Third Expansion Tank in three months

[mightysquirrel]

For those who've had to do it, the replacement of the coolant expansion tank is a real treat of a job.

It's one that really wants you to have to proper tool for the clamps on the hoses unless you like tearing your hands up and spending countless hours trying to do the job the wrong way.

It was a bit of work the first time you try it, but I did have the advantage of having the tool to uncompress the hose clamp and was easily able to loosen the hose. I went in right from the top, I didn't even contemplate jacking the car. From the passenger side I was able to reach down and get the tool on the clamp by snaking it through from the opposite (driver's) side of the car.

The first time I did the tank on our 2002 it only took about 1 hour and 40 minutes. Too bad that tank only lasted a week before it failed. That time it failed in a completely different place than the original, but it failed, spraying coolant all over the interior of the trunk.

So we talked to the shop and they agreed that that was Bull$h!t and they ordered up another tank for us at no charge. So the second time around I was able to get the tank in in a mere 45 minutes. The second time was a breeze as I knew all the proper contortions and had the cracked one out of the car 10 minutes after draining the thing. A few minutes later I was topping up the tank, pulling the bleed valve up and running the heat up to wow to bleed off the system.

I got the system fully bled and all was dandy. Car ran like a top, no leaks, everything was fine.

So it's been about 5 weeks and all was well until...

Last night after coming home from dinner my wife looks down under the rear passenger wheel and sure enough, there's that familiar puddle under the wheel. **** IT! I put my hand into the trunk and didn't have to go far before I felt the dampness. The stench of ethylene glycol was enough to choke a horse.

So we'll be calling up the parts desk again on Monday to get another (yes count 'em... one.. two.. three) tank. The third in just 2 months.

I'm actually starting to get pretty pissed off here. I'm a **** careful mechanic. I use a torque wrench on everything and I have been very gentle with the installation of these tanks. They just keep failing. There's no logical reason for it. It's obviously a really bad design and they've superseded the part enough times to make it clear that they have some serious problems with them failing.

Sure we drive the car harder than most, but we don't abuse it or bounce it off curbs. That's why we have Porsche's. If I wasn't driving the ******************** out of my cars I'd buy something else, but these things are designed (and intended) to be driven like this. I'm a former racer and my wife spent countless weekends at the track with me tearing engines apart, so we're no strangers to working on cars.

So I'm just curious, has anyone else seen this sort of issue with these &%$)@#! expansion tanks?

m

[silverboxter]

squirrel- maybe it's not the tank(s). it might be a blown head gasket leaking exhaust gas into the cooling system and over-pressurizing the tank causing it to burst. take your box to a shop and have them check it out. i hope this isn't the cause but i'd hate to see you put a fourth, fifth, and sixth tank on.

good luck

[mightysquirrel]

It's not the case.

The motor was replaced by PMNA just 7,000 miles ago and if there was a blown head gasket it would be eating coolant prior to failure. This last time it went over 1,000 miles and a few weeks without losing a drop of coolant.

If there was a blown head gasket there would have been coolant consumption that would have warned us. The oil would also show foaming and a caramel like coloration which is not the case.

Although the cap is a highly ranked suspect at this point. I replaced the cap the first time, but I'm starting to suspect it's the cap allowing the system to over pressurize.

S

[Boxtaboy]

Strange....I've never heard of anyone needing to replace their coolant tanks that many times in such a short period of time. My first tank lasted 3 and a half years and 30K miles. I'm at 53K miles now on my 01, and the second tank is still holding up fine.

[mightysquirrel]

Yeah, I'm pretty stumped myself. I am really suspecting the cap is allowing the tank to over pressurize.

We're replacing the cap along with the tank this time and with some luck it will resolve the problem once and for all.

9

[funster]

I agree that it sounds like there is excess pressure building in your tank because you have passed the point of coincidence on getting faulty tanks. Perhaps the drain tube is plugged

You could try dip the tank in a resin to further reinforce it. Sort of like an extra leak barrier. Ive seen where someone just epoxied the hole in his tank and it held up.

[blinkwatt]

What are the last two digits of your coolant cap?

Where are these tanks being supplied from? Are they re manufactured or brand new from Porsche?

[jbox53]

I just replaced mine for hopefully the first and last time. It was ugly...doing it in the garage under a jack. I had 58K on mine. The dealer was suprised it lasted that long and the replacement tank and cap have a new part numbers. One would think having a little slack in the tank lines would be a smart thing but what do I know. I have currently removed all of the tank carpeting to watch for leaks.
30K miles of life.....hope not!

[mightysquirrel]

I'm also going to put a couple rubber grommets under the tank where it contacts the firewall at the top & the trunk floor. I think a little give here is probably a good idea. Hopefully any stresses related to body flex will be somewhat relieved.

9

[staflat]

Catch tank failure pretty common on the boxster. after my second tank started i ended up making one out of amuminum.i routed the returnee line far back in tank and used baffels.has about twice the capacity of stock tank.only downfall i wasn't able to figure out how to hook up the coolant level semsor.me myself am always scanning gauges while driving so IM not too worried about coolant levelness when I track car no more problems.

[saaber]

Originally Posted by mightysquirrel

Sure we drive the car harder than most, but we don't abuse it or bounce it off curbs. That's why we have Porsche's.

So I'm just curious, has anyone else seen this sort of issue with these &%$)@#! expansion tanks?

m

What is the hottest temp your car runs at? I was just thinking that after I pressure washed my radiators from the outside the temp dropped about 7-10 degrees in all conditions and stayed much more steady than before. I did this a few weeks after I changed my tank.

I think it is the heat cycle that kills these tanks. I have a strong suspicion that lowering the peaks (via washing radiators or?) and raising the valleys (via garaging when cold, plug in heater?, other?) of that cycle would make a big difference in the longevity of the tank. It is just a theory though and I have no real world evidence to back it up.