Water Temp - is it right?

[timmaaah 0]

My normal journey to work is a fairly constant 60mph (!!). When I bought my car a few months ago, with the nice weather, the car would heat up to just over the 70 mark, and stay there. Now, with the colder weather, the temp guage hardly seems to get off the rest. I get hot air from the vents after just a couple of mins. If the car sits in traffic, the temp will climb up to 90 and stay there, only to drop back to 70 when back upto speed. I've tried the search, but can't seem to find anything. So, any ideas? Thermostat? Sensor fault? Or should I not even worry? Don't know if the temp gauge will affect how the car runs? Help - please put me out of my misery!!!!

 

Oh, by the way, I'm a bit green when it comes to 'fiddlin' in the engine, but willing to give it a go!!

 

- '94 VR6 by the way!!

[Walesy 0]

Although i'm no expert on the vr6, that sounds like a blue temp sender foofed, I had exactly the same problem with my ole 8v .

[dr_mat 0]

Sounds like the thermostat is stuck open to me ...

[NickVR6 0]

Yep, likewise with my 94 vr. Changed the blue jobbie that sit by the side of the rad iirc. Now it slowly creeps up to 85-90 (or just under in this weather) and stays there. Goes up to 100 in traffic but drops down to above when fan cuts in you get some speed back up again. Worth a shot as that sensor is fairly cheap in the scheme of things.

 

Actually matt has just reminded me i had the stat and housing done at the same time so it could of been either!!

 

Out of interest what oil temp does your mfa show mate??

[Walesy 0]

Actually matt has just reminded me i had the stat and housing done at the same time so it could of been either!!

 

 

Yeah, me too!...the stat sticking open does sound like it could be the cuplrit aswell :wink:

[dr_mat 0]

Had exactly the same symptoms on an old cavalier once - it was the thermostat stuck open.

And let's face it, why would the blue temp sensor read correctly while sitting in traffic and wrong while moving at speed?

[NickVR6 0]

I presume the sensor could fail in such away as to be inacurate at low temps, ie prob where voltage is lower if thats how it works, but i think matt is right about the stat for sure and again, its peanuts to buy.

 

Stat housing wouldnt re seal on mine, and it turned out to be cracked and warped i beleive. Its a pest to get down there twice if as you say your "green" as i was. Might be worth getting the stat and housing. Not trying to get you to spend more, just letting you knwo what my experience was.

[gibber 0]

I have a lower temp thermostat and thats how my VR behaves.

 

So I would say you eiher have a stat stuck open, is there anyother mods to the car that would sujest the opener mite have bought a lower temp jobbie?

[timmaaah 0]

Only mod is an induction kit - oil temp normally around 80 - 85 degrees. I suppose there's no way of checking the stat unless you get it out - as it were!!! I'm getting heat from the heater, and the engine seems warm after only a couple of mins. Will the temp sender affect the fueling mixture or anything - or should I not let it worry me?

[gibber 0]

I wouldnt be worried myself.

Best way to check if you have a faulty stat, start you engine from cold and see if both your radiator water pipes get warm at the same time.

The stat should stop the water flowing throught the radiator till your car gets up to the temp of the stat.

[dr_mat 0]

I'd get it fixed. The engine is designed to be run with water temp > 80 deg. That's what the thermostat CLOSES in the first place for!

[timmaaah 0]

Ok - I'll check the hoses in a bit. If it is the stat - how big a job is it - I'm guessing not a 10 min job?

 

Prob goes like this: Drain system, skin knuckles getting to a really inaccessable bit of the car, put new stat in, re-fill system - start car - car over-heats coz I've put the stat in back to front - curse, and start all over again? I know that sounds like I'm talking from experience, but that was about 10 years ago on an old Sierra!!!

[dr_mat 0]

I got Stealth to change mine .. ;)

(In fact, they only changed it cos it had to come off to do the timing chains ..)

[Kevin Bacon 5]

Timmaaah, try cleaning up or replacing the yellow temp sender in the thermostat housing first.

[Roger Blassberg 0]

Yes, yellow one controls the temp gauge. The blue one tells the ECU what the water temp is. Quite easy to change it, make sure you change the sealing ring and the retaining circlip as well. Just be careful - the housing for the sensors is quite fragile. Have a litre of G12+ to hand because your coolant will fall out when you remove the sensor.

 

Best wishes

 

RB

[StuartFZR400 0]

All the above is right Timmaaah.

 

Start off by taking out sensors and cleaning them, clean thermostat ; if problem still occurrs then replace - quite cheap !

 

You are right to be worried, but the biggest worry is engine temp which must reach a minimum of 100 before you drive it firmly - ok. You dont want those sensors keeping the fan on and water running if it makes it cooler than that said.

 

Now just make sure it doesnt over heat :lol: