Mysterious loss of coolant

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tomyoud

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Hi guys,

I was wondering if someone could shed some light on this for me as it's starting to drive me crazy-

I have an A4 1.9 TDI (engine code BRB) and every week I check the coolant and it's always loosing a small amount very time I check. If I fill up the expansion tank anymore than half way between the 'max' a 'min' line it just chucks coolant out of the overflow.
I can't see any signs of leaks either.

The coolant is crystal clear and no indication of coolant in the oil. The water pump was changed about 10,000 miles ago and the thermostat was change at about the same time too.

I don't think it's a head gasket issue as the the coolant pipes I'm able to squeeze and would expect them to be really hard from the system being overpressurised.

One thing I have noticed very recently when I drive the car within the first minute or two is I can hear what sounds like water/coolant in a pipe flowing which I'm guessing is going through the heater matrix?
After that first minute or two I never hear it again until I use it the next day when I drive it.

Many thanks
 
If there's no obvious leak, no sign of burning coolant then unfortunately it's very likely the head gasket mate :/ If your putting in coolant when not needed, when the system does depressurise it will spew the excess out of the overflow. I had the same problem on my wife's car - That was on an A3 8P. The heads are made of sponge! Maybe time to part ex? Not a cheap fix...
 
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Mike J said:
If there's no obvious leak, no sign of burning coolant then unfortunately it's very likely the head gasket mate :/ If your putting in coolant when not needed, when the system does depressurise it will spew the excess out of the overflow. I had the same problem on my wife's car - That was on an A3 8P. The heads are made of sponge! Maybe time to part ex? Not a cheap fix...
Click to expand...

Thanks for your reply mate, I was worried it could be the head....only had it for a year but probably have to think about trading it in for something else.
The only other thing I've noticed is - when I drive it hard, say rev it to 3000rpm I can see a very faint cloud of white smoke out of the rear view mirror (but only when it drive it hard).
I'm guessing that faint cloud of white smoke is the coolant??

Cheers
 
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Highly likely it is unfortunately mate. What's the oil like and is the oil cap clean?
 
Mike J said:
Highly likely it is unfortunately mate. What's the oil like and is the oil cap clean?
Click to expand...

The oil is fine mate....just the usual black colour and no mayo looking stuff on the dip stick or cap.
I was wondering whether to use k-seal, I never really like using that sort of stuff and like to repair things properly but heard mixed reviews about it clogging up the heater core and the tiny coolant pathways.

Worth a shot?
 
I have heard of K-Seal and Steel seal however no experience of using it. I would think for simple leaks it may work but not sure for high pressure problems in the head. There are forums on using it with mixed results. May be worth a try especially if it delays the expense of a new head gasket..
 
Hey guys,i have an A41.9tdi sline and i am having the same problems... No sign of leaks and needing to top up the coolant. I have had a new cap for the coolant bottle,new thermostat and new water pump(timing belt too since i was there) and still no joy. The only difference that has made is the temp never goes over 50 degrees... Still loosing coolant and the engine bay looks like a dogs dinner. Gona have to bite the bullet and get the gasket changed...any one know a good mechanic who is an expert in this field??? Its doing my nut in now
 
Dan burns said:
Hey guys,i have an A41.9tdi sline and i am having the same problems... No sign of leaks and needing to top up the coolant. I have had a new cap for the coolant bottle,new thermostat and new water pump(timing belt too since i was there) and still no joy. The only difference that has made is the temp never goes over 50 degrees... Still loosing coolant and the engine bay looks like a dogs dinner. Gona have to bite the bullet and get the gasket changed...any one know a good mechanic who is an expert in this field??? Its doing my nut in now
Click to expand...

Hi Dan,

I know how you feel. I'm afraid I don't know anyone who is an expert.
One thing that might want to get checked out is the EGR cooler.
I spoke to someone at the weekend who said it can be the EGR cooler which can fail and let coolant into the inlet manifold.
I'm going to pressure test mine in the next week or so to see if thats the issue....worth a shot as it's alot cheaper than a new head.
£319 for the cooler (from Audi).

Cheers
Tom
 
Cheers for the tip tom,might look into that myself,my car is out on finance about 7months now. Rang them today and told them the whole story. The girl said i should be hearing back from the investigation department to see if they can help me out. I got 6 months warranty with the car and this started to happen towards the last month of the warranty. The dealership thought it was maybe a broken propeller on the water pump so that and the timing belt were changed. At first it was leaking out the overflow hole beacause it was boiling over but now its not and the level seems to be dropping every other day. As i had a guy clean out all the hoses and coolant he said it can take a while for the car to find its own level and that it will drop untill it does. Dont know if this is true or not or i am just being super paranoid now
 
tomyoud said:
Hi Dan,

I know how you feel. I'm afraid I don't know anyone who is an expert.
One thing that might want to get checked out is the EGR cooler.
I spoke to someone at the weekend who said it can be the EGR cooler which can fail and let coolant into the inlet manifold.
I'm going to pressure test mine in the next week or so to see if thats the issue....worth a shot as it's alot cheaper than a new head.
£319 for the cooler (from Audi).

Cheers
Tom
Click to expand...
If it is the cooler and that's just the part cost it may be worth seeing if you could get rid of cooler and egr valve all together? Sure I've read before this can be done, I know the egr valve definately can be dumped but not 100% sure on cooler. It may just be cheaper and will save you any egr related issues in the future.
 
My old B6 TDi 130 developed a coolant leak where a hose crossed the exhaust manifold. I think there was a heatshield missing, and the combination of heat and rubbing caused a hole to form - might be worth checking for this. From memory it wasn't that expensive to fix.
 
Thanks for the tips guys.

SDHA4Sline - I know on some cars you can't take the EGR cooler out. I was thinking about blanking my EGR as I cleaned my EGR valve whilst looking at the EGR cooler at the weekend and noticed the difference in performance and MPG after cleaning it. Do I need to tell the ECU that there is no EGR valve if I do blank it off?

Dan - Sounds like similar problems to me - if the coolant level in the expansion tank was inbetween the 'max' and 'min line or over that level it was chuck out the overflow. What I did find strange is that sometimes it didn't chuck it out at all and other times it did.
For the last few days my coolant hasn't dropped at all, and it stay just below the 'min' line...maybe that's my cars own level?!?
 
audi upgrades
Thanks for the tips guys....tom thats good to hear,hope it stays that way. I will def check out those pipes to see if they are touching each other. My mechanic did say to me that after having the coolant flushed out completely and refilled that it can take anywhere up to 60 miles for a car to find its own level.. I was reading the owners manual too and it says that when the engine is cold the coolant level will always be at minimum and when its warm it rises to the max so i suppose if you have overfilled then while driving it would chuck it out?
 
That does make sense, as the coolant level with rise because of the pressure in the system...but I don't think it's under too much pressure, I think I remember hearing it was about 2 BAR. Though I have the car serviced at Audi recently and they topped up the engine coolant to the max when it was cold and just chucked loads out.
I'd be interested to hear what the Investigation department say Dan as it really does sound like we both have a very similar issue.
 
I will keep you posted on that out come,i just hope they say leave it into audi and we will foot the bill.. Its a great car apart from this one issue and i dont want to get rid of it as i have a few plans for it,tinted windows/nice wheels and chrome mirrors. A bit cliché i know but they do look good.
 
Great cheers! Looking forward to hearing the outcome.
Totally agree, great car apart from the damm cooling system.

Cheers
 
tomyoud said:
Thanks for the tips guys.

SDHA4Sline - I know on some cars you can't take the EGR cooler out. I was thinking about blanking my EGR as I cleaned my EGR valve whilst looking at the EGR cooler at the weekend and noticed the difference in performance and MPG after cleaning it. Do I need to tell the ECU that there is no EGR valve if I do blank it off?

Dan - Sounds like similar problems to me - if the coolant level in the expansion tank was inbetween the 'max' and 'min line or over that level it was chuck out the overflow. What I did find strange is that sometimes it didn't chuck it out at all and other times it did.
For the last few days my coolant hasn't dropped at all, and it stay just below the 'min' line...maybe that's my cars own level?!?
Click to expand...
Yes I'm sure you will have too if you don't want errors popping up
 
Assuming this engine has the same layout as the 2.0 petrol, have you checked the temp sensor coolant flange at the back of the head? Known source of leakage as they crack. Also, although it looked fine, the header tank on mine leaked coolant from the cap orifice even with a new cap. New flange, sensor, cap and tank - no more coolant loss. And I was convinced the head gasket had gone !
 
How much did the above items cost all in?? Never heard of a flange? Can you provide any links for the items please
 
Assuming your engine is the same, at the back of the engine there is a temperature sender which slots into an L shaped black plastic flange bolted to the engine. Total cost of all the parts mentioned was maybe £50. Putting "audi a4 temperature sensor flange" thro Google image search will find you lots of reading - hope this helps.
 
Just booke my car in with audi . Fed up so i decided to bite the bullet and see what they have to say,booked in for wednesday morning,will keep you guys posted on the out come
 
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