Jay M

Last summer my heater core was leaking... or so I think. It has been noted on the forum that sometimes a bad hose could give the appearence of a leaking core.

To solve the issue for the moment I just bypassed the heater core by running the larger of the two hoses in a loop in and out of the water pump.

For an unrelated reason I hadn't driven the car for several months. This weekend when I opened the hood I saw that the heater hose was "sweating" It was completely covered in coolant. My assumption is that the hose is pourus.

I haven't taken out the heater core yet, so I am wondering if there is a good way to pressure test it while it is still in the car?

~Jay

cchristo

Never tried it, but you can take a bike innertube, cut it so you now have a rubber tube with two open ends and a valve in the middle. Use hose clamps to attach the ends of the tube to the heater core pipes. Pump it up so it's nice and fat then leave it for several hours. If it's lost air, you have a leak.

You can also use a vacuum tester, you'll just have to figure out how to seal one of the pipes and attach the tester to the other.

StickShiftCorvette

You can test a heater core with compressed air.

VERY carefully remove the old hoses. Install new hoses a few feet long to allow easy access to their ends using hose clamps. On one hose install a plug with a hose clamp (a 5/8" drill bit works well on the smaller hose , a 5/8 or 3/4 rod will also work). On the other hose make up fittings to get you to a ball valve (available in any hardware store) and to your air fitting. Set the regulator on your compressor to 30 psi. (New cores are tested at 40 to 50 psi; your maximum cooling system pressure is 15 or 16 psi). Pressurize the heater core with 30 psi air and hold it for a couple of minutes. Then close the ball valve and remove the air line. The core should hold pressure for at least half and hour. If not (and all your connections are air tight) it is shot.

My last core corroded right at the hose.

lucky76

I would also stick it in a tub of water and look for bubbles. Otherwise you don't know if the ends leaked or the core actually has a leak.

theandies

I didn't need to leak check mine. It leaked all over my new carpet one day. I have mine bypassed but I am thinking of replacing it. When it started leaking I lived in Texas where you don't need heat. I now live in VA and sometimes in the winter I think I could use heat. I think the water tank is the best way to test it. Compressed air is too unpredictable on what it can do. It may pressure check fine but if there is a weak spot it may just damage is enough so when hot pressurized coolant is circulating it may just fail. I'd plug the inlet and outlet and dunk the thing under water and look for bubbles as stated above. If you are unsure then just get a new one for less that $100. It sure beats buying new carpet.

tommyleea

There is a pressure tester for the cooling system. It connects to the radiator. Autozone has them for rent. They work well..

LannyL81

Don't bother testing it.....just replace it. The heater cores are just to blasted difficult to get to...if you have the old one out...put in a new one.

My $0.02 worth.

LannyL81

GTR1999

I test new core too @15 -20 psi

Jay M

I guess I'm just being lazy by not wanting to take it out if I'm not 100% sure it's broken.

I have read other threads that say new heater cores sometimes leak so they need to be tested before they are installed.

I kind of like the bicicle innertube idea. I just don't know if I can get a tight seal with it.

~Jay