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MG TD TF 1500 - Help..still running rich

I need some help here. My rebuilt motor will run OK for about 4-5 mins then start blowing greyish smoke.
If I leave it for a while it will do exactly the same.
I've set the floats a little lower in case that was the problem but to no avail. Before I set the Blue Heeler on to it any clues?? (it's an Australian Cattle Dog)
Regards, Don TF 4887
D J Walker

Don,
What do the plugs look like when it is blowing the greyish smoke??
.
Open the rad cap when you first start the car,, is there any indication of bubbling in the coolant? That would indicate a leaking head gasket,,

SPW
Steve Wincze

Hi Steve, the plugs are black and wet!
No bubbles in the coolant.
The odd thing is I can run it again 30 min later it's the same, 4-5 min OK, then grey smoke.
I'm gravity feeding it at the moment but I'm sure that is not causing it.
Regards, Don TF 4887
D J Walker

How long have you let it run hot? Could it be something in the exhaust system that is "burning off" ??

SPW
Steve Wincze

Hi Steve, it has a brand new stainless steel exhaust.
However I did change the oil and it was as black as....
That is from about 30-40' running in total.
I may have to look deeper. It doesn't seem as bad with the new oil!
Regards, Don TF 4887
D J Walker

Are the jets seating right up to the adjusting nuts? If they are binding and not returning up all the way this will cause enriching of the fuel mixture. Also check that the needles shoulders are set flush in the pots and the needles are centred so they don't "hang up", in the jet.
C.R. Tyrell

Grey smoke sounds like oil, not fuel. Considering it is a rebuilt engine, has it had this problem ever since the rebuild, or just started out of the clear blue sky? One of the biggest clues should be whether all 1 plug, 2 plugs or all 4 are wet.

That 4-5 minutes could be the valve area filling too much oil for some reason. There is a lot of drainage down the pushrod region, so it is hard to imagine a blockage (reminds me of an old Chevy engine I had). One of the banjo bolts feeding the head should have a small hole to limit the oil to the rockers. If that banjo bolt isn't used, you may be pumping way too much oil up around the valves.

A damaged valve guide would show up as only 1 cylinder. If you have some breather hose drawing oil, it would probably run to just 1 air filter?... and show up on 2 plugs.
JRN JIM

A worn rocker shaft will contribute to oil build up at the head, and the pooling will go somewhere, sometimes past the valve guides.
Dave Braun

JRM JIM, I think you might have a clue there, I'm sure the banjo bolts I got from LBC had the same size holes, I have a TC motor I know has the small hole banjo on the head so I will change them over.
Thanks also Dave, I have a spare rocker shaft I will inspect.
Regards, Don TF 4887
D J Walker

Some good suggestions above. If the grey smoke is what many call "blue" smoke, it would probably be oil burning, which would get worse when the oil warms up and is thinner. If it is "black" smoke it would probably be a rich mixture which would also get worse as the engine warms up. The breather is not blocked? ... if there are no holes in the sideplate gasket and no other way to breathe, the pressure would build up and force oil into the valve guides / rings etc? That would also cause oil leaks and would be extreme if the car was driven under load on the road. Bob
R L Schapel

Thanks Bob and all, the general result is that the rings have not yet bedded in properly. "Don't worry and wait until the car is on the road and run it in under load".
It's running 12-15 mins before the smoke issue, and a lot less!
Regards, Don TF 4887 TC XPAG 7730
D J Walker

This thread was discussed between 07/07/2014 and 11/07/2014

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