Coolant Expansion Tank: How important is OEM, really?

Yesterday my 911 wet itself near the driver exhaust tip, and it looks to be coming from the expansion tank. In my pre-purchase research I recall something about an updated version and how it's critical to purchase a Porsche replacement, not a cheaper non-OEM replacement. I've seen this mentioned in threads I've found searching, but little on the why. Is it really worth the 3x premium to replace some molded plastic? Current price from Pelican is over $600, and I just want to make sure it's worth putting out for the OEM tank.

ECS seems to have OEM one for $180. I've used them in the past for my VW and Audi needs and I always look there as prices tend to be very good. https://www.ecstuning.com/b-genuine-...k/99610615704/

What year car? I recall there is a expensive one and a cheaper one depending on the year. Having done the job recently and the work involved, I wouldn't buy a non OEM replacement based on the responses I got from here earlier. I went with the consensus on the OEM but went cheaper on the fluid I recall. Someone more knowledgeable will chime in for sure.

Quotes source post: 16962397

Have you replaced your coolant cap with the newest version ending in 04? Old coolant caps can leak, and the overflow pipe is about where you say the coolant is. Check your coolant cap first.

I don't think of replacing the coolant tank as a big deal. I remove the air cleaner and the two engine mount nuts and lower the engine an inch or two and slide it out. The 996.1 cost about 3x the 996.2 from Porsche. Mine is still the original Tank from 99, if I replaced like the normal consensus from Rennlist, I would be on the third tank. The tanks usually leak a small amount ( gives plenty of time to intervene)and I have never seen one just split open. So I will face that when/if time comes, maybe the great climate here in Bama is favorible to them... If you are not a DIY'er and are paying a shop to replace, I can see buying the OEM part and having it installed "while you're in there"...

All German cars seem to design very unGerman-like coolant tanks. BMWs, Mercedes and Porsches all have similar problems. There are very regular incidence of owners getting stranded due to busted coolant tanks and as touted as German over-engineered cars, they totally ignored this very important area. Why ? ... I don't understand. Its not rocket science to design a better tank other prohibited by cost....but then their cars are too expensive to be penny wise pound foolish.

Thanks everybody for the input. It's a '99 C2 (~62k miles). It's not a bad leak, only a slow-ish drip every 5-10sec or so. Black coolant cap (04 is blue, correct?). I checked the coolant level as soon as I parked and saw the leak actively dripping; it was dry around the cap and there was no residue built up on the threads. The tank is yellowed, but only slightly, not a dark opaque yellow. I don't see a replacement in my service history, so I will just assume it's the original tank.

FLEX TAPE! Joking of course...., or am I?

Quotes source post: 16962623

Unfortunately a Porsche replacement tank for your year is about $650 compared to about $160 for an MK-II.

Quotes source post: 16962623

Be very careful when ordering. Lots of companies claim OE and even some OEM. Because this part is PITA to install, I'd order it directly from Porsche to make sure you get the genuine part. Get the updated cap too. Remember, do RIGHT or do it TWICE. Check this out... You Tube

A key thing to note when removing the tank is that you only need to move it inboard about an inch or so to drop it down from it's bracket and not the whole length of the bracket due to the scalloped bracket design. I didn't notice that small detail from the many videos and write-ups I researched prior to doing the job myself.

Quotes source post: 16963055

Good tip to remember!!!

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You can see how you only need to slide the tank over an inch and then drop it due to the bracket design.

Quotes source post: 16963055

Or, you can do what the previous owner of my car did: break the bracket off the car and leave the coolant tank secured by the hoses.

What would need to be changed to run a mk2 tank on a mk1 car? I can't fathom paying $600 for a plastic bottle. Is the bracket on the chassis different? Are the hoses different?

Quotes source post: 16964598

There is a hard pipe behind the coolant tank towards the front of the engine bay that is in the way of the later model...it really won't fit.

I have a 99 as well and when I purchased it, noted slight leakage and bought this before being educated in the forum but it is 3 years old now and no issues. My indy installed in about an hour and didn't even have to drop the engine. I guess he has good hands for this. https://www.ebay.com/itm/171052676831 $178 I bought the updated 'blue' cap somewhere else. Not sure if I did right by not purchasing OEM, but seem to be happy so far.

When my original tank ('99 C2) started leaking, I purchased an aftermarket replacement from Pelican. I also replaced the cap at the same time. The tank's threads weren't properly molded, so it couldn't seal, and sprayed coolant as soon as the system got up to pressure. So, I had Pelican replace it under warranty (thanks Pelican!). The new aftermarket tank leaked from a molding. Pelican refunded me in full, less my shipping costs. After spending hours to replace the tank twice, I was determined to be done, so I bit the bullet and bought the genuine Porsche part. One year later, no leaks. As B3Freak put it "Do it right or do it twice" (or three times?)

I just replaced the tank in my '99 as well. Jake Raby said he tried all the aftermarket tanks and they all had problems. That was good enough for me. I bit the bullet and paid the $600 for the Porsche brand tank from Pelican. I also replaced the bracket, cap and coolant level sensor.

Quotes source post: 16967819

Nothing against Pelican but you'll always pay their mark-up on any genuine Porsche part. I usually use Sonnen in Marin or Sunset in Oregon. For example, the tank is $488.00 at Sonnen. You can buy a lot of beer with the $100.00 saved. https://www.porschemarinparts.com/oe...ir-99610614756 And $492.00 at Sunset. https://www.sunsetporscheparts.com/o...ir-99610614756

This tank is something where a genuine Porsche part matters.. I see aftermarket tanks and even OEM with stripped threads for the coolant cap, sideways threads, and some are seam cracked right out of the box.. Genuine only on this one, fellas.. it des make a difference.. It's all we use.

Quotes source post: 16967881

Good to know. I did check one of the other suppliers. Their tank was cheaper but I couldn't tell if it was genuine Porsche or not.

Surely in this day and age, somebody has figured out who actually produced Porsche�s tank�

Quotes source post: 20122514

I believe is was Behr, but I don't think they sell them via aftermarket channels anymore. I installed a Behr tank in my 996.1 several years ago and it's been fine.

Quotes source post: 20122514

I don't see a good reason not to just make an aluminum tank like Moroso does for BMW E36 (also notorious for blowing up their tanks). No challenge for any competent fabricator, just need to remember to put in a sight glass so you don't lose that important function of the translucent plastic.