Now you see it...Now you don't

[BennyWA]

I'm with Rodge on this one!! Mines doing it for a second time...

[Rodgebone]

just happen to be doing a rad this morning so will post a pic later so u can see what to look for

[bruggz351]

Thanks Rodge,
that would be grouse. Hope ya wrong though.
I'll have to find me reciept, might still be under warranty.

cheers

[Deezelweazel]

Is it a original thermostat? Or a cheap rebuild?
A popping thermostat is a thermostat that does not open smoothly, preventing flow. So as a result the engine boils because coolant exchange is way to small. Usually it opens but with a "pop" because the pressure of the wax chamber against the spring tension gets bigger and overrides the clamping force preventing the opening.

If you open the coolant system take out the thermostat and watch the proper opening procedure while checking it with a thermostat.

Hint: Don't use water- use sunflower oil, you can reach higher temperatures without boiling.

[bruggz351]

Originally Posted by Deezelweazel

Is it a original thermostat? Or a cheap rebuild?
A popping thermostat is a thermostat that does not open smoothly, preventing flow. So as a result the engine boils because coolant exchange is way to small. Usually it opens but with a "pop" because spring tension gets bigger and overrides the clamping force preventing the opening.

If you open the coolant system take out the thermostat and watch the proper opening procedure while checking it with a thermostat.

Hint: Don't use water- use sunflower oil, you can reach higher temperatures without boiling.

Thanks Deezelweazel.

Great hint by the way...

The thermostat I'm using is a Trident extra-flow 195*F.
I don't have overheating issues any more, just this odd leak. It hasn't leaked again since I tightened the top hose. Touch wood, I've fixed it. Had a long trip today and all good...
Oh also, I'm sure the thermostat is good as I run two temp gauges, the factory one and a after-market jobbie. The sender for the after-market one is in the top hose so it tells me when the thermostat opens. So far I have learnt, depending on ambient temp, it takes between 2 and 3 klm to get to running temp, or to open thermostat. It now, ALWAYS opens spot on 100 on the dash gauge. And, apart from the other day when it leaked, the e-fan hasn't been used since all the work was done. Its (the fan) full manual and just hasn't been needed.

Big thanks again to everyone, your collective knowledge is a godsend.

I'll be keeping a close eye on things for a while, just to rule out a couple of things suggested. If anything happens I'll let yas know..

cheers

[Hanoman]

I reckon Rodge is right on the money, same scenario, pressure test, leaking rhs tank, new Adrad radiator $385, problem solved.

[Rodgebone]

heres pics of a classic radiator failure on an XJ...this one actually puked at the top of the seam instead of along the side but its still typical (its always the driver side). might be good sticky photo Phil