Changing the coolant breather valve - Page 2 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

shlim8 · 03-08-2011, 03:51 AM

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 ??

insite · 03-08-2011, 04:36 AM

you have a crack. time for a new tank.

Dale_K · 03-08-2011, 06:17 AM

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.

Andrew McD · 03-08-2011, 02:01 PM

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

Thanks, A.

shlim8 · 03-08-2011, 05:13 PM

Quote:

Originally Posted by Dale_K

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.

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.

schoir · 03-08-2011, 05:25 PM

Quote:

Originally Posted by Dale_K

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.

Dale:

Top of coolant tank with bleeder valve assembly removed:

Regards, Maurice.

schoir · 03-08-2011, 05:28 PM

Quote:

Originally Posted by Andrew McD

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

Thanks, A.

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.

shlim8 · 03-08-2011, 05:38 PM

Quote:

Originally Posted by Andrew McD

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

Thanks, A.

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).

Dale_K · 03-09-2011, 03:48 AM

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.

insite · 03-09-2011, 04:08 AM

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.

Quote:

Originally Posted by Dale_K

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.

insite · 03-09-2011, 04:10 AM

slim -

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

shlim8 · 03-09-2011, 05:34 PM

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.

insite · 03-10-2011, 03:02 AM

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.

shlim8 · 03-10-2011, 08:53 PM

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.

Dale_K · 03-11-2011, 04:02 AM

Quote:

Originally Posted by shlim8

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.

Andrew McD · 03-11-2011, 04:23 AM

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

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

Dale_K · 03-11-2011, 12:46 PM

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.

Dale_K · 03-19-2011, 06:42 AM

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.

The cap

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.

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

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.

rkporshe · 08-31-2016, 10:59 AM

"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?

PCinDC · 02-26-2017, 07:21 AM

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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