Yet Another Coolant Question - Hissing, Running Hot, Condensation
 

Hi Everyone,

Last October, my coolant level was doing a disappearing act which stopped for no apparent reason, and I haven't given it too much thought since then. I did end up topping up with a bit less than a half gallon of distilled water. Now that it is starting to heat up (about 98° F today), I have noticed my 986 has being running a bit hot, closer to the 220° tick than the 180° tick.

When I parked today, I checked the coolant cap, and heard a hissing from that general area. I very carefully loosened the coolant cap 1/8 turn, which confirmed the hissing was coming from gas escaping from the coolant tank. A few minutes later I noticed some condensation on the trunk lid in the same area. My water pump has already been replaced, but not recently.

Any thoughts on what this may be, bad tank, bad cap, leak?

Thanks,
-Rick :cheers:

Additional Info: Went out to check the radiator fan fuses (C8 & C10, which are fine), and noticed the interior of the car (and garage) was very humid. Looked around back, and some coolant (complete guess, but maybe 2 liters) had leaked out of the overflow above the rear passenger wheel. This is about 20-30 minutes after being shut off/parked.

Car shouldn't be running at 220. May need to replace thermostat.

The other things you mention are a faulty or leaking cap. Go buy a genuine porsche cap and you will be good. All the things you described about the fluid in front of the rear right side tire and the condensation in the truck are BINGO.

Once new cap is on, replace with proper fluid to proper level. Back in the coolant filler area in trunk, flip the little wire cap thingie in upright position and drive around for 2 days. This allows the coolant system to purge in air bubbles. Flip wire cap thingie back down and you are good to go

Thanks Slate, I was guessing the tick after 180 was about 220, but it could be 200°-ish. I will try a new cap and report back.

getting simple pressure test done would go a long way before you start throwing $ at parts...

Rick, don't listen to Burg, don't even waste the time, you need a new cap, trust me. They aren't very expensive. It will take care of the problem, but don't forget to bleed the coolant system. If you type a search for bleeding the coolant system you will see exactly what to do, since my description is thin. It is about the easiest thing you will ever do on a boxster.:cheers:

Diagnose twice, replace part once. Pull up the carpet under the coolant tank. If there is coolant under there, its the tank and my condolences.

If you buy just the coolant cap ,the latest part number ending "00" is the best according to other Forum members.I have been unable to find a part number on my cap.
The latest listing I found is for : 996-106-447-04
http://www.pelicanparts.com/catalog/SuperCat/1048/POR_1048_WATRAD_pg2.htm#item5
This may help you:
Porsche Boxster Coolant Tank Replacement - 986 / 987 (1997-08) - Pelican Parts Technical Article

Thank you everyone for the input, I will do some more investigating.

r3k,
Ignore san reshno, me and hundreds of posts prior from BTDT members regarding your issue. You've got more than enough alternative "guidance" to keep you occupied for quite some time. No sense you getting confused w/ facts et al...

One cannot make up this kind of entertainment... :cheers:

Good luck :)

I always search for answers first, lots of knowledge on this and other websites. But I always like to post, to see if the more mechanically inclined members here concur, or if any aspects of the issue 'click' and lead to a consensus solution.

The plan is to inspect the trunk and the area around the tank and under the carpet tomorrow. Then I'm going to replace the cap and top off with distilled water and drive it, to see if it is still heating up as much, hissing, condensing, etc. Assuming the cap solves the issue, I will do a pressure test and have the coolant flushed just to be on the safe side, since the 50/50 mix will be off after I add that much distilled water.

Hopefully, it's just the cap. But if not, then I will be checking the water pump, and looking for leaks.

Thanks again for the input everyone! :cheers:

The latest part number is 04 and if you buy a genuine one the number is on the top!

Have you ever cleaned out the rads and condensers by removing the front bumper? It's amazing how much crud had accumulate in there.

That was the first thing I checked, I clean them every now and then.

Obvious to many but may not be for all, in addition to the other checks mentioned, bleed the system properly, and fill only to the full level.

After some further investigation, I am pretty sure this is more than just a bad cap. I pulled up the carpet, and the trunk is damp with coolant, so I think the tank is probably cracked. I don't have the tools or time to replace the tank, and pressure test the system, so I will be taking her to a mechanic tomorrow. Considering a new OEM tank is $350+ I am not looking forward to this one.

Rick ,
It would have been gracious to acknowledge you were given the 'wet carpet' suggestion by San Rensho way back in Post 6.People get disheartened when they help and get ignored. Many of us rely on helpful Forum members to help fix our cars so am concerned the good guys get the credit due them for their kindness.
Moving on,
I posted this in a similar thread. Suggest you make sure you know if your mechanic is using an OEM tank or generic:
"You can find cheap coolant expansion tanks on EBay.Part # 996 106 14708 . Whenever I contact the seller they concede they are not OEM. They are aftermarket of an unknown manufacturer and from an EBay Seller with less than perfect Feedback. Price is $90.They claim to offer a warranty but provide no details !
Note this seller claims in the Title of the Listing "PORSCHE..Coolant tank" -but it is not Porsche - it is no-name generic of unknown quality with no written warranty.
The labor in the task of replacing the tank is such an issue that the risk/savings just are not worth it IMHO.
Porsche Radiator Overflow Coolant Tank New with Cap | eBay
Note:- the only review of a Pelican aftermarket coolant expansion tank(996-106-147-08-M127) had a failure. But at least Pelican would handle the issue honorably .It is $228.The OEM is $383.
2001 Porsche Boxster S Convertible - Radiators - Page 4"

Gelbster, I am not sure how to respond to your post. I am very appreciative of San Rensho's post, and it is what caused me to pull up the carpet. I have said thank you to everyone in a few posts in this thread.

Thank you for your input on the tank, I will make sure it is an OEM replacement, assuming that is ultimately determined to be the issue.

Crashclint on RL offered the best air bleed routine I have seen for those who do not have an Airlift.Here is a quote:
"I do know if you didn't get all the air out of your coolant system temperature will bounce around when it hits an air pocket. I followed the steps below when I change the pump in my Boxster. On the advice of a Porsche mechanic, if the temp light comes on, turn the car off and let it cool awhile before starting the procedure again. Mine did come on during the process so I let it cool for about an hour and went back to it. This process should be a little easier on the 996, less to remove.


1. Consider covering the trunk with plastic in case of a coolant overflow.
2. Remove the radiator cap, oil filler cap, and dipstick.
3. Pop the cover trim plate off the filler access area. This reveals the bleeder valve. If you remove the little screw above the trim plate to do this, be extremely careful to not drop the screw into any of the filler necks.
4. Flip the bleeder valve locking clip up to release it.
5. If you have an automatic transmission, remove fuse B1 (the ATF cooler valve).
6. Fill with coolant up to the bottom edge of the filler neck.
7. With the engine idling, occasionally revving the engine, fill up with coolant until there's no more room when the engine is revved. (Revving may raise the level a bit.)
8. Replace radiator cap.
9. Warm up engine until you are sure the thermostat is open. 10 minutes at 2500 RPM should do it, and you should hear the radiator fans come on.
10. Run 5 more minutes at 2500 RPM, revving to 5000 RPM every 30 seconds.
11. Carefully open the radiator cap, and top up the coolant.
12. Replace the radiator cap.
13. Run 5 more minutes at 2500 RPM, revving to 5000 RPM every 30 seconds.
14. Idle until the radiator fans cycle on and off once.
15. Carefully open the radiator cap, and top up the coolant.
16. Put everything back the way it was. "

If you are replacing the tank this diy may help.Lots of photos +tools:
http://www.pedrosgarage.com/Site_3/Replace_Coolant_Reservoir.html

The tank and cap have been replaced, there was a nice big crack in the side of the tank. It is still running hotter than I would like, although it is in the mid-hi 90°'s F here. When I do the water pump, I will definitely be installing a low temp thermostat. Thank you to everyone for the guidance and advice! :cheers:

Bumping this thread with one more question. I am going to install a low temp thermostat to try and get my 986 running a little cooler this summer. (And because of the many recommendations to add one on this forum.) It looks like I should be able to clamp most of the coolant hoses, and do the install without having to replace all of the coolant again.

My question is, what is the shelf life for coolant in an unopened container?

I just found a brand new, unopened gallon of Porsche Coolant in my garage. It must be from about 7 years ago. While in the garage it has been exposed to temperatures from about 100° F to 32° F, but it is unopened so I am hoping I can use it to top up after the thermostat install. Or should I dispose of it? (safely, of course)

Thanks! :cheers: