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Model specific boards => Golf mk7 => Topic started by: JP2021 on 26 October 2022, 19:00

Title: Overheating or not??
Post by: JP2021 on 26 October 2022, 19:00
Driving into work today through some horrendous traffic, I had a peculiar moment whilst stuck in a jam. All was fine until I glanced down to the dash and saw the dreaded exclamation mark alight. Immediately looking towards the temperature gauge I saw the needle was almost touching red, something that I've never had before. I then flicked to see the oil temperature which read 109 degrees, which didn't seem excessive.

At this point, whilst still stationary in traffic, I switched off the engine with some trepidation as to what to expect next. 30 seconds later I started the engine and the temperature gauge went straight to the usual 90 degrees, the explanation mark gone and all was fine for the rest of the drive. However, on parking and stationary the temperature gauge again read just off red. I switched off the engine, restarted and again all was fine with oil temperature reading 100 degrees.

Has anyone else experienced this? Is the analogue temperature dial directly connected to the temperature sensor and if so, why the huge change in reading after having the engine off for just 30 seconds? Also, wouldn't the oil temperature rise excessively in line with the water temperature? Lastly, there is obviously a problem, any idea what it may be?
Title: Re: Overheating or not??
Post by: clubsport on 26 October 2022, 19:36
These are the symptoms of the dreaded thermostat housing issue, if you are lucky, it may well be a temperature sensor playing up. The only way to check is with an OBD reader to analyse the codes which are shown, hope you have a warranty?
Title: Re: Overheating or not??
Post by: JP2021 on 26 October 2022, 20:12
Alas not in warranty as a 2014 model! I do have an OBD reader and have checked the fault codes, the engine fault reading 'Engine Coolant Flow Low/Performance'. The expansion tank is showing no signs of loss of coolant?
Title: Re: Overheating or not??
Post by: symonh2000 on 27 October 2022, 08:51
With the engine running and the expansion tank cap off can you see the coolant moving about?

If not it could be a failed waterpump, or the little belt which drives it.

Has anyone ever had the little belt snap yet? it seems a bit of a fragile design by looking at it.
Title: Re: Overheating or not??
Post by: Finglonga on 27 October 2022, 09:18
Put your aircon on and see if the Fans are working they should both come on. Never had the temperature rise with any on my water pump/thermostat housing leaks.

Also worth looking if the Oil temperature has risen as well if it happens again.
Title: Re: Overheating or not??
Post by: theminty1 on 27 October 2022, 10:46
Agree about the fan check, I have a mk5 Golf and the temperature went up in traffic past the normal 90degrees. Turned out neither of the two fans were working. Replaced both fans, now no issues. I got vw original parts and fitted myself. Pricey but they work:)
Title: Re: Overheating or not??
Post by: Carbon VW on 27 October 2022, 16:32
It’s the thermostat housing.
Title: Re: Overheating or not??
Post by: JP2021 on 27 October 2022, 20:18
So I drove home last night, 60 miles on M25 and a few on country lanes (no traffic) and rock steady 90 degrees and oil temperature an average of 107 degrees. Drove to work today, 30 miles country lanes (no traffic), again all fine. All fans operate and can't see anything strange. The weird thing that doesn't make much sense is that when it happened yesterday, the analogue temperature gauge read one notch off red with oil temperature of 110 degrees. Switching the engine off for 30 seconds whilst in traffic, on restarting the analogue temperature gauge went straight to 90 degrees and stayed there, wouldn't have read higher and gradually dropped? It was almost like a sensor was feeding the analogue dial and on restoring the engine it kicked the sensor back to normality? Make sense??
Title: Re: Overheating or not??
Post by: joe6 on 28 October 2022, 09:07
I had something similar a whilea ago that eventually was diagnosed as a sensor. Did not have any error code initially.
Title: Re: Overheating or not??
Post by: Carbon VW on 28 October 2022, 11:13
You do understand that the analogue gauge is the coolant temperature, and tje digital readout is oil temperature ? A lot of people think they are the same thing. Get it checked out by a good independent garage. I’m pretty sure it’s the thermostat housing issue.
Title: Re: Overheating or not??
Post by: symonh2000 on 28 October 2022, 12:20
Oil temperature rises much more slowly than coolant temperature.

By the time the oil temp has risen to a dangerous level the engine would probably have seriously overheated and cooked.
Title: Re: Overheating or not??
Post by: JP2021 on 28 October 2022, 17:36
Thanks for all the replies, I'll keep an eye and get it down to my local VW independent. Will update when/if I get to the bottom of it. Good point re the analogue temperature gauge / digital oil readout, I do understand which does what and what they're displaying but know quite a few people who may not :grin:
Title: Re: Overheating or not??
Post by: Badluck on 14 November 2022, 14:07
Driving into work today through some horrendous traffic, I had a peculiar moment whilst stuck in a jam. All was fine until I glanced down to the dash and saw the dreaded exclamation mark alight. Immediately looking towards the temperature gauge I saw the needle was almost touching red, something that I've never had before. I then flicked to see the oil temperature which read 109 degrees, which didn't seem excessive.

At this point, whilst still stationary in traffic, I switched off the engine with some trepidation as to what to expect next. 30 seconds later I started the engine and the temperature gauge went straight to the usual 90 degrees, the explanation mark gone and all was fine for the rest of the drive. However, on parking and stationary the temperature gauge again read just off red. I switched off the engine, restarted and again all was fine with oil temperature reading 100 degrees.

Has anyone else experienced this? Is the analogue temperature dial directly connected to the temperature sensor and if so, why the huge change in reading after having the engine off for just 30 seconds? Also, wouldn't the oil temperature rise excessively in line with the water temperature? Lastly, there is obviously a problem, any idea what it may be?

Did you get this sorted? I had something similar around 4 years ago. Warning light flashed up, looked at the temp gauge and it was in the red. Pulled over asap, called breakdown who plugged the computer in but couldn't find any errors. Booked into dealer and they couldn't replicate the problem. In the end just put it down to being a rogue error.

https://www.golfgtiforum.co.uk/index.php?topic=283481.msg2589698#msg2589698
Title: Re: Overheating or not??
Post by: JP2021 on 21 November 2022, 20:38
I haven't driven in heavy traffic so replicating the scenario in which it happened hasn't occurred. I am a little concerned as I don't want to cause lasting damage to the engine and causing West London to come to a standstill whilst I cool the engine and investigate further isn't a tempting proposition! I'm tempted to have the water pump/thermostat/housing replaced (I've lost approx 3mm of water from the expansion vessel over 9 months) and have been quoted £860 from a local indy. This does seem to be the likely culprit having aired the issue on this forum and speaking with others, but an expensive 'fix' if it doesn't cure the issue. As you mention 'Badluck', your symptoms appear to be identical to mine, could it be just a glitch in software????
Title: Re: Overheating or not??
Post by: willni on 22 November 2022, 10:20
I'm tempted to have the water pump/thermostat/housing replaced (I've lost approx 3mm of water from the expansion vessel over 9 months) and have been quoted £860 from a local indy. This does seem to be the likely culprit having aired the issue on this forum and speaking with others, but an expensive 'fix' if it doesn't cure the issue.

If you're considering that you might as well do the timing chain and tensioner while you're at it since it's all part of the same job, to save yourself paying twice to do it when the car heads towards the 100k mark, that's if you're near it and know you'll be keeping the car for that long.
Title: Re: Overheating or not??
Post by: JP2021 on 25 November 2022, 11:57
Out of interest, these two error codes appear quite regularly when I do an OBD11 scan - another clue pointing towards the water pump/thermostat being faulty??
(https://i.postimg.cc/BnNkvpLR/OBD11-Air-Con-Code.jpg) (https://postimg.cc/ZWBV7rLL)

(https://i.postimg.cc/25KtQ5xw/OBD11-Engine-Code.jpg) (https://postimg.cc/zLTp586b)
Title: Re: Overheating or not??
Post by: joe6 on 26 November 2022, 09:24
The low flow fault suggest water pump problem.
Title: Re: Overheating or not??
Post by: JP2021 on 12 December 2022, 17:46
A quick update. I've decided to get the water pump/thermostat housing replaced. Called two local independents who both quoted £850 inc VAT but both couldn't do until second week of January as their diaries were absolutely choka. Out of curiosity I called my local VW dealership assuming I'd be quoted a silly price, however, was quoted £830 inc VAT and can do week beginning 17 December. Is this as surprising to you as it is to me that the dealership is the cheapest with best availability?? 
Title: Re: Overheating or not??
Post by: symonh2000 on 12 December 2022, 22:01
The dealership has probably had plenty of practice doing them under warranty.