Re: Cooling System Condensation - Bleeder Valve??

I have an 04 S Tiptronic and took the car out today for two hour long runs (~100 miles RT). At the end of the first run I noticed condensation on the rear trunk lid above the oil fill cap and cooling system cap. The liquid was clear and appeared & felt "oily". Both caps were on tight and pressure was released when I opened the cooling system cap. The car never went over temp during the drive; just stayed slightly over 180 deg F.

White steam was was also coming up from the area where the caps are.

I removed the cover under the caps and saw that the bleeder valve had little bits of crud surrounding all the bolts. I also noticed my cooling system cap is an original -01 (so I'll be replacing that as well).

I've seen other posts with similar situations, so I believe it's the bleeder valve. Anyone with a better diagnosis, please let me know.

Can anyone tell me if the bleeder valve can be easily replaced or can it be rebuilt? Can anyone let me know the what the part number is?

Thanks in advance

... Most likely it's a bad coolant cap or a cracked coolant reservoir.

Happy Boxstering
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

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threads the cap screws onto and the sealing surface the cap seats against. Buy a new cap. Top up the cooling system then drive the car with the A/C off until the engine is up to temp. When you hear the radiator fans come on that's up to temp. When the fans come on shut off the engine and observe/inspect the cap area and the tank. (You can remove the plastic panel that fits at the bottom the fluid bay and which covers the tank to better see this area. Keep your face away in case something gushes hot coolant. If the bleeder valve is bad or the tank is cracked you'll know as the hot engine raises the coolant temperature and pressure.

This will be this weekend's project. Thanks.

Sometimes the gasket will go bad within the bleeder valve, but I don't recommend trying to replace it. I don't think it will ever go on as well and as tight as it originally was. My condensation had gotten a little worse after replacing the two gaskets. Change the cap and if that doesn't work either live with it or replace the entire bottle.

Quote
CK in Chatham NJ
Sometimes the gasket will go bad within the bleeder valve, but I don't recommend trying to replace it. I don't think it will ever go on as well and as tight as it originally was. My condensation had gotten a little worse after replacing the two gaskets. Change the cap and if that doesn't work either live with it or replace the entire bottle.

I've ordered a new expansion tank cap and am waiting for it's arrival. I checked under the carpeting in the trunk and that is dry I really didn't want to tackle that project yet.

Hopefully the cap will solve the problem.

You may still have a pinhole opening that only leaks a tiny bit when the car is fully up to temp. Feel around the tank when the car is on to see if you feel any moisture. Be careful not to get burned. What color is your tank, with the turbos they say if the tank is yellow replace it.

Thanks for the info, I'll keep that in mind after the new cap is installed & tested.

Did you get the bleeder valve from the dealership?

At the dealer. If you order the o rings, 5 bucks. It's molded plastic and out of round, so I can understand why it does not seal well. When I had this problem the condensation was on the trunk cover directly over the boot. I pulled up the carpet and everything else was dry. Pretty simple trouble shooting.

Still waiting for the cap to show up to eliminate that possibility, but I have the sizes and part numbers. I can probably pick them up from my O-ring supplier, just trying to decide if natural rubber, n-butyl or buna-n is a better choice. All are compatible with ethylene glycol.

I have some condensation issues too. I updated the coolant cap to the latest
revision. I also read about replacing the bleeder valve O rings, but someone had the idea of just
trying to tighten the screws that holds the bleader assembly. It worked. Be careful to
not tighten them too much as they are very easy to break.

5 years and 40K miles ago I had the same problem. The dealer wanted 1K right off the bat, bad tank. I bought a new bleeder assy. 60 dollars, because the o rings were not in stock. Replaced it and not a problem since.
2003 boxster S

Installed the new cap last evening and drove the Boxster to work this morning. A very pleasurable one hour commute. No condensation on the trunk lid after the drive. Problem solved.

Thank you for all of your help and information.