So, for the first time today my car started creeping past 90 degrees and would not stop whilst I was stuck in traffic having just come off the motorway. It was a scary experience because the needle crept up to approx 105 degrees before its started to cool back down to 90 degrees.. any thoughts on this? What should I do? I am at work now and thinking of going for a test drive to see if it happened again before heading out. Any help would be great
Engine Overheating for short time
- Thread starter Jay20VT
- Start date
Thanks for this.
it was a scary moment but driven it twice on a short run since and not done it again. When I parked up and idled it after a blast it stuck to 90 and both fans kicked in fine. Not sure what to do now if anything at all
Take it you've checked coolant for any leaks, cracked reservoir?
yeh bud.. did a visual and nothing untoward.. a colleague told me just to keep an eye on it but looking through the paperwork I can't see when the T stat was last changed so perhaps it might be worth doing that. Noticed in the colder months it does take a while for it to get to op temp, could that mean a sticky stat?
I think the thermostat could be your culprit. The fans are obviously working independently, so it's down to the stat to regulate. A cheap, easy fix so I would definitely go with that first. You could always run a diagnostic after if you get any further problems. It is scary driving though when that temp creeps up & over. Hawk eying that temp guage when stuck in traffic is heart racing stuff!
I would, it's a cheap option.
Alternatively, if you really want peace of mind before doing anything, have a diagnostic test first & if the thermostat is goosed, or any other issue, it should throw up a code & you can accurately see what temp the fans are kicking in.
Yeh, it was fine when I was using it last but not used since the weather has been tame.
As we speak I'm getting the wheels refurbished, had this booked in ages ago but happy to go through some diagnostics ?
Thanks you
I agree with what everyone else said, with the thermostat being a cheap and easy to fit option, i would go with that first just to rule it out if nothing else.
The fans are controlled by a thermostatic electrical switch screwed into the back of the radiator. From memory I think stage 1 should trigger at somewhere around 90C and stage 2 (emergency/full speed fan mode) kicks in at 105C. If you have continued problems after changing the stat the I would say there is a pretty high chance that is where your problem lies. They are available for somewhere around £25, you just need to make sure if you have the square or triangle shaped plug when you order it (mine was the triangle). It's another easy job, there is a drain tap on the bottom of the radiator, drain the coolant below the level of the switch, then simply unplug the connector and swap the switches, before refilling the coolant.
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Another possible option is the fan control unit that lies under the battery area. This can also fail, although it's usually pretty reliable.
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The other thing is as Badboy said, the usual slow speed fan failure. Common issue, although they usually fail completely rather than intermittantly.
The fans are controlled by a thermostatic electrical switch screwed into the back of the radiator. From memory I think stage 1 should trigger at somewhere around 90C and stage 2 (emergency/full speed fan mode) kicks in at 105C. If you have continued problems after changing the stat the I would say there is a pretty high chance that is where your problem lies. They are available for somewhere around £25, you just need to make sure if you have the square or triangle shaped plug when you order it (mine was the triangle). It's another easy job, there is a drain tap on the bottom of the radiator, drain the coolant below the level of the switch, then simply unplug the connector and swap the switches, before refilling the coolant.
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Another possible option is the fan control unit that lies under the battery area. This can also fail, although it's usually pretty reliable.
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The other thing is as Badboy said, the usual slow speed fan failure. Common issue, although they usually fail completely rather than intermittantly.
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If you get stuck in creeping traffic with no fans, open the windows and put the heater on full blast.
The engine will now be happy stuck in traffic all day.
You will be miserable though.
The heater also bypasses the thermostat too.
One thing that p1sses me off about the VAG temp gauges, is they lie. At least on TDi's.
The temp gauge is not the engine temperature, it is what the marketing department forced the engineers to program the engine management to send to the gauge.
That reassuring, perfect, sign of a quality engineered car, that steady 90 degrees that the gauge is showing you, is actually any coolant temperature between 70 and 110 degrees.
If you drive with VCDS connected, you will see this.
You are denied the ability to get early warning of problems.
If I could work out how to program it out in the engine management, I'd be in there like Flynn.
https://www.vwaudiforum.co.uk/forum/showthread.php/96923-Vag-com-engine-coolant-temp-reading
The engine will now be happy stuck in traffic all day.
You will be miserable though.
The heater also bypasses the thermostat too.
One thing that p1sses me off about the VAG temp gauges, is they lie. At least on TDi's.
The temp gauge is not the engine temperature, it is what the marketing department forced the engineers to program the engine management to send to the gauge.
That reassuring, perfect, sign of a quality engineered car, that steady 90 degrees that the gauge is showing you, is actually any coolant temperature between 70 and 110 degrees.
If you drive with VCDS connected, you will see this.
You are denied the ability to get early warning of problems.
If I could work out how to program it out in the engine management, I'd be in there like Flynn.
https://www.vwaudiforum.co.uk/forum/showthread.php/96923-Vag-com-engine-coolant-temp-reading
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I've always wondered how such basic engineering kept the temp at 90degrees perfectly no matter what the conditions were. Thats a really useful bit of info.
Some really good info here guys. I will deffo get the garage to replace the stat and drop in some new coolant to start with. I will keep you all posted.
Really appreciate your help in this, which was a heart racing moment for me.
Really appreciate your help in this, which was a heart racing moment for me.
It's the same on the petrol engines too. If temp is in the normal operating range, (76C-105C in the case of the 1.8t) you'll just get 90C on the gauge.
There are many systems on the car that are more 'computerised' than you'd think for the age of them, the folding electric mirrors being one example. Rather than the switch operating a relay, it just signals to the CCM module, and the CCM commands the mirrors to move.
When you flip the switch for the first time after disconnecting the battery, it can take upto 10 secs for the mirrors to actually start moving, i'm guessing while the CCM is working out their position.
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