A4 Phil

Yep, all those items are on my replace list (the standard Audi timing belt list) for this work on Monday. Thanks for the feedback guys.

Yes, and I do wish that this had all boiled down to the cracked tank. Though the timing belt was in zone to be replaced anyway in less than a year.

I have been putting the miles on recently as my commute has changed from five miles a day to 70 highway miles a day. The timing belt needed to be replaced soon anyway.

Airbag

look at it this way .. better 1 year early than 5 seconds too late .. Good luck

Just Me

i would suspect:

1. t-stat closed or partly closed, or
2. water pump volume low and failing
and,
as a result it is shutting off the AC to protect the engine.

You should never let it actually overheat as you did. That just might become expensive.

G

A4 Phil

Ok, so here is the rollup of my repairs for my 2002 S6 Avant with 71K on it. I took it in because it was overheating and the primary and aux cooling fans had stopped spinning.

VAG'd and threw a P0117 for a faulty coolant temp sensor.

Further diagnosis after replacing the sensor also proved that the thermostat was stuck in the closed position.

Thermostat is 7 hours of work to replace so I opted to get my 80K timing belt work done at the same time.

Timing Belt
Tensioner lever
Water pump
Damper
Roller X 2
Water pump gasket
Thermostat
Drive belt
Pentosin
Expansion tank (based on initial overheat)
Expansion tank cap (based on initial overheat)
Coolant temp sensor (initial item that was diagnosed as failed)

Total damage to my pocketbook = 2K

All work comes with a 24 month warranty.

All in all, not too bad. It hurt, but not nearly as much as engine damage would have and the timing belt was within striking distance of needing to be replaced anyway. I could have saved money just replacing the thermostat, but then I would be doing the same front end tear down in less than a year for the timing belt replacement. As somebody posted above, better a year early than a month late.

Just Me

annoying. My T-stat stuck closed at 55k. fortunately, that meant the CPO warranty covered the first $750 of MY TB. But they shoudl not routinely stick closed at 50-70k!

Anyway - all's well that ends well?

G

Airbag

Well Glad to see your back on the road .. I just did all that and wonderd what it was worth .. I replaced all the items you listed except for the coolant sensor and expansion tank but did change the front 2 cam seals and was wondering what I saved .....

A4 Phil

Interestingly, my mechanic claims that the temp sensor fail fairly routinely but is far easier to replace. He claims that the thermostat has LOTS of problems between the 50K and 70K zone and further states that for the amount of work involved, you are better off replacing the T-belt and associated parts at that time. He calls the OEM thermostat the weak link in the chain.

Airbag

i would agree about the collant sensor staement but I have NEVER had my thermostat fail. I change it when i do my timing belt but personally would not consider it a weak link .. have 3 audis with over 350,000km
but i guess he sees more cars than me ..

Just Me

to both the above comments. 1. Yes, the temp sender fails a lot. Its also intermittent. Mine has been so for ages. Typically though, its easy to spot. It randomly goes to dead cold. Then pops back to temp. This isnt really very misleading to me. 2. The t-stat. Airbag is blessed. I've had t-stats fail open (1995 C4) AND closed (1991 B whatever and 2002 S6). Now 3/4 is not statistically significant because the sample is way too small. but it makes me wonder big time.

The t-stat is partially behind the water pump pulley and flange, and the water pump is driven by the t-belt, so yes, once you do the t-stat you have to consider continuing. On a 4.2 the (dealer) cost is abut $750 t-stat alone and another $1200-1800 to complete the job, depending on the area, labor rates, and how many kids the service manager has in college.

G

Just Me

just for the record - this can generally be diagnosed with a remote-read thermometer ( infra-red). Shoot the upper and lower hoses. if one's cold and one's very hot, you have a problem.

G