Coolant Loss, no smoke, not overheating (yet)

[my_01_S4]

01 S4 w/ 150k. I'm the 2nd owner but from the carfax records I know it's been maintained well (all dealership serviced) but now I'm loosing coolant. Not while driving (that I can tell) but after I come to a stop and shut off the engine. I don't see any leaks right away but after it's cooled ~ a cup can be found under the car.

Where are the common failure points it could be coming from?

I don't detect any sickly sweet coolant smell when driving which I expect w/ a typical coolant leak so I'm hoping this is a known error that's easy to diagnose and cure.

TIA

[lrg8683]

secondary coolant pump is what was broken on mine when it was doing the same thing.

[my_01_S4]

Do you mean the Auxiliary Water Pump (#5 in this illustration from the Bentley manual)?

[lrg8683]

i believe so

[my_01_S4]

This seems simple enough to access. Have you R&R'd it before or did you have a shop do it? IF you did it yourself, how hard was it?

If you didn't, has anyone else done it?

[lrg8683]

i just took it to audi..

[Syndromeofadown]

Pressurize the coolant system while the car is off (special tools needed!) and check for leaks. Or just man up and let the car run after beating up on it with the heater on so the thermostat is open - then look for visible leaks.

[Jsmooth65]

Are you sssuuuurrre its coolant that you are finding on the ground? If you are losing a cup everytime, you should be filling your reservoir alot, are you?

[Rican_S4]

I'm going to bet it's the Afterrun Coolant Pump or a cracked reservoir. Mainly betting it's the pump.

[looseboost]

Im having the same problem they diagnosed it as the water pump which is a 900$ job but the leak i see it coming from the back of the motor and dont know if the dealerships trying to rip me off?? any ideass??

[Tifosi]

Im having the same problem they diagnosed it as the water pump which is a 900$ job but the leak i see it coming from the back of the motor and dont know if the dealerships trying to rip me off?? any ideass??

A leaky after-run pump can leak from the rear. Remove engine plastic engine covers and use a flashlight to look at the valley area underneath the intake manifolds. If you see pink dried coolant, then you certain does have a leak in your after-run pump. Try an ind. shop, you may be able to find someone for ~$500 or so.

[Jsmooth65]

This is what bad afterrun looks like without the intake manifold:

[looseboost]

Very helpful i will be takeing a look at this when i get home even thow the smarties at audi decided to give me Green coolant instead of g12

[my_01_S4]

Thanks for those pics. I tried to look in between the cracks and crevices to see if there's any residue. None. My BIL who's a mechanic suggested I lift her and check underneath to trace back where the fluid is coming from. Will check up top again but if no luck I guess I'll have to do that. Luckily he has an 02 Passat w/ the same engine but normally aspirated so he's quite familiar with it.

...the smarties at audi decided to give me Green coolant instead of g12

[Tifosi]

Thanks for those pics. I tried to look in between the cracks and crevices to see if there's any residue. None. My BIL who's a mechanic suggested I lift her and check underneath to trace back where the fluid is coming from. Will check up top again but if no luck I guess I'll have to do that. Luckily he has an 02 Passat w/ the same engine but normally aspirated so he's quite familiar with it.

About where are you seeing this puddle of coolant, underneath the front, center, right rear or left rear of the engine ? Try to be a little more specific if you can. Also, do you notice more coolant loss if you were to drive the car hard ?

[u7401087]

Hi.....Tifosi

you mention something about more coolant loss under hard driving.....

could you talk more about this?

Paul

[Tifosi]

Hi.....Tifosi

you mention something about more coolant loss under hard driving.....

could you talk more about this?

Paul

If this condition is also associated with mysterous misfires at idle and noticing a lot of pressure buildup when you open the cap of the coolant expansion tank. Unfortunately, these symptoms are a good indicator that you may have a head gasket leak.

A bad head gasket seal can over-pressurize the coolant system and cause coolant loss through the over-flow valve/hose of the expansion tank. This can be easily confirmed or ruled out by using a block test kit from your local auto part store. It is a simple test but amazingly accurate.



http://www.napaonline.com/MasterPage.../+Engine+Block

[jed3s4]

the orings that seal the rear coolant pipe sometimes go bad, or perhaps even a heater core hose, look at where your evaporator drains to see if any coolant is coming out of there then you may need a heater core or one of the associated hoses, just be hoping the turbo coolant lines aren't leaking, they usually don't unless from a bad install. if it is a head gasket do a compression test to make sure they are all at somewhat equal levels just to try to rule it out

[my_01_S4]

I've been waiting to find a leak for the past few days but my commute to work & home barely lets it warm up. :(

[Charlie]

I found my leak to be the T in the coolant reservoir, it was small but still needed me to fill the reservoir every day almost

[looseboost]

My leak was the AUX waterpump.. It was comeing from the back of the motor and only leaking when the cars front end was at an angle... the tank would be completely empty when i came out but the car would not leak on straight ground.. hoepfully give u some insight

[my_01_S4]

Thanks again. I've been checking the coolant tank for loss each day. This even after driving it to full operating temp over the weekend.

[Auburnsky1287]

secondary coolant pump is what was broken on mine when it was doing the same thing.

Same thing happened on mine too.

[drkenan]

The aux water pump is a very common problem due to it's location.

Linky link link...

http://www.audizine.com/forum/showth...light=aux+pump

[JayyyyyC]

Interesting. I'm losing coolant as well and don't notice any smoke. I'll check this out. Haven't noticed a puddle of coolant leaking on the bottom of my car though...

[my_01_S4]

The aux water pump is a very common problem due to it's location.

Linky link link...

http://www.audizine.com/forum/showth...light=aux+pump

Maybe you missed it... I'm already trying to check for a leak from my Aux Water Pump (w/out removing the intake manifold). Still no luck finding evidence of one much less another puddle under my car.

I know that I'm still loosing coolant though when I check the reservoir level.

[one4eyes]

the orings that seal the rear coolant pipe sometimes go bad,

How and how hard would it be to change the O-rings in the coolant pipe?

Thanks.....

[The_Jerbel]

It's not that bad, but a little bit of a pain in the arse because you've gotta get down below the big bundle of wiring that runs across the back of the engine. The hardest part is just getting your hand down in there.

[The_Jerbel]

Maybe you missed it... I'm already trying to check for a leak from my Aux Water Pump (w/out removing the intake manifold). Still no luck finding evidence of one much less another puddle under my car.

I know that I'm still loosing coolant though when I check the reservoir level.

Take a pic from underneath showing the coolant streaming down the side of the trans/engine.

[fla]

i have a similar issue in that the coolant level drops every 2-300 miles. I have replaced the rear coolant flange, the temp sensor seal and it still drops. Now white smoke, no pressurising of the header tank (other than normal) so i'm sure the HG is ok. I had a jubilee clip on the rubber t-piece pipe connected to the steel header going over the top of the engine so replaced this with the original Audi constant tension clamp.
Can seem to find any coolant trails anywhere, perhaps i'm not looking in the right areas?

Welcome any suggestions. 2004 1.8T BEX engine btw.