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Discussion Starter #1
Hi team! Sadly I’ve got a bit of an issue with the 2008 3.0 tdi A5.

It’s losing coolant at a rate of half a litre every couple of days but no sign of it going missing anywhere...

The other day after losing coolant for a few days (and having been topped up), the serpentine belt shredded a tooth (v belt). I pulled over and noticed a fair amount of liquid dropping on floor from centre of car, probably come down undertrays from somewhere.

Had it in a garage who replaced belt and pressure tested the coolant system but it’s rock solid on pressure so they couldn’t find a leak.

Out of the garage and it was solid level for a couple of days and again dropping.

Level increases when hot, but goes back to below original level when cooled.

Any ideas would be awesome!
 

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Could be gradual loss through perforated head gasket, and as its only a relatively small amount this may not be very noticable coming out as white exhaust vapour until it worsens- hopefully it's not this, but def worth getting it checked to avoid a potential overheat & head warp. Otherwise, there may be a slight bearing seizure somewhere, poss water pump related, causing resistance, leakage and the belt to go?
 

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Discussion Starter #5
I was hoping it wasn’t the heads! They’re not renowned for it I guess?

If it was water pump wouldn’t I see it on the floor with the undertrays off whilst it’s stationary?

Also why couldn’t they find it when pressure testing?
 

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I really don't know- just a couple of suggestions, but although I've not heard of head gasket issues on these, for your own peace of mind and the purpose of elimination I'd get the head tested first, and see what they suggest if it's OK?
 

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Discussion Starter #7
Does make sense!

New piece of information... slight spotting underneath the car after leaving it for the weekend, and orange liquid in the v behind the water pump.

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If it’s coolant, why is it orange? Coolant is pink....
 

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Well, that means if its coming out its better than dissapearing into the engine somewhere and it should be possible to spot, and hopefully nothing like this:
'This page is devoted to addressing a problem afflicting the Audi 2.7 liter turbocharged engine – a slow coolant leak into the engine oil circuit.
QI have a coolant leak; does my car have this particular problem?
A – There are a variety of places where coolant can leak from the cooling system. One common location is the auxiliary coolant pump, that I discuss on this page. The focus of this page is one particular problem; a slow loss of coolant into the engine oil with no indication of loss, other than the slow drop in coolant level.
What follows is a suggested list based upon the experiences of people who have been through this.
  1. Check your coolant expansion tank for discoloration. This could indicate that oil is also entering the coolant system. Note: This has not been a symptom for the people who have been affected by coolant contamination of their oil.​
  2. Have a thorough visual inspection performed by someone who knows where to look for coolant leaks.​
  3. Have a coolant system pressure check performed.​
  4. Have an engine compression test performed.'​
Also this: ..'When VW coolant is new, It looks just like pink lemonade. If yours is darker than that, time for a change. I've had a few cars where it started to appear orange as well, it can be to do with the mix, among a few other factors I'm sure. As noted above, it is suggested that the coolant is changed out every 2 years'..
 

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I know you can't really tell in the summer, but does it warm up ok and stay on 90 deg and not drop when running downhill - granted this is more noticable in winter months!

I replaced the EGR thermostat which is in the middle of the V next to the EGR stuff. It is a push and click fit. I thought when I changed the stat that it could be a source for a leak!?
 

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Discussion Starter #10
Funny enough, I just phoned the specialist I used in Brackley and they mentioned a thermostat in the v from another customers car. Big job to do it? Looks like full strip down to get to anything... intake manifolds off etc
 

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It is a bit fiddley and can be done without removing the manifolds. Just a few fuel pipes here and there. But the less you remove, the more fiddley it is, but I managed it on the driveway at home. :)
 

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Discussion Starter #12
Good effort. Problem is, without removing a fair few bits and bobs, you can’t see where it’s coming from. And it’s only really losing when hot, but won’t be able to get it hot with the engine in bits.

So bit more information. Gave it some beans on the way home from work. Temp never moved off 90. But parked at Asda car park, came back and fair few drips on the floor, pink, so defo coolant. Does appear to be coming from the v.
 

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Discussion Starter #13
Just to close down this thread. Took the car to AWESOME GTI and they diagnosed it as leaky EGR cooler seals. Replaced pretty much everything in there and the coolant is rock steady again!

Thanks all for your help along the way!
 

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Glad it's sorted and thanks for sharing the cause- so you say the EGR cooler was replaced recently and yet the seals leaking on that were causing this problem?
 

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Discussion Starter #15
Awesome think that some of the seals were reused when the assembly was put back together. Said some were deformed. There’s tonnes of seals around all the adjoining pipe work so they just replaced them all. Lots of part numbers on the receipt 😀
 
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