Testing Heeater Core before reinstall.

[Longhorn 70]

I am going to replace the AC/Heater box under the hood. I wanted to test the heater core prior to reinstall. I have the inner fender out and am ready to go with the new box, gaskets seals and such. I also have a good blower moter ready to go in....

The heater core looks good. I was going to just hook it to water supply pressure in the yard. We have 30 lbs+ of water pressure. Will that make it blow up like a baloon? Is there a better reccomended way?

Does it matter if it is hot, cold supported for testing?

Edit: BTW the one that is in there is a Stant core from 92. It has been disconnected for a couple of years due to bad heat valve that kept it on all the time....

[Sammy]

You can tell by simply capping one end with the palm of ur hand use ur mouth to blow as hard as you can in the other side. Even a pin hole will be obvious to you. Never tried a water hose before. I'm sure there are better ways. If you can cap an end and use compressed air in a bucket of water??

[Longhorn 70]

I do have a 5/8 cap that came off a new water pump I bought several years ago. I wondered why I held on to that thing. GOOOD IDEA. I'll cap, clamp and put about 20 of air pressure in it....


Wish me luck.

Thanks.

[terry b]

Longhorn 70 what are the replacement heater cores made out of? Copper or alum?

[sameyrasmea72]

I would take it to a radiator repair shop so they can pressure test it. Call and see how much it would cost to test it first.

[Daner]

I would be wary of using too much pressure to test your core. I probably wouldn't go too far past what your cap psi is. Be a shame wreck a core that would have worked fine.

[Andy4639]

Pressure cap is what 15 pounds on a radiator. I wouldn't get to happy with it. Like they said would be asham to mess up a good one by over pressuring it.

[cheyenne shortstep]

Buy a new one and be done, you don't want to do it twice.

[Longhorn 70]

To answer questions in order.

The core in there now is brass tanks with a copper core. I don't know about replacements, yet.

I am having problems finding a radiator shop in my area. It seems I live in a throw-away society.

I have a low pressure regulator for air. I am going to try 20 lbs/in2 and see what goes.

I have had new parts fail...especially of late as things aren't made as well as they used to be. One reason I like my 42 year old truck.

Thanks all for the suggestions.

I'll post resolution when complete...

[SS Tim]

I'd be inclined to make one of the caps with a regular valve stem in it and use a bicycle tire pump. Toss the whole thing in a bucket of water and see if any bubbles come out at about 10-12psig.

[bk2life]

last heater core i bought was 19 dollars. with a warranty.

rad cap only has 15psi. i wouldnt put any more than 10-15 in it. even then id err on the side of 10 psi. thats alot under water.

[Longhorn 70]

I just got a DUH moment.

I will just start the truck with the hoses on the core but not installed yet..... Just set it on the tire, start the truck and let the pressure build. I only have water and a rust preventative in it right now until the core goes in. Once it's up to temp, turn it off and let the pressure build as the coolant soaks up heat.

THEN if all works, I'll install, drain, fill with antifreeze and be on my way.

Thanks for the help guys.

[haysonj]

I used the pressure reducer from my RV and tested my radiator. They only cost around $10 and keep the water pressure from blowing the seals in a RV when you hook up to a water faucet.

[Sammy]

Recently replaced a core in a 80's S-10 without testing from O-Rielly's. A real pain in the rear to do. New outta the box that leaked. Yeah sure it was exchanged but wasn't fond of the amount of work involved to pull it a second time around. Pre-testing for leaks before installing it is time saved for peace of mind. Not to mention the damage it does to new carpet on the floor, of course they don't cover that part.

[Longhorn 70]

My final DUH moment, well at least on this subject.....

I have the A/C box under the hood off to replace the box. Why don't I just hook up the hoses and see what happens? If I hook up the hoses and warm up the truck, maybe a little hotter than normal, and run it for a while and it doesn't leak, I'll put it together. ANY sign of leakage and I mean any I'll replace with one that matches the one in there. Not one that's close, one that matches. The one in there is brass tanks with a copper core. I have seen new ones that just don't look the same quality.

[cdowns]

if i went thru the effort to setup a pressure test i'd b checkin at least 40-50lbs to make sure of the extreme limit testin



in the end i'd probally just keep turnin it up till i could blowit up on the second one i'd know the limit to not cross in the service test