The Stovebolt Site Forums The Shop Area General Truck Talk Heater Core Test ??

I picked up some great parts in the junk yard this weekend and the real find was a 40's Hudson aftermarket cab heater that will be just the ticket in the 45 one and a half ton.

The fan motor is bad but that is an easy fix but what I want to do next is check the heater core for leaks. I'm thinking I may plug one end and apply my household water pressure (30-35 psi) to the other end and see if there are wet spots or worse. Is that too much pressure? not enough?

I'm looking for any all suggestions on how to test the core. There are no radiator shops around for miles so I'm looking to do it myself.

-mike-

Household water pressure is way too much. The Chevy engines of the era were low pressure cooling system so I imagine the Hudson was too.

You need to rig something up where you can apply a few pounds of pressure with a bicycle tire pump.

Ditto on the bicycle pump. You probably shouldn't exceed 10 PSI. Cut a section out of a bicycle innertube with the valve stem attached, clamp the ends to the heater core nipples, and pump it up. Then use bubble soap from a spray bottle to check the core for air leaks.
Jerry

I use two hunks of heater hose and two tubeless tire valve stems. I secure it all with gear clamps. I pump a little pressure in, check it with a tire gauge and then immerse the core in water.

Thanks for the description.

Also, I had never seen the term "gear clamp" (I see "hose connections" in the USA Shop Manual) but it makes sense (and, is used in Google Images).

Low pressure is the ticket with 60 year old cores. You have to remember many of these trucks ran with 0-4 pound caps on them. Truckernix has the right set-up for checking them, if you go to a radiator shop they immerse completely to check for leaks.

The pressure from the pressure system is not the only pressure on a heater core. The water pump blocked by the therm builds up pressure. A radiator shop I dealt with years ago put a pressure gauge on it. It ran as high as 50 lbs.

Thank you all for all of this good information. Now I'll keep my fingers crossed that the core checks out OK.... otherwise my next post will be "How do I fix a heater core?"