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[Entwood]

Hi

The indicated temperature as been slowly dropping since I first got the car 2 months ago. It was never hot - only low 80's on the engine gauge, now sits at about 75C

ELM327 arrived last week so spent today playing ... now have the following:

Starting from cold the top pipe stays cold until a sudden warm flow commences - indicating I think that the thermostat has opened. Temperature from ELM shows as 73C - which agrees with engine temp gauge - ish. This is with aircon in auto. It sits there without hardly moving whilst driving (damned difficult with the fuse cover open but we didn't hit anything !!)

Switch aircon off or ECO and engine temp rises to 85C and also stays there whilst driving.

Come to a halt (with OFF or ECO) and the engine temp very slowly rises to, eventually, (and it takes a long while) 97C when the fan starts, temp rapidly drops to 93C, fans stop and it cycles between 97C and 93C.

I'm thinking thermostat is opening way way too early and controlling at the "wrong" temperature... the question is ....

Given the expected difficulty in changing the thermostat, should it be changed? Am I doing any harm running at the low temperature - especially "long term" damage ? Especially as I'm going to have an LPG conversion done sooner rather than later.

Any advice / ideas gratefully accepted

[Kevin Wood]

That sounds pretty much what mine does. Possibly a little cooler but mine's rarely much above 80 on the move. Will have to look at the live data on mine as I haven't compared it with the gauge.

Kevin

[Big_Roger]

Hi,
Yours is behaving much like mine, but at slightly lower temperature.

Mine is usually showing 85 deg with air con on, 90 -92 on eco.

I connected my scanner on live data, and my temp gauge does not keep in step with ECU indicated temp which seems to stay around 90 irrespective of any settings, but goes to 95 idling in traffic.

It seems to me that the wax thermostats are very general in the temp range they are quoted at to operate, and have quite a wide hysterisis, and very slow response time.

It has always puzzled me why having the air con condenser fans on should affect the ability of the thermostat to keep the engine temp constant. I can understand that the water returning to the engine may be cooler with the fans on, but why oh why does not the thermostat shut down a bit to compensate?

 I can only think that we are expecting greater accuracy than they are capable of.
I did wonder if there was a cold climate version of the thermostat as there is for some Renault models, but my Vx dealer says none listed.

If the single fan behind the rad is operating at around the 95 deg range I don't think you have too much to worry about.

I have only had my car since Christmas, so I await with interest how it reponds to summer temperatures of 20 deg +

HTH

Roger

[Mike Collins]

Similar problem on my 2.6 last year, changing the thermostat cured it straight away.

If it were me, 'stat change now.

[Richard A]

The first 'key' to Omega engine temperture is the 'engine fan' cutting in at 97 deg which should switch on at slow speed. The thermostat is working if the hose changes from cold to hot quickly. According to 'model type' all cooling fans have two speeds, rare to have them run above slow. Took a 3 litre to the south of France some years ago, aircon fans on high, engine fan on low, temp outside 32 deg,  in stop/start city traffic. The fans and there speeds can be checked by useing the 'six pin' check.
regards
richard a

[Kevin Wood]

The temperature will always depend a little on engine load and the cooling effect on the radiator (whether the air con fans are running and / or the vehicle moving). When there is poor cooling on the radiator, the water pump is running slow or the engine is under heavy load the thermostat has to open wider to give more coolant flow through the radiator and since the thermostat opening is a function of temperature the engine must get hotter.

Many dashboard temperature gauges have a "dead spot" in the middle of the range to stop the reading fluctuating too much and worrying the driver! Mrs. KW's MX 5's coolant temperature gauge indicates mid range from a few minutes after starting until it's practically boiling over.

Kevin

[shyboy]

I wouldn't consider either the temp. guage or the sender unit to be precision instruments.

[Kevin Wood]

I wouldn't consider either the temp. guage or the sender unit to be precision instruments.

Precisely(sic.). I don't know why they put numbers on them, TBH. A red section that means "too hot" is all you need.

Kevin