2.5 R5 TDI Water Pump Failure

[Moonan]

Hi folks, this is the story so far...
It concerns my R5 Touareg, and I believe could just as easily be a T5.

I'll tell the story, and then welcome any comments and advice, particularly if there's anything I should be worried about or ask the dealer..
My Touareg is the base model R5 TDI, 18 months old and with 72k on the clock. We left Newcastle for a weekend in the Barrington Tops (Upper Hunter Valley, NSW):

On Thursday night - with the long weekend ahead (oi, oi, oi) - we were heading out into the dark. Pub dinner at Eatons Hotel in Muswellbrook was over, we were past Aberdeen in the Hunter valley, next town Gundy, then true deliverance country...
Minding our own business, a bit of something pleasant on the phatbox, our only care was to miss the kamikaze 'roos on the quiet road.

Suddenly, three loud squarks drew attention to the MFI and there were the ominous words:

STOP
CHECK
COOLANT
SERVICE
MANUAL
(below a symbol of a thermometer)

A look in the manual and a quick call to "Volkswagen Assist" (still in CDMA range at that stage), and we discovered the coolant level a bit low. None visible with the little torch on the end of the mobile phone shining into the reservoir.
The VW Assist man said it was OK to top up with water as required but get it checked by a dealer on Monday.
It took ~1.5 litres!
Continued on to our destination feeling a little sheepish (should we have been checking it daily? weekly?), and thinking that it might have been gradually dropping for some reason over time. At the same time, it is reassuring that the warning system works before there is any change in temp...
24 hours (and probably 100km) later and the same MFI message. This time also 1.5 l to get back to correct level.
Now a serious look in the manual, and there is no mention that we could find of total coolant volume. Still, 3 litres is a lot to add in a day.
Home the next morning (another litre), then to the dealer today (another litre or so). Turns out we have done a water pump, and all that coolant / water is now inside the engine!!
Apparently there is no motor damage, and it has all been flushed out. They want the car for at least 3 days. I told them I don't need a loaner for the first 2 days (work vehicle available), but I need either my car back or another vehicle by Wednesday pm. This has been promised.
Apparently, water pump will be there tomorrow, and transmission needs to be dropped to get at it.

Details to follow as they are available....

cheers,

..Neil
_________________

[Bug_racer]

Sounds like a trans cooler has gone . This was common on t4 transporters as well!!!

Make sure the gears change smoothly and it goes into 6th gear without a problem , if it doesnt better go back to the dealer , you'll most likely need a rebuilt trans !!

[brackie]

You did the right thing

Time action saved your car. Modern engines/transmissions are so sophisticated that without the warning systems you would have wrecked it. At least the dealer is playing ball and everything will work out. Pay heed to bug_racer's warning however as you need to feed back anything that you'e not happy with as quickly as possible.

[Moonan]

Thanks guys for the quick responses...
The dealer is changing out the water pump, an almost identical case to another Touareg owner that I know.
Bug_racer, should I direct them towards the tranny cooler, or accept the water pump replacement?
I've just been talking to a mate who's in the equipment reliability business. He's offered to arrange engine oil testing due to the possibility of there being water in the oil due to the pump leaking there.
My big mystery is that (a) I put at least 6 litres in it in 72hrs, and never saw obvious leakage on the ground. Surely all of that water in the engine would have damaged a big end or something... The standard oil fill is 9 litres, and the water would have wanted to stay near the bottom, at least at first.

[jets]

Read this

http://www.brick-yard.co.uk/forum/forum_posts.asp?TID=12577&PN=1

[Edison]

A loose hose on my little golf does a similar thing, when it's hot, you don't notice but it'll let the water out and probably onto the ground, but when you slow down and have a look all looks well, just the tiny difference in the temp gauge, just tiny too, to hint at it.
I want to get both coolant and oil LEVEL guages for my upcoming GLD for exactly those reasons. they aren't used much, but heck, when you need them, YOU REALLY NEED THEM!

[Moonan]

How it turned out...

Well, after 5 days in the shop, I've got my car back!
I have attached a photo of the innards of the pump - this is what they replaced.
Could anybody who knows better please comment on my pseudo-technical description of the design and what I think happened.

thanks,

..Neil

First, a general description...
Left end is the impellor (new part has a "closed" type impellor).
Next is the primary water seal, then the centre gallery with the drains, then the next seal, then the mounting and shaft that is in the oil-lubricated bit with the drive gear etc.

My observations:
1. You can't directly see it from the photo, but the impellor wobbles around a lot, making me think that the bearing at that end (ie inside, behind the first seal, assuming there is one) is shot. A new pump insert I played with does not have this movement.
2. Related to 1, there is some sign of this impellor having scraped around the inside of the pump casing. This shows up more in another picture.
3. The centre section has lots of surface rust. This does not happen in 5 minutes, so we can assume that some water gets here quite a bit. Maybe the fact that this area is drained is a sign that it is almost "normal" for this area to be wet.
4. The drain holes are "gunked up". Maybe this is where my problems became serious, ie if draining did not function properly, then pressurised water is pushing on the second seal, which is probably designed to keep oil IN more than water OUT. The "gunk" appears to be grease-like in consistency, maybe refugee from the bearing (see 1).

So, the design fundamentally attempts to avoid the extreme silliness of pitting the water pressure against the oil pressure to see who will win when a seal fails. There are 2 seals, one to keep water to the left of the "open" centre section, and one to keep oil to the right of this same centre section. In my case, either both have failed, or the water got out to the centre area through the stuffed bearing hole and pressurised this area, and pushed past the oil seal with the results that I saw.

Waddyareckon?

(OK, I am on a very slow link and photobucket is having difficulty arcing up. I'll post now to avoid losing what I have typed and edit the pic in later)