Has anyone repaired a cracked coolant reservoir?

[elgyqc]

I just replaced the coolant reservoir and since the engine was out I did not have to destroy the old one to get it out. Since I hate to throw away things I got to wondering if it would be possible to fix this.



Plastics are a mystery to me, is there a spray on coating that would seal the existing and future cracks (I have my doubts). Or is there a sealant that could be poured into the tank that would seal and strengthen the bottom? It would have to adhere to the tank and be flexible enough to not crack itself.

[JFP in PA]

Many have tried, I know of none that succeeded...................

[78F350]

The best automotive analogy I can think of is an aged out tire. Even if it has tread left, the material is degraded throughout. You can put a tube inside and get some more miles from it, but at any time it could fail catastrophically.
The material of the coolant tank has been pressurized and heated for many thousands of cycles. The bonds that bind the plastic on a microscopic level are failing. I don't think there is any practical way to extend it's use. Any patching of a crack would be short lived as the crack extends or a new one develops outside the patch.

[elgyqc]

Originally Posted by 78F350

The best automotive analogy I can think of is an aged out tire. Even if it has tread left, the material is degraded throughout. You can put a tube inside and get some more miles from it, but at any time it could fail catastrophically.
The material of the coolant tank has been pressurized and heated for many thousands of cycles. The bonds that bind the plastic on a microscopic level are failing. I don't think there is any practical way to extend it's use. Any patching of a crack would be short lived as the crack extends or a new one develops outside the patch.

Well you let the air out of my tires
Sounds logical to me.

[Gilles]

Originally Posted by JFP in PA

Many have tried, I know of none that succeeded...................

I did it and it worked.. (but not recommended)

Many years ago, bought a Fiat X1/9 (I was living in Mexico..) and the coolant tank burst a seam, in those years without internet I had to wait a long time to get a new tank shipped to the Texas border and then shipped to me in central Mexico (+/- a couple of months..)

Therefore, my McGiver solution was to mix a kind of 'runny epoxy mix' and pour it inside the tank, one side first and then again for the other half of the reservoir and it worked just fine for a couple years until I installed the new tank.

[MasterDesigner]

there is a jb weld product specifically design for plastics, you sand the area to make it rough and it works very well but as others mentioned I would not trust it as a long time solution

[nuvolari]

I just found a product that so far has worked wonders for me. And judging from reviews on Amazon, for others as well.




Captain Tolley's Creeping Crack Cure.

I've used it to cure a nasty leak in my 944's front windshield. The leak was sucking in mass amounts of water due to capillary action. I've known of capillary action since I was a young Porsche admirer but didn't really know how powerful it is. It will draw water uphill through tiny cracks and in my case was completely drenching my car's ECU's and passenger compartment. After some magic from Captain Tolley, the leak/leaks have stopped completely. I've also had the same experience with the 944 taillights which were filling with water before Captain Tolley. Presently I'm trying it on my 944 rear hatch which some of you will know is a major problem on these cars where it becomes detached and leaks into the rear compartment. Normally, this requires separation and resealing with a 3M industrial sealant. Captain Tolly is trying his best but his proper usage is on small cracks whereas the rear hatch gaps get larger than the Captain is meant for. Still, I can see this solution filling the gaps slightly over several applications (I can see the milky solution creep in using capillary action which is amazing to watch. It then dries clear.) It'll most likely need additional window sealant but it is filling the tighter areas. I'll see if filling a little at a time works out or if a thicker sealant is required.
Anyway, not sure of its chemical or heat resistance so it'll probably not work for a hostile environment such as a coolant tank but worth a look. And also worth a look for other leaks you can't cure; trust me, you'll thank me later!

One thing I can't figure out is why no one has made a metal coolant reservoir replacement for our cars. I've been meaning to look into fitting a generic or maybe a tank designed for a different car into a 986. I'm sure all the connections will complicate things but I worry about other things that aren't so obvious and which would require an engineering degree in fluid dynamics to understand. Any engineers out there who would know if complicated coolant flow is at work here or am I over thinking it? Also, the bleeder valve is more trouble in the design of a replacement. Still, so many other cars have aluminum reservoirs made by aftermarket companies in the $300 range. I always thought that was pretty expensive but in the 986's case, it doesn't sound so bad. And I think there are countless Chinese reservoirs for under $100.

[redpepperracing]

Interesting. I don't know if it would work with a coolant reservoir, but you've given me an idea on how to fix the headlight on my wife's Subaru.

[nuvolari]

Originally Posted by redpepperracing

Interesting. I don't know if it would work with a coolant reservoir, but you've given me an idea on how to fix the headlight on my wife's Subaru.

I agree on the coolant reservoir. But then again, who knows? And I wouldn't be such a fan boi about Captain Tolley but it seems to have worked for me. I think one problem with fixing leaks is not understanding how powerful capillary action is. For example, I never thought water would go uphill against gravity through a crack but when you apply the Captain to a leak where you can see the crack, it's shocking how quickly it flows and how all the other solution will continue to follow.

Also, I believe in this product due to the reviews of similar success so it's not just me.

Anyway, no connection to the Captain; just a happy customer.

Oh, and even more off topic but I'm sure Grant won't mind, I have another product of a similar ideology if not actual usage: The Bish! The Bish is to fabric what Captain Tolley is to cracks!

Anyway, look on the websites for these products and I'll say no more here.

[lkchris]

By German regulation, plastics on these cars are designed to be biodegradable.

Repairing something 20 + years old will be futile.

Time for a new reservoir.