Replace the coolant tank cap

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I had the same thing happen to me I replaced the coolant cap evidently the ones ending in 00 are faulty I have an 02 Boxster S I replaced it with the newer caps ending with 02 ....problem fixed

Coolant overflow question - 986 Forum - The Community for Porsche Boxster & Cayman Ownersreported fixed

So you just replaced the coolant cap and it fixed the problem? Not sure what function the cap itself has in these cars, but I am curious because I may have a similar issue. Have not noticed any fluid o the ground, but I park in various spots both at work and my apartment complex so that part is a little harder. I just know that the car gave me a low coolant warning, and smelled like coolant wh

The illusive coolant leakreported fixed

r is white (cream), a leak would be obvious. Bone dry. Except sometimes water from the middle of the car, which I assume is condensation from the AC. I had the coolant cap ending in 01, changed it for an 04 and issue persists. I cleaned up around it and no coolant seems to be pooling up there. No traces of coolant underneath the tank either. After running the car (and letting it cooldown, but not completely) I came to add coolant. I unscrewed the cap and a lot of hissing occurred and the coolant level went up a bit. like if i

996 Loosing coolant - no leakunresolved · Original poster

UPDATE: So I changed the coolant cap and that did not solve the problem. My next step is to replace the coolant tank but first I want to make sure that its bad. Whats the maximum PSI that I should add to the cooling system to check for leaks?

Coolant overflow due to hot weather?unresolved · Original poster

garage had brought it up to temperature and then sat it running as a last test. All good, until it suddenly spewed the guts of s litre of coolant out thru the coolant cap. The dash temp was at about 100 degrees st this stage. Half way between the two dashes. I'm hoping it just hasn't been 'burped' properly, but it still doesn't explain the first loss of coolant. Pissed off and getting stuck into a bottle of Gordon's. This is no way to start back into 996's. :grin:

Mysterious Coolant Loss... Part Deux,unresolved · Original poster

I would top it off with the Petosin I had left. Once he replaced the reservoir he used Porsche coolant. Funny thing, the new reservoir came with the old 'bad' reservoir cap. I had the new 'good' cap on the old reservoir so I save it for later . thank you

Porsche coolant, why?suggestion

This is what I did with my '99 996, might not work for a Cayman: Lifted the rear bumper to about 3ft. Removed the coolant cap and re filled it until it was full. Then started the engine and kept refilling untill it didn't take any more coolant. Then I replaced the cap and opened the venting valve and let the engine run until it came up to operating temperature. Then I shut the engine down and let it cool down. After the engine was cold I removed the filler cap again and topped off

Question on Coolant Filling with Uview Airliftsuggestion

tremely effective method of filling without air pockets. Not saying it's impossible though. The very first thing I would inspect would be the coolant expansion tank cap. How does the seal look? Clean up the area around it and look for any white residue, which is residual coolant. Coolant vapor can escape through a poorly sealing cap, and often the caps aren't closed all the way.

low coolant level and........suggestion

Source-mentioned parts

99610644700

The coolant cap is P/N 996.106.447.00. It's definitely not coming from the cap and I can't find any signs of a leak from up top. I'd have to start removing things to pinpoint it. Honestly, with how old I believe it is, I wouldn't mind replacing it anyway.

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99610644704

You can purchase a genuine "04" for under $15.00, no tax, free shipping from here: Porsche 911 Boxster Cayman Expansion Tank Cap FEBI BILSTEIN New 99610644704 | eBay I replace mine every year as part of preventative maintenance; I don't even test the existing one. I've heard of water pump failures because of old, faulty caps, so I don't even mess with them. It may be an old wives tale, but then again, I haven't replaced a water pump yet. Just sayin'............... TO

Original source

99610644701

or your help guys, I've just pulled the carpet out and no signs of any coolant. Everything's dry and no signs of any previous leaks either. I had a look at the coolant cap and the part number on it is 996.106.447.01 so looks like that needs replacing. I then lifted up the plastic horizontal plate and there was lots of signs of moisture and coolant in the little gaps and corners so definitely looking like it's the cap. Will get a new one ordered asap

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