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MG MGA - Engine 'Blowby' and Smoking ( again )

Had a compression and leak off test done.

#1 130
#2 135
#3 125
#4 130

Leak down 10%

The plugs are not excessively fouled ( chocolate brown )

engine still smokes constantly, especially on start up, under acceleration and when "hot " ( 190 or so ). It does not overheat. The carbs have been adjusted .

What's next ( I think I can guess....)

DA MacFarlane

Is smoke/air rushing out of the vent on top of the valve cover? The compression numbers look pretty good.
Is oil fuel fouled?
R J Brown

I have one of those aluminum valve covers with the tiny hole in it .

I have an old "normal" one and will swap the aluminum one out.

Can't tell about the oil ...would it be obvius ? Smelll, colour, viscosity... ??
DA MacFarlane

You don't say whether it is smoking out the tailpipe or just smoking in the engine compartment. I'll assume that you are talking about the tailpipe. Was your compression test done cold warm or hot?

Smoke on startup could easily be valve guide seals. This would stop almost immediately after starting. Bad seals could also cause smoke on deceleration. Generally not during accelleration. Smoke on acceleration is usually rings. But as RJ stated, your compression looks OK indicating good rings. Could have a craked head or bad headgasket that gets worse when the engine is hot.


C Schaefer

The smoke is coming out the tailpipe.

The compression test was done on a cold engine with the throttle open.

There is smoke upon start up. It is not too bad when driving until the engine warms up.
Then it is very obvious on acceleration, gear change ) load ). It continues upon idle, once warm.
The head should be good as it wa installed by a reputable mechanic with ARP studs.

I will see if the valve cover makes any difference...I don't think it should but I'll try anything to avoid a rebuild right now.
DA MacFarlane

I had a similar experience after rebuilding the engine (1500). Heavy blue smoke from the tailpipe and worst on initial acceleration from idle. The problem was the lower, oil control rings on the pistons which I found to be the wrong ones for my pistons. I rehoned the cylinders for a nice cross-hatch pattern, put in the correct rings, and all was well.
Tom Heath

I removed the filler cap on the aluminum valve cover.
Much less fact acceptable.

Now to replace the cap or go back to the original cover.

DA MacFarlane

I had a similar problem and a huge oil consumption problem that went away when I changed valve stem seals on the 4 intake valves. I used the Sealed Power 2001 as suggested by Barney.

Kris Sorensen

What did you change the valve stem seals ? Felpro umbrella seals ?
What is Sealed Power 2001 ?

DA MacFarlane

This thread was discussed between 03/07/2008 and 04/07/2008

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This thread is from the archive. The Live MG MGA BBS is active now.