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MG TD TF 1500 - Hot Start Problem

Hello All - I have a new problem with the 54 TF. When, after a run and
the car is hot and the car sits maybe for 5 minutes but is still hot.
Upon startup it runs VERY rough. Cracking the enrichment BRIEFLY
smooths things out and everything is fine. This problem must be
carburation and heat related. For whatever reason the mixture must be
lean at this point. Cold startups are normal and the car is fine on
the road. It only happens after hot shutdowns (IE at gas stations).
This is a recent problem. Any ideas? Roger Smith
Roger Smith

I had a similar problem. Turned out to be the distributor bushings. When hot the shaft flopped around, and didn't open the points consistently. It eventually smoothed out after sitting a minute or two. I had the distrubtor rebushed. Before starting it, try removing the cap and wiggling the shaft that has the rotor on it to check. Mine was fine when cold, by the way.
Larry Ayres

Sure sounds like vapor lock to me,,, check the archives for many suggestions to clear this problem.

Steve Wincze

There seems to be a magic 'time' for a car to sit when hot... mine starts on less then one turn over for about 7 minutes after shutting down hot...then from 7 to about 15 minutes it runs very rough when started and takes a minute or so to smooth out again...have always thought this was the fuel evaportating out of the carb bowls from the manifold heat and the new fuel entering to boil or whatever!
gordon lawson - TD 27667

In hot sunny Florida, my TD has always done this to some degree. Some years ago I fitted some spacers (like on the TF) which helped a little. It may be worse if you still have winter blended gas which is a bit more volatile (?). There are several heat sheild designs out there you could also try. However- if it is a new problem, maybe the distributor/coil/condensor suspect? george
George Butz

Pretty normal for hot climates. Sometimes the car can run on too if its been idling hot for awhile. There are probably many ways to deal with it but since it only happens to me on days above 100 F (which I don't particularly like to drive in) I have just put up with it for the last 30 years or so.

Last year I had my radiator redone and it rarely gets above 75C and I have not experienced the problem since then, but my driving in very hot weather has been reduced too.

Chris Couper

Your fuel is boiling somewhere. New cars rarely do this because of the pressurised system. These are old cars. I doubt if you'll eliminate the problem, but isolating fuel lines and float bowls from heat is about all you can do.

A friend of mine had an XK120 that would just 'not start' if left idling for any time... We were on a photo shoot one day and after idling for about 10 minutes while the cameras rolled, he had to shut it off and said 'this won't start for an hour'....We grabbed some ice from the caterers and held it on the started right up... Guess it was the same concept!
gordon lawson - TD 27667

Hi Roger - apart from all the above good advice re. fuel vapourising your symptoms are classic T series made worse on the TF by the restricted space under the bonnet (hood). Suggest you also advance static ignition timing by say 5 degrees - modern fuels burn hotter and the 'Manual' TDC timing is obsolete.

Good luck with sorting it out,

Cheers John.
J.C Mitchell

We hsve had a lot of this trouble in our club with some of the cars, my 51TD included. most of us who have the problem raise the hood when we stop to relieve the heat build up. The TF in particular seems to be prone to this and it is usually vapor lock.

Hello all - I solved the problem. Accepting the fact that the fuel was
vaporizing in the float bowls, it seemed the practical solution was to
just insulate the bowls. I went to the dollar store and bought two
foam pop can insulators, made the proper cuts and wired them on. Took
the car for a 10 mile run. Let it set for a few minutes. Problem
gone. Now then, no way am I going to run around with pop can covers on
the carbs. I just wanted to prove the problem. If someone wanted to
make really good looking insulated float bowl covers it could be a way
of getting rid of the problem. Again, thanks for all the help. - Roger
RCS Roger

Had same years ago on my TF.
I did everything to cure.
Problem is I did most of them at same time!
Have not had the problem since though.
Here is what I did ...take you pick:

Changed "rubber" fuel lines to stainless.
Had Carbs re-built.
Installed insulated spacers between carbs & manifold.
Had exhaust manifold "JET-HOT" coated.
Installed pertronix ingnition in place of points.
Switched to Bosh Platinum spark plugs.

IMHO the Jet-hot was the biggest improvement. Operating temp was lowered considerably.

Before this I did for a while (and still have them in the car) use the "instant ice packs" you can get at drug store. Snapping one of those and holding it on the carb's would bring temp down and she would start right up! (I learned that trick after having car towed home several times only to have it start right up by the time I got it home! Arghhhhh ...nothing worse than shelling out $50 for a flat bed only to have it start when you back it off the truck!
David 55 TF1500 #7427
David Sheward

David - Do you remember which jet-hot coating you had done? The other items you mention have been done except for the spacers and jet-hot. Take care - Roger
RCS Roger

Yes I do ...Sterling ...the cheapest!
You can see mine here:

I have had a couple others done there as well. Two of our other cars are also notorious for "running hot" (A TR7 and Opel GT)

I like the looks of the Sterling ...but if you are going for "correctness" you might want to check there other coatings.

I will say the new spacers I ordered from Moss were considerably wider than the ones I took off the car (nearly 3/4" compaired with 1/4")...but I really feel the JET-Hot is what cured the problem.

In the backs of old 50's mags I have seen lot's of ad's for aftermarket "heat shields" for these cars, so I think there might have been a problem here very early that was known. I was too young to remember if my dad had this problem with his 1500 when new and he passed away in Jan so I can't ask him about it. I do remember Dad driving this car in a couple of parades and putting dry-ice in both the bonnet & passanger compartment though to keep things cooler!
David 55 TF1500 #7427
David Sheward

Forgot to mention...same link as last can see how "wide" my new spacers are as well!
David Sheward

So.. where did you get the spacers... Seems I need to try this here in Arizona in the comming months..

mkg grogan

This thread was discussed between 02/06/2006 and 13/06/2006

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