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[peejayel]

Help - 2.5 V6 Automatic 1998 (R reg)
Engine has started seriously overheating and loses water when it hits max. The radiator doesn't get even warm (most of the time) and before the problem started, the fan would continue running for a while after only a short trip and when the temp gauge showed normal. I'm assuming that its not a head problem as there are none of the usual signs like the milky deposit on the dipstick or the oil filler cap.
The big hose at the top of the rad (right hand side) is hot but doesn't seem to have any water in it.
Any suggestion would be very welcome

[STMO123]

When you say it loses water, can you see where it's losing it from?

[peejayel]

I think its coming from the overflow pipe

[STMO123]

Overflow pipe? Where, exactly, is the leak? Is it at the front of the engine or at the rear? The cooling system is sealed and pressurised and doesn't have an 'overflow'.

[peejayel]

Sorry, I assumed there was an overflow, not used to new fangled engines! Then I'm not sure where the water is coming from just that when it boiled up there was steam coming from the expansion tank side and there was water all over the road. Should I let it overheat to that point again to pinpoint exactly where its coming from?

[STMO123]

You do really need to investigate exactly where it's coming from. It may be  a hose which is leaking but does so only when there is sufficient preesure in the system to force the water out. It may not leak that badly when the engine is cold. Fill it up with water, switch on and let it gradually warm up. DONT let it overheat, just keep an eye on the hoses (please dont put your face right in there, for obvious reasons) and as soon as you spot the leak, switch off.

[hotel21]

Have you (or someone else) recently done any work on the cooling system or changed the antifreeze or similar?

As per the above post, if you spot a leak, fix it!  If the system is tight and dry, try the following as it sounds like a chunky airlock in the system.

Let it cool, top up the expansion tank to the mark then start the engine WITH THE CAP OFF and let it idle. Put the heater on max with the heater fan running.  

Regularly 'burp' the main hose beside the battery (squash it and release) to ensure that water gets pushed from the most extreme left hose into the expansion tank.  Keep an eye on the water level and make sure it keeps upto the mark.

Once its all hot, let it cool, top up the expansion tank if required and replace the cap.  Take it for a run and all (hopefully) should be resolved.  

[TheBoy]

If the dash gauge reaches 100C on the dash, you are in serious danger territory, so don't let it get that high.

So engine hot, but rad cold? Check:

Aux belt still there! And not slipping on waterpump pulley.

Airlocks, as per Hotel21's post above

Waterpump - shaft not spinning on impellors

Stat - normally fail open, but could fail closed I guess.


What is the recent service history, esp cooling system, of the car?

[peejayel]

That seems to be sensible, and something that even me as a complete engine dummy should be able to get to grips with. I'll try it in the morning and let you know how I get on, and thanks for the advice,  

[hotel21]

Who or what work has been done regarding the cooling system recently, please?