Defective New Expansion Tank? Leaks at cap
#31
Rennlist Member
Thread Starter
Join Date: Sep 2011
Location: Long Island, NY; South Florida
Posts: 4,099
Received 4,073 Likes
on
1,767 Posts
As did mine, only 3 months after installation by a shop. I lowered the engine down and replaced myself. Leak was not caused by the cap.
YouTube Video of the Leak (from 2013)
YouTube Video of the Leak (from 2013)
#32
#33
#34
Burning Brakes
You seem to have a cap that doesn't fit. Since its supposed to be OEM (but not Porsche) I would guess that the manufacturer intended for a different cap than Porsche supplies. Probably a cap with a different design altogether, given that the threads appear to be too short.
Point is, I would discuss with your mechanic replacing this with the genuine Porsche part and not just replacing it with the same part he gave you in the first place.
#35
Rennlist Member
Thread Starter
Join Date: Sep 2011
Location: Long Island, NY; South Florida
Posts: 4,099
Received 4,073 Likes
on
1,767 Posts
You think the threads are too short? I'll measure them. Anyone have one handy to measure and share those numbers?
#36
Burning Brakes
Measuring the the number of threads on the neck may help if it's different than the Porsche part for that convo with your mechanic.
#37
Rennlist Member
Thread Starter
Join Date: Sep 2011
Location: Long Island, NY; South Florida
Posts: 4,099
Received 4,073 Likes
on
1,767 Posts
Yea, the threads/neck are/is clearly bad. I just don't think it's too short since it gets tight, but I can go beyond if I keep turning and it slips. I'll see what the mechanic says for sure. And I'm sure everyone (both the mechanic and supplier) will want to check this issue before installing the new tank of any brand.
#38
Rennlist Member
Thread Starter
Join Date: Sep 2011
Location: Long Island, NY; South Florida
Posts: 4,099
Received 4,073 Likes
on
1,767 Posts
I realized I never circled back here with info that may be helpful for others in the future regarding replacement expansion tanks...
I had mine done when the AOS was replaced as preventative maintenance (along with a new water pump, just for grins). Old one was not leaking. New German part was installed by a very highly respected indy. He pressure tested it and the system was fine... that is, until I got it really hot. The fluid was perfectly filled to the cold line and checked A LOT (each morning during my issues). Yet once it got really hot, it seemed the coolant would leak from the cap a little bit, and then the cap would also be able to turn past fully tightened (like a medicine bottle safety top). When cold, it was fine.
I replaced the cap, twice. OEM. Same symptoms.
Mechanic replaced the tank under warranty. Same symptoms!
We suspected that the system just might be operating normally for a system that was a little over filled (even though it's not). If over filled, once hot, the cap is designed to allow pressure/fluid to escape to avoid bursting something like a hose. That dribbles out onto the "balcony/shelf" of the tank where it runs downhill to the drain hole and out the hose behind the rear wheel like rain gutters on a house.
So what did we do? We let it naturally level off without constantly topping off the tank. Guess what? PROBLEM SOLVED. So my tank has a "new normal." It's just a few ounces lower than before (see pic) but for the rest of the summer it's been fine. And fyi, it NEVER ran hot during all of this testing.
So I don't know if something is slightly different on the new tank design (remember, two German made OEM replacement tanks did the same thing) or what, but all I know is it's fine now. Just thought I'd share.
Happy cold weather motoring.
I had mine done when the AOS was replaced as preventative maintenance (along with a new water pump, just for grins). Old one was not leaking. New German part was installed by a very highly respected indy. He pressure tested it and the system was fine... that is, until I got it really hot. The fluid was perfectly filled to the cold line and checked A LOT (each morning during my issues). Yet once it got really hot, it seemed the coolant would leak from the cap a little bit, and then the cap would also be able to turn past fully tightened (like a medicine bottle safety top). When cold, it was fine.
I replaced the cap, twice. OEM. Same symptoms.
Mechanic replaced the tank under warranty. Same symptoms!
We suspected that the system just might be operating normally for a system that was a little over filled (even though it's not). If over filled, once hot, the cap is designed to allow pressure/fluid to escape to avoid bursting something like a hose. That dribbles out onto the "balcony/shelf" of the tank where it runs downhill to the drain hole and out the hose behind the rear wheel like rain gutters on a house.
So what did we do? We let it naturally level off without constantly topping off the tank. Guess what? PROBLEM SOLVED. So my tank has a "new normal." It's just a few ounces lower than before (see pic) but for the rest of the summer it's been fine. And fyi, it NEVER ran hot during all of this testing.
So I don't know if something is slightly different on the new tank design (remember, two German made OEM replacement tanks did the same thing) or what, but all I know is it's fine now. Just thought I'd share.
Happy cold weather motoring.
Last edited by AdamIsAdam; 11-15-2018 at 10:28 AM. Reason: Where's my pic?
#39
Rennlist Member
One thing I've discovered is that an "OEM" part may not be the same as a genuine Porsche part even though the OEM may be the Porsche vendor. I had both a new RMS and a new AOS fail recently that were OEM parts. Subsequently replaced with Porsche parts and no issues...yet.
Last edited by jhbrennan; 11-15-2018 at 11:05 AM.
#40
Rennlist Member
Thread Starter
Join Date: Sep 2011
Location: Long Island, NY; South Florida
Posts: 4,099
Received 4,073 Likes
on
1,767 Posts
All I know is that it works now. Dry, runs normally, etc with the "self correcting fluid level" design. lol
#41
Rennlist Member
I had the same conclusions as you in another thread from a few years ago. My tank was leaking and I did replace it with an OEM tank.....and it was all good after that, but I think leaving some expansion room in the tank is good practice and prevents the system from over pressurization during extended runs.
#42
I was thinking that myself. But seems odd that the same vendor/manufacturer would make two different expansion tanks, with different specs, for the same car. On the other hand, maybe there's a reason the Porsche part cost over $600 when the other one was around $350 (don't quote me on that figure, I don't recall exactly, but it was a less for sure). I assumed that was just Porsche mark-up, but who knows. My indy said he's installed MANY DOZENS of these tanks and never experienced it, despite my experiencing it twice on my car. So maybe there's another factor at play we're not considering, some other variable.
All I know is that it works now. Dry, runs normally, etc with the "self correcting fluid level" design. lol
All I know is that it works now. Dry, runs normally, etc with the "self correcting fluid level" design. lol
#43
Rennlist Member
Thread Starter
Join Date: Sep 2011
Location: Long Island, NY; South Florida
Posts: 4,099
Received 4,073 Likes
on
1,767 Posts
#44
Just for clarity going forward, the MK-I Porsche brand tanks are in the $600 range while the MK-II tanks are about $140..
#45
Rennlist Member
Thread Starter
Join Date: Sep 2011
Location: Long Island, NY; South Florida
Posts: 4,099
Received 4,073 Likes
on
1,767 Posts