Re: coolant 'hissing'

2000S with a little issue. After turning off the car with warm engine I've noticed that when I open the rear trunk I can hear what sounds like pressure releasing from the expansion tank. It is not real loud but certainly noticeable.

I replaced my coolant tank and cap (.04) last summer due to a cracked tank. Coolant was changed about the same time with a 50/50 blend of Porsche coolant and distilled water. No issues with the change or bleeding the system.

The cap feels tight....

ideas?

Thanks!

dghii
2000 Boxster S 6speed 112k miles

Check the bleeder valve, where it is bolted onto the top of the expansion tank and at the silver lever on top of the assembly.

Aside from the hissing, you may be able to detect some coolant residue in that area. You have to remove the thin, black plastic cosmetic cover that is over the oil fill and coolant caps to get a good look.

Sometimes it is one of the two o-rings inside the bleeder valve, and sometimes it will be the rubber diaphragm that is inside there and that lets go/gets warped.

The good news is that the O-rings are available separately, as is the complete bleeder valve assembly. If you do go in there, be VERY careful not to overtorque the long screws that hold the bleeder valve assembly onto the top of the coolant tank. Very, very, very easy to break them. I haven't broken any yet, but I have seen it happen a couple of times.

Regards, Maurice.

I'm aware of the bleeder assembly but I guess I dismissed it as it comes with the coolant tank I replaced last summer. I will check it out.

dghii
2000 Boxster S 6speed 112k miles