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Can a hose leak when hot and not when cold? Also stat house seal failure


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Forty year old coolant hose ?! Standard hoses - the rubber & braid type - often become porous after about ten years dependent on the under bonnet temperatures & cold/hot, hot/cold cycles of the cooling system. The failure points are generally at the point where the jubilee clip compresses the material & tight bends.

And yes they will leak cold & hot.

Silicone hoses are the good solution if one can find the correct shape.

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IMG_7303512px.jpeg.29932c2c50de4dffaf19119ef3997647.jpegit seems all hoses were replaced in the rebuild , I believe they are all silicon, except the one to the overflow, which I have now replaced. However, still hunting for the cause of the loss of system reduced pressure allowing atmospheric pressure to push back the overflow content in to the system. No leaks and the unreturned coolant exactly matches the coolant "loss" in the system when I put it back in (using a syringe).


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My current air leakage suspect is this:


all those wrinkles of age..  so I have applied so far two layers of make up and we look younger:


granted this is a last resort short of replacing the stat housing - which I will do if this works edit or anyway



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I found this diagram that explains things, so my problem is the vacuum valve operation suffering from air ingress which cancels the "vacuum" and so fails to draw back coolant from the overflow tank (yes, technically pushed by atmospheric pressure). I have replaced the very old hose, the cap and that leaves only the stat housing as pictured above.


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