Repairing an aluminum radiator

[Brads70]

I thought this might prove useful to someone else down the road so I thought I'd make this post.
I had bought this radiator 3 years ago. It was an e-bay purchase from a seller selling surplus/used Nascar take off's. This rad was built for a Craftsman Supertruck but never used. I modified it for my purposes and it did an OK job of cooling my 451" stroker, until it started leaking last fall. I did make rubber mounts but I'm guessing they were not allowing enough flex and thus caused the leak. I'll remedy that when I install it.
I removed it from the car and rigged up a pressure tester and found it to be leaking from the tubes to the tanks. That area can't be accessed to be welded so it was either I try some stop leak products, scrap the rad or I had this motorcycle tank epoxy sealer kit from another project  that I never did use. So I though "meh" what the heck nothing to loose? My concern is how this epoxy works with heat?
Remains to be seen I guess, time will tell? Nothing to loose at this point.
http://www.caswellplating.com/epoxy-gas-tank-sealer.html

I used brake cleaner and compressed air to clean it best I could , then mixed half the kit up and poured it into the tank area. It is raised so it acts like a cup to hold about 1/8" of epoxy. I let it harden overnight then flipped it over to do the other side.

[Brads70]

In case some were curious... its a double pass rad, but not in the traditional way. It's actually two rads in one. The entire front of the rad gets coolant first then the entire back half of the rad. I've never seen another one. I'd bet it was quite expensive to have built!  I can't remember the exact amount but I paid somewhere around $300 for it after trying multiple radiators trying to cool this motor in traffic. This one worked the best so far. I hope this repair is successful I'd hate to have to scrap this one.   

[RUNCHARGER]

Great piece! Hope it works.

[Cuda Cody]

Is there anything you can't do?     Let us know how it turns out.

[YellowThumper]

Great job there. Hope it holds up for you. My tale ended up being scrap and replace.

As for allowing more flex from your mounting to the core support. I have seen a setup where they rubber mounted fairly solid the bottom bolts. They then used a rubber grommet (same on bottom bolts) that sandwich rad to core support. But utilized a longer bolt with washer and heavy spring (like a die spring). Bolt was sleeved so you could still tighten it without fully collapsing spring. Shoulder bolt may even work.
You would keep tension but not be solid.

Good luck

[Brads70]

Well it held 20psi overnight so I installed it today and let if run for 1/2 hour or so. No leaks and it's holding pressure. (for now?) If I was a betting man I'd say a new rad is in my future but time will tell? Not sure how well the epoxy will hold up with the heat? I poured a silver dollar sized blob and let it harden for a couple days. I then boiled some water and stuck it in. It seemed to keep it's shape but it did soften up and become somewhat flexible?
I found some rubber bumpers at Princess Auto that were just the right height to support the bottom. I then went to a wrecking yard and found these  cool rubber grommets on various Mercedes and used them between the rad and the mounting surface. I can wiggle the rad now so maybe that will help? 

[RUNCHARGER]

It will help for sure.

[Chryco Psycho]

I am thinking the epoxy will hold up OK 

[HP2]

Interesting approach. I'm anxious to see how it holds up.

Back in the brass days, I'd just heat up an area with a map gas torch, clean it with flux, and then brush solder into the seam. Given the tempermental nature of aluminum and its small window of heat tolerance, I'd think home repairs on these are limited to epoxy.

[RUNCHARGER]

Yes, that's a troublesome spot to repair too.

[Brads70]

No good it leaks ..... scrap rad.    It was worth a try I guess...
Ordered this as a replacement.... should be here Friday.
https://www.summitracing.com/int/parts/cir-802-31191/overview/

[RUNCHARGER]

Dang: Oh well it was worth trying for sure.

[usraptor]

No good it leaks ..... scrap rad.    It was worth a try I guess...
Ordered this as a replacement.... should be here Friday.
https://www.summitracing.com/int/parts/cir-802-31191/overview/

Well at least you gave it the old college try.  The shop that repaired my original 26" radiator said that the aluminum radiators in old muscle cars are only good for 2-3 years (obviously depending on how much you drive them) because they flex too much and end up breaking the welds.  Don't know if he's smoking his socks or not, but it's a reputable shop that been around a long time.    Just passing along what he said.  In the meantime, I'm hoping my 4 row 26 incher keeps my 512 stroker cool in traffic or I'll be biting the bullet for an aluminum one also.    So far it kept it at normal all through the 30 minutes break in run and now while idling.  So here's keeping my fingers crossed.

[Spikedog08]

Ok I have to assume where you stated in your first post that the area CAN be accessed to weld . . . You actually meant it cannot be accessed or you would of welded it.  I sat there wondering why you tried that route instead of welding it. 

[Brads70]

Ok I have to assume where you stated in your first post that the area CAN be accessed to weld . . . You actually meant it cannot be accessed or you would of welded it.  I sat there wondering why you tried that route instead of welding it. 

Your correct ! I edited my post should have said "Can't"