earlier. That would dump raw gas down into the oil through the oil separater. On mine the connectors are very much different in size so that problem would be minimized but I don't know about the Zenith.

Other than that I don't know maybe someone more familiar with the Zenith Stromberg would know.

I agree it would not be wise to run the engine with that diluted mixture in the oil until this is resolved.

Also there is a section on tuning the Zenith-Stromberg on page 27 in the Moss catalog.
Bob

[ 04-17-2004: Message edited by: mrbassman ]</p>

 

[GTsRFine]

Mea Culpa on not reading the post carefully. I must have mixed it up with another post about swapped ZS to SU.
I don't know much about ZS carbs but, in general, leaky float needles can dilute engine oil.