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Running Temperature

21K views 23 replies 9 participants last post by  Thapelo 
#1 ·
Hi there

Recently brought myself a second hand 3.0 V6 TDI Quattro A5 so figured id pop on and say hi and also to ask for some advice.

Having been a previous Audi owner, I know for a fact that they all tend to sit bang on 90'c on the temperature gauge, and surprise surprise, mine does not. Maximum temperate of around 70'c but usually sits at 50'c - 60'c.

Been doing a lot of reading on the issue and the thermostats / CTS sound like a fairly common issues on these engines. In doing this research it has become apparent that the thermostat is a complete pig to change, some even mentioning ripping the front of the car of to get at it. Is this the case? As any videos or images I have seen have been on the A8's or Q5's, not A5's.

In relation to which, all images thus far have shown the timing to be belt driven but I have had an Audi main agent advise that these engines are chain driven, can anyone clarify as if it's belt driven I may as well replace them if I need to take the front off to replace the thermostat.

Cheers
 
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#2 ·
The 3.0L V6 TDI quattro engine is chain driven so no need to change it.

Mine runs at 91c and only fluctuates a few degrees either side depending on driving style. Sorry but can't comment on changing the thermostat but it does sound likely.

Have you scanned the car with VCDS? This would tell you of any known problems with the system.
 
#3 ·
Thanks for the reply.

As suspected, should be bang on 90 with this mode as well then. Have only scanned a cheapo plug and play unit that a family member happened to have spare. Only picked up the usual swirl flap error, but that's since been resolved with a new linkage.

Would the lite version of Ross-techs VCDS suffice or is it going to be a case buying the full version?
 
#4 ·
I've not used the lite version so I wouldn't know. Hopefully someone on here has and they can tell you. Let people know which area you're in and there may be someone close with a full version!

Good luck!
 
#5 ·
Thanks for the help Paul, much appreciated.

I myself am down in Brighton on the south coast, hopefully someone near hear will be willing to lend a hand if they have full VCDS and happen upon this thread.
 
#6 ·
Spoke too soon about things going wrong with this car after reading about them on here... it's like this site is jinxed ha ha.
Noticed mine isn't hitting temp. I'm getting more like 70 and sometimes 80 in traffic.
From memory I'm sure it used to run a little higher so might have to get that looked at. What are the consequences... as it doesn't appear to drive any different. Perhaps a little more fuel consumption. Need to take it for a long run out at the weekend to double check.
 
#7 ·
If the thermostat is nadged then it allows the coolant to flow constantly, which then means the engine can't get up to temp which affects the heating system.

You'll usually find the heating won't function properly by not getting hot enough. It won't damage the system in the short term but I wouldn't leave it like that cos I'm sure it will affect something!
 
#8 ·
Had this on my first A5. Ran for 3 years at bang on 90C, then suddenly wouldn't go above 80C and hunted between 70C and 80C. Suspected thermostat, and got my trusted independent Audi specialist to change it. Operated at bang on 90C again after that right up until I traded the car. Interestingly no error code when scanned with VCDS!
I didn't leave it, got it changed out straight away. Thought that long term running at cooler than designed temps would increase wear.
It's your stat, no doubt.
 
#9 ·
Cheers guys for the speedy responses! Hopefully a warranty job if it's labour intensive. Was looking at another thread DIYer guide... didn't look like he dropped the front which surprised me.
At least I can get them to finally install my tranny mount. After all Cuppas efforts it's been sat in my glove box ever since [emoji15]
 
#10 ·
When I first acquired my 3.0TDI it would have similar issues. Had the 'stat changed; no improvement. Changed both temp sensors; no improvement. Changed water pump; no improvement. Finally found there's an EGR thermostat, little thing, which the previous owner/garage had removed entirely leaving the housing empty; only a small pipe but the flow of water was enough to keep the engine cold.

Thermostat and Water pump were both front-end off jobs (though actually they were both showing signs of wear and the thermostat had certainly been leaking). EGR thermostat didn't take them long to do at all.

Not sure about your location, but I only take mine to MidlandVW in Cannock as Jody was brilliant when mine was having its issues. Very reasonable prices and they know their stuff inside out.
 
#11 ·
Cheers Jamie... really useful to know. I've got a good local indy.. they're not too pricey but always discuss in depth any faults and available options. They're getting to know me quite well with this car ;-)
 
#12 ·
Just spoke to garage. They reckon it's fine to drive temporarily... they just said it might be a bit choked and heavier on fuel. I mentioned about engine wear and they didn't seem to think it was running too low temp to be of significance... as long as I didn't ignore it for months on end.

So in short... using this forum, and paying a bit more attention than I normally would, has possibly highlighted something that could have been missed on a fault read or by a hasty mechanic... so thanks again all [emoji106]
 
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#13 ·
Received my new stat on Friday to be fitted Saturday. Took a few bits of trim off to get decent access to it and low and behold I've been sent the wrong part despite matching it to my registration, so that was a complete waste of a Saturday. Note to self, do not use Eurocarparts again!

Spoke to Audi and there cheaper by a long shot, about £36 if I recall correctly. Will post up a brief how to for others once completed next Sat as only three bolts hold it in situ.

Interesting read on the EGR thermostat? Didn't realise there was such a thing but if this fails to fix it that will be my next port of call.
 
#14 ·
Had a run out this weekend and it does occasionally hit just above 80... but mostly sits at 70 even after a good 30mins driving.
The fact it's not out by a massive amount I'm wondering if it could be the EGR stat instead of the main one. Guess I'll know soon enough.
 
#15 ·
Mine did exactly that, and mine was the main stat MJ.
 
#16 ·
Finally replaced the thermostat today, and bingo, bang on 90 degrees and MPG increased up to average of 45 on a run from 32.

It's not a front off job as I was told. Only need to remove a few bits of trim and excess hosing, push the auxiliary belt out the way, undo three nuts and off it pops. Note that you will need a minimum of 2 jubilee clips as you have to snap off the crimp rings Audi use. Hope it helps.
 
#17 ·
As I said, certainly sounded like the main stat. Glad you're sorted.
 
#19 ·
Nice one MJ. Glad you're sorted mate.
 
#20 ·
The main thermostat allows water through to the cylinder head when the engine is up to temperature, the idea being that water only circulates in the block until warm so it takes less time to heat up, the 70-80 degrees read on the temp gauge will just be the heat soak through to the head and not an actual coolant flow temperature if the thermostat hasn't opened.

Prolonged engine operation under those conditions can be deadly for a cylinder head so its best to get these swapped out as soon as possible.

Glad your all sorted now, quite surprised there is no coolant flow warning for the head but I guess thermostats are seen as pretty bulletproof in general so one isn't necessary.
 
#21 ·
Good morning, I have a A5 2.0 T and now when I start the car it shows the message for temperature malfunctioning and I drive it for few minutes water start boiling, what could this be? And the other thing can sound goes up and when I park the car the fan will still run for almost five minutes and the fan sound was still up and noisy.Please assist
 
#22 ·
If the coolant starts to boil after a few minutes, this sounds like the coolant pump has failed or the thermostat is stuck in closed position. I think the thermostat on your engine is electronic, so that maybe the temperature malfunction message. Try changing the thermostat and coolant pump.
 
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#23 ·
Wow another old thread revived eh Dave?? But your tips are as helpful as ever. Thapelo have a good search on here and you will find many threads talking about the thermostat, it seems that VW changed supplier and the new ones are not so good so it is a common fault, but fairly cheap to change luckily.
 
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