Engine 850: B5234T/2.3/20v/T5: '96 T5 - Overheating

[GMC]

Whilst driving on the motorway today, I was aware the temperature gauge was higher than usual, and continued to rise towards to red over the next 6-7miles!

As I stopped, steam started to appear from the expansion bottle.

When the bonnet was lifted it became apparent that the engine & water was extremely hot, infact, it took about 10-15min of gradually releasing the screw cap before it could be removed.

Water was added, but the car started overheating within a mile, so was stopped immediately.

On each occasion, I noticed the radiator top hose was roasting, however the bottom hose was only mildly warm?

The car has 105,000 miles and has had no previous overheating problems.

To me, the problem is one of the following:

1. Thermostat failure (jammed close)
2. Blocked radiator
3. Water pump failure (impeller failure perhaps)

Has anyone experienced any of the above problems, or are any of these common on the 850 T5?

Thanks!

[Psychobiker]

heh, the irony! I've just replaced my temp sensor AND thermostat. It certainly looks like your thermostat has failed closed. Piece of cake to change

[bb54]

was it a long time into the journey that she overheated ?
reason i ask is... if so, the therm would have been open.

i read alot about the grey expansion tank caps releasing pressure and water causing overheat, they should be replaced with the green E,T,C.

i have a grey on mine with no probs, but i will replace with green.

it may have just been an air lock after the coolant refil that caused the second overheat.

food for thought.

wayne.

[Sprintman]

Hi GMC, I had the same problem some months ago, the thermostat failed closed after about 20 miles into the journey. The 'stat is dead easy to change - if you have male Torx sockets to undo the bolts. Be VERY careful not to drop a bolt beside the housing when replacing, they can get lodged down below and are a b****r to get out again as I know from experience! I've also had a grey cap on the expansion tank until recently [only changed 'cos I got a green one off a scrapped car] and never had any problems with it. Hope you get it fixed OK.