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

[anthonym]

Can a hose leak when hot and not when cold? This hose could be nearly 40 years old and is chafed.

Given heat makes things expand, my guess is yes. But I need to know for sure.

Anthony

[Jonathan Kay]

Yes. What's it made of?

And of course it's connected to other things that can be affected by temperature.

Jonathan

[ScottR400D]

That's when they're prone to leaking. Hot hose is softer, system is under pressure.  
 

40 yo?? Due a change then I would think!

[anthonym]

thank, yes indeedy, changed this evening, t'other thread; this was just a specific I was desperate to know :-)

[jbcollier]

Dont 'run a car with 15 year old hoses, never mind 40.

[Geoff Brown]

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.

[anthonym]

it 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).

[anthonym]

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

[OldAndrewE]

Is this the housing you have Anthony?

Special thermostat housing: X/Flow, pre-X/Flow, Lotus Twin Cam & Raceline water rails (burtonpower.com)

I think Redline has them as well

[anthonym]

thanks, duly ordered one - that pristine circle where the seal happens is calling to me loudly.

given my search is for leaking seal(s)

[anthonym]

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.

I

[John Vine]

Hi Anthony,

Had you considered flat-sanding (linishing, even) the sealing surface of the housing?

JV

[anthonym]

Hi John, seems I omitted to post my reply. Yes I thought about it, but a new part is easy and inexpensive .. and ordered. I might see what I can do with it once it's off the car. 
 

what's linishing"? 
 

anthony

[John Vine]

Linishing.

I was thinking you could remove the housing and sand down that sealing face on a flat surface covered with abrasive paper?  If there's too much metal to remove by hand, a local machine shop would have a linishing machine.

JV

[anthonym]

as it happens I discovered such a shop today; I'll enquire on my next visit. a.

 

p.s. new stat housing has arrived 

 

[SM25T]

Waiting for report on fitting and testing.

[anthonym]

due to heat wave I never tested it, and for under a tenner a new housing seems wise.

[anthonym]

curiosity wins: ok so I "screwed" the cap on to the removed old housing and undid it, several times. It went on smoothly and no damage at all to the layer of sealant. That says to me it would have worked.