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MG TD TF 1500 - Vapor lock

Hello MG friends,
MY 1951 MG TD runs perfectaly well but I am facing a vapor lock problem due to the abnormal temperature we have here. Since 15 weeks the outside temperature is each day between 36, 40 degre C. And sometimes the vapor lock problem occurs, the engine stops and I have to wait sometimes, waiting for carburator cooling or I have to use water to cool down the system. I have a screen between the 2 carburators and the exhaust pipes, but it seems that it is not enough. I am sure that other MG mens have faced this problem. Is there somebody who knows a better technical solution?I must say that the engine temperature is around 85 degre C.
Thanks in advance
Georgibus.
Georgibus

Are you at altitude? If everything is working as designed you should not have vapor lock even at those outside temps near sea level. I am not convinced that those shields actually help and may in fact hurt the air circulation adding to the problem.

Make sure that your fan is installed correctly and that you have good air flow through the radiator slats. I would suspect you would have boiling problems too. Also make sure that your fuel pump is operating correctly. Do you have another one that is like new you can test?

I drive in temps that is over 40C without problems. Only time I had problems was at 3,00+ meters at ~38C climbing a steep long grade at low speeds. In this case I opened up the right side of the hood and drove that way until I got to the top of the grade. That was with another car, not mine.

Chris
Chris Couper

Also try a different fuel. Some cars vapor lock on lower grade fuel and not on higher grade.

Chris
Chris Couper

Thanks for your reply. I must say that I am using 98 unleaded free petol with additive.The fuel pump is new. I am in a region where the normal alitude is roughly 600 mts but we have a lot of climbing, mountains around. I agree that in such a level of temperature opening the bonnet is a good solution. The air flow trough the radiator seems ok, the core is new, modern style, and the fan is an electric one coming from Kenlowe. I am thinking to surround the exhaust pipe with an isolating material?
Other suggestion?
Octagonaly you Georgibus
Georgibus

Georgibus,
DO check the archives from about 2 years ago on this BBS! (Vapor Lock) I had quite a long thread going on the subject then and I think we covered just about every possible cause / cure!
Let me know if you can't find it and I will try and locate for you!
Cheers,
David 55 TF1500 #7427
David Sheward

Try using the phenolic spacers between the carbs, & manifold, TF spacers will fit but are 1 1/2" I.D.I think that the smaller carb size spacers were used on various other cars, perhaps in the '60's. Also Rolls Royce, & Sprites used a smaller float in the same chamber, to increase fuel capicity, in the float chamber, [same float chamber as the TD]. Thanks to Joe Curto for the last tip! How about a richer needle, esp. if the fuel is oxygenated. Len
Len Fanelli

Although it's not pretty, wrap the copper fuel lines with heat insulation. Go clear down to where the exhaust pipe and fuel lines run close together. The foil kind with fabric face. I used material that was intended as an upgrade for the Datsun 260Z when they had fuel percolation problems.
Bullwinkle

The spacers for 1 1/4" carburettors exist, they were made for Minis or other cars. That is a must.

Also put some shield between your Kenlowe fan and the front carbutettors: the fan pushes all that hot air directly the to the carburettors. In fact, the front one is always hotter than the rear one. A shield between manifold and carburettor does nothing in my experience - and also in that of the late Don Jackson, Su expert.

I also have such temperatures in sub-tropical Southern Switzerland, but no serious vapor lock.

At your disposal - you can write me in French.

Denis
dbaggi@cimsi.cim.ch
Denis L. Baggi

This thread was discussed between 09/08/2003 and 10/08/2003

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