30 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHBlue coolant cap tightening issue
Leading reported evidence
Install less than 3 years ago and a cap
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
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1
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Performed · outcome unconfirmed
I have a genuine MK2 tank that was installed less than 3 years ago and a cap that is less than 6 months old and it has white coolant reside on it already.
Leading evidence: 'Install less than 3 years ago and a cap' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check cap seal' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed
Finally installed OEM tank and no problems whatsoever.
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Performed · outcome unconfirmed
Of note: I've been replacing the level sensor at the same time, and the non-Porsche sensors from Pelican each cause the coolant light to flash slowly- never a problem until I replaced my original sensor (my '99 C2 has under 30k miles).
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Suggestion · Original poster
OK, I recently completed a half coolant change along with a new expansion tank and a new blue cap.
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Performed · outcome unconfirmed
I have a genuine MK2 tank that was installed less than 3 years ago and a cap that is less than 6 months old and it has white coolant reside on it already.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
Of note: I've been replacing the level sensor at the same time, and the non-Porsche sensors from Pelican each cause the coolant light to flash slowly- never a problem until I replaced my original sensor (my '99 C2 has under 30k miles).
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Suggestion · Original poster
Mine tightens to a certain point and then if I try to really tighten it as tight as possible it loosens up and then I have to try to tighten it again and try to hit the maximum tighten mark perfectly before it gets loose again.
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30 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261026T144035Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
OK, I recently completed a half coolant change along with a new expansion tank and a new blue cap. Car has been running in the normal temperature range since the change. But today in heavy stop and go traffic with lots of idling I noticed some coolant was exiting the overflow hose and onto the headers and the needle hitting just at the limit of the "0" of the 180 mark. After parking the car I noticed the coolant had dropped from the max to min mark. About an hour later, the level was back to the max level again. Strange. So 2 questions:
1. Maybe I overfilled the system with coolant and so the system is naturally bleeding itself of excess coolant? I'm confused with this because the coolant has been at the maximum level for the past few days since the coolant change. Or maybe there's an air pocket somewhere?
2. Is the blue coolant cap supposed to tighten all the way to the point that it cannot be tightened any more? Mine tightens to a certain point and then if I try to really tighten it as tight as possible it loosens up and then I have to try to tighten it again and try to hit the maximum tighten mark perfectly before it gets loose again. I'm a bit confused about this. And I'm not sure if this is related to the loss of coolant.
Any suggestions are appreciated.
The new expansion tank is it an OEM tank? I have read there are some issues with the secondary market tanks that have to do with exactly what you are reporting. Bad threads/short threads. The cap should tighten down until you can't tighten anymore.
The replacement tank was not Porsche OEM. I guess I�m gonna have to return this tank and buy genuine.
If the tank is faulty I�m not sure if it would cause the max to min to max issue or maybe they are 2 separate issues?
I had this exact thing happen with a new cap. Turns out the rubber seal inside the cap was not fully seated from the factory. It's tricky to get it all the way down as the fit is tight. The overflow hose will catch anything that accumulates in the "lip" of the coolant tank around the cap. When cool take yours off and check the cap seal.
I�ll take a look. The new cap is an OEM with the supposedly improved �04� part number.
I�ve looked at the inside of the cap before and it looks ok. Maybe press down on the inside seal with a screwdriver just to make sure it is fully sealed?
My bet is on the aftermarket non OEM coolant expansion tank. Lesson learned...use only a Porsche OEM coolant expansion tank and 04 cap. This is one job you don't want to repeat anytime soon.
100%!!
Biggest rookie mistake I made. Purchased a non OEM tank and brand new cap and the threads were toast within a week. Didnt want to do it again, but the vendor took it back and sent a replacement so I installed that one - never quite sealed right and started to panic "is something more serious going on?"
Finally installed OEM tank and no problems whatsoever.
Nothing worse than doing this job 3 times in 3 months...
i have the same issue with the cap slipping, i purchased another cap and same problem
my solution, i put some electrical tape around the threads of the coolant tank and now it holds perfectly
I�m gonna give this a shot and see how it works as a temporary fix until the new tank comes in. Seems like a brilliant idea. Maybe I can use plumbers tape and wrap a around the threads a few times to get a good thickness .
I did the electric tape fix and it seems to work. So hopefully this will hold for another week or so.
Guys is it normal to hear a slight depressurization sound at the cap when the car is turned off after it�s been running at normal temperature? Almost like a very slight hissing sound. Or maybe the electric tape is not fully sealing. I have read elsewhere that the cap automatically depressurizes?
i still can�t believe what total pieces of crap these aftermarket tanks are.
Should not be any hissing sound. The aftermarket tanks are junk and you're not the first one experiencing that.
The long-term solution is to replace it with an OE tank.
New Genuine Porsche OEM tank has been ordered. The bad is that I have to do this job all over. Replacement should be fairly easy the second time around. The good is that I get some extra 1/4 more new coolant into the system.
Yep, second non-OEM tank I'd get the hissing, then unexpectedly it would just cut loose again. I'd try to tighten up again, rinse repeat.
Yes, the second (and third!) time I did it was easier, although I did somehow bend badly the temp sensor the third time (go figure) so that slowed me down a few days. For the cost you may want to order one and have it on hand as insurance against hurling tools around the garage in frustration, Im sure you can return it if you dont need it.
Yea that damn coolant level sensor where the electrical connector bulges out at the bottom does get in the way. The trick is to maneuver it through at just the right angle and not hit anything.
i thought maybe the fan resistors may have failed and hence the slightly higher coolant temperature but after checking both fans are working so it looks like the inadequate seal is causing the higher temperature. Still no leaks after the stop gap repair.
Genuine tank is the way to go, I have a feeling that even the genuine .04 caps aren't that great. I have a genuine MK2 tank that was installed less than 3 years ago and a cap that is less than 6 months old and it has white coolant reside on it already. I've ordered another cap - see if it stops - threads on the tank look good and it screws down well too.
You can reach down and remove the sensor before pulling out the tank. It makes it easier and saves the sensor from getting damaged. Someone here suggested that an MK-II tank could be used in an MK-I car but I don't remember if it was ever confirmed. That would be a big savings as the MK-I tanks are 4 times the price. Can anyone confirm that?
Removing the coolant level sensor was the easiest part IMHO. Maneuvering the tanks in and out is the MAJOR PITA!
I think giving birth to my children was a much smoother process after carrying out this procedure.
No, male. But I was there holding her hand through hours of labor pains and of course, the birth... without a doubt watching the doctor gave me a new appreciation for patience and proper lubrication.
I shared that with the group after reading (another forum) that a member successfully put a .2 tank into his .1...If anyone wants to try this and has issue with the .2 tank not fitting, I will buy it off of you. We need to confirm this for others!
I am sad for OP, but really happy to see this post. I have just gone through two "OEM" (but not Porsche) tanks sold to me by Pelican, with this exact problem: garbage cap threads that leak once the system goes under pressure.
I'm ordering a Porsche tank after this.
Of note: I've been replacing the level sensor at the same time, and the non-Porsche sensors from Pelican each cause the coolant light to flash slowly- never a problem until I replaced my original sensor (my '99 C2 has under 30k miles).
The OEM brand tank that is leaking is from Pelican also. I tried to go cheap and bought a Uro brand sensor from Rockauto and it would not fit correctly. The Porsche OEM sensor fits perfectly.
i was able to tighten the cap another quarter turn and now no more hissing. I�ve got a return authorization from Pelican but I�m thinking of just keeping the tank in until it blows to hell and then install the Porsche tank that I just ordered. If this POS tank lasts me a year or two I�ll be quite happy actually. And I�m not going to be taking any long cross country trips anyway so I wouldn�t be stuck somewhere.
i am also curious to see if the Gen 2 tank would fit the Gen 1. Also aren�t the tanks different depending on coupe or cab?
I can't say I know anything about cab vs coupe tanks.
My defective tanks don't blow a substantial amount of coolant, so your plan could be a winner. I just want to be done dealing with this.
Good luck!
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