The Stovebolt Site Forums The Shop Area Interiors Round heater cores and repairs

I wanted a recirculating heater for the simplicity and the fact it is not needed much in my climate. I have had very poor luck with these heaters and have now spent enough money to buy a completely rebuilt fresh air heater.

I purchased 2 restored ebay heaters guaranteed not to leak. They both did soon after operating them. I had one repaired twice and the second one once. They were pressure tested by the shop doing the repairs each time. I even took them to a second shop for pressure testing after the first one starting leaking a second time. The were tested at 18 psi (I know that is too high!) and were not leaking even though the one leaked after installing it for the 3rd time. When they leaked, the leaking occurred at the seem between the cores and and the tanks. The shops I had repair/test these cores are long standing businesses with excellent reputations.

The heaters only leaked when the truck was up to full temperature and coolant had been flowing through them for a while. I have a valve to control flow. At first I thought it was due to pressure build up but the core sees the same pressure whether water flows through the core or not and I am only running a 4# functioning radiator cap.

The only explanation I can come up with is there is enough thermal expansion that the seam opens enough to allow a small leak. It has never been more than rapid drips. The shops both agreed the only real fix would be to completely disassemble the unit and re-solder the tanks to the cores. Neither place wanted to take that on. They said there was no guarantee and they didn't want to gamble with my money. I think they just didn't want to do the job.

I finally bit the bullet and purchased a replacement core and fan from the Brassworks. I posted about this in the general truck forum since I thought it might have general interest.

Chuck

The first red flag I see is testing it at 18psi. Any thing over
7psi on any of those heaters expands the tubes to a point that
the can be damaged. Sounds to me like the tubes have been
distorted at the header from over pressurization which weakened
them and probably lead to some cracking.


Denny Graham
Sandwich, IL

I purchased a heater from ebay with the round heater core, took it to the local radiator repair shop for testing, the guy at the shop tested and said it had some leakes, he repaired and told me that you don't want to pressure test these old heaters over 7 lbs and that I needed to run a a 7 lb cap or less on my truck. He said that the old heater cores weren't design to handle a lot of pressure and if it was tested with more than 7 lbs of pressure it would weaken the core. I told him that I had a 14 lb cap and he said that the core would probably hold for awhile and then start leaking, so I changed the cap.Still working on restoring the heater so don't know if it will leak on me or not.

Denny, you have been issuing those warnings long enough I knew to make that request but it doesn't get passed along to the person doing the work. In any case, it appears to me from the staining that it is leaking at the seam with the tank and not around any of the tubes. The radiator shop doing the repairs said I would just continue to chase a leak around the tank. When they explained that the only proper fix was to completely disassemble the tanks from the core, clean the joints well, and re-solder they weren't trying for more money because they turned down doing that.

Chuck

Taking the tank off and resoldering it is the easy part. Finding all the corrosion and repairing it is the hard part. Getting a good fit is also important. A slip fit is desired... any looser than that and the solder has to much of a void to fill. Capillary action only goes so far.

If its a tube and fin core I would attempt it if the fit and metal are good.

If its a stamped/honeycomb core then no.. you will need a big ol tub of molten solder.

Cleaning up a heater core?
Need to get rid of the corrosion?
Lazy?

Try Molasses!
You'll be pleasantly surprised what you get from a week or two soak and a hearty rinse...

Molasses to clean copper and brass??

John

Yeah that's what I thought and why I gave it a shot with the old heater I picked up.

It's not like it's ready to solder but it IS clean and ready to work with.

edit: Also the motor spins free and just needs to be cleaned and lubed from what I can tell so far.

Are you saying that you put the whole thing in the bath, motor
and all????

I've been reading bout this mole asses thing with much
skepticism for almost a decade. The other day I was getting
solar salt at Farm & Fleet and the agricultural molasses was on
the shelf right behind me. I had a little room left in the
cart, so I picked up a 2 1/2 gallon jug, fifteen bucks. Figured
I'd give it a shot on an old 2 bottom plow that I've got
disassembled and laying out behind the barn that I'm in no
hurry for.
I saw somewhere that they were mixing it 1part to 5 of water?
That sound familiar?
Denny Graham
Drawing ants in Sandwich, IL

I think I put about 3.5 gal in a 30 gal garbage can with a tight fitting lid (Keeps the stench down till you take stuff out), so thats about 9:1 which is what I'd read most often.
Yep the whole enchilada all at once for a week.
Took it out and hosed it off, got the screws out (almost all anyway) and put the pieces back for another week or more.
The copper come clean quicker than the metal.

The Motor? Like I said I haven't taken the motor apart yet but I'd bet it works as it sits if I gave it the juice.
I rinsed the crap out of it spinning the squirrel cage with the hose and generally abused it, then set it out to dry for a day or four.

I'll let ya'll know when I tear into it and what I find.

Posted photo's showing the motor innards after finally getting the squirrel cage off.
The photo's are after dumping some dish soap in/on them and then used an acid brush, a red scuff pad and lot and lots of hot water.
I didn't use any solvents other than the Kroil and Kearny cutter to loosen the fan and the nuts.
Pic's of heater motor after mollasses bath