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MG MGA - Radiator blow off

I finally put my 1500 roadster back together after 3 months. I took her out for a road test, about 30 minutes, and she ran flawlessly.

Parked her in the garage and noticed there was considerable blow off from the rad overflow tube. Could this be possible overfill of coolant when I installed the new rad? I was quite sure I used 1 1/2 gallons. Other possibilities?

Fran
F Valenzano

It sounds like it is overfilled.
Do not fill it according to a volume, but as shown in the Driver's Handbook (attached).
This is assuming that you still have the original long neck on the radiator filler.
Do not add coolant, let it cool and then drive it again and then let it cool again.
Does it return to the same position?

Mick

M F Anderson

Thermal expansion will make two gallons of coolant change volume by approximately one pint. If you fill to the top then run until hot and shut it off, this one pint of fluid will be expelled. Once cooled down it will leave one pint of air space in the radiator top tank. Leave it that way, do not overfill.

Unfortunately the MGA has an "L" shape filler neck, so it is difficult to see how much fluid in in the radiator when cool. My solution to this is to install a coolant recovery bottle, low pressure plastic type, so you can watch the fluid level rise and fall with temperature change, and you never need to remove the radiator pressure cap.
Barney Gaylord

I second what Barney says about the coolant recovery bottle Fran. A simple and effective device that takes away all the concern about how much coolant is in the radator. As long as your recovery bottle has some coolant in it, you radiator is always full, whether it is hot or cold.
Lindsay Sampford

This thread was discussed on 19/10/2010

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