8v Temperature Sender

[neuon2003 0]

Just wondering if anyone can provide some advise, please.

 

I have a 1996 8v (ADY) which runs with the temperature gauge barely registering 70. The only time the gauge really rises is in standing traffic after a run. I have just done a 180 mile, mainly motorway, run at average of 65 mph and returned 41.3 mpg. The gauge just registered 70.

 

I have confirmed that the fan kicks in at 100-ish and have measured the rad hose temps which all seem to be OK. I have no overheating issues, just the gauge reads low. Mind you, the indicated mpg when the car is under 70 is pants.

 

Is this likely to be a duff temp. gauge sender? Anyone know where this is on an 8V? Is it item 12 (yellow sender) on the attached from VAGCAT?

 

Many thanks.

[seanl82 23]

Alright mate, I'm assuming you mean the water temp gauge, and its a classic example of a duff thermostat when it rises in traffic, and goes down again when cruising. Long runs won't make much of a difference in overall MPG as the ECU takes MAP readings from oil temp. More likely to see worse than usual MPG on shorter runs where it takes longer to reach normal operating temperatures and switch over to the warm MAP.

[davidwort 0]

Does sound like a stuck open stat.

[neuon2003 0]

Alright mate, its a classic example of a duff thermostat when it rises in traffic, and goes down again when cruising. .

 

Hi Matey,

 

Yes, water temp gauge. I have only really done 6 x long runs in the car. The limited town driving has the gauge below and on 70.

 

Much appreciated on the steer. I'll change the thermostat as a first action and see what happens. Any idea where it is on the 8v 2.0l?

 

Cheers

[neuon2003 0]

Does sound like a stuck open stat.

 

Many thanks, David. Where is the stat on the 8V? Do you need to change any plastic housing at the same time?

[davidwort 0]

you need to remove the power steering pump to get at the 90 degree plastic elbow on the bottom of the water pump, the hose connected to there goes straight to the bottom of the radiator. all you need is a new thermostat and the O ring that seals the elbow to the pump, and new coolant as virtually all of it will drain out.

It's a fiddle to change the stat as you have to hold it up as you put it and the sealing ring in place and bolt up the elbow again, much easier with the water pump off, but if your water pump is fine there's no need to disturb it. Just be careful not to overtighten the 2 10mm bolts that hold the elbow on, they only need a very low torque.

When refilling the coolant, do it very slowly onto the header tank, an upturned 2L fizzy drinks bottle with a small hole in the cap is ideal, this helps reduce trapped air, make sure at least 3 Litres of new coolant goes in bfeore running the car (full capacity is about 4 Litres ) and top up after running the first time if necessary, squeezing the top and bottom radiator hoses helps to force some trapped air out as you refill.

[neuon2003 0]

Wow! Thank you David. That's a splendid answer :clap:

[tony_ack 0]

Check the thermostat first by seeing if the bottom pipe from the rad gets warm as soon as you turn the engine on. If the stat is working, the bottom pipe should be stone cold until the temperature gets up to about 90. If it starts getting warm before the top rad pipe is hot (and I mean proper hot), then it's definitely the thermostat.

 

In answer to the original question, the temp sender is either 12 or 13 in the pic - I can't remember which. Blue is usually ECU, black or yellow is usually the gauge.

[neuon2003 0]

Check the thermostat first by seeing if the bottom pipe from the rad gets warm as soon as you turn the engine on. If the stat is working, the bottom pipe should be stone cold until the temperature gets up to about 90. If it starts getting warm before the top rad pipe is hot (and I mean proper hot), then it's definitely the thermostat.

 

In answer to the original question, the temp sender is either 12 or 13 in the pic - I can't remember which. Blue is usually ECU, black or yellow is usually the gauge.

 

Many thanks indeed tony_ack. Much appreciated. Very helpful fault diagnosis :-)

[Butterfly 0]

This is in no way a technical answer but both 8Vs I've had and I'm sure both of Kips have all ran with a 'cool' water temp.

 

My current 8V has had new stat, water pump and header tank to try and solve a flashing water warning light. It still flashes and I'm 100% sure it is the warning sensor at fault and there is nothing wrong with the cooling system. Its MPG is as expected for an 8V and the pipe work gets hot as expected.

 

I'm sure I've heard others with 8Vs saying they run cooler...

Are you really sure you want to start tinkering with it if everything runs fine?

Edited September 26, 2013 by Butterfly

[James. 9]

Same here. Mine runs cool and returns the expected MPG. Pipes get hot at the right times. Fans come on as expected. Not saying don't investigate it, just throwing another cool running hat in the pile.

[neuon2003 0]

Many thanks everyone for the comments and help. Changed the thermostat for a new VW one on Thursday (with David's excellent instructions) and all is now well. Took a run to the NEC on Friday to see the Cycle Show and the gauge is now steadily settled at 88 degrees, rising and falling as expected and with fans coming on as designed.

 

When doing the work I was also able to spot and re-secure the CV joint heat guard which had worked loose and was resting on the drive shaft.

 

Thanks again.

[tony_ack 0]

This is in no way a technical answer but both 8Vs I've had and I'm sure both of Kips have all ran with a 'cool' water temp.

 

My current 8V has had new stat, water pump and header tank to try and solve a flashing water warning light. It still flashes and I'm 100% sure it is the warning sensor at fault and there is nothing wrong with the cooling system. Its MPG is as expected for an 8V and the pipe work gets hot as expected.

 

I'm sure I've heard others with 8Vs saying they run cooler...

Are you really sure you want to start tinkering with it if everything runs fine?

 

It's sometimes down to a faulty voltage regulator in the clocks as well. I've NEVER had a VW that has run dead on 90 (or warm for that matter) and I've had a few. The MK2 (8v) runs just above cold on the gauge and the VR runs at 80 on the motorway. The MK2 was tested by a garage and the temp was spot on, even though the gauge said it was too low.

[davidwort 0]

. I've NEVER had a VW that has run dead on 90 (or warm for that matter) and I've had a few. The MK2 (8v) runs just above cold on the gauge...

our's always have, 2 polos, 3 old golfs, a jetta, a passat, an Audi 80, a6, 2 corrados, a mk4 and a MK 5 golf, the only one that didn't/doesn't is the modified 16v which likes a good flow of air and some revs or the gauge rises a little higher. I find my handheld IR thermometer really useful, you can check sump temp, head temp, water inlet and outlet temps, different parts of the radiator, it's shown the Corrado oil temp gauge to be quite accurate and also inline with the mot testing sump oil temp probe,

but I've no doubt that old wiring, especially in the engine bay, dodgy earths, sensors and even gauges/ clusters can give some variation.

[KIPVW 0]

How much was the thermostat Andrew? think my 8v is running a bit too cold to be fair too.

[neuon2003 0]

Hi Paul,

 

S044121113 Thermostat £19.04

S038121119B Washer £2.42

 

TPS prices incl. VAT, with 10% discount. The "S" means superseded part numbers.

 

Andrew

[stuarttaylor37 13]

I replaced mine earlier with Vw parts

New thermostat £18.41

New Housing £7.91

Washer £2.42

+ VAT