Plastic radiator collar and metal barbs - Oops!

[samualt]

I have this radiator I want to use, but the inlet and outlet were huge. So I cut them off leaving about a 1" collar. I had intended to solder my brass barbs onto the copper collar. However the moment I began to cut, it was obvious I was cutting plastic. The top and bottom of the radiator are plastic.
Well, solder is out of the question now. Should epoxy hold the brass barbs in good enough? What kind of epoxy would you use? I have 5-minute clear epoxy and some cool plumbers epoxy that comes in a stick that you mash up like playdough and stick to things (best for metal). But I'm not sure what will hold to this black plastic that the top and bottom of the radiator are made of.

Has anyone else come across this?
What worked?
:shrug:

[jman1310]

what diameter is the inlet and outlet?
what size barbs?

if it is a soft plastic you may be able to use the barbs to cut threads into the in/outlet
consider using different barbs so they will fit over or inside the in/outlets
you can use rtv sealant to seal or use a 2 part epoxy that is for use with plastic and metal
or get nylon barbs so you will have a plastic to plastic bond

plastic to plastic is better IMO because similiar materials expand and contract at similiar rates

[bigben2k]

The plastic is probably a PolyEthylene, a soft plastic. You can use a polypropylene barb from any hardware store.

An adhesive question... CyanoAcrylate will probably serve you best here, unless you find another glue specifically for it. I'd still use some kind of silicone sealer on top of it (aka Plumber's Goop).

[Butcher]

Not sure that cynaoacrylate does well in water, I have had experiences of it softening when exposed to warm water. You should be able to find a two-part epoxy designed for plastic or plastic/metal though.

[bigben2k]

True, a lot of CAs don't take too well to water. The Goop ought to work well though.

[jlrii]

Look into loctites products for plastic epoxies.

[eander315]

What kind of radiator is that? Got any pictures or dimensions?

[samualt]

eander315:
It is an after-market Honda Civic radiator (92-00), supposedly all copper. The top and bottom tanks seem to be molded plastic. The plastic doesn't bend, and at first I thought it was metal. The fins and the rest of it are probably copper though. It's hard to tell because it is painted black. Even looking inside it you can't really tell. The fins look copperish. This guy on Ebay sells them really cheap ($50 US shipped.) It has a core size of 13.75" x 14" and 1.25" thick. It is a double row (has dual fins one in front of the other) and is single pass (no U turns).


jman1310:
The plastic collar on the radiators (the neck of the radiator inlet and outlet) are .865" or 22mm. The metal barbs I wanted to use are 1/2" but have 3/4" (19mm) threaded ends.
I hadn't thought about it expanding and contracting at different rates! I had my heart set on that shiney brass look. But I think now I'll try to find some nice plastic barbs instead. Probably easier for the glue to bond to anyway.

bigben2k (or anyone):
Is there any real difference in Silicone sealant and Plumbers Goop? Is the Plumbers Goop brand really better?

[Butcher]

Sealant is just to seal a joint, goop is an adhesive as well, I wouldn't use sealant, it lacks the mechanical strength.

What fan(s) are you going to run on that monster? You could put a nice big 12" fan on that...

[BillA]

Ben is all wet, as usual

Goop is a solvent cement; ALL "Goop" is the same (different printing on tubes), strong when dry
silicone 'sealant' is RTV silicone, no strength to speak of

the plastic is doubtless glass filled, use an amine cure epoxy - car rads are repaired this way

[TerraMex]

looks beefy.
can't you "close" the existing inlet/outlet and bore in new ones? ...
... thread them, put some plastic barbs and just some sealant (and probably more manageable ).

[samualt]

Butcher:
I'm using a 10" Comair/Rotron Caravel model fan. It is 115V and can be controlled by a $5 light dimmer switch. Although, a friend told me not to run it too slow or it might get a little warm. I find that at half speed or just a little faster it is very quiet.

[mad mikee]

I'm looking into getting one, could be great silent cooler :shrug:

[Butcher]

In my experience big fans are not silent. You get a degree of bearing rumble at any speed. They do push a lot of air though, and deal with restrictions much better than smaller fans.

[samualt]

I tried Goop and didn't like it for this application. The space between the barbs and the radiator inlet/outlet is too big. Goop flows just like water, only much slower. It was flowing everywhere. Plus, it came off pretty easy. Of course, I didn't let it dry the prescribed time either.

I've decided to go to the hardware store and see if I can't find a threaded copper pipe that will fit the inlet/outlet. If I can find a threaded pipe the right size I can solder the brass hose-barb to a brass washer, solder the washer to the end of the pipe, and put the threaded end of the pipe into the inlet/outlet with some lock-tite or something. It would make a much better mechanical bond. Much better than globs of glue.

Anyway, just thought I'd leave an update of my experience. Your milage may vary.

[jman1310]

you can try making a dam out of masking tape to hold the Goop in place

[Butcher]

You could probably get a barb with a larger thread which would fit the hole better as an alternative to soldering everything together by hand.

[mad mikee]

http://www.usplastic.com/pdfdatafile...ing11-2003.pdf
Gotta be dang close?