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MG TD TF 1500 - TF1500 Radiator Cap

Hi gang!

I was checking the radiator today and noted the old (10 years)radiator cap had corroded away somewhat (inside metal flange). I had gotten it from NAPA as I recall, but there is no part number on it. Nonetheless, I saw a thread from some years ago on the topic, that referenced a NAPA P/N of 7031410. It's rated at 4 Lbs. Was planning on getting one in the next few days as they have one in stock. I checked the MOSS catalog, and they list one there as well. Any suggestions on which one may be a better fit on the TF? Also, Moss lists what appears to be an alternate 7 Lbs. cap. While only 3 Lbs. different, does it make a difference and if Is it intended for perhaps colder climates or some other reason?

The car seems to run fine using the 4 Lbs. NAPA cap. Any reason to get one from MOSS?


Jim Rice

A higher pressure cap will elevate the boiling temp slightly, which can be an advantage for a higher ambient temp, but it sounds like you don't need it. The cap is a fairly standard push and turn type that looks like many others, but its deeper/taller than most - this is easy to get wrong. If you get it from Moss it should be right.
Dave H
Dave Hill

Measurements for a TF cap. PJ


Thanks gentlemen,

Between the explanation and measurement, should be able to secure the proper cap.

Best regards,

Jim Rice
Jim Rice

The height is the important one, as there is a short one & a tall one. Stant brand is the best on the market, either 4# or 7# but no higher.
Len Fanelli

Keep in mind that a higher pressure cap puts more pressure on core plugs that were originally designed for an unpressurized engine. If its running fine at 4 psi I would stay with that.
Jack Long

I must have got the short one, because it needs about a 3mm rubber washer to seal properly. I thought it was just my car being difficult - I must try to pick up a long one.


Well...I elected to get the 4 lb. one from Moss. I asked where they got them, and they said a source in England.....of course we don't know where they get them from! We'll see!


Jim Rice

This thread was discussed between 23/05/2016 and 24/05/2016

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