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MG TD TF 1500 - Slight leak from radiator cap.

I have the slightest of leaks from my radiator cap. This is evidenced by a small dribble of fluid running down from the cap and light spray splatter on the hood after a drive. The cap is on as tight as I can get it by hand. Is that sufficient? I see advertised these wooden spanner type devices for tightening the cap. What puzzles me is that as I understand it the cooling system is not under pressure and that there is an overflow. It seems odd to me that coolant is being forced past the threads of the cap? Thoughts anyone?

Thanks
Simon
S Griffin

Are you using a rubber O ring? Could be time to replace it. I cut one from some compressible rubber for the TD.

Matthew.
M Magilton

Simon, you might want to check to see if your overflow tube is blocked. Try running a piece of wire up from the bottom of the tube. The big O-ring should handle that with no trouble. The system is normally open, with no pressure. But, there is some sputtering right after turning the engine off when it's fully warmed up. And, the the end of overflow tube is in an area of airflow that will can the coolant onto your fenders.
http://www.ttalk.info/Tech/Overflow_tank.htm Bud
Bud Krueger

Above good ideas. Has the car just been restored or reassembled? There has to be clearance between the rad cap and the chrome false nose, otherwise it tightens on the chrome rather than the o-ring. Of course check all sealing surfaces for gunk/burs, etc. Don't overfill either. There needs to be quite a bit of air space, unlike a modern pressurized car. Geroge
George Butz

Simon,
If the overflow tube is clear, and the O ring is in good shape, lets go "out of the box",, Might there be a crack where the neck of the rad (where the cap screws into) attaches to the top radiator tank ??

Steve
SPW Wincze

Ha, thank you. No O Ring at all! I'll blame the DPO :-) The DCO had failed miserably to notice the O ring on the parts suppliers web sites. Curiously it is not shown on the cooling system/radiator section but on the rubber parts, hence I missed it. I think I will explore some form of overflow catch system as described on Bud's site.

Best wishes
Simon
S Griffin

The o-ring is obviously critical to sealing that part of the cooling system, but I have found that TC/TD radiators pretty much reach their level, and stay that way. An overflow bottle is not really necessary, in my experience.

I fill the system, drive the car for a bit, and then measure the level in the radiator. If I add more coolant mix, the next time I drive the car it just drops to that same, original level, so that's where it is happiest.

Tom Lange
MGT Repair
t lange

You should have checked the Abingdon Spares website! 19-103 Sealing ring is shown in the chassis section with the other components of the radiator, and also on the rubber parts section. We also have the cap wrench, 59-019Q. It does add an extra bit of force to tighten it up.
EC Cooke

Not only did I check the AS web site, but I ordered the part and received it yesterday, once I figured out it was not on the Cooling System page where I would have logically expected it to be.
S Griffin

Great,glad we could help,and thanks for your order.Logic is a relative term when discussing MGs!
EC Cooke

Finally had a nice day and was very pleased to find that the leak is gone with the introduction of the sealing ring. Also the fuel system is now not leaking as a result of various other goodies that I picked up from Abingdon Spares. Slowly but surely I am getting the car sorted with the little things that needed doing.
S Griffin

Thanks for letting us know. Every repair that works is worth documenting, even the basic ones!

Tom Lange
MGT Repair
t lange

This thread was discussed between 02/01/2017 and 22/01/2017

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