Expansion Bottle Cap

[chromedome]

I am starting to lose a little coolant with the tell tale smell. There is no pressure build up apparent when I remove the expansion bottle cap. I have noticed a sign of some lime scale or water leakage around the cap, fine white power. I can't see a seal on the cap or bottle, should there be one?

 

Thanks

[insanitybeard]

It's not obvious or easy to see but if you remove the cap and look at the inside, where the circular black pressure relief valve insert is, there is an O-ring on it's outside surface part way down which seals against the bore of the coolant bottle neck. If this O-ring is deteriorated or the valve suspect it could be allowing some coolant bypass, so it may just be worth substituting the cap in the first instance and seeing if that sorts it.

[chromedome]

Thanks for the reply insanitybeard, I've ordered a replacement. I will go and have another look just in case I have a poltergeist......................................

[chromedome]

I found it. From what I could see it looked a bit flat at one spot. I have put some Vaseline on it as a temporary measure until the replacement arrives. I must admit the cap went on really easy with the Vaseline on.

[chromedome]

I have since found a coolant drip on the engine. Haven't got a clue how to reach it so my mechanic is going to have a look. it's around the thermostat housing area.

 

No driving the wife's Fiesta until I get it fixed, don't want it letting go all of a sudden.

[chromedome]

Pipe repaired and now no leaks, cut the damaged part off (about 15mm) and refitted as it was still long enough. The replacement pipe would have cost around

[xavier]

so is the cap OK in the end? I'm also leaking water from there but am getting abit of pressure build-up, however given that water should be incompressible it suggests to me I have an airlock somewhere.

[chromedome]

Cap seems to have been ok but left the new one on anyway.