VR6 Thermostat

[hombre_paulo 0]

Hi All,

 

I replaced the thermostat on my VR6 two weeks ago as the one currently in was stuck open and therefore the car was not warming up properly and churning through petrol. The car has run great since then, normal water/oil temps, fans coming on, temp never going above 90c even in traffic, life was peachy.

That was until yesterday. Started the car and was on my way to work and the temp guage didnt stop where it usually does at around 85-90c, it just keeps going up. I pulled over before and switched off before it got to 110c, no sign of the fans coming on. Had a feel of the rad hoses and the top is roasting, but the bottom although warm was nowhere near the temp of the top hose. Which makes me think that my new thermostat has now broken and jammed closed keeping coolant in the block, does this seem logical?

The heater will pump out hot air continuously so i dont think i have a air block and this suggests the water pump is doing its thing.

I assume that the fans are not coming on due to the location of the thermoswitch (bottom of rad next to bottom rad hose inlet) which is not getting the hot water to trigger the switch? I`m gonna test that the fans work this weekend, by shorting the thermoswitch.

It seems odd that a thermostat should do this after two weeks of use, is it just because I bought a gsf one? Are the dealer ones more reliable? What are the chances of getting a replacement one (and some more G12) out of GSF if it is a dodgy part?

 

Thanks

[andy 0]

It does seem very odd, especially if your new stat has been working up till now. I've never had an issue with a GSF stat, I've used any number of them in different cars. Thats about all I can offer, further investigation required, you sound like you know what you're up to. You haven't lost some coolant have you.....like most of it?

[hombre_paulo 0]

I dont think so, expansion tank seems to stay between the max/min mark. Might be a starting point to burp the system this weekend, but i wouldnt expect continuous heat from the heater blower if it was low on coolant.

[Jon_vr6 1]

When it comes to cooling id always go genuine OEM, i remember some people having trouble with the thermostat for a VR a while back and then someone suggest using an R32 one (as it runs similar temp to the VR6 one) maybe an option for you

[aide 0]

the aux water pump would circulate heat round the matrix, and stats are designed to fail open. fans are controlled by the rad thermoswitch and the yellow sensor, have read at the definite vr cooling guide, good stuff in there.

 

is there water being retured to the expansion bottle when warming up.... water pump/ impellor?

[hombre_paulo 0]

I`m positive its the thermostat gone. Just ran the car up to temp with the expansion cap off and the bottom hose remained cool. Water is definitely making its way back to the expansion tank so the pump is running right, also explains why the fans arent coming on.

GSF said they will replace it but want to see the old one as well, just the hassle of actually swapping them again now!!!

[hombre_paulo 0]

Well I have replaced the thermostat and took it for a run and everything seemed fine, for about 5 mins.

The temp gauge in the car started shooting too 110c within 2-3 miles of starting the car, so i replaced the yellow temp sender today and although its not going to 110c its still making its way to 105c with no signs of the fans coming on or the thermostat even opening.

I`m about to run vagcom and see what the ecu thinks the water temp is. Any other suggestions?

[hombre_paulo 0]

I Have just run the car up to temp with vagcom plugged in and from its perspective everything is normal. Water temp sits between 92-96 on my drive, with the fans coming on a switching off at the appropriate times. The thermostat opend just above 80c and water is being pumped to the radiator and back to the expansion tank.

However the gauge in the car is reading 110c+ and the coolant light is flashing. As in my previous post i have replaced the the temp sender today (yellow one, now black/blue). What is going on with my car?

[hombre_paulo 0]

Any ideas?

 

I`ve tried cleaning the gounds on the battery terminal and under the isv. Havent testing to see if this has done anything but any other suggestions would be good

[andy 0]

If the coolant level light is flashing you either haven't got enough in the expansion bottle or the sensor in the bottle is duff.

I can't remember which of the sensors feed the guage in the car but that sounds like it may be duff too. It sounds like mechanically everything is working as you would hope, just that you're getting some duff feedback from the sensors.

[hombre_paulo 0]

The light only flashes when it gets over 110c (vagcom reading ~90c) and i changed the temp sensor for a brand new one on friday, old one was also reading too high.

I`m baffled, i checked the wiring too today and there are no obvious nicks in it that i can see, the rest is still firmly covered by the wire wraps.

[andy 0]

I think I'm correct in saying the guage uses one sensor, the ecu, a different one. Are you aware of that?

[hombre_paulo 0]

Yup. I`ve replaced both the yellow (temp gauge) and the blue (ecu). Do you know which one vagcom reads from?

[hombre_paulo 0]

Drove to southampton and back today with vagcom plugged in and the laptop says coolant is at a constant 84c @ ~75mph but the gauge was reading close to 110c

 

I dont know what to do?

[PaulMoVR6 0]

You could try sourceing another set of dials and seeing if your dials are dodgy?

 

My gauge was doing this before but now it dosn't work atoll and the coolant light constantly flashes even if the car has been sat for a few days so iam just going to book the car into a auto electrician as i can't seem to find out what wrong with it :mad2:

[hombre_paulo 0]

Anyone in the bournemouth/poole area with a set of vr clocks i could borrow?

[Critical_Mass 10]

I think its highly unlikely the gauge is wrong. Vagcom reads the ecu sender (blue), i'd possibly try another yellow (or black as the new ones are) before you start looking at changing the clocks.

[andy 0]

I think its highly unlikely the gauge is wrong. Vagcom reads the ecu sender (blue), i'd possibly try another yellow (or black as the new ones are) before you start looking at changing the clocks.

100 per cent agree, don't start changing clocks yet!

[hombre_paulo 0]

I`ll give that a try. Vagcat says the golf senders are the same so i`ll try and get some from the scrappy.

Are there any fuses/relays on the main fuse board which could impact this. I`ve been looking at wiring diagrams and this seems a possibility?

[Critical_Mass 10]

I`ll give that a try. Vagcat says the golf senders are the same so i`ll try and get some from the scrappy.

Are there any fuses/relays on the main fuse board which could impact this. I`ve been looking at wiring diagrams and this seems a possibility?

 

tbh i'd use a new one as the scrappers one could also be fault - just by chance

[hombre_paulo 0]

Thing is I have already replaced the sender for a new one last weekend.

[Critical_Mass 10]

Thing is I have already replaced the sender for a new one last weekend.

 

If there can be some gaurantee that the second hand one works then go for it :D

[hombre_paulo 0]

Well, i managed to pick up a new set of clocks which have fixed an old issue i had where the mileage wouldnt show.

Now though the temp gauge reads nothing at all, wont budge an inch. I`ve got another temp sensor on its way but i`m still confused as to why i had an over inflated reading before a clock change and now nothing (fuel guage works fine)

[Critical_Mass 10]

Well, i managed to pick up a new set of clocks which have fixed an old issue i had where the mileage wouldnt show.

Now though the temp gauge reads nothing at all, wont budge an inch. I`ve got another temp sensor on its way but i`m still confused as to why i had an over inflated reading before a clock change and now nothing (fuel guage works fine)

 

Maybe the second set of clocks are knackered? :shrug:

 

Get the new sender changed and take it from there.

[tandino 0]

Sounds like you need to reset the temp gauge as i would hazard a guess that the gauge has maxed out on the previous car.

You need to remove the dials from the car, then remove the dials from the housing (easy) then you need to physically lift the temp needle up until you feel it click, once this has been done reassemble the dials and fit them back into the car.

Job done