Fluctuating temp.

[Bo!]

My golf gti BWA .
takes considerable amount of time to come up to temp in the region of 20 mins driving and some times does not reach 90 on the dash . When it gets up to temp 90 if I'm on a long drive it will fluctuate down to around 70 then back up to 90 . I still have some approved warranty left on the car from a VW main dealer and was wondering if many people had thermostat carried out under VW approved warranty ,and how you've gone about getting a dealer to take action and change under warranty. I have no warnings on the dash or fault codes which is what I have read on other threads the dealers may say I need to make a warranty claim .

[GrayMK5GTI]

That should be covered under warranty. Parts are around £35, but labour will be around £200 if you had to pay.

[Bo!]

Booked in next week at the dealer in the meantime I will do the climate control trick to see how the coolant temp is behaving. The guy on the service desk did say is shave to pay for labour if the part is faulty but I don't think that is correct .

[Bo!]

Been out for a long drive today and used the secret menu on the clima control to monitor the running temp . I used setting 19.2 on the secret menu . For the first 10 minutes the temp did not go above 74 , but the operating dial on the dash showed 90 after 10 minutes of driving .Got on the motorway for 20 Minuites and the temp went up to a max 76 on the secret menu but no higher. Coming off the motorway under engine breaking the temp on the dash did drop a little bit but the temp on the secret menu stayed at around 72-75 .  the final 10 Minuites of the journey was in town and a lot of stopping and starting the temp on the secret menu then rose to 87, Not sure what all of this means but I think I may have a sticking or stiff thermostat. I'd really appreciate anyone's opinion on what they think could be going on the car is going in the dealers on Tuesday and id like to get this sorted under warranty if it needs sorting .

[tlnds]

There is plenty of similar threads so if you do some searching on here you should be able to determine if its main or inline stat.

I've had my GTI just under a year and I had to replace the main stat, as it was behaving as you describe above, and then the inline ones recently as it was taking an age to warm up.

[Bo!]

I've looked at lots of threads on the forum but a lot of symptoms can differ, from what I can gather correct me if I'm wrong but these are my definitions

Reaching 90 on the dial then dropping off at all the main thermostat is the culprit.

Taking an age to get to temp then the inline thermostat is a possibility I have a 57plate BWA manual so there is 1 inline thermostat located in the front of the engine down the side of the oil dipstick  .

Finally if the dial will not reach 90 then it's temp sensor or inline stat .