Club 80-90 Forums

For 13 years the temperature gauge has always been perfect - bang on upright. Then I had the flashing red light problem. After 3 expensive sessions at the local garage, the expansion tank, the thermostat, the radiator switch and now, most recently, the radiator fan have all been replaced. It's been drained and bled 3 times but now the temp gauge sits relentlessly at 3/4 (even with heater going full blast) The garage swears blind that the water temp is OK (so reads their infra red temp gun) and say that the only thing left is new cylinder head gaskets. I'd really appreciate any comments and help. Thanks

Is the rad fan on at 3/4 on the gauge? Mine would be. Mine sits just above the led, if it goes any higher the fan cuts in. Does the rad feel hot?

what engine?
what year?
Has the temp sender been changed?

sounds like you might have a gremlin in the temp gauge or the wiring for the low coolant warning.
I currently have a problem with the flashing red LED in the temp gauge.
The temp is ok, coolant level ok and system well bled, but still the flashing!
If van has been left for several days the LED may stop flashing when started but if the engine is then stopped and re-started the LED stays flashing - but temp and coolant level are ok.

I realize this doesn't explain your problem but before you throw more money at the problem and start engine repairs that may not be needed, perhaps you also have a similar gremlin.
Apparently the LED warns of low coolant level AND high temp. If triggered by high temp the LED will go out when things cool - and I think, when stopped and re-started. If triggered by low coolant the LED will stay flashing.
Obviously because low coolant wont fix itself!
It seems there are 2 suspect parts - the temp gauge itself and a Module 43 on nearside front door pillar behind glovebox. Plus a number of earth connections. The module 43 looks like a relay and deals with the low coolant sensing. The gauge deals with temp reading and also high temp warning on the LED.

So perhaps your garage is correct in saying that the temp is in fact ok and the fault is in the gauge and associated parts...
I haven't managed to fix mine yet so cant be of much help! But hope this helps save you some money.

good luck, jon

might be worth a look?

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Mine sits at 3/4 and never really moves above that, even stuck in traffic on the hottest day this year no problem. Rad fan kicks in at the right time red light flashes all the time I've tried everything to fix the flash apart from a new dash pod. I have noticed that if I remove the sensor fron the header tank the temp gauge goes straight to the right.

I have a friend that works for vw, and his machanics all say 3/4 is ok as long as the rad fan kicks in and out as it should.

So I dont worry about it now well not so much anyway

Thanks to everyone who responded. I probably didn't make the situation crystal clear. The red light's stopped blinking now but once the thermostat and the sender were changed, the temp gauge then started to stay at 3/4.

edoh wrote:might be worth a look?

They all refer to the blinking red light which doesn't seem to be the problem anymore - just an overzealous temp gauge.

ChrisTriple wrote:It seems there are 2 suspect parts - the temp gauge itself and a Module 43 on nearside front door pillar behind glovebox. Plus a number of earth connections. The module 43 looks like a relay and deals with the low coolant sensing. The gauge deals with temp reading and also high temp warning on the LED.

Thanks - I'll take a look.

kevtherev wrote:what engine?
what year?
Has the temp sender been changed?

1984 Petrol 1900cc. The temp sender; is that a radiator switch?? (That's what's on the bill)

Dad wrote:
Is the rad fan on at 3/4 on the gauge?

I personally can't say; I've just had a 'new' 2nd hand fan fitted and the garage tells me it's kicking in at the right time. Again they tell me the water temp is as should be.

Thanks you all.

Temp sender is on the thermostat housing..you have a bill for the radiator fan switch.
Change the sender (brickwerks)
You might have either fitted the wrong thermostat, or incorrectly fitted it... or it might not be open fully

piersoc wrote:I've just had a 'new' 2nd hand fan fitted and the garage tells me it's kicking in at the right time. Again they tell me the water temp is as should be.

Then it's simply time to recalibrate your expectations of the needle position, by the sound of it.

If they have changed the sender for the temp gauge, then it might well be chucking out a slightly different resistance for a given temperature than the old one - since it's the resistance which "tells" the needle where to sit, then that's obviously going to change "normal" position. The gauge calibration isn't an exact science. There's probably an adjusting screw on it somewhere to move that "normal" slightly, if it scares you.

If their IR thermometer's telling you and them that it's right, and the fan's kicking in and out again, then it's right. The fan switch and thermostat operating temps will be marked on them.

hi

worth considering that there are actual three separate (but linked) factors here. temp gauge, fan, flashing light. my experince is that non t25 specialists tend to focus on the major things that can lead to over heating, whereas often the real problems are just electrical.

temp gauge. mine (1.6 turbo diesel) sits just above half way and rises in traffic and on hills to about 3/4. this is kinda scary, but I've not actually had any problems.

fan on mine kicks in c 3/4 on gauge and seems to do what it should (i.e. cycles in for about a minute and and out when sitting in traffic)

as has been mentioned, the flashing light indicates 2 different things: dangerously high temperature, or low coolant level.

the flashing light is a source of a lot of worry and misdiagnosis. it's a horrible thing to have it flashing at you, so we try all sorts of expensive remedies, but it may well just be faulty. 1. a simple problem is the sensors in the header tank being a bit corroded, thus giving a false reading of low coolant level - just pull them out and give them a clean to see if that helps. 2. it could be the circuit board in the dash, which get faulty when they're old (also runs the oil light). these are i think a couple hundred quid, so you don't want to change it unless you are fairly sure. the temp light should run through a flashing cycle when you switch on the ignition, if it doesn't that's a good (but not definitive) sign the circuit board is faulty.

hope this is helpful, and good luck!

Dino

Thanks very much to everyone who wrote in to offer advice. I've sort of fallen out with the garage who've replaced everything, thermostat, coolant cylinder, fan, temp sender so I guess I'll just have to live with it. Thanks again

This is where it gets frustrating.
y'see the forum can offer all sorts of advice, but you are powerless to act as you entrust all work to a garage.
Volkswagen has successfully made their owners into mechanics for fifty years.. perhaps it's time to take the next obvious step.