Temp gauge reading too high - advice please

86audicoupe · 05-08-19, 07:57 PM

Evening all

Been slowly working through little niggles on the Coupe. The temp gauge is reading too high. I'm sure this subject has been covered before on here.

So far I have changed the temperature sender for the gauge, the fan switch (as a precaution) and tonight I have completely flushed the system and removed the thermostat (partly so I can test without one and ready to fit the new one). I did think the thermostat was the culprit - it was sitting in murky water - either very old or possibly the original! I know you lot like photos so I took pic of it!

The pic below shows where it likes to sit when warmed up. The fan kicks in and out correctly as it should.

Am I right in thinking it could be the voltage stabilizer that's the issue and giving a false reading?

mikes2 · 06-08-19, 03:57 PM

Normally the stabilser impacts both gauges - fuel and temp but I suppose it's possible only one gauge would show the symptoms.

It's not expensive to change.

Is it like that all the time on move or just at idle / slow traffic ?

Radiator isn't blocked is it ?

86audicoupe · 06-08-19, 07:01 PM

Thanks for your reply Mike. It's there all the time once it's up to temp. Fluctuates slightly when the fan kicks in and out. I'm pretty sure the radiator is okay. I left the hose off the thermostat housing, and flushed everything through. According to the previous owner the radiator has been replaced, there's no paperwork but it looks new-ish and is an aftermarket Nissens.

The fuel gauge seems to operate correctly, I filled up and it progressively comes down and doesn't fluctuate. I think it still must be electrical fault linked to the gauge as I've ruled out the temp sender with a new one. Unless Meyle parts are not reliable...?

mikes2 · 07-08-19, 06:52 PM

The last Meyle temp sender I fitted was to my 90 20v and it always showed a high reading.

They're well known for it on the mfts 3 pin version. your car has a different type but I'd be trying another brand

Isimmo · 07-08-19, 07:20 PM

Ever since I put the AAN in the rally car I’ve seen the temperature gauge that high. I hate it. So I had an additional Porsche 986 main front radiator put behind the grille. It still reads the same. In conversation with my brother he said his standard GT also does it. Next time we were out and about when we stopped, he grabbed me and behold, exactly the position yours is, and the rally car. I’m less paranoid now.

86audicoupe · 08-08-19, 06:00 AM

Thanks both for your replies

For the sake of £15 I could try a different make of temp sender just to see. It’s interesting you’ve experienced the same thing Ian - I’m pretty sure my old coupe quattro was giving a similar reading too! Would be good to know what’s the actual cause. I’m still tempted to change the gauge voltage stabiliser to see if it cures it but as Mike said, theoretically both gauges would be inaccurate. Some fit an aftermarket gauge for an accurate reading but I’m trying to keep it looking all original.

I’m going to put the thermostat and fresh antifreeze in for now then revisit it!

06-08-19, 03:57 PM	#2
mikes2 4 ring whore! Classic Audi Club Member Join Date: Nov 2007 Location: Polmont Posts: 2,617	Normally the stabilser impacts both gauges - fuel and temp but I suppose it's possible only one gauge would show the symptoms. It's not expensive to change. Is it like that all the time on move or just at idle / slow traffic ? Radiator isn't blocked is it ? __________________ 1991 90 quattro 20v sport 1991 90 quattro

07-08-19, 06:52 PM	#4
mikes2 4 ring whore! Classic Audi Club Member Join Date: Nov 2007 Location: Polmont Posts: 2,617	The last Meyle temp sender I fitted was to my 90 20v and it always showed a high reading. They're well known for it on the mfts 3 pin version. your car has a different type but I'd be trying another brand __________________ 1991 90 quattro 20v sport 1991 90 quattro

07-08-19, 07:20 PM	#5
Isimmo Super Moderator Classic Audi Club Member Join Date: Jul 2007 Location: Sissix-by-the-sea Posts: 15,218	Ever since I put the AAN in the rally car I’ve seen the temperature gauge that high. I hate it. So I had an additional Porsche 986 main front radiator put behind the grille. It still reads the same. In conversation with my brother he said his standard GT also does it. Next time we were out and about when we stopped, he grabbed me and behold, exactly the position yours is, and the rally car. I’m less paranoid now. __________________ 1985 WR quattro, 1985 20vT RallyRep, 1993 MTM ABY S2 Avant. 2010 S3 Sportback.

06-08-19, 07:01 PM	#3
86audicoupe Classic Audi Pervert! Classic Audi Club Member Join Date: Dec 2007 Location: Dorset Posts: 2,182	Thanks for your reply Mike. It's there all the time once it's up to temp. Fluctuates slightly when the fan kicks in and out. I'm pretty sure the radiator is okay. I left the hose off the thermostat housing, and flushed everything through. According to the previous owner the radiator has been replaced, there's no paperwork but it looks new-ish and is an aftermarket Nissens. The fuel gauge seems to operate correctly, I filled up and it progressively comes down and doesn't fluctuate. I think it still must be electrical fault linked to the gauge as I've ruled out the temp sender with a new one. Unless Meyle parts are not reliable...?

08-08-19, 06:00 AM	#6
86audicoupe Classic Audi Pervert! Classic Audi Club Member Join Date: Dec 2007 Location: Dorset Posts: 2,182	Thanks both for your replies For the sake of £15 I could try a different make of temp sender just to see. It’s interesting you’ve experienced the same thing Ian - I’m pretty sure my old coupe quattro was giving a similar reading too! Would be good to know what’s the actual cause. I’m still tempted to change the gauge voltage stabiliser to see if it cures it but as Mike said, theoretically both gauges would be inaccurate. Some fit an aftermarket gauge for an accurate reading but I’m trying to keep it looking all original. I’m going to put the thermostat and fresh antifreeze in for now then revisit it!