Changing the coolant breather valve

[shlim8]

I've been losing coolant... by not much, but still at a consistent rate....

After further investigation, I discovered that the rear boot lid above the coolant cap, is wet from condensation. After taking off the flat plastic piece, I noticed that the 3 of the 8 bolts that lock down the breather valve seem to have whiteish sediments and looked like it might be leaking from there. The is almost no sediment from the top of the valve.

When I used a hex bolt to check the bolts, they were only hand tight.....

As the bolts are probably screwed into plastic, I refrain from tightening them...

QUestion is, how tight should those bolts be ?? Any reason there should be some leakage from the bolts ? Or is it a sign that the 2 O-rings are deteriorating ??

[JFP in PA]

More likely would be that you simply have a bad cap on the tank. If your number ends in anything other than "-04", your cap has been superseded and needs to be replaced. Bad caps cause the condensation you describe, which seeps down and corrodes the bolt heads on the system bleeder valve assembly. Change the cap first, and then clean up the area, most likely the problem will not reoccur.

You are correct, the bolts thread into plastic, so be very careful about tightening them, they snap off easily.

[insite]

i noticed the other day when i put the car up that the pressure release was up, like it would be if i pulled the bleed tab. is this normal? i would think it should stay down in all but the most 'heated' situations.

[JFP in PA]

You referring to the small rectangular metal wire "handle" on the vent?

[insite]

no, the handle actuates the part i'm talking about. i know you know this, but for others reading who may not: this entire apparatus is a pressure bleed valve, much like a conventional radiator cap.

when there is too much pressure in the system, a spring loaded valve will open and allow pressure to bleed out through a tube that exits under the right side of the car. the system is supposed to hold some predetermined amount of pressure, but to relieve that pressure if it gets too high.

the bleed valve is ALSO used to 'burp' the system, and this is done by actuating the wire handle JFP is referring to.

in my situation, the valve is actually opening under normal operating temperatures & relieving pressure when it shouldn't be. i suspect the valve is bad & needs to be replaced.

[JFP in PA]

No, it should not be “open” all on its own. Either the part is acting up, or you may have air in the system and are seeing the results of a “hot spot” somewhere in the system. Do you have access to a vacuum filling tool? If you do, pull a quick vacuum on the system when it cools down, if air comes out the coolant level in the tank will drop, and you can top the system off using the tool while under vacuum. If you pull a vacuum, and nothing comes out, you should look at replacing/rebuilding the bleeder assembly.

[shlim8]

I've got a 04 radiator cap. Just bought about 3 weeks ago but am still getting condensation and losing coolant. It does look like the water is seeping pass the3 of the bolts.

Is the bleeder valve a simple unbolt and replace part ? How tight should the bolts be ? Depending on the parts availability I might have to change just the 2 O-rings. I presume that should do it. The bleeder valve is in the closed position when I looked at it with the coolant cold.

[JFP in PA]

Yes, you can easily "rebuild" the bleeder assembly, there is a step by step in the Boxster Wiki:

Boxster Wiki

Be careful, if you snap off the bolts, you may end up replacing the entire tank assembly.........

[sasha055]

I have same problem, I replaced the o-rings and I still have condensation going.
Same symptoms as you, condensation and white powder on the bleeder valve bolts.

Does anyone know part nr for the whole valve assembly? maybe changing it will solve the problem.

Sasha

[schoir]

Originally Posted by sasha055

I have same problem, I replaced the o-rings and I still have condensation going.
Same symptoms as you, condensation and white powder on the bleeder valve bolts.

Does anyone know part nr for the whole valve assembly? maybe changing it will solve the problem.

Sasha

Sasha:

The part number for the complete assembly is 996.106.347.02. It supersedes two earlier part numbers and lists for about $33.

Aside from the O-rings, the rubber gasket/diaphragm sometimes gets torn or distorted. If replacing the O-rings did not solve the problem, check the diaphragm or just replace the entire assembly.

Here is a photo showing a distorted gasket/diaphragm. You can see old coolant residue in a number of places on the underside of the hard plastic piece that is showing, and you can see residue around one of the holes through which one of those fragile bolts passes.

Regards, Maurice.

[shlim8]

schoir, ah.... a bleeder valve like the one in your picture would certainly explain my situation... I think I'll refrain from opening up the valve until I get my replacement valve.... Opening up the valve now might make the leak worse and I still need to use the car

[PCinDC]

I had a problem with coolant in the trunk, so replaced the entire overflow tank. It still leaked and I thought the water pump was going, so I just changed that. When running, coolant drips out of the overflow tube near the right rear wheel. I can hear occasional gurgling near the bleed valve, which came with the new tank. Any suggestions on what to look for?

Sent from my SM-N920V using Tapatalk

[rexcramer]

It is very difficult to get all of the air out of the system after opening it. My guess is you still need to purge the system. Use the search function and or Pelican Parts for some DIY guidance.

[Pdwight]

You must pry (carefully) the top off, you only have half of it off right now....the O rings are under. Take notice to the orientation as it is asymmetrical. I just did this job on my car and my O rings looked fine, but after replacing my O rings with new ones it stopped leaking. Make sure you get the exact O rings and don't just come close with these.

look at this diagram, you can see the two different size O rings under the part you still have in;



Dwight