Overheating revisited

The comments on 'overheating' have been very helpful - thanks.

Where I am is this:

- the needle is mostly in the middle, though it does go for a wander at times.
- when I short the top temp sensor the two engine bay fans come on.
- when the engine bay gets hot, the turbo extractor fan comes on, but the air intake fan doesn't.
- when I short the bottom sensor, the red warning light in the right comes on.

Weird. Why would the two fans not come on automatically?

Any thoughts?

It doesn't seem to take much to activate the temp sensor...once the engine is warm, 5 mins of reasonably spirited driving would do it.

PS - BIG_MVS. I did try to load up some photos, but they seem to be too big to attach. Sorry!

Colin

Ensure turbo cover is fitted and that no bolts are missing allowing hot air hit sensor,
Secondly ensure sensor is not bent towards turbo.

Dave

[mettersl]

And check that the lower rated sensor is the one at the top controlling the fans, and that it works...in the oven at home maybe?...I am not sure that they are waterproof.....

Thanks guys.

Metersl - if the left fan is coming on with the sensor, I don't understand why the right one is not, when shorting the sensor puts them both on. The sensor must be a switch I think. I'm mystified!

I'll check for missing bolts, but the sensor isn't bent.

Colin

I have two different circuit diagrams of the rear engine bay fans, covering the GTA turbo depending on model year..... can you tell me what year yours is?

And were you able to read the temperatures stamped on the rims of the two sensors like I suggested you did in your previous "Overheating" post?

1987

I tried to find a threshold temp on the collar but couldn't see anything.

If you short the top sensor you will get 12volts to the fans. When the car is running if the temp is high the fans will run at 6 volts so i think you have a fan that needs oiling as it is sticking at 6 volts

If you short the top sensor you will get 12volts to the fans. When the car is running if the temp is high the fans will run at 6 volts so i think you have a fan that needs oiling as it is sticking at 6 volts

Andrews has a good point if your Alp is the 1986 model year..... yours may have been first regesterd in 1987. All sucessive model years did not have the 6 volt fan running facility.
So question is..... has your Alp got an oil temperature sensor mounted on the off side of the sump?

Dec 87 I'm afraid!

Back to the drawing board...

Colin cars as late as 1988 had the 6 volt as well check if you have an oil sensor in the sump that will tell you

Colin cars as late as 1988 had the 6 volt as well check if you have an oil sensor in the sump that will tell you

Andrew, what you have said is quite interesting. I have every Model Year Wiring Diagrams for the GTA's (1986.... 1987 to 1988.... 1989.... 1990) and only the 1986 shows the 6/12 volt mode. But as we both has asked, the Oil Temperature Sensor in the sump will either prove the manuals to be right or wrong, OR.... there are 1986 Alps out there that were regerstered or reimported well after 1986. We wait and see. (looking for confused smiley. ??? )
Over to you Colin.....

Brilliant. Thanks guys...I'll have a look.

Was quite amused to see from the logbook that the first owner took delivery the week before Christmas...a little gift to himself!

Colin