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MG TD TF 1500 - Vapour lock in not-so-warm weather?

I thought everything was ok now. New dynamo and all. But after having driven slowly in a queue today, the car did not behave perfectly when i speeded up again. It felt like a vapour lock. But the temperature on the meter only showed 80 degrees C.
Can I have a vapour lock even when it is not very hot?
Raymond Wardenaer

raymond, i have never heard of vapor lock affecting these cars when you are driving. it usually occurs after a run when the car sits for a short period of time and everything under the hood gets heat soaked....and then it is at the higher summer temps..not cooler fall weather. if your fuel pump is operating normally i would not suspect vapor lock for the conditions you described. regards, tom
tom peterson

tom, but others have written here that they copuld never take part in parades with the TD, because of problems with vapour lock.
Raymond Wardenaer

If the engine compartment and block are warm enough, vapor lock, can happen, when going slow, because demand for gasoline is low, and there is more fuel "stored" in the fuel line, awaiting the carbs to use the fuel in the bowls...The fuel in the lines can begin to boil, and the vapors are created.....
It would be very unusual for this to happen at lower ambient temperatures...
If your fuel pump is working properly, the chances are, your carbs picked up some impurity from the tank, and caused a temporary "hiccup"...Lots of bad gas out there, these days. Another explanation, is the possibility of a stuck float or float-needle.
Next time it happens, try pulling out the choke slightly,and see if that cures it....If so, it's probably vapor lock.
Edward
E.B. Wesson

Thinking about it, I have wondered lately about the thermometer. Even when driving for some time, the temperature has not gone higher than 70 degrees. And we have had almost summer temperatures here for a few days now.
I have a feeling it has been vapour lock, because going normally for some time, the engine works perfectly.
I am going for the extra fan in front of the radiator. A friend who has that told me he had no problems like this anymore...
Raymond Wardenaer

A fan in front of the radiator???

Anyone have more information about this?

Thanks,
Mort
Mort 1950 TD Möbius

Mort, I have.
As I said, a friend with a TD has put in a fan between the grill and the radiator. There is very little space there, so some part of the fan (not the moving part) will touch the grill. It is not a fan that you can buy for the MGs from Moss or other car parts companies. The chairman of the Norwegian MG club works for or owns, a company importing fans for different use. He is the one who delivered the fan for my friends TD, and I saw him a couple of weeks ago, when he measured which fan I should have.
Raymond Wardenaer

raymond, this summer i drove on a 250 mile trip with temperatures in the 33C range... 1 1/2 hours was stop and go..creeping traffic. not a hiccup.
i stand by my statement. if the car is running..fuel is moving through...under pressure from the pump to the carbies..the only place you have low pressure is from the tank to the pump. i only have a decade with this car. there are others here who have far more experience than me. regards, tom
tom peterson

Hello Raymond !

Who is the MG Club fan guy? I am considering an electrical for my TF; have to pull the rad this winter anyway to install the Hi gear five speed kit

Regards,

Jan
Jan Kristoffersen

Jan, good luck with that! And you can look forward to the electrical ignition, I feel I got a new car...
Raymond Wardenaer

Raymond,

I agree with Tom. I drive thousands of miles a year all over the central USA and never have vapor lock while moving.

I would be looking for things like exhaust leaks at the manifold, fuel too low in the bridge (although it can be really low and still work!) timing too far advanced, poor cooling circulation... anything that would raise under hood temperatures. Finally check the pump output.

Next time you get vapor lock, check to see if you have good amount of fuel in your float bowls. A block needle will act like vapor lock. If so, clean the filter in the bottom of the fuel pump, and the filters in the banjo fittings at the carb float bowl lids.

warmly,
dave
Dave Braun

raymond, in regard to the electric fan idea, this will only help during stop and go traffic. if the car is moving at any speed you are getting more air through your radiator than any electric fan can move. regards, tom
tom peterson

Mort,
in case you want to look for such a fan in the US, it is a Stal fan.
Raymond Wardenaer

Jan, the MG club fan guy is the chairman, Ola Thygesen. You will find him in Oslo.
Raymond Wardenaer

Raymond,
Thanks for the information. I Googled and found it to be Spal not Stal. There is a lot of info on their site and I will bookmark it and read it later.

I believe that Dave is correct and I am still in the the process of fine tuning the car to handle the heating issues.

Thanks again,
Mort

Mort 1950 TD Möbius

Mort, I am sorry about the wrong name. I heard it over the telephone, and my hearing is not so good any more.
Raymond Wardenaer

Spal is a great fan, (and I have used them on other cars), but make sure there is plenty of clearance between the fan-blades and the radiator....The blades on most models, are not interconnected at the tips, and will flex...sometimes toward the radiator...NOT a good thing, if there isn't enough space!
Edward
E.B. Wesson

I don't see how vapor lock would even be possible. If there's a gas bubble in the feed line to the carb, it seems to me it would sit there until the fuel level in the float bowl dropped and the needle opened, and the vapor would then burp out the bowl vent. If the bubble was in the connection from the bowl to the jet, it would get sucked out the jet and fuel would replace it. So I don't see how vapor could block fuel flow.

I have the common complaint with my car that after sitting a bit, it's hard to start and runs rough for at bit. I think what's happening is fuel boiling in the jet connection or bowl itself and forcing liquid fuel up & out of the jet and so the engine floods. So not vapor lock (insufficient fuel) but /too much/ fuel!
Rob Edwards

Tom, of course I would only switch on the fan in go and stop situations. It is also in these situations I have some problems with the engine not thriving for the first hundred yards after the go and stop. Otherwise, the motor goes very well these days.
Raymond Wardenaer

Raymond, do you have a fellow TD owner who would be willing to swap carburetors with you for a few days? I think that such a thing could answer a lot of your questions. Bud
Bud Krueger

Bud, I went to some carburetor specialists today. They agreed with most people here, that it was not vapor lock this time. That is why I put a question mark behind the title at the top.
I think they fixed the problem. They adjusted the carbs and checked the sparking plugs. Two of the plugs were very black. They were all replaced. The test drive looked very good.
I still have to test it in the situation with stop-and-go slow. But the people in the workshop almost guaranteed no problems.
Raymond Wardenaer

A great thread guys! I have the same problem when I park after a hot drive. The car struggles to start and then rums ruff until fresh fuel gest in. So I will tune the carbs, clean the filters and change plugs.
Thans, Geoff
Geoff Kimler

Raymond
I will be very interested in a follow-up, to find out if the carb adjustment actually cured the problem...Also, if the tuners found your carbs to be too lean or too rich, or one lean and one rich, etc.
Edward
E.B. Wesson

I don't have a vapor lock problem and I live in steamy hot S. Carolina. As a precaution however, I did the following:

1. Wrapped 1/4" vinyl foam rubber insulation around the fuel line connecting the jet to the float chamber. I held it in place using plastic spiral wound electrical wrap.

2. I also added a piece of 1/4" thick Hardie Plank cement house siding to the underside of the heat shield.

Frank Grimaldi
Frank Grimaldi

Edward, I shall come back to you next week. The tuner went to Germany today, but will be back over the weekend. But the car runs very well now.
Raymond Wardenaer

This thread was discussed between 30/09/2011 and 05/10/2011

MG TD TF 1500 index

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