I'm getting ready for a 4,000 mile trip. And I need to do some part replacement due to age/ minor leaks.
1. The T-stat is now stuck open and needs to be replaced. What temp in F do I need to get? 180 or 195F?
It doesn't matter. I have run both and saw no difference either way. Diesels like to run hotter but the 195 thermostat made no difference in the other wagon compared to the 180 in my B4. I have not had good luck with Wahler but have had good luck with the Napa 238. The Wahlers seem do die early and I have not replaced a Napa thermostat twice. They could be made by the same company for all I know.
2. Should I replace the T-stat housing inlet pipe as well? What is it really called?
Yes, as Peter mentioned, they tend to warp. I have found the non-OEM VW ones tend to warp and distort whereas the OEM VW ones do not, but they often require replacing the o-ring which has gone though heat cycles and lost its elasticity. IDParts or Cascade German are reputable places to get them and both are top notch. I get 90% of my stuff through them but haven't had to buy much lately since the car doesn't see as much use.
3. The water pump is weeping at the front seal. Which brand do you recommend?
I had two Graf metal impeller water pumps die on me early (<10k miles) so I am not a fan. They use stamped metal impellers whereas the Hepu or Geba used a different metal impeller that was more robust. I have a picture somewhere but cannot find it right now. The stamped one on the Graf heated up, expanded, and slipped on the shaft, causing the car to overheat, but this was 10 years ago. I have installed Graf pumps after that and they were fine but I never fully trusted them. Definitely get the metal water pump gasket, it saves time works well, and is easy to just strip off when doing the next one.
4. The harmonic balancer just started to squeal when cold. I see them from 80 bucks to several hundred. Which one to buy?
The one I have is Valeo, and I think it's made in Italy. Not sure if they're still available since I've had mine for years. I have installed Chinese ones and they never seem to last so I try and avoid Chinese parts when I can.
5. I've always used VW OEM coolant. Is there an aftermarket just as good?
Pentosin SF is available at Napa and a direct replacement, but it can cost as much as the OEM coolant. It comes as a concentrate in a quart that you dilute.
