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[Strangechap]

Ever come across this before?

Usually when sitting in traffic, but also sometimes after a fast run, followed by some driving at 30mph, my temp gauge creeps up until it pegs out and the red light comes on.

First few times it happened I'd pull over, heart pounding and switch off.

I wasn't convinced it was actually overheating, as the fans don't come on.

So I wondered if it was the fans, but the fans do work, they often kick in and I see the needle drop as it should.

I started carrying an infrared thermometer and when it happens, I'll pop the bonnet and take the temp of the top hose. Which will be 90-95. Not far off what it is 'normally'.

But upon experimenting, I've found that when the needle pegs out at max, all I have to do is stop (I'm usually in traffic) pop it in neutral (it's auto) turn the engine off, then start her up straight away and the needle will instantly go back to the 'normal' temp position, and stay there. The fans stay off.

Makes me wonder if it's not actually getting too hot, but an ECU is getting confused and turning off resets it.

The needle literally drops 10 degrees in a few seconds. No way it would cool that quick if it was overheating.

Cooling system is in good order, all fluid levels as they should be.

Anyone ever experienced this? Any ideas?

Cheers,
Tim

[Strangechap]

I think I should have posted this in 'Omega General Help'. Apologies for being a numpty. 

[Broomies Mate]

Strange Car for a Strange Chap! 

Coolant Temperature Sensor is duff. 

EDITED TO ADD: Guide is here -----> http://www.omegaowners.com/forum/index.php?topic=113765.0

[05omegav6]

Strange Car for a Strange Chap! 

Coolant Temperature Sensor is duff. 

EDITED TO ADD: Guide is here -----> http://www.omegaowners.com/forum/index.php?topic=113765.0

The V6 has two temperature sensors, one for the gauge and one for the ecu. Both sit on the coolant bridge.

It also has two thermoswitches on the radiator... Both part of the fan control system.

Also see the fan test guide that BM has linked to... It's in the maintenance guides

[Kevin Wood]

I actually wonder if the dash is faulty.. or the connection to the coolant temperature sensor is intermittent (try that first, as it's easiest).

[Andy B]

grounding the blue wire from the sender should give a full deflection to HOT on the guage

[Lazydocker]

I had the same... Changed the rad (was planned anyway as missing some fins) and it never did it again

[TheBoy]

If its post 1998, it has been known for the dash to lose its config, which causes high temp readings.

[Strangechap]

Thanks chaps, all good advice.

It is a 2000 on a W.

Yes, I am a bit strange, just like my car lol.

Ok. I will work through all those tips, starting with the easiest first.

Don't you just hate intermittent faults though, I can never guarantee that it will misbehave at any certain time! Although to be fair if it's going to do it, it's when I come off the A404m at Marlow and sit in the traffic on the off slip for 20 mins. (when I'm trapped by traffic if it DID overheat!)

I'll let you know what I discover. Hoping its that sensor or the connection. I need to change my cam cover gaskets again in the next couple of months, so will have the inlet stuff off for that.

Thanks again!

Tim

[Broomies Mate]

I need to change my cam cover gaskets again in the next couple of months, so will have the inlet stuff off for that.

Thanks again!

Tim

No offence, but you can change them week in week out.....  You need to clean the breathers and breather box, else you are pissing into the wind.

[Kevin Wood]

I need to change my cam cover gaskets again in the next couple of months, so will have the inlet stuff off for that.

Thanks again!

Tim

No offence, but you can change them week in week out.....  You need to clean the breathers and breather box, else you are pissing into the wind.

.. and use genuine gaskets. Most pattern ones are very poor.

[Strangechap]

No offence taken. I cleaned the breathers when I fitted them, then again about 6m later, but they were still pretty clean.

The last gaskets I fitted were Vauxhall ones and they lasted about a year before I started getting that burned oil smell again, so I put up with it for ages, then took the covers off to see what had happened and they had gone really brittle in places. (the breathers were a bit gunky this time, but not blocked like the first time)

I was skint, so I took the gaskets out cleaned them up and slathered some hermetite red all over the place and they've been ok for another last year or so, but now it's smelling again.

I'd expect genuine ones to last longer than that surely? 2 years with pretty clean breathers?

[Kevin Wood]

Yep, I would expect genuine gaskets to last a good few years.

Note that many suppliers quote genuine parts yet actually supply parts from other suppliers "who originally made them for GM, honest, guv".

The safest way is to buy from a dealership.

Also, the only reason mine failed in the first place is because the cam cover bolts loosened. Worth checking them at each service.

It's also worth blowing through the complete breather system to ensure no blockage is present.

[TheBoy]

It is a 2000 on a W.

Any members local to get the CI off the instrument panel?