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Erratic temp gauge

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Erratic temp gauge

I?ve just picked up another ?83 GTi (must be a glutton for punishment!) and am trying to sort out a few niggles.

As soon as I start the engine from cold the needle on the temp gauge starts climbing. When the car is warm it seems to behave but stop at lights for a minute or two and the needle starts climbing towards the max. I?m pretty sure the engine isn?t really overheating. I let it idle for 10 min and it doesn?t smell hot, no coolant loss and the fan kicks in as usual. Besides even if it was overheating I can?t see how the gauge would climb the instant it started from cold?

I tried changing the temp sender but that didn?t help. Could the gauge itself be faulty? Or the connections on the back of the gauge? Anyone else has this problem?

Cheers

Forgot to add, the oil temp seems normal. On a 100 mile run down the motorway it stayed at a constant 90 degC.

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Sounds almost like an air lock with bubbles trapped....Have you checked the coolant and ensured theres no air in the system?

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I wondered this too. I left the expansion cap off while the engine warmed-up and massaged the top hose but didn't notice any air coming out the return hose. There was a tiny pocket of air when I removed the sender (no coolant came out of the hole). What would the guage read if the sender was sat in air?

Cheers

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hot

try overfilling for a short while and see if this solves it

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Thanks will give it a go when I get home. :y:

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did you fix this this is exactly what mine does. goes up from cold even just with ignition on. it works just reads way to hi even when cold. if i disconnect the sensor it still reads the same. i have installed a new gauge and still the same

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Must be the season for this thing, as mine started doing the same as mtricks says recently. It was working fine, now goes straight to hot with the light flashing as soon as I turn the ignition on. The resistance of the sensor reads correctly, so I'm thinking the wiring has broken or shorted somewhere.

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I've had this. It was a bubbles in system. I done this.
Run car till warm and fan kicks in and add water to radiator till it bubbles over. Repeat till no more bubbles..

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It was a while ago but to fix mine I ended-up unplugging the relay that controls the coolant warning lamp. After that the temp gauge behaved normally so I guess there is a fault in the wiring somewhere. I haven't been able to trace the problem as the car is in storage while I'm working away from home.

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Hi, on my 83 gti the temp gauge doesn't seem to move, only starts to go up when very hot, but the warning light flashes when revs go over 3000 rpm, Once the revs drop the light goes out, any ideas could this be a faulty sendor? also the oil temp gauge doesn't read at all?

cheers mat

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Hi, Can anyone tell me where exactly the wire for the temperature guage should go? I have just bought an 1984 GTi and have located a loose wire that should be connected to a sensor - but where? INcidently if this wire touches any part of the engine the temperature guage will increase rapidly with lights flashing etc… could be the reason for some of the probs above.
I would love to get my hands on a Haynes manual for this car - but cant seem to find one on the net anywhere :(

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It attaches just infront of the rocker cover in the middle!  I will take a photo tomorrow so you can see.

J

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Hey thanks dude! I think Im seeing where you mean.. theres a small sensor there.. many thanks for the support.

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Just wondering if anyone had figured out what was causing these problems?

My cabrio recently started doing the same thing. Temp gauge rises from the moment i turn the key and eventually sits around 7/8th of the way up.

If i leave it to idle, the gauge goes all the way to the top and the fan cuts in.

Its definately not overheating as ive measured the temperature of the block and rad with an infra red thermometer, but i'm lending the car to a friend for a few weeks and would like to get it sorted…

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disconnect the dash temp sensor and try again, its got a red/yel wire and will be located on one of the coolant flanges on the front or side of the head. it may be single or 2 pin.

if temp gauge still rises the red/yel wire is shorted somewhere, if not then its the sensor at fault or an airlock as above.

bleed coolant system as follows, this method has never failed me:
If you have an issue with the coolant system, the 1st thing to change is the header tank cap (MK1/2/3 Golf/Polo/Passat etc). The older black caps have a problem with the pressure valve in the cap which can vent to late/early, so its always a good idea to upgrade to a new blue one.

The system takes just over 5 litrs when empty, there will always be some coolant left in the block unless you remove the thermostat though
Use G12+ coolant from VW, or G12 from AVS Car Parts - [The VW - Audi - Seat - Skoda Parts Specialist]
Use at least 40% coolant, I normally use a 50:50 mix in my GTI 8v and it runs nice & cool

Bleeding the system after refilling:
Run the engine from cold with the cap off and rev it to 2k now and again.  While you are doing this squeeze all the pipes you can get your hands on, and keep the coolant level topped up.  It will eventually start to boil over, at this point turn the engine off.  Once its settled down top it up to the max mark and you should be good to go!

Checking the operation of the system:
Check the lower rad pipe is stone cold until the temp gauge reaches the half way point, if it gets lukewarm straight away then the thermostat is stuck open or missing, if it stays cold then it is stuck shut.
Check the fan kicks in when the gauge gets near 3/4, if not disconnect the plug from the radiator sender in the bottom, passenger side of the rad & bridge the pins.  If the fan spins then the temp sender is broken, if not jump the fan direct from the battery, if it still dont spin then the fan is knackered
Hello my name is John and I'm a dub addict.



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