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MG MGB Technical - Stuck Oil Ring?

Hi Everyone,

Put my '69 MGB-GT on the road this week for the first time since 1996. Smokes right much. Blueish in color and smokes acclerating and decelerating. Sometimes it seemes like it gets O.K. for a mile or two but then it starts again. Seems worse after warming up. I had new valve stem seals put in and cleaned out port going back to oil pan but didnot do a complete head job. Engine had been rebuilt about 8,000 miles before I took it off the road in 1996. I did a compression test and all are between 135 & 145psi. Also, I have new carbs, plugs, wires, pts., condenser. The two center plugs are black after only 60 to 70 miles but the outside ones are tan. I was thinking it may be stuck oil ring(s). Tried engine flush. Any suggestions? Penetrating oil in cylinders? Thanks in advance! Paul
Paul S. Canup

Penetrating oil and then drive it some. They may unstick if you let it all heat up. Also, do you have emissions? There is an oil breather on early cars that can fail and cause oil to be sucked into the head.
J Arthurs

In UK we have redex which is a upper cylinder lubricant with anti-gum properties

there will be something similar in US

technique is to put 2 tablespoons in each plug hole and leave at least overnight and better still for a day or two

then you blow remnants out by turning engine over without plugs, replace, and start

then dribble a significant quantity into each carb with engine running

you will get enormous amounts of smoke but it often will free gummed rings

in ant event a good heating up will help - a good long run with plenty of second gear work etc

Chris
otherwise only cure is remove pistons and immerse in paint thinner in a soup can
chris

Here in the US, Marvel's Mystery Oil seems to be similar to the Redex which Chris mentions and is used in the same manner. There are also "upper cylinder lubes" which are added to the gas tank and run through the system. J is also on target that, if the mushroom style valve has a bad diaphram, you will have oil sucked into the intake manifold and blue smoke. The diaphram is available as an individual replacement part and had to be replaced on my 68 last year for exactly the same problem. As I remember it, you just remove the spring "bail" that holds the top on, remove the top and you can inspect the diaphram. Les
Les Bengtson

69 didn't have the "mushroom head" PCV, that year changed to a Y-pipe connecting the front tappet cover to the carbs. I would try the Marvel Mystery Oil in the manner that Chris suggested, and as he says, if thet doesn't cure it, the pistons will need to be pulled.
Paul K

Thanks everyone for the information. I tried penetrating oil overnight twice but no luck yet. I'll get some Marvel Mystery Oil tomorrow and try it. Hope I can loosen them without going into the engine.

Paul
Paul S. Canup

Paul , go to Kano Labs website , they have some good stuff for un-gumming engines , I like to run short oil & filter changes using synthetic oil as it is _incredibly_ detergent .

Good luck , try some short oil changes and then flog it to really heat it up and get that gun dissolved .

-Nate
Nate

This thread was discussed between 13/09/2002 and 19/09/2002

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