Changing the coolant breather valve
 

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 ??

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 If your number ends in anything other than "-04", your cap has been superseded and needs to be replaced.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.

http://www.pelicanparts.com/techarti...small/Pic5.jpg

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.

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

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.

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.

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.

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.........

http://img299.imageshack.us/img299/6474/dsc00613vn7.jpg

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.

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

After a run up a mountain road, I popped the rear boot open and guess what ? I found steam escaping from underneath the flat plastic plate that goes above the breather valve.... guess it should be from the breather valve. Definitely not from the coolant cap.

I'm now waiting for my new breather valve. Hopefully that cures the coolant loss.

Shlim:

When you get your new breather valve and go to install it, remember the caution about the fragile bolts. DO NOT over-torque them!

Regards, Maurice.

Thanks for the advice. After I saw pictures of the broken bolts, I understand why ! I didn't even try to tighten the bolts on my current breather valve any more than a millimetre...

I had thought of changing the entire coolant expansion tank, it's still good but has yellowed to the point that I can't see the coolant level. But after reading the instructions on the replacement of the tank, I decided not to...

Please post the results of your bleeder valve replacement. My 2000 S also has some condensation in the same area. I have a new cap on order but suspect the bleeder valve may be at fault. I'm afraid to touch it for fear the tank will crack/break when I attempt to loosen the perimeter bolts. I'm interested to see how your repair turns out.

A wise idea not to replace the coolant tank unless it's leaking.

To get a better view of the coolant level through a somewhat opaque, yellowed tank, you can take the coolant cap off and put a flashlight vertically on the opening. That usually "clears things up".

Regards, Maurice.

Maurice, where did you see the valve for 33$?
Pelican parts has it for 80$

Do you know of a secret place thet sells these parts cheap?

Thanks
Sasha

Sasha:

I replaced mine about three years ago, and I think I bought it from either Sunset or Suncoast.

Here it is from another source, apparently available for $32.68, but with an .01 ending on the part number. (Same part, but an earlier version, according to Porsche nomenclature scheme): http://dcauto.gotdns.com/illustration/index/471829446

Let us know if you are able to get it, etc...

Regards, Maurice.

I ordered my breather valve from the OPC in Malaysia and it cost about US$49. Which was surprising as the OPC in Singapore wanted more than twice that.

Anyway, I tried keying the part no into Pelican Parts and I think the price that came back was about US$80 if I wasn't mistaken.

It's a long wait for the part though.... up to 3 weeks was what they said.

Dale, I'll keep you updated once I get the breather valve.... it's no fun listening to the hissing sound from the area of the valve every time I do a spirited run. At least the coolant loss is quite small (fingers crossed !!!).

Finally got the breather valve installed this morning. The hardest part of the whole install was only the removal of the old breather valve housing. There is just no space to get a good grip of it. I used 2 allen keys (for the ikea furniture) and stuck them through the holes in the housing and yanked the housing out.

My old breather valve diaphram was in pretty good shape but the bolts were totally rusty and the O rings were slightly deformed. I found that everywhere the coolant came into contact with the plastic, the plastic looks different - you can actually see the fibres, whereas the dry parts were smooth. Does it mean I have corrosive coolant ??

Went for a 15min drive and after letting it idle for another 5 mins, the breather valve went to work and vented. Is it supposed to vent so quickly ? The housing was just somewhere between hot and warm and I could still touch it (water temp was around 85 degrees C, I have the low temp thermostat). This is a brand new breather valve that I just bought from the OPC. If it still vents so quickly, I presume I'll still get condensation on the trunk lid ??

The breather valve looks like an over-engineered item, on my E36 BMW, it's just a screw like thing on the radiator... (I know as it broke once !)

Sigh, the new breather valve did not solve the problem.... or maybe I've got a new problem, don't really know as I never knew where the "old" leakage was...

I've now got bubbling from the bottom of the breather valve housing, when the car is hot and left idling for a while.

My first thought was that the 0 rings were not seated properly. I've re-installed the breather valve 3 times, checked for dirt, cracks or anything that might cause a leak. Can't see anything and the bubbling is always at the same exact spot !

The threads of the bolts holes in the coolant tank seems fine, but is it possble that the leakage is from one of the bolt holes ?? Bubbling is from the side of one of the hole locations. I'm pretty sure the O ring is seated properly. The bolts are tighten to hand tight and then about 1/8 of a turn more or less. The bolts were really loose on the original breather valve.

Any ideas ?? Other than a new coolant tank ??

you have a crack. time for a new tank.

Anybody have a picture of the tank opening once the bleeder valve is removed? I replaced my bleeder last week and didn't see any o-rings at all. There was a circular disc with a couple rows of holes sort of near the center but I didn't lift that off. Are the o-rings under that? I doubt my bleeder valve was actually bad. The new and old looked and operated identically.

Is it possible to remove the valve to see if it needs replacing? And if so what would I be looking for?

Thanks, A.

The O rings are below the breather valve housing (the one with a couple row of holes).

My new and old valve were NOT the exactly the same.... It looked the same but after installing it, I realized that the valve (centre plastic piece with the metal ring) was sticking out alittle higher. I thought I messed up somewhere so I removed it - and noticed that the rubber diaphram was alittle thicker. Hence, the valve sticks out more after installing.

It was the second install that did me in.... It was perfectly dry after the initial install. I started getting bubbling from the housing after the 2nd install. Sigh... should have left it. I think my expansion tank just went south.

Dale:

Top of coolant tank with bleeder valve assembly removed:



Regards, Maurice.

Andrew:

Yes, it can be removed... See the photo I attached in the previous post for what you end up with once it's completely removed.

If you go to the trouble of removing it, you may as well replace the O-rings.

Also inspect the rubber membrane immediately under the top portion of the assembly.

There is a photo of a defective one earlier in this thread.

BE VERY SURE to heed the cautions against overtorquing the bolts.

Regards, Maurice.

It is possible to remove the valve, but I wouldn't mess around with the valve unless u intend to change it or the O rings. The design of where the bolts go into the coolant tank is downright scary. There are just holes on the top of the coolant tank, not raised or marked so it's easy to mis-thread them. And this is 10 yr old plastic (in my case).

There is only 2 things you can change - the entire valve (which includes the valve, housing, 2 O rings and the bolts in one set) or the 2 O rings (can be bought separately).

Thanks for that picture. I ordered the bleeder valve and O-rings from an online parts house and then before the order arrived I got an email with a $5 credit, which kind of confused me. When the shipment arrived there were no O-rings with the bleeder. Instead there was a brake pad sensor, lol. I guess the guys got it wrong when they packed the order and then noticed the extra O-rings laying around and figured out what happened and gave me the credit. I can get O-rings from the hardware store now that your picture shows me where they're supposed to go.

Dale -

FYI, it's not an o-ring, it's a square ring. there is a difference, and an o-ring probably won't work here. be sure you pick up a compatible seal. see the photo in post #10 above.

slim -

in maurice's photo above, from where is your new leak bubbling?

Hi insure, the bubbling is from an area below the valve housing, close to one of the bolt holes. After careful inspection, there are 3 small and light "scratches" there. Turns out they are prob hairline cracks. Very hard to see and bubbles only when the water temp goes beyond 80 degrees C. The tank is toast, got that changed yesterday. Guess it's better to discover the prob now when I'm monitoring the breather valve than the tank letting go in the middle of the highway.

Btw my Porsche original O rings are really round not square.

sorry to hear your tank is dead. thx for the info that your kit came w/ an o-ring & not a square ring. looks like the factory thinks either solution is ok here. take care.

Dale, just in case u need it - the size of the O rings are listed as 17 x 4 and 47 x 4 (I presume in mm).

I'm now enjoying a stable 80-85 degree celcius coolant temp.... (with the LN lower temp thermostat). It used to spike up to 90+ even with the lower temp thermostat... guess I was losing coolant pressure.

That's good to hear. My car is in the shop for a vacuum leak fix and a Tiptronic service, so I haven't checked it. Part of the trouble with buying an old car is you don't know what things are supposed to look like or whether somebody left out parts in the past. I'm not even sure my car has the o-rings at all. I sure didn't see them when I removed the bleeder valve cap but I didn't take out the circular disc with the holes in the center.

Sorry Dale, but on a different note, what is a tiptronic service?

Mine is a 1999 and the tiptronic is getting a bit lumpy.

The Tiptronic service basically means draining the fluid in the pan, dropping the pan, changing the filter and refilling the fluid, per the 101 projects book. Possibly draining and refilling a second time to get a more complete fluid replacement. I think it's supposed to be done at around 80k miles. My car displayed a CEL for a vacuum leak but there was a 0740 code too, which has to do with torque converter clutch operation. It shifted a little funny going up hills under light load when cold. Worked OK after it warmed up. I'm hoping the fluid replacement will fix it but it might need a new torque converter.

I have some more information and pictures about this operation. I was confused because I didn't see any o-rings when I removed the bleeder cap.

http://i19.photobucket.com/albums/b1...ervalve022.jpg

The cap

http://i19.photobucket.com/albums/b1...ervalve023.jpg

Some of the posts made me think that maybe some tanks didn't have o-rings but I finally managed to wiggle the part with the 8 bolt holes and realized it was a separate piece. It's hard to pull out but I got some big channel locks on it a eventually wiggled it enough to get it out.

http://i19.photobucket.com/albums/b1...ervalve024.jpg

Below are pictures of the tank with and without the o-rings.

http://i19.photobucket.com/albums/b1...ervalve026.jpg
http://i19.photobucket.com/albums/b1...ervalve025.jpg

O-rings don't seal by vertical compression like a gasket. They are squeezed between the OD of the male part and the ID of the female part. I could feel the old o-rings had become kind of square shaped and might not seal anymore. I have a feeling that some of the threads about condensation on the trunk lid near the coolant fill are due to these o-ring seals.

I visited the hardware store and got some generic o-rings since the Porsche parts place didn't include the genuine ones in my order even though I specifically added them to my online cart. They did give me a credit for the unshipped items.

I haven't driven the car yet but the housing felt good going together over the hardware store o-rings some I'm hopefull.

"Some of the posts made me think that maybe some tanks didn't have o-rings but I finally managed to wiggle the part with the 8 bolt holes and realized it was a separate piece. It's hard to pull out but I got some big channel locks on it a eventually wiggled it enough to get it out."

I am exactly at this stage wondering what to do next. took out the 8 bolts and the cap. Any additional info is appreciated. Did you use any tools to get the bottom housing of the bleeder cap to come out?

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?

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