MK3 Golf 97 Coolant Temperature not moving up

[mecind]

hi
i just found out my temp. gauge is not moving up even on the 39 degrees last few days ago and i had been driving for more than 30 minutes.
when the car is stopping the needle moved up to 70 but again dropped down to the cold bar when the car is moving.

the mechanic plugged his scanner, with the car air cond. is on (it's not working (not cold) by the way) and his scanner displayed 56 degrees which is about similar to the gauge in the car.

he said it could be the sensor, but needs more time, so i booked for next year because
i need the car.

the car also has red colour/white powder stuff under the engine ,maybe under the thermostat? and i have to top up the coolant every week.

anyway where do i get the sensor that he is talking about? can i get from ebay/aliexpress?
what part number, or how do i tell it's the right part?
any links to the part please

according to the rego, it's year 1997 , Model GOLF94A, Engine Capacity 1984.0, Engine Number AGG176100

so what is my car? is it Golf MK3?

[mecind]

it's a hatchback GL

[birdman]

With a stuck open thermostat i'd guess.

[feenix74]

And a leak in the coolant system somewhere (the red/white powdery stuff is dried coolant). Usual areas to look at are where the coolant pipe flange mounts to the engine block and around the water pump.

[yowie]

You can get parts from lots of UK and Ebay places or locally call Tooleys, they are usually pretty good on price and delivery. Not sure I'd want my parts involved in the Xmas rush. You will need your VIN to order.

Also check when the coolant was last changed.

Your mechanic can test the fluid if its not in your log book. (Topping up doesn't count

There are dis-similar metals inside your engine and coolant stops a variety of bad things from happening, but it wears out.

[mecind]

Thanks all. Is this the right coolant sensor?
VW Golf III IV Passat Coolant Temperature Sensor 1.8 2.0 357919501A 6U0919501B | eBay

this U.K. Is much cheaper and has yellow ring similar to mine. But there is no gasket.
VOLKSWAGEN GOLF MK3 2.0 PETROL (1994-2002) COOLANT WATER TEMPERATURE SENSOR | eBay

[mecind]

Anyone need help with small electronic work? I may be able to help.
i have resoldered the pins in the cruise control board and it's working now.

[feenix74]

That coolant temperature sensor should be the right one but it may not fix your problem. If understand is correct (I will happily take a correction from a more experience amateur or a professional mechanic) the Golf Mk3 uses an electric radiator cooling fan, that coolant temperature sensor is what triggers the radiator cooling fan. What you should be looking to replace is the coolant thermostat like this:

http://www.ebay.com.au/itm/THERMOSTAT-VW-Golf-Hatchback-GTi-MK-3-1992-1998-2-0L-150-BHP-Top-German-Qual-/191586924252?hash=item2c9b7876dc:g:49kAAOSwKrhVYUG l

Which is installed near the bottom of the engine block close to the water pump and can be replaced just like this:



Now please note that the video is for a US Jetta Mk3, so there are probably some slight difference between the US-spec 2.0l and yours but the general principles are the same.

I need to do the same repair on my CL but have been holding off until I can afford to get my mechanic to do replace the timing belt, water pump, thermostat and coolant temp sensor all at the same time as I am lacking the time, garage space and tools to be able to do this without alot of swearing, cursing and throwing of tools and stuff.

[birdman]

Here is a quick test for you. Does your heater blow hot air?
If no, your coolant is not hot enough. As indicated by your temp gaage.
Which means your thermostat is busted.
Replacing a sensor will not change the temperature of the coolant it is sensing.
Get a new mechanic.

[mecind]

Thanks feenix74