Temp Gauge Rises When Motorway Driving

Hi there everybody, just joined!! Got A problem with my 166 2.5 V6, thought i'd try the forum before putting it in the garage for some (probably) costly repair. By the way loving the car!!

The temp gauge rises and the warning light comes on when im driving down the motorway, it seems ok when driving through town and even when stuck in traffic!! the fan kicks as normal (just above 90 degrees) and when driving down the motorway it kicks in constantly. Ive noticed its using a bit of water/coolant when this happens, but its fine on town journeys - CONFUSED!!!

Hope anybody can help!!! Please.

Obviously it's very unusual for a car to get hot when its moving as normally the airflow keeps it cool. Assuming you're not getting stuck in traffic on the motorway than the fist thing I'd do is check the oil level and also see if the radiator is blocked (check to see if its the same temeprature all the way around).

Possibly the plastic water pump impellor is cracked and slipping at high speeds...a known V6 problem.

wrinx

hi there, thanks for the reply. Do you know if theres a way of checking the impeller on the water pump?
cheers

how many miles has your current waterpump done? Check radiator carefully for external blockages to air flow...dead flies and dust and crap.

Mike

thanks for the help, will check the radiator tomorrow. obviously the cold air is constant when driving. Its not due to being stuck in a motorway traffic jam. Maybe a stupid question, but what does the oil level have to do with the cooling?

not sure how many miles the pumps done, iv ive just bought it a couple of months ago. its covered 108,000 miles. ive got all the service docks and reciepts ( i cant remember anything on them for a waterpump change). just had a coolant and oil and filter change though - does it matter what coolant is used??????

mark

If the car is loosing oil or is low on oil the engine will get hotter, which will cause a rise in the temp' gauge (obviously if the car has an oil temperature gauge you'll notice a rise in this first of all). At town speeds the oil is unlikely to get very hot, and so won't effect the overall engine temperature noticeably, but at motorway speeds the oil will get hot, and the less oil there is, the hotter the engine will become.

Things to check:
faulty thermostat - default sticks open but it could have stuck closed
faulty rad - check the temp allover, blockages or missing fins - the wafer thin metal stuff, it does corrode badly.
Check all the hoses - whre's it losing water from? If you can't see any white deposits at a join then it could be the pressure relief valve ontop of the coolant reservoir.
Check tensioer on aux belt - could slipping on water pump.
Checking impeller? - well you have to take of the water pump I think - don't think you can get access to look or check via any hose.

I don't think its really loosing water as such. It sounds like its loosing a bit when its got hot, but that's normal and it will be coming out the expansion reservoir.

could also be binding brakes - what mpg are you getting?

possible, been getting about 20 - 30 mpg depending on journey type.

Originally Posted by couling78

possible, been getting about 20 - 30 mpg depending on journey type.

Not the brakes then - that is normal mpg

with reference to checking the water pump. ive noticed theres a flow of water back into the resevoir (most probably a return feed). This is constant when the engine is ticking over. If I increase the engine revs would the water flow increase? thus ruling out or pointing to the pump -- any ideas??????

mark

Well, if its not the oil the water pump is the most likely cause...so check the oil first as that's easy, and if that looks okay then its probably the water pump.

just remembered a point with the fault. Once i stop the car and turn off the ignition and then turn it back on again the temp gauge moves back to the 90 degree mark (from full with warning lamp on), once i move off again and regain speed it starts to move up again (depending on the speed being driven at).

How long would the car have been stopped?

hmmm - could it be a dodgy temp sensor?