High temp gauge reading on MK2 Golf

[AllanCooper]

I have searched the forums and cannot find the answer - can anyone help please?

I have an 1989 F-reg Mk2 Golf Gti 8v PB engine. Recently due to coolant leaks and no heater I have replaced the thermostat and blue temp sensor. The temperature gauge has been erratic until I recently found RubJonny's advice re running the car until hot to remove any air leaks. Initially the temp gauge was sitting around 1/2 but this week it has been sitting just near the first of the two spots on the v hot side. The oil temp seems right from other posts on forum.

I bought a new two speed switch for the radiator fan, and the fan seems to kick in at just over 1/2 way. After a 15mile run either early morn in the cold or end of day when its been hot this week, the temp gauge is right up there, yet I was able to remove the expansion cap carefully and nothing happened!? I have not seen the fan on top speed, although maybe it should be.

I don't seem to be losing any coolant at all now.  I am wondering if maybe the water pump needs replacing? Is there any way to test the coolant temp to check if the gauge is working properly? Strangely the temp gauge has only started working again after a long break, recently after sorting water leaks.

I have read about replacing BOTH temp sensors on front of engine but have only been able to change the blue one. I have a coolant flange on the front of the engine which houses two push-in, round ended, square plug topped sensors; the rear one is blue the front one is old white colour - it's this front one that I cant seem to get a replacement for - if indeed it needs replacing. Part shops only seem to offer a small pin-type sensor which I think maybe for older cars?

Any help as to how to check if the coolant temp really is as high as the gauge says, or to check the gauge is working properly would be appreciated. Thanks!

[gazareth]

my e reg 8v was like that. the gauge would go up to 3/4 before fan came on. but on my g reg it only goes 1/2 way before fan comes on. no problems with either of them. if all else is working as it should I wouldn't worry about it.

[AllanCooper]

Thanks gazareth.
Trouble is I really would not like to get stuck in traffic as it is. I would have expected the gauge to sit firmly in the middle - and it is not normal (for my car) to be up near the high point.

To be honest it has been doing my head in. When the gauge is up in the high point and you take the blue cap off, nothing happens - I would have expected it to at least hiss. I just wish I could either get the gauge to read right - if its wrong - or get the temp down if its running high...do you have any hints?

[Gti_Jamo]

Is the coolant system pressurising sufficiently?

[Sgt_Lemon]

What colour is the cap?

[gazareth]

What colour is the cap?

reply no2. second paragraph sgt.

[gazareth]

if it was actually overheating the water would be gushing out when cap is removed. I would run it up to temp until fan comes on. then once fan stops check both rad hoses with your hand. if you can hold the hose quite comfortably then all should be fine. oh and the second speed on the fan very,very rarely comes on so don't worry about that one. but you should get a hiss at least when you remove cap whilst engine is hot.

[gazareth]

oh I was meant to ask. was it the same degree rating of thermostat that you fitted?