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MG MGA - Aerated oil

I'm starting to see tiny bubbles in the oil when I check the dipstick. There aren't any noticeable changes in the running of the engine. I only see the bubbles when the motor is hot and been running on the highway- I never see them while cold or after around-town driving. I don't think it's a head gasket because there is no discoloration to the oil and it smells normal. I checked the archives and there is only one instance of this that I can find; however the final solution to the problem was never posted. Someone had suggested that if the wrong oil pump gasket is installed it will aerate the oil, however I don't think that's likely since there are 26k miles on this engine and the problem only appreared about 5k miles ago. I don't really like the thought of air bubbles reaching my bearings at 4000 rpm. I plan on doing a compression check to rule out the head gasket but after that I'm at a loss here when it comes to troubleshooting. If I open up the sump what should I look for?

Thanks
Mark
Mark J Michalak

You would think that the only place air could be picked up is the joint between the strainer and the pick up pipe and the joint between the pick up pipe and the pump.
Have you done a cylinder compression test?

Mick

Mick Anderson

Mark, have you over-filled the sump? Rod ends could whip up foam (maybe)
Art

Art is correct, if you have inadvertantly overfilled the sump sufficient for the rodends or the counter weights of the crank to dip into the oil, it will (not maybe) whip up a froth in the oil. If it become bad enough, a loss of oil pressure will be experienced. This is why there are warnings to not overfill the sump. Good luck - Dave
David DuBois

I had thought about the crank dipping into the oil and whipping it up, but I'm running at the max line on the dipstick, not overfilled. I'll try running at the "min" line and see if that makes a difference.
Mark

I don't know if this is an issue like on the MGBs, but do you have the correct dipstick? Cheers - Dave
David DuBois

David

Good call about the dipstick. The 1800 engine I put in 4 years came into my possession without a dipstick so I used my 1500 stick. I calibrated it by pouring in the correct volume of oil and then raising/lowering the dipstick until it showed full. I then secured the rubber gaiter at this level. I have never been certain in my mind if I got it right. However, the engine is still turning and burning very happily so I can't be a million miles out. You mention about it being an issue with the MGB so, as I have the 1800 5-bearing engine, are there other ways of setting the dipstick at the right level? And what are the issues you refer to?

Many thanks
Steve Gyles

Barney Gaylord has a tech article on this subject
at http://www.mgaguru.com/mgtech/engine/ds100.htm
Ralph
Ralph

Yes, if the oil level is too high the conrods can froth up the oil, definitaly not desired. The "correct" MGA dipstick does not have any collar stop, but sits down on a small flat bump in the bottom of the oil pan. Oil level is determined with the dipstick being marked a specific distance from the bottom end. The MAX mark should be about 2-1/16 inch from the bottom end of the stick. More info here: http://mgaguru.com/mgtech/engine/ds100.htm

Barney




B Gaylord

Please note also that engines are sometimes bounced when setting down out of the car. The oil pan can get pushed-in or dented upwards. The stick may rest on this high spot, creating a modified (higher) max level. Best to go with the manual-specified fill amount, which may be increased appropriately if an oil cooler has been added.
Jon Bachelor

Steve - As I recall there are at least three different dipsticks for the 1800 MGB engines. 1 for the 3 main bearing engine, 1 for the early 5 main bearing and 1 for the later 5 main bearing engine. Cheers - Dave
David DuBois

This thread was discussed between 10/04/2005 and 12/04/2005

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