3.9 V8 Disco - Cloud of steam, but not hot on guage

Automatic gearbox/torque converter slipping too much under load? The oil might be cooked - not the cause but a possible consequence.

I'd be fitting a Kenlowe sharpish. Normally if the autobox is getting hot you'll get the dreaded "Transmission Temp" light coming on.

Sounds to me like the ignition might be too far advanced and the motor is just working too hard. Kenlowe and a tune might cure it, otherwise it's going to pop a head gasket or crack a head pretty soon if you keep doing it.

On or around Wed, 02 Apr 2008 01:45:55 +0100, Pete M enlightened us thusly:

TBH I'd be checking the compressions anyway, sounds suspiciously like an incipient head gasket

The disco here overheats, on the gauge, when asked to work hard - I reckon it needs a new rad.

With the cap off I wouldn't expect the gauge to indicate more than normal as there is no way for the pressure to build up and thus raise the coolant temp above 100C.

The cap shouldn't blow off, assuming that is what you mean by "has blown the header tank cap", rather than just venting excess pressure. In which case I would expect the temp gauge to indicate hot...

Inspect all the fixing lugs or threads, seats etc on the cap and header tank for broken/bent/missing. Not sure how you could test it's vent pressure. How much is a new cap?

Liners? Head gasket(s)?

Martin

Agreed. A new cap will be less than not much, and is the first thing I'd look at. If the cap isn't keeping the required pressure, then the gauge will read normal but coolant/steam will escape under load conditions - excatly the OP's symptoms.

My money is here too. I can even dig out the shirt though it's sponsored by Renault Espace.

Lee D

I'd check the thermostat .. have seen this on a V8 before. It spat its dummy out 3 times on a long journey. We removed the thermostat and it was a happy engine again. There was no indication of it overheating because it was essentially boiling the water in the "other" half of the engine....

A few pence.