coolant loss

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Coolant is escaping - the level goes down a little with each flight. No leaks around the hoses. It seems to be going out the overflow tube, which is wet. How can that happen?

I have to taxi a long way downwind, and the coolant temp goes into the yellow. Is it boiling?

Inside the expansion tank, the surface where the cap makes a pressure seal seems rough; maybe it isn't sealing. Could that allow boiling at a low temperature? New tank costs $400.

Any other ideas?

 

[Darin Watson]

Head gasket leak or cracked head

I hate to say it, but if you are lucky it’s a head gasket leak and if you are unlucky a cracked head. Either can leak a little glycol into the combustion chamber with no outward sign of where it is going.

 

[Piper J3]

A few questions….

What year is your 12? Is oil cooler mounted with very little clearance in front of muffler? Most 12’s have oil cooler relocated forward of muffler by 1” clearance which solves most elevated oil temp problems.

Check weep hole at bottom of water pump to see if ceramic seals are leaking coolant.

 

[Amadeus]

-12 or -12iS?

If -12iS check the radiator itself.
Check where the bottom fins attach to the radiator frame.