RMsALFA

I have a annoying coolant leak - not a very big one, but annoying, none the less.

It only seems to leak when the ambient air temperature is LESS then 20-25F. When it's this cold, there is a small amount of coolant that, by following the dry, pink trail, seems to be coming down the front of the motor and dripping off the passenger side front of the oil pan. It only seems to leak well AFTER engine shut-off, when things are cooling down. I've never seen more then maybe 30-50 ml (1-1.5 ounce), at worse, at one time.

To me, it's saying WATER PUMP - but I just had that changed out at my timing belt maintenance, less then 10K miles ago. The shop used (I'm pretty confident, knowing the shop) a OEM replacement, not a low quality aftermarket part.

Anybody have a guess ?

Joby

which is kinda early, but 10k seems really early, I guess, unless it's made in china maybe. What side is it on? Can you get pictures of the highest point where you can see it? Look down in the "lifter valley" and see if there's any coolant pooling there. It usually runs down the back of the motor, but if you park on a hill...

RMsALFA

The pooling and running down the rear thing sounds like you're suggesting aux coolant pump failure. I can't see any sign of that and I don't smell a lot of coolant smell - I would think it would smell strongly if it was sitting up on the warm manifold.

I'm pretty sure all the leakage is down the front of the engine. What else is up there besides the water pump ?

Anybody else have poor results with VAG-packaged water pump replacements ? Is this the common failure mode for these pumps - leaking when the engine is off and cooling down, with no leaks when running and no leaks when sitting static and cold ? ?

2.7Lturbo

how much is leaking? they do weep a bit after the first install..... seriously getting sick of these posts bashing OEM parts, unless you PUT THEM IN YOURSELF and made sure it was done 100 perent correct, it premature to jump on the OEM parts suck bandwagon.......


i would take the intake manifold of and inspect the aux pump, it will also give you more room to inspect the coolant trail. also, it HARD to follow the trail up to the water pump as its covered by like 2 different metal shrouds so at this point its a crap shoot, could be leaking from ANYWHER hitting the belt or something and being flung elsewhere, we dont know. pics would help too

Joby

I stole it from ECS' website, as I've never had a camera avail when doing a timing belt. I hope they forgive me. The only thing I can figure is that either when the water pump and or thermostat housing were installed the installer didn't use a torque wrench or maybe the water pump is failing.

The bolt torque is IIRC only 7lb/ft, so over torquing may cause the water pump or t-stat housing to warp. The only way to find out is to remove the t-belt covers and inspect. If it's the water pump, there should be dried coolant down the front and in the water pump pulley; a pink trail.

You'll have to remove the tubes from the inter cooler, serp belt and upper t-belt covers to see.

RMsALFA

The trail of pink is on the sump pretty much under 'G' on that picture. Where is the water pump on that picture - 'D' ? Also, where on that pic is the thermostat ?

2.7Lturbo - I'm NOT bashing OEM parts. I indicated the shop most surely used OEM, that's why I'm surprised about a leak I think (but can't confirm without major tear-down) is coming from a less then 10K mile pump. I had read about premature failures on pumps but it wasn't clear if these were OEM or knock-offs.

As I stated in my OP, it leaks maybe 1-1.5 fl oz after engine shut-down when the ambient air temp is below 20F. It doesn't seem to leak when it's warmer - at least I never noticed it. The water pump was replaced in May '09 but has less then 10K miles on it (the car isn't a daily driver anymore - I drive various cars in 'the fleet', on rotation). The last time the front was opened up was for a alternator repalcement last summer. I first noticed the leak after the tie-rod ends were replaced in December, although I'm sure THAT had nothing to do with it. That was just the first time the car was driven in sub 20F weather since the previous winter (and before the alternator was done - a connection maybe ? ?)

Joby

Yeah. D is the pump, just above the A is the t-stat housing. It starts in the middle of the block and continues to the left. You can see the lower rad hose is still on it in the picture, just below the pass side cam pulley.

My geuss would be that the leak is comming from the t-stat housing just under the A in the picture. The t-stat seal is a little tricky some have said, so I can imagine that if the seal isn't in properly it would leak.

rocketman4321

Joby, I think the housing between A and E is the thermostat housing. At least on the 2.7t, there's a hose off the lower right-side end, like in the picture. And yes, it's easy to mis-seat the thermostat and put a hairline crack in the plastic housing, which will leak much as described--although mine did it at summer temperatures. Look for coolant on the alternator and on the engine recesses near "A".

If it's a little further left, I wonder if the bleed port on top of the engine wasn't closed after filling the coolant? It's just a bolt above D, but on top of the engine.

Joby

As described by the red rectangle.

RMsALFA

OK ! Now we're getting somewhere !

I know liquid finds it's own way but I have a hard time seeing how a water pump leak can drip off the sump where it's dripping in my case. I'm beginning to think it's the t-stat (which was also replaced at the belt maintenance). I wonder if a t-stat leak would also effect the warm-up duration of the engine ? About the time the leak was noticed, I started thinking it was taking a LOT longer for the water temp gauge to begin moving. The heat seems to start up normally but the gauge gets to normal operating temp a lot slower (at least I think it does - never really paid any attention before). I even bought a new temp sender, thinking the factory fit unit was finally biting it. The leak and the gauge lag could certainly be connected !

Next step is to strip off the bi-pipes and try to get a good look down the front.

Yes..Yes..I know I should just tear into it. Frankly, the idea of service position scares me a little. I'm reasonably mechanically inclined and have a full complement of tools, but it's that 'unknown' factor that makes me hesitate. I was a engineer-type in a past life and find I need to know everything about a problem before I dive in - it's a personality fault that I admit to