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MG TD TF 1500 - Lot of smoke from the breather pipe on my TD

Hello everybody and TD specialists ,

I have just buy my 1953 mg td and I already meet a problem with it. This TD seem totally restored 20 years ago in USA but the engine is not perfect. In fact, I have lot of smoke from the breather pipe on the tappet rocker cover (see picture, blue arrow).
The engine start easily and run well but seem not very powerful. The compression is very good (8,5 or 9 bar on each cylinder), the oil pressure is fine (40 to 50 LBi) and the cooling is not too bad (70 °C until 90°C according to the conditions). The smoke from the breather pipe is clear grey near withe color. I have also smoke from the breather pipe on the cover rocker but less (see picture, red arrow). I have take a look on the tappet clearance and all is good.
Have you got an idea what is the problem ?
Valves guides, segments, other ? I dont know very well this car so if you have an idea it will be fine.

Thanks in advance. Didier (from south of France)

Roussel Didier

Sounds to me like blowby. Probably due to poor piston rings. Or stuck rings, believe there are ways to free up stuck rings. But right at the moment can't remember what the treatment was. (senior moment).
Cheers,
Bob
R. K. Jeffers

Wouldn't "clear grey, near white smoke" be an indacation water is someplace it should not be?
i.e. Head Gasket leak?
I wouldn't think you would have good compresion and/or oil presure with bad rings?
Not sure what "8,5 or 9 bar on each cylinder" would be in lbs?
David Sheward

David...

1 bar = 14.5037738 pounds per square inch so the compression is running between 124 and 130 psi.
Gene Gillam

1 bar is atmospehric pressure. 14.5 psi.
( X 14.5 is 130.5 psi.

Jim B.
JA Benjamin

Roussel, all the readings and indications you have reported are good. The white/gray smoke is probably from a pair of cylinders that are receiving water from the cooling system. Examine your spark plugs to see any differences in appearance to see which cylinders are getting the coolant. Also, look in the radiator for bubbles in the coolant or a drop in the coolant level.
A broken head gasket is the first thing to suspect.
Bonne chance mon ami!
Jim Merz

Gene & Jim,
Haven't heard the term for so long I forgot! Thanks
David Sheward

David,

No problem...I didn't remember either so I jumped on Google.

Gene
Gene Gillam

Bonjour Didier,

Your problem could also be stuck valves or a too small rocker clearance. Try running the engine with the rocker cover removed.
Where in the South of France are you? I am in Antibes.


John

52 TD


J Scragg

If you do this then block off the rocker oil supply,otherwise the oil will go everywhere.That is you and the garage roof.Don't ask me how I know.
Ray TF2884
Ray Lee

Thank you everybody for your indication.
All the 4 spark plugs are black, surely because the mixture is too rich. I have take a look in the radiator and I have no bubbles in the coolant. Tomorrow, I have a little run to Bandol (Renowned for its excellent white wine), in the south of France - 160 km (100 miles) - so I could look coolant and oil level after. Perhaps I could diagnostic a cooling system problem, oil consummation or other.
PS : I believe at Marignane (near Marseille)
Roussel Didier

Didier,

I will see you at Bandol. Should be about 300 British cars.

John

J Scragg

Why not John, my TD is clipper blue with tan interior. I will be with the MGCF.
Roussel Didier

If a coolant leak, wouldn't white/gray smoke come out the tailpipe rather than the breather? I thought breather fumes were blowby from stuck or bad rings. Bad/worn valve guides suck oil into the cylinder, it burns and out the tailpipe- unless the rings are bad. If the oil is clear and not milky, likely not water. There are all kinds of "miracle" oil additive products out there that claim to unstick rings, give one of those a try. George
George Butz

I think your car is beautiful!

For the 'underpowered' issue, try running the engine at 8 degrees before top dead center (BTDC) which would be about 7mm before the timing mark, below 1000 RPM. Then check to see if you have all in timing (complete advance) at about 27mm at 3500 RPM. The original timing figure was for a much poorer grade of fuel than available today. Set your points first, of course.

Ten download my PDF on setting carburetors. You can find it at my website, http://www.dbraun99.com

Warmly,
Dave
Dave Braun

Hello everybody,
Some news of my TD default.
I have dismantled the cylinder head and I have seen the origin of my problem. In fact, they are a little peace of piston loose !!! We can see the segment back the hole. I think it is necessary to pull the engine and take a look at the pistons/segments isn't it ???



Roussel Didier

Yes, Roussel, your problem is sufficiently serious to require you to remove the engine for a rebuild. Pistons are damaged like that, in my experience, from detonation, which can be caused by timing issues, and/or a lean mixture. You will obviously see any other problems when the engine is apart. If you are lucky, you may be able to get away with just new pistons and rings, and not have to over-bore the engine more.

I would be sure and have the distributor rebuilt, and be sure your car is not running lean or too far off in timing, in the future.

Tom Lange
MGT Repair
t lange

Rouselle.
The head gasket appears wrong for the cylinder block as the holes are round. Does your culinder head have the same round holes. If the head has round holes then you need the later headgasket.
But, If the head has long holes then the gasket type you have is correct.
Sandy
DARNOC31

Bonjour Didier,

This proves what we suspected when we discussed the problem at Bandol. You will need to remove the engine. If you need information on where to buy parts, let me know.

John
J Scragg

Thank you everybody for answer.
Just a question : do you think it is possible to pull the engine without the gearbox ? If yes, it is easy ?
I am looking for somebody to rebuilt the head cylinder (in UK or anywhere) and evantualy over-bore the cylinder (in France). John, do you know a man in south of France who's able to do the job ?
Thank in advance. Didier
Roussel Didier

Didier,

The engine can be removed by itself, but I find it easier to remove both.

These people will do your machining work.

http://www.comptoir-allard.fr/

They are in La Bocca, near Cannes. They do a lot of work on the boats here. I have not used them but they have a good reputation.

You can do the cylinder head, yourself it is not difficult.


John


J Scragg

Jack is right, of course - remove both engine and transmission at once.

As for the machine work, the engine will have to be pulled apart to determine whether the bore is worn enough to need enlarging for new pistons. That is the time to check the followers, the cam, the oil pump cover, the main and rod bearings, etc. I would not immediately assume that you need an over-bore; just last year I was able to replace just the pistons on an engine with a burned piston and valve, and all is well so far.

There are so many variables with the cylinder head that I would not really recommend you take it on yourself. The valve guides can be worn, the valve seals broken, the valves themselves can need to be replaced, the seats (especially the exhausts) often need freshening up, the head may well need re-surfacing, the rocker gear should be checked for wear at the tips and bushing, etc.

Do find a good machine shop and rely on them. Perhaps a holiday visit to the UK is called for!

Tom Lange
MGT Repair
t lange

Tim,

John not Jack.



J Scragg

Sorry, Joe, Of course, John is right Jack.

Todd
t lange

>The head gasket appears wrong for the cylinder block as the holes are round.

The "banana" gasket can be used with round holes in block/banana holes in head; banana holes in block/round holes in head; or banana holes in both head and block. Only if both the head and block both have round holes can the round-hole gasket be used*, although the banana gasket can also be used.

More succinctly, if you have round-round you can use round. You can always use banana.

*Note that if there is pitting in the block or head from previously using a banana gasket, then a banana gasket will need to be used, even if both the block and head both have round holes.
Rob Edwards

New pics of the piston (STD)

Roussel Didier

And the cylinder head :

Roussel Didier

and detail of the valves :

Roussel Didier

Do you think that it is possible to change only piston without over-bore cylinder ?
John, you give me the method at Bandol to dismantle piston without pull the engine (from below) and I want to try it.
Roussel Didier

Bonjour Didier,

I will work with you directly through your email "en Francais"

John
J Scragg

Bonjour John,
Thank you. You can write me "en français" by email at the address near my name and country at the beginning of this message
Roussel Didier

If you try to just change one piston, make sure you remove the ridge at the top of the bore. If you do not, the new top ring will hit it and break your new piston. I proved this many years ago. George
George Butz

This thread was discussed between 01/06/2013 and 12/06/2013

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