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TR2/3/3A TR3 Coolant coming from overflow

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CCURTISS

CCURTISS

Jedi Hopeful
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I have a TR3 small mouth and it was running under 185 with an outside temp of 78 and I noticed I had coolant coming from my overflow. I opened the cap and I can see coolant though it is not all the way to the top. Is this normal expansion or is there another problem brewing?

I did recently change the coolant and filled it to the top and I do have a new cap and hoses.
 
Hey, Curt -

What's the pressure rating on the cap? Should be low - 6-7 lbs., maybe...
 
According to the Moss catalog the TR3 calls for a 4LB cap so that is what I purchased. Any harm in going with one rated at 6 or 7Lb's?
 
I knew it was low - probably best to stick with the 4...
 
CCURTISS said:
I have a TR3 small mouth and it was running under 185 with an outside temp of 78 and I noticed I had coolant coming from my overflow. I opened the cap and I can see coolant though it is not all the way to the top. Is this normal expansion or is there another problem brewing?

I did recently change the coolant and filled it to the top and I do have a new cap and hoses.
Click to expand...
This is normal. When the water heats up, it expands and it has to go somewhere. Modern vehicles have a catch tank and when the engine cools off, it sucks some of the water back it. On these oldies the water just runs out the overflow. When you take a look in the radiator, you will see it is no longer totally full when cold since the water will have contracted again.
 
:iagree:
The normal level, once it has sorted itself out, is a couple of inches below the filler cap. You should be able to see some coolant when you remove the cap.
 
About 1/4" in the bottom of the filler box is the correct level. If you think about it, this is the height of the top of the header on the radiator. Since this filler box is sloped, you want to see no more than 1/4" when you remove the cap. The cap should be 4 psi.

If you add more water than this, you will get the excess to overflow out the tube as you already know. When it stops flowing out the overflow tube, you know that it has reached the normal level. And it will stay there unless you have a leak. So check the coolant periodically.
 
I run 7 psi in my TR3A with no problems BUT I also removed the original Smiths heater. If there is a weak link in the system, that's it.
 
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