Coolant Loss - 2.5 TDI AKE

[allan_audi]

I have a 2000 Allroad with 2.5TDI AKE engine (156k). I replaced the thermostat earlier this year, all has been fine for months, engine finally running at correct temperature.... until yesterday. I had the coolant warning light when cold, checked coolant, not showing, had to fill a litre or more.

I looked and can't see any obvious leaks or signs of leaks, anybody know the most common problem on these engines??

[Peter D]

Assuming it is not a hose or rad pin hole and no water in your oil then it could be your Exhaust gas recirculation cooler, you need to pressure test it stand alone. Regards Peter

[allan_audi]

Ok thanks, I assume this is under the engine cover, I did take that off last night, but probably wouldn't see water there as it would evaporate. I'll take a closer look later. Might be better to check when cold or pressure test as you say.

[mickmcvw]

I had a coolant hose pop off at the bottom of the rad on mine (same engine) for no apparent reason. Mind you, the coolant loss was a bit more dramatic than yours sounds like but maybe it was slowly working loose over time before it completely popped & I never noticed. Easy to check though when the under tray is off.

[allan_audi]

Yeah, I checked the bottom hose first, because it didn't seem right when I changed the thermostat, but it seems ok.

I can't see any signs so far, I'm wondering if its the water pump, more investigation required. There is no water in the oil, still clean inside the cam covers so don't think its head gasket.

[Peter D]

Run the engine until hot late in the late evening ( dark ) then search the engine and rad with a powerful torch, this will highlight the steam from a pin whole in the rad. Regards Peter

[allan_audi]

Well this is weird, I had the car up on ramps last night, took the under trays off. I looked everywhere for coolant leaks using a bright lamp, I couldn't see any evidence of leaks at all, yet it appears to be using around a litre of coolant every 100 miles. I checked the radiator, top bottom hoses, even the hoses around the back, central and sides of the engine. I looked for leaks around the water pump and cylinder head, nothing, no oil either. I ran it for half hour or so (after a 50 mile trip from work), it was really hot.

The only thing I found suspiscious was when I removed the expansion tank cap (radiator/filler cap) there was no pressure, and there was water all round the outside of the cap (where excessive pressure normally escapes).

I can't believe for a minute that its the cap, but I'll get a new one just in case. Yet I can't condemn anything else yet, the radiator does look tired, it has debris in the core (mostly remains of dead creatures!!), I'll replace next time the front is off. I expected the water pump but no signs, and the head gaskets, well it runs beautifully always stays at 90Deg, no smoke, oil level is fine, nice colour, no oil in the water.

Anybody else have any ideas??

Ps. Peter D, couldn't find anything like an EGR cooler, just the EGR valve with its usual exhaust/inlet connection.

[Peter D]

The EGR on an AKE is water cooled and the EGR may be leaking water into the exhaust thus no signs of a leak externally. A faulty cap will cuase the loss of pressure but water loss at 1ltr per 100 miles I doubt. Regards Peter

[philfingers]

On my 2.5 AFB engine I had a hose go (in -5c the night before I was due to leave on a 1000 mile trip to Scotland) which was under the inlet manifold, under the RH cyl bank is that makes sense. it was also use the same amoutn of water. I thought it was the cap, so got a new one off ebay for £5-6 turned the old cap into an adaptor for my pressure test kit. It weas only by pressure testing it that I found the leak. In fact it's right under the oil filler cap, as I reckon it was dribbling oil that had caused it to perish. luckily I had a 205 gti hose that fitted perfectly. I thought adding something french would add some unreliablity and keep me on my toes.
Also they show 90 deg whether at 80 or 100. I'm told it's built in feature to prevent worrying owners!

[allan_audi]

I checked those hoses last night, right next to the inlet manifold but both seem fine, yeah I'm aware of the temp gauge deadband (I write software for Instrument Packs), but even so you would know if the engine were overheating. It runs really well, I'm still not sure where the problem is.

[allan_audi]

The EGR on an AKE is water cooled and the EGR may be leaking water into the exhaust thus no signs of a leak externally. A faulty cap will cuase the loss of pressure but water loss at 1ltr per 100 miles I doubt. Regards Peter

Pete, yeah I understand what you're saying, but I can't find any coolant pipes going to the EGR, if you take a look at the picture attached the EGR is top right, the only pipes to it are the exhaust and inlet pipes. I've even checked underneath too....

[Peter D]

I missed that you has an Allroad. They had a fuel heating/cooling system and did not use a water cooled EGR valve. Regards Peter

[allan_audi]

On my 2.5 AFB engine I had a hose go (in -5c the night before I was due to leave on a 1000 mile trip to Scotland) which was under the inlet manifold, under the RH cyl bank is that makes sense. it was also use the same amoutn of water. I thought it was the cap, so got a new one off ebay for £5-6 turned the old cap into an adaptor for my pressure test kit. It weas only by pressure testing it that I found the leak. In fact it's right under the oil filler cap, as I reckon it was dribbling oil that had caused it to perish. luckily I had a 205 gti hose that fitted perfectly. I thought adding something french would add some unreliablity and keep me on my toes.
Also they show 90 deg whether at 80 or 100. I'm told it's built in feature to prevent worrying owners!

Hi, I'm replacing the cap today, how did you make your pressre test kit? Did you drill hole in old cap and use for airline adaptor? I reckon the only way I'll find the leak is to pressurise the system, as you say.

[philfingers]

Yes, pulled the guts out and used a bolt in tyre pressure vale like this http://cgi.ebay.co.uk/Bolt-Tyre-Valve-Choose-Quantity-/290461684408?pt=LH_DefaultDomain_3
I have a proper pressure test kit but really all it will tell you is if the pressure drops that you have a leak.
I probably put around 15psi in with my tyre airline run off the compressor. You could use a bicycle pump. Just be aware that pressure will build quickly if the right amount of coolant is in there, there's little air and that's the only compressible medium!

[allan_audi]

Well I wouldn't believe it but saw it with my own eyes...

Fitted new expansion tank cap yesterday and fluid level fine this morning. Seems to have been the problem, will keep checking over next few days. Need to top up with pink fluid at some point.

So if anybody is losing coolant with no obvious signs check you cap first. Especially if the cap is loose even when tightened up and water/moisture is visible on the vent/relief side of the cap.

[DukesA6]

Hi Allan

I have a 2.5tdi quattro that has the same engine as the allroad (AKE), my car also looses water every now and then. I must replace my cap, didnt think about that!

Just out of curiosity, how much did the cap cost you and did you get one from Audi?

Thanks

Duke

[allan_audi]

Hi Allan

I have a 2.5tdi quattro that has the same engine as the allroad (AKE), my car also looses water every now and then. I must replace my cap, didnt think about that!

Just out of curiosity, how much did the cap cost you and did you get one from Audi?

Thanks

Duke

I wanted one ASAP so ordered from a local Factors, £10.90, its been fine since, not used a drop of water, but I would get an Audi part, its slightly cheaper too, about £10 from Audi. This one came apart when I took it off to check the level on Sunday, it went back togther but!! Nasty.......

[allan_audi]

Weird, just about to set off for work this morning, get the coolant warning light. Needed to put 2 litres of water in the tank.

Yet, last week it seemed ok, I checked it several times, towed the caravan to peak district, checked on Sunday, still ok. I haven't checked since but done about 400 miles this week.

Maybe something else has started leaking, thought it was sorted!

[allan_audi]

I finally got round to pressure testing the system, turns out an O Ring is leaking from the metal pipe going from the rear of the thermostat housing on the block to the rear of the drivers side cylinder head. Its the pipe which houses the coolant sensor on the top. I've managed to disconnect/dislodge the pipe and can see that the O Rings are perished.

I've bought all the O Rings, cost about 2 quid! But.... does anyone know how you get this pipe out, I cannot get to the end with my hands (to fit the O Ring), so it looks like you need to remove a) the turbo and b) the oil filter housing.

Does anyone know how?? Any Audi technicians?

[Peter D]

If you can not access this pipe then you have to remove the Oil Filter Bracket. You not goint to like this, but the Turbo and exhaust elbo have to come off. PM me your email address and I'll send you the data. Regards Peter

[allan_audi]

Finally removed coolant pipe, was big job, took about 6 hours.

Looks like the pipe itself is faulty, has a small hole near the joint. Doesn't look like corrosion either, more like a defect in the pipe from the factory.

Now to order the pipe/several gaskets etc... put it all back together.

I did manage to change the glow plugs while its all dismantled, every single one of the old ones was open circuit. Didnt like changing them, felt like they were gonna snap!!

[Peter D]

If it is not corrosion have you considered having it silver soldered or siffbronzed. Regards Peter

[Peter D]

As it is stripped down you may wish to consider changing the oil retention valve. Check your emails.

Regards Peter

[allan_audi]

As it is stripped down you may wish to consider changing the oil retention valve. Check your emails.

Regards Peter

Thanks, I'll order these, I may aswell replace them since they're accessible at the moment.

Looks like the coolant pipe is around 80 quid from dealers, I might look into brazing or welding the hole as your suggestion.

[Peter D]

Are you sure it is not corrosion, if it is then brazing will fix that hole but others may be waiting to surface. Regards Peter

[allan_audi]

Are you sure it is not corrosion, if it is then brazing will fix that hole but others may be waiting to surface. Regards Peter

I'm fairly sure its not corrosion, there is some light surface rusting. There is a hole approx 3mm in diameter right next to the steel sealing ring which the O Ring mounts onto, looks like the sealing ring has not been attached correctly and eventually the water has found its way out. Not sure what the 3mm hole is there for, but it doesn't look like its corroded.

[allan_audi]

Car is finally fixed, friend of mine silver soldered the coolant pipe, I used some Plastic Padding leak fix on the inside of the pipe to smooth it down a bit.

Looks like it was corrosion afterall, but the rest of the pipe looks fine.

Changed the oil retention valves and it doesn't rattle when cold anymore. Thanks Peter, I wouldn't have known to change those.

Cleaned all the intake pipes out, was loads of sludge, really thick n dirty stuff! Also freed up the turbo VVG actuator, was quite stiff, I'd had a couple of fault codes thrown up for this.

Full set of glow plugs fitted, I tested that they weren't on all the time too, good suggestion from another thread on here.

It was a right pain to get started, I'd removed all the fuel hoses and injection pipes. Nearly flated a battery. Finally caught and I just left it to idle for a while.

I'm just running some coolant flush, will drain and fill with G12 later, re-fit the undertrays......

Big job, took 7/8 hours to assemble, mind u I think most of that was spent parts washing and cleaning hands, never seen such sludgy crud!

[Peter D]

I'm not sure I like the plastic padding fillett inside the water pipe. If this dislodges where is it going to get stuck and reduce the water flow. Regards Peter

[philfingers]

I'm not sure I like the plastic padding fillett inside the water pipe. If this dislodges where is it going to get stuck and reduce the water flow. Regards Peter

Agreed, or jam the water pump and break the cambelt. . . .

[allan_audi]

It won't dislodge, its an epoxy made to fix coolant leaks (and various other leaks), plus I think you're assuming I used vast amounts. I used a mix about the size of a pea and spread it over the corroded area, after cleaning the inside with a dremel and a small grinding attachment. I then smoothed it down with a sanding attachment after a 24 hour cure.

[philfingers]

Sounds ok, industrial adhesives are good these days. They glue the Lotus Elise together after all!

[DukesA6]

Sorry for bringing up an old post...

My local car spares have asked which psi cap i wanted, he said there is a 22psi and 29psi cap for the coolant / reservoir tank. Can anyone confirm which one to buy?

Mines a 2.5tdi Quattro 2001 180bhp - i think its the AKE engine.

Thanks

[allan_audi]

Don't bother with a copy part, the one I bought snapped in half after a couple of days.

Phone your local daler and order one, its cheaper too!

[philfingers]

I had a copy one and it was fine but as per the last post I'd buy original

[Peter D]

Go and buy one form Audi/VW 22 psi. Spec is 1.4 to 1.6 bar. Regards Peter

[DukesA6]

If you can not access this pipe then you have to remove the Oil Filter Bracket. You not goint to like this, but the Turbo and exhaust elbo have to come off. PM me your email address and I'll send you the data. Regards Peter

Peter - Sorry for bringing up an old post, think i have the same problem! Please could you email me the above info and also info on the oil retention valve i have PM'd you my email address. Mines an AKE engine.

Many thanks

Duke

[allan_audi]

Peter - Sorry for bringing up an old post, think i have the same problem! Please could you email me the above info and also info on the oil retention valve i have PM'd you my email address. Mines an AKE engine.

Many thanks

Duke

Do you have the same leak I had with the metal coolant pipe?

[DukesA6]

Do you have the same leak I had with the metal coolant pipe?

Hi mate, to be honest im not 100% sure where it is coming from. Im getting through about a litre every 100 miles or so. Ive always had a leak but this week its got worse and am planning to get the car on the ramps to have a better look as the leak is not clearly visable.

One thing i have noticed is that when sitting in traffic i dont get any heat through the heater but when driving its fine, which kinda makes me wonder if its the water pump that has packed up!

Also if it is the head gasket that has gone, what signs would be visable to prove this? Would there be white crud etc on the bottom of the oil filler cap? Any other signs? Car runs fine otherwise, pulls good etc. I have noticed that it seems a little 'rattly' in the past few weeks but wondered if that was something to do with the cold weather?!?

Duke

[allan_audi]

Best thing to do is pressure test the system, it takes 30 mins to setup and found the leak within 5 minutes. One of the guys here suggested it. I did it slightly different.

Basically tap into the small coolant hose going to the coolant tank with a t-piece and inject air pressure bout 15-20psi. If there's a leak you'll hear and eventually see it.

It the best way, you really don't want to be dismantling anything until you know.

You can do this with an old tyre valve and footpump or if you have one a compressor (just make sure you restrict the pressure).

[philfingers]

mine was leaking from a rubber hose under the near side rocker cover. Oil I guess split during filling up at persihsed the hose and it was delaminating. An old 205 gti hose i had kicking around solved it

[rotelmotel]

hi mate i had the same problem loss of coolant,kept topping up for about a year till it came time to do cambelt, then spotted the problem waterpump. under the telltail ther was a stalagnite it must have weighed a kilo,replaced pump no more coolant loss

[DukesA6]

hi mate i had the same problem loss of coolant,kept topping up for about a year till it came time to do cambelt, then spotted the problem waterpump. under the telltail ther was a stalagnite it must have weighed a kilo,replaced pump no more coolant loss

Could you see the water leaking by the pump before you changed it? Ive had these go on cars in the past and you could literally see the water running out the bottom.....?