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MG MGA - blue smoke while idling

We have been driving our MGA for a while now. It has some 800 miles on it after a complete rebuilt of the engine and cylinderhead. It runs great but when idling it starts to smoke (blue smoke) after a little while. If you open the throttle, it will go away.
I found come comments on this site and it looks like installing the valve stem rings a not a bad investment. Just the MGB standard seals. I found a suggestion to put some air pressure on the cylinder to avoid the valves to drop in the cylinder. WOuld not hurt putting that cylinder in the TDC first.
But I don't see how I can install the seals without removing the rocker assembly and therefore the cylinder head nuts. What is the trick there.

Moreover what tool to use to push the valve springs down to remove the cotters.

-- Paul
Paul van Adrichem


You may have a problem with the valve seals but the problem could also be with the cylinders if they have not been properly honed or with one of the scraper rings.
I suggest you do nothing for the time being - measure the amount of oil you burn. Remember these engines are supposed to burn oil (3% of fuel consumption is acceptable) and it is possible that it will settle down.
Roger Walker

Hi Roger,
I also measured the compression: All within 9.2 and 10 BAR (133-145 PSI). Plus I have take out the cylinders and checked the rings and they look fine, as did the cylinder walls. I also found a Performance Tool W84001 to compress the values. Just popping in these rings would not hurt?
As for the oil consumption: THat is 1 liter per 300kms or say 200 miles. So that is a bit too much. The spark plugs are black because of it.

-- Paul
Paul van Adrichem

I have found on several occasions that valve stem seals havn't been fitted correctly
If you have a look through between the coils of the valve spring and can see the O ring on the valve stem they are wrong
The correct method is to--
Compress the spring and cap down over the stem
Then fit the O ring to the stem
Fit the colletts to the stem
Release the tension of the spring, and the cap should come up and trap the seal and colletts against the stem

IF you don't want to disturb your head studs--
Lever down on a selected valve cap/spring till the pushrod comes loose and clears the adjuster screw, then slide the pushrod clear and pull it out.Then you can spin the rocker around out of the way to gain access to the spring etc. Sometimes there is a need to slide the rocker accross on the shaft a bit while the spring is pushed down to get the pushrod to clear and come out
If it's like that you will need to remove the split pin and washers on the 2 end ones to get them accross a bit

TDC while doing the air compressor method is a good idea
but select 4th gear and pull the handbrake hard on when you have it in place incase your engine decides to spin over--This would naturally happen at the worst time possible otherwise

William Revit

This thread was discussed between 25/05/2015 and 26/05/2015

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