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MG TD TF 1500 - Vapor Lock ?

I thought I would pass this diagnosis on, since it may benefit others. My 52 TD, which I had just purchased, wouldn't start after short trips to the store, until it cooled. However, where I live the temperature rarely goes above 70F for very long, and this was spring, so this was the high temperature.

The temperature gauge was not showing a high reading either. Also, the car didn't have to cool for too long, maybe 15 minutes. Sometimes it would start, but then run very rough and irregular, and appear to be surging.

I took the car to my mechanic, who apparently has a lot of experience with old cars, and as he was hooking a tester onto the distributer, while the car was hot, we noticed that it moved. In fact the distributer flopped around terribly, to the point where the points wouldn't open.

It turns out that the distributor bushings were badly worn. The points only open .012" (from memory). When badly worn bronze bushings get warm, they can increase the play, which looks insignificant when cold, to where the points won't open.

Proof of this diagnosis occurred when I installed a good used distributor, and the car has run perfectly ever since. Another local person had a similar problem, so I don't think it is that uncommon.

Hope this is of help to someone. If you think you have vapor lock, but it's not very hot outside, it could be this.
Larry Ayres

Larry
In the recent heat wave over here my TF runs a bit rough after starting a hot engine when the coolant temperature has risen 5 or 10 degrees while parked. Pulling out the choke a quarter of an inch or so for about half a minute cures the problem, which tends to confirm a minor vapor lock. Fitting a pertronix electronic ignition unit reduces distributor wobble. I bought mine from Skip Kelsey and have never regretted it. http://www.shadetreemotors.com/
John James

This thread was discussed on 02/07/2005

MG TD TF 1500 index

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