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Water Temp and Pressure

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Phantom over heating"

Hello All,

Not sure f this should be in engines or electrical but here goes…1800 DX engine in a '83 Mk1 golf GTI

For some reason on putting the key in the ignition (not even starting the car) the water pressure starts immediately blinking and the temperature gauge starts risings over (about 5-10 seconds to full temp as per the below pic.  This is with the car stone cold and not running.

IMG_1861 - Copy.JPG

If i start the car it stays showing over pressure and maxed out on temp…so no change even though it's stone cold…the car warms up as you'd expect, after a few minutes the thermostat opens and upper and lower hoses on the radiator get warm too.  Leave it long enough and the fan will eventually kick in and out, again as it should.  Basically I think it's happy and not overheating in reality.  But for some reason the gauges think it is?

I'm fairly confident nothing is blocked in the actual engine.  Since this issue first started being investigated it has had a new water pump (when I did the cambelt)  new thermostat and elbow, and I replaced the hose that goes from the upper outlet on the front of the head to the water pump.  I've also had the rad hoses off and they're clear.  I've flushed the engine water system 3 times so it's clear and clean and also run water through the radiator, cyclinder head and cylinder block water channels, everything runs fine and flow appears unhindered.  Even the heater blows hot air happily.  No airlocks in the refreshed coolant it's now filled with and the fluid level is where it should be.  No leaks either (replaced a slightly perished hose and also an o-ring on the manifold outlet on front of head.  Below are the below and after of how the water outlet and sensors look.  The temp sender wire was broken but has since been re-terminated.  Hasn't seemed to make the slightest difference whether it was open circuit or terminated?!

Before:
Before.JPG

After:
After.JPG

As an added conundrum sometimes (but not always) when it does get fully up to temp then the gauges seem to sort themselves out as below.  It's only done this a couple of times…is that about where you would expect the temp to be generally?

IMG_1862 - Copy.JPG

Has anyone had this before and can put a finger on it before I go spending on needlessly replacing sensors or pulling the fusebox apart searching for connectors etc?

Sorry it was a bit of an essay but worth pointing out everything to date.

Many thanks in advance!

Dave

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the red/yellow wire from the sensor must be shorting out somewhere to make the gauge go to full, or possibly the coolant level warning control relay has died. pop it out and see if that solves it, #42 or 43 above the fusebox

Hello my name is John and I'm a dub addict.



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Thank you John,
I shall take a look asap.  The level sensor wires are taped up with electrical tape just above the connector on the tank so if that can affect things I'll untape and see if anything is going on there first and then look at the relays.
Thanks again, sill post back shortly
Dave

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the level sensor wiring wouldnt affect the temp gauge, it'll either make the relay thing the tank is full or not so warning light on or off, its the red/yellow for the sensor you need to look at :)

Hello my name is John and I'm a dub addict.



My wiring diagrams and other documents have moved here:

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mine does the exact same thing, tried other clocks but didn't change.

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I spent a while trying to fix this and found mine is ok if I remove the level sensor relay, this also seemed to fix my mfa which would go blank when ignition is on

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suggests the relay might be stuffed, or the wiring for it. without the relay in temp gauge and overheat warning light will still work fine, just loose low level warning

Hello my name is John and I'm a dub addict.



My wiring diagrams and other documents have moved here:

VAG Documents & Downloads

You'll need to sign into google/gmail for the link to work! (its free!)

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my mfa went to 8888 again so removed fuse 3 then tried plugging level relay back in and filled reservoir up and everything now works fine, suggests it could of been low coolant level  
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