OK, so I searched this forum for "overheat" and it looks like I'm not alone. But no one described my symptoms, so I'm starting a new thread.

Boought a 2003 TT for daughter a year ago; it's had a Check Engine Light since we got it - coxe is 2181, which translates as "cooling system performance" - really helpful. Previous owner had replaced the thermostat, temp sensor and cooling fan module - still have a CEL.

Last week daughter was driving to school when the temp gauge spiked, overheat alarm went off. She pulled over, & we brought it baclk to the house. While driving it I observed the temp gauge would spike from centerline up to full HOT, but if I slowed down or let the engine idle (coasting with trans in neutral) it would cool back down to centerline.

First attempt at repair, I replaced the thermostat. Upon test driving after that, a hose on hte drivers' end of the engine blew, and we lost a lot of coolant. Replaced the hose, refilled as best I was ble - now I'm back where I started. Once the motor wamts up, temp will spike & alarm will go off until I slow the motor down. Then teh temp gauge willdrop (very quiclly) back to fcenter. I've alsonoticed hte followiing:

- Passenger side fan comes on OK - haven't seen drivers' side fan run since changing thermostat (even when temp is spiking)
- Bottom radiator hose stays cool even when temp gauge is spiking. Top hose gets hot as exoected
- NO heat inside the car even with controls set to max
- Coolant will boil over if I let off pressure on the cap

Questions:
- Is this a bad pump? Any way to erify before tearing the whole front of the car apart?
- I've been unable to find a "burp point" anywhere on this cooling system - but I'm reading in these forums that it's vital to burp the system - so HOW do I do it?
- I'm using standard green prestone coolant - is this a problem? If so, what specifically do I need to use and where do I get it?

 

If you have mixed the green with the stock coolant, it could have it gelled up and be causing these problems. Also, if your drivers side fan is the aux fan for the ac. But both should be on so you may alse need a new fan relay.

 

+1. don't mix green (g11) with audi purple (g12). also, original water pumps are known to fail as the plastic impellers tend to break. most folks update water pump to new ones with metal impellers at the time the timing best is replaced...done that?

If you don't have a bentley service manual, get one. while not the most detailed, it's the best out there and is very helpful with diys. surprisingly, the cooling-system chapter (19) actually has a trouble shooting section.

good luck.

 

Coolant is all green AFAIK; I had the radiator off a few months back & drained most of the system at that time - what I drained was green. So it sounds like I'm OK as long as I don't mix?

Haven't done the timing belt thing yet - but at 70k it's time - so I'll go for the whole timing/water pump kit. Is there any data on when the 2nd fan _should_ run? DOn't want to replace relays/controls/fans that aren't actually broken, so I'd like to confirm what's expected.

Suggested source for that manual?
Any advice on the pump/timing belt job? It looks pretty tight inside that fender....

 

amazon.com is cheapest for the manual. paper or cd. I'm old school so got paper last year (for xmas.)

Here's a link to the definitive DIY timing belt/wp replacement. Not mine, but awesome.

http://public.fotki.com/BlueTTop/mod...t-replacement/

cheers

 

Thanks, I'll get onto Amazon.
Oen more "duh" type question. I've noticed that the timing belt kits are for either a 180 hp engine or a 225. How do I tell which I have?

 

225 is 6 speed manual and quattro only, all years. Anything else is a 180 (or 3.2 with auto beginning 2004.) FWIW, early 180 TTs were 5spd manual or auto and FWD or quattro, but the availability of manual plus quattro was slowly dropped by audi during the run. 180s in 2003 were either 5 speed manual/FWD or automatic/FWD. i'm not sure when the 180 went to auto and FWD only...it may have been as early as 2003. I know that by 2005, 180s were auto/fwd only, no manual.

 

So - thanks ot the advice in this thread, I found detailed instructions online (several times), finally got the whole thing apart. Pump impeller was completely separated from the shaft - split down one side. I had to fish it out of the block after I pulled the pump. Now waiting on the parts to arrive - apparently UPS has taken a 4-day weekend & it won't get in until Monday. So I'll be a bit rushed reassembling. But I'm relieved to know what the core problem is.

 

So what happend did that fix the problem?

 

Replacing it should have fixed it Edgar. If the impeller split on the pump then the coolant wouldn't be circulated.