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

Curious problem with my Disco whilst dragging the caravan last week.

Had done over 100 miles with no problem. Dragging up a slow hill, i got a quick puff of steam when I lifted off at the top of the hill, but as I had just driven through a load of water on the road i thought i had spashed something hot.

about half a mile further on, i notice more steam so pull over. coolant has blown the header tank cap look, and is bubbling out. However, the temperature guage never got above the usual mark.

Wait for it to cool. Top it up and set off. Going up another big hill, and as i lift at the top, pop she goes again!

Again no movement on the guage, just the sudden blow.

Wait for it to cool, top it up. Run for 5 mins at fast idle with the cap off, top it up a couple of times, but no bubbles or anything else. so we setoff for the campsite (only a couple of miles away.

All is fine for the rest of the week, (gentle running, but still a couple of big hills.)

Fine on the way home, but 200 miles of towing uses a coulple of litres of coolant. Running without the van does not seem to use much if any at all.

Any ideas for a cause, or what to check before my next trip out with the van?

cheers,

MW

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

Reply to
jg

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.

Reply to
Pete M

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.

Reply to
Austin Shackles

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?

Reply to
Dave Liquorice

Liners? Head gasket(s)?

Martin

Reply to
Oily

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.

Reply to
Rich B

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

Lee D

Reply to
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....

Reply to
Neil Brownlee

A few pence.

Reply to
hugh

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