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I just had some work done by a very qualified shop. They dropped the motor and did the AOS, associated vacuum lines, intake gasket and a new coolant expansion tank while in there (the water pump was done 2 months ago). Now with the new coolant tank, the cap will not seem to stay tight. It leaks out of the top and coolant runs down the drain line. I HAVE CHECKED THE LEVEL COLD and filled it to the MIN line several times, thinking this only happened due to over filling, but it is not above the MIN when cold.
I bought a new cap and that didn't help.
The strange part is that if I over tighten the cap, it will loosen and then tighten again, like it's stripped. You know, like it goes "around" again and then tightens. This seems to be worse when it's hot. In fact, when it's hot, I can hear the air escaping.
The threads on the tank look ok, and remember, I tried two different caps.
Is the tank defective? Is this normal for it to be able to let fluid out of the cap (I'm thinking it is designed to allow some to escape in the event that it is over filled) but why is it continually doing so?
I will say it seems to stop if the coolant level is below the MIN mark. Is it possible that the calibration of the lines is somehow off for my car? Should I just let it self correct and as long as it runs normal temps and doesn't throw a low coolant light, leave it alone?
Hmm, I just realized that my garage floor is SLIGHTLY inclined, but I do mean slightly. Like, I can't leave the car without the parking brake on or it will roll out of the garage, but again, it's slight. And I pull in forward, meaning the nose of the car is SLIGHTLY elevated. But honestly, I mean SLIGHTLY.
Top it off again when cold. Then manually open the expansion valve and drive the car about 5 miles until 180+ F temp. Then let it cool off again and check the level. I wouldn't worry if after removing the expansion screw top you can still feel the coolant on your finger. Close the expansion valve and drive again.
Yep. Sounds like a bad tank. Fluid should almost never leak unless it’s overfilled (even steep inclines or declines should not matter or else everyone in San Franscico would be leaking coolant). The cap will only open up under severe pressure due to overtemp or overpressure situations. The cap should be tightly sealed and not so easy to come off.
This is crazy. Who is going to pay the Indy's labor to RR a defective tank?
As for driving with the valve open, I assume you suspect air on the system. I can try it, but I don't think that's the case because would air pockets cause the cap to come loose? Also, I've put about 400 miles, including 100 DE miles on the car since the new tank and probably added easily 2 quarts of coolant over that time. I would think any air pockets would be gone by now, no?
This is crazy. Who is going to pay the Indy's labor to RR a defective tank?
As for driving with the valve open, I assume you suspect air on the system. I can try it, but I don't think that's the case because would air pockets cause the cap to come loose? Also, I've put about 400 miles, including 100 DE miles on the car since the new tank and probably added easily 2 quarts of coolant over that time. I would think any air pockets would be gone by now, no?
Did they use a Porsche part numbered tank or an aftermarket one. What did the invoice show? Often you'll see a Porsche part number where the parts supplier actually provided an "equivalent". Are you using the latest version of the cap - I believe it ends in 04. If tank is defective it should have at least a 90 day warranty - I'd think the shop would honor that including the R&R costs.
Good comments above. Confirm that cap is on tight...repeat tight. It should not loosen up. Early in my ownership I put on new cap to the 04 version due to info in this forum. First drive to temperature water was puking on garage floor on return. Let car cool then TIGHTENED the cap. No problems since(4 years). Indi should stand behind his work if it is the tank, especially if he supplied it. I have read much bad about after market tanks.
I think it's a Porsche part. It looks like it, and the cap is blue. The invoice shows 996 106 147 56 and the cap is blue. The aftermarket cap I tried is black, made in Germany and the part number ends in a 4.
I cannot tighten the cap cold or hot without being able to over tighten them have it loosen then spin around again.
Sounds like a defective tank. Bad threads.right?
PS. I want to expand upon my earlier comments about who will make good on this repair. My mechanic is very honest and also a friend. I'm kind of wondering who's gonna make HIM whole? Manufacturer? parts supplier? I have a feeling I know the answer and I don't like the idea of him getting screwed.
Last edited by AdamIsAdam; 07-01-2018 at 11:33 AM.
It's hard to say for sure from the photo, but it looks like the part number ends in 00 which is the old part number. My upgraded Porsche cap is blue too. That being said, it still shouldn't slip after tightening. If the threads on the tank are stripped you should be able to see it. I've heard that some of the cheaper tanks have problems but the ones made in Germany, with or without the Porsche part number, are good.
If you can get a good seal on the cap, open the vent valve and drive around for a few miles. You might have some air in the system and that will purge it.
That blue cap is not the 04 version. Not sure how you managed to buy the "old" 00 one brand new, but I would get the 04 cap and try it before doing anything else. You are going to want/need one anyway.
"West Germany"? I'm guessing that it's pretty old. The stripping symptom must be with the tank. How much did they charge you for the tank? Do they say if it was OEM? They should replace the defective tank for free. If they just hand you a new tank, let me know. I just installed a tank in my car last week and would be happy to help you with the install.
Are you sure it's the cap and not the pressure release black cap. I went through 2 new after market tanks and both black pressure release caps were bad and the system would not hold pressure. I put a genuine Porsche pressure release cap on one of the after market tanks and everything was fine. I used an Airlift system to refill.
I'm 99% sure it's the cap leaking. I see fluid around the rim of it and the pressure valve is dry. Plus, there's that issue that I can't tighten the cap and have it bottom/stop, instead it goes around (both caps).
I know my shop will replace it. I just feel bad that he's going to be out the labor for a defective part.
07-01-2018, 02:15 AM
Defective New Expansion Tank? Leaks at cap
