Boiling when stopped?

[Alun]

Just drove up the road to drop little 'un off (approx 5 miles).

When I returned to surf it was boiling in expansion tank. (engine not running)

Drove home worried, jumped out with it running, no boiling.

Any clues?

[NiftyNev]

When cold remove thermostat housing cap and check the coolant level.If ok check expansion tank and top up to approx half way if needed.May just be faulty cap.If unsure how old it is replace immediately.There will be slightly more pressure in cooling system immediately after switching engine off because the coolant is no longer circulating.This is why I suggested replacing cap as you said is was ok while running.

Neville

[Billy-knu]

I've been through all this with my 1993 2.4 SSRX. I asked all the questions on here - people were very helpful. In the end, the boiling was compression getting into the cooling system via a crack in the head....
New head, gaskets, belts last month - £1400. It kept going, sometimes playing up worse than other times, for 4 months, until it finally gave up...
Sorry.

[NiftyNev]

I've been through all this with my 1993 2.4 SSRX. I asked all the questions on here - people were very helpful. In the end, the boiling was compression getting into the cooling system via a crack in the head....
New head, gaskets, belts last month - £1400. It kept going, sometimes playing up worse than other times, for 4 months, until it finally gave up...
Sorry.

You may be correct but -

Always check the simple things first.After all you don't amputate your leg just because you have a sore toe.

Neville

[Snortingbull]

I had the same problem with another toyota engine (not my surf), bought new cap, flushed out rad, bought Toyota cooling fluid, still boiling out off the header tank. So i took the head off and found the gasket gone across two cooling ports, replaced gasket no more trouble.
The engine never ran hot untill all the coolant was gone! I never thought it was the gasket but it was.
I hope this is of some help.
Mark.

[da SLUG man]

have you been off road? could be muddy rad?... poor airflow

[TonyN]

Could easily be the rad cap as mentioned before, when the water stops being circulated when the engine is turned off, it get much hotter for 5mins then when running, if the cap is duff will blow past and fill the expansion tank (what it should do! but not as badly)

A blown gasket/cracked head won't pressurise the cooling system when the motor is switched off, only when running.