Coolant loss

[humphrey999]

2.0tdi PD 140 BRE, MY2008 103,000m fully serviced etc...

I have a gradual coolant loss that, until this morning, I haven't needed to do much about, I had just noticed the level in the expansion tank slowly decreasing over the past 6 months or so. Today I got a red warning -"Stop engine and check coolant level". The tank wasn't completely empty but almost; the level has started dropping much more quickly. Are there any common sites of coolant loss in these engines that I should be looking out for or should I send it into the shop for diagnostics?

In a previous car I have had a leaking heater matrix but I don't get any of the similar condensation and misting signs this time around.

Thanks,
H

[Alan02]

Look around all hoses. Rad.and Oil cooler etc for signs of Antifreeze tell-tale crusty build-up. Water pump area (behind cam covers). Check both hot and cold for signs of water leak in all areas.

[humphrey999]

Thanks Alan, when hot there seems to be a pool of water on the undertray by the left of the rad (looking from the front of the car), the other end from the inlet/outlet pipes; could there be a crack in the rad there? No sign of any crusting anywhere else that I can see but I haven't managed to survey the water pump area yet. Presumably the rad doesn't corrode because it's aluminium but it could get holed by a stone?

[humphrey999]

So, there is no consistent sign of water loss in the engine bay and today as I was topping up the oil I noticed black mayonnaise under the oil filler cap. I'm now fearing the worst...

BRE 08 104000m and regularly serviced.

Are there any other possibilities beyond a new cylinder head or gasket?

[Brycie]

I have the same engine & have also noticed over the past 6 months that the coolant level seems to drop quite quickly. I've had it pressure tested though & the results came back fine. I just put it down to the water/coolant being added when the engine was hot & me noticing the dropped level when cold, but I'm starting to doubt that's the case.

[joshA6]

it could be a leaking oil cooler so don;t assume that it is a head gasket problem. Get the engine pressure tested (it needs to be done properly) to help work out where to begin.

[humphrey999]

OK, so reading around, my oversimplified understanding of the possibilities are the following:

Oil cooler failure - but seems to lead to oil contamination of coolant rather than the other way around since the oil is under greater pressure.

Head gasket failure - but usually given away by the smell of coolant in the exhaust and doesn't normally lead to contamination of oil by coolant

EGR cooler failure - but I think I have contamination of the oil by coolant.

Now, I'm confused, will try the garage in the morning!

[humphrey999]

The car's going in for diagnosis tomorrow morning so Ill report back with any news! I'm still losing 500ml of coolant every 2 weeks and the black sludge under the oil filler is getting worse...:1zhelp:

[humphrey999]

OK so inspected and pressure tested this morning. The black sludge is normal, it would be a problem if it was creamy or grey but black is OK apparently. The pressure testing didn't indicate any leaks. Mark (MDMTechnik) said that he pressure tested the system, the header tank and the cap and all was normal plus he couldn't find any telltale residue in the engine bay. Despite this I know that I'm losing coolant consistently but the fact that the oil is normal is reassuring. From what I read the most common internal loss of water is EGR coolers...

[apole]

Hi,

Mark at MDM is a top guy and knows his stuff so good call to use him.

One thing to consider is the heater matrix(s) in the car, this or a connecting pipe could be leaking. You'd expect damp carpets, musty smell, maybe some steaming up though.

When you say leak, if you left it alone would the header tank run dry? Reason for asking is with some cars if you overfill the header tank a bit, the level will drop to a point then stay there.

Had this with a past car, thought the worst and all it was this - so the problem was me !!

Do you do short or long journeys, if longer ones then any small leak via the cooler etc could just burn off with the heat, wheras with shorter journeys it could then turn to mayonaise.

Did Mark suggest any further course of action?
Has the coolant remained the normal pink colour? Anyone know if the cooler is leaking, would you not expect some of the oil to get into the coolant and change it's colour?

[humphrey999]

Hi, thanks for your reply, yes I really like Mark, he has done all the work on my A6 since I got it and he's my top reason for potentially getting another VAG (or Bentley!) for the future; so that I could continue using him!

I have no misting/fogging in the car and no fusty smell so I don't suspect heater matrix - I had a Citroen that went through 2 so I think I know what that would be like. UNless it's happening on the engine side of the bulkhead but there's no residue.

I think the leak is occurring when I'm driving it but then it very rarely sits undriven for long so that's hard to prove. All my journeys are over 30 miles at motorway speed, very rarely do i do short local journeys so yes you're right, I had been consoling myself that even if coolant was getting into the oil I would be burning it off quickly butI thought with oil cooler issues the oil got into the coolant not the other way round and the coolant is still perfectly pinky

The header tank level drops after each journey - Mark had suggested that if I had overfilled it it might overflow whilst I was driving it but there's no residue and the level is dropping consistently.

Mark didn't have any suggestions other than keep driving it - that was one worry I had whether I was doing any damage - and come back when the coolant loss is significantly worse. No big bill today then....

[Whippy53]

Is this an auto? There have been instances of coolant leaking into the gearbox oil via the heater in the box.

[humphrey999]

Hi Whippy, no it isn't, it's a 6 speed.

[Whippy53]

GOOD!! least we can rule that out as a source of worry!

[Brycie]

It would be good if other 2.0TDI pd engine owners would check their coolant level when the car's cold, because like I said earlier, my coolant level drops too (to about an inch under the min line), but then from what I can see, doesn't drop any further. Mine's also been pressure tested (to a higher pressure than they would normally test to) and has been found to be fine.

So I hope it's just a trait of this engine rather than being a bad omen of problems to come.

[humphrey999]

Thanks Brycie, I'd love to think it was normal but I've had the car for 2 years now and never before needed to top it up. Then, a month ago, I got the red warning for low coolant and have had to start topping it up, coolant was only just visible in the neck of the expansion tank. It's not normal but I'm hoping it's not serious! If the water isn't going anywhere near the oil then i'm happy to keep my eye on it and keep it running till it gets considerably worse.

Pictures of my oil filler cap... show me yours!

2040720408

[Brycie]

I started a tgread when I first noticed mine dropping, so I have a point of reference for when it was last topped up. I'll keep an eye on it & keep you posted on any developments.

[humphrey999]

OK so I's still topping the tank up every week - ten days and there's a very definite loss of coolant still. today I had another look under the cap and the black mayo is worse

20928

...and when the engine's hot and you take the cap off there's quite a lot of steam.. is this normal or indicative of excess water in the oil? The cooling system has been pressure tested and passed and the black mayo has also been deemed to be normal...



http://youtu.be/QkyIAjv9MCg

[humphrey999]

OK, so I wrote sometime ago about the fact I was losing coolant and I didn't know where it was going. The system was pressure tested and seemed fine and I carried on driving it to see if it got worse and became easier to identify the source. Bad mistake,my turbo has failed... What I have just done and wish I had done much earlier was send a sample of oil to a lab to check the coolant wasn't getting into the oil.

I have nothing to do with The Oil Lab but they have turned around my sample in less than 24 hours of receipt and identified heavy piston and crankshaft wear and very high levels of sodium (associated with coolant). This has helped me make the decision to strip the engine before replacing the turbo - something the garage was more than happy to do without further checks.

If you are worried you are losing coolant, spend £35 on a sample kit and test your oil. You could save yourself loads of money in the future!

[zollaf]

normally any water in the oil will appear as a creamy coloured emulsion.

[humphrey999]

Agreed, I had a thick black emulsion on the oil cap - never white/grey. All my journeys are over 30miles on the motorway, and often many times that, so if the oil got hot and there wasn't a mahoosive leak them the water could have been driven off by the engine heat?

[zollaf]

all very strange, have you found out how the water is getting into the oil yet ? i could rule out the oil cooler as the oil is at a much higher pressure, so its either the head gasket or a crack in the block or head.

[humphrey999]

Not yet, the engine starts being stripped on Thursday... I expect gasket or head as you say :(. the oil report suggests quite heavy bearing wear but the oil is ready for a change... it's done 18k.

[Guest 2]

but the oil is ready for a change... it's done 18k.

Longlife at its best. Get it done every 10k/1year from now on.

[humphrey999]

I suspect that loads of coolant in the oil hasn't helped either. :zx11: To be honest it has always burnt a litre of oil every 3000 miles so has had a complete oil change one and a half times between every longlife service anyway!

[MarkTM]

Humphrey, sorry to hear.

Which engine do you have and what year?

[Guest 2]

Humphrey, sorry to hear.

Which engine do you have and what year?


2.0tdi PD 140 BRE, MY2008 103,000m fully serviced etc...

I have a gradual coolant loss that, until this morning, I haven't needed to do much about, I had just noticed the level in the expansion tank slowly decreasing over the past 6 months or so. Today I got a red warning -"Stop engine and check coolant level". The tank wasn't completely empty but almost; the level has started dropping much more quickly. Are there any common sites of coolant loss in these engines that I should be looking out for or should I send it into the shop for diagnostics?

In a previous car I have had a leaking heater matrix but I don't get any of the similar condensation and misting signs this time around.

Thanks,
H

;)

[humphrey999]

now 112,000 miles :(

[humphrey999]

Progress report... head came off today, the gasket looks fine apparently :( and there's nothing to report visually on the head, it's been sent off for pressure testing...

[humphrey999]

Progress report #2 - pressure testing found a crack in the head between a coolant tract and oil return duct. Unrepairable, so new head required...:zx11:

What with the oil pump issues and head issues these really are some troubled engines, I thought by MY08 these issues would have been sorted.

[furfurfur]

Progress report #2 - pressure testing found a crack in the head between a coolant tract and oil return duct. Unrepairable, so new head required...:zx11:

That sucks, sorry to hear that. I too have a small coolant loss problem but it doesn't seem anywhere as bad as yours was. I hope you're able to get a replacement head for not too much money.

[humphrey999]

Thanks Furfurfur,

My one big regret is heeding advice to carry on driving till the leak got worse and I would recommend to anyone who isn't sure from where a coolant loss is occurring is to get their oil tested asap.

Apparently the turbo was completely dry of oil - a blockage in the oil pipes had been caused by all the black emulsion sludge. I have no idea what further damage has been caused by other blockages so as soon as it's fixed it's gone.

[humphrey999]

Recon turbo - £420, new head rebuilt with old internals, £900, labour and ancilliaries including new nearside engine mount £1500. All inclusive of VAT. Ouch... and I'm not even sure I want to keep it now...

[MarkTM]

Someone I know saw a 2.0 PD 2006 Avant yesterday, high mileage hence the £3,700 price :aargh4:

Told him if the garage will let him I'd be happy to scan it for him, but am thinking that the problems you've had wouldn't show up on a scan anyway :(

[humphrey999]

No they wouldn't but they would on an oil sample though. No one I have ever seen on a forum talks about oil analysing but it's a mine of info. Can you imagine your GP diagnosing disease without taking blood?

[MarkTM]

Preaching to the converted here humprey as have used blackstone labs stateside for the last 13yrs (before it got more popular here). That said even using a UK company with a 48hr turnaround there's a possibility that you'd miss out on your dream car in that time..wonder how the selling garage would react :confused:

[Hobb99]

I reported quite a while ago that I had a coolant loss, but didn't get much feedback on what could have been the cause.

I even let Kings Lynn Audi have it for half an hour to investigate, and they came back with a possible cylinder head issue that I poo-poo'd!

Having given the car to the local Indy to replace the timing belt and water pump, he suggested using Steel Seal when the pump wasn't diagnosed as being the culprit. Its a chemical composition liquid that you pour in similar to Radweld etc but does not have the fibrous content in it. It sets hard where the leak is, but remains in suspension for the rest of the time.

It's taken me a while to get around to it, but I put it in over the weekend following the instructions and left the car to cool down overnight before filling up with antifreeze yesterday. As I took off the expansion tank cap, it popped! It's not done that for ages!

I'm not saying it's going to work long term, but I sympathise with you Humphrey for all the heart-ache you've gone thro and what you have been good enough to report. It has raised my eyebrows to the fact that I pretty sure my engine is consuming coolant.

Now that the Steel Seal is apparently sealing the leak, the car is booked in tomorrow for its intermediate service and oil change - but I've also asked if they will flush the oil system rather than just change it. I hope I've caught it early!

Cheers

Mark

[gupsterg]

What with the oil pump issues and head issues these really are some troubled engines, I thought by MY08 these issues would have been sorted.

Hi ya chap,

Sorry to hear about the head issue :( . As your getting the engine stripped, etc, I'd also get the oil pump hex follower checked. This guy Link:- Oil Pressure Warning! Boom! (http://www.vwaudiforum.co.uk/forum/showthread.php?145062-Oil-Pressure-Warning!-Boom)! had it go even on a MY08.

I'd also view this post/thread Link:- 2007 A6 2L TDI 140bhp - Engine needs replacing according to Audi - Page 8 (http://www.vwaudiforum.co.uk/forum/showthread.php?123811-2007-A6-2L-TDI-140bhp-Engine-needs-replacing-according-to-Audi&p=814016#post814016)

ATB
G

[humphrey999]

Yeah, I'm sure, with my luck that's round the corner but the oil pump is a total different area of the engine isn't it? Requires lowering of subframe, removal of sump etc? I had talked to the garage about taking of the sump and clearing it of all the emulsion gunk but they were happy to receommend a number of oil changes with flush rather than dropping the sump off. Agreed, though, I'd like to check the oil pump hex shaft out, I expect I will have traded it in before then though...

[gupsterg]

Yes oil pump is lower end of engine.

I don't think the complete front subframe is removed but some bolts are removed which hold the engine mount consoles to it and hold subframe to chassis.

As you know I have no hands on experience of this or seen the 2.0 TDi in the same way as my 3.0 TDi but I'm sure Zollaf or Crasher or another will be able to advise better with first hand experience.

From a previous post your stating current repairs are costing £2820? I suggested it due to that spend.

Is it worth repairing if your gonna P/X soon? I'm thinking a 2008 with just over 100K miles is £6-7K sold privately? lower on P/X?

I think we practically get held to ransom by these car's, I know I feel that way.

[humphrey999]

I struggled with the financial equation but I don't think it's clear cut. I tried to be rational but at the end of the day it was a lot of money tied up in a lump of metal that I couldn't shift if it didn't work and I didn't want to get held to ransom by an unscrupulous trader. Also, I point blank refuse to bodge it and pass it on to some other unfortunate. I run this car instead of a company car and I get an allowance. I'm still up on where i would be with a Company car so I thought I'd push on and repair it. I may run it for a bit before shifting it but I daren't keep it - if parts of the engine have been starved of oil then I don't want to be in the same position again.

[humphrey999]

So, got the car back yesterday. I had a chance to look over the old head but the crack was too small/deep to be seen. I asked about other potential damage to the engine from other oil channels having being blocked but they said that they the camshafts were the next weakest components and they looked fine. The car drives smoothly with no lag (an improvement) and I have a 2 year warranty on the head so I think I might just keep it after all...

All ex VAT:
Costs - £728 for rebuilt head with new casting
Labour to fit new turbo and head £650
Other gaskets and sundries (head bolts etc) £500
recon turbo from turbodevelopments £340
Carhire £230