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Hi guys, Ok got a new thermo. replaced all hoses, antifreeze, thermo. Now I have a leak in my heater that I didnt have before. Antifreeze leaking out under truck and onto floor in the cab. Any easy fix I hope
Thanks Rick
This is a new post to an older thermostat problem. wasnt sure if I should repost or continue old one

Leaking heater core happens frequently were you running a pressure cap. After years of sitting/use the coolent slowly weakens an area. probably a pinhole. A radiator shop could evaluate if it is repairable. There are repro/nos cores available but can be $$.

the 'fix' is to remove and repair the heater as necessary, might be easy or not .... until you do that you can loop the heater hoses on the engine so you're no longer routing water to the leak

Bill

Cap looks pretty basic. Should I have pressure cap. Its a drag because I didnt have the leak before I put the new stuff on. Will I need the whole heater unit

What size and year engine?
What size truck?

depending on the style of heater you may only need to remove a leaking Ranco valve, or you may need to repair or replace the core .... a '58 should have a pressure cap, 4-7# .... regardless if you put a 'modern' 14# cap on [bad idea], now that it's leaking it needs fixing

Bill

https://www.stovebolt.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=834343#Post834343

The first part of the story.

Red 58 you say to loop the 2 heater hoses. Another guy told me to just block each one, which I have done already. Is that the same as looping them. Also any idea how much antifreeze this thing holds. I am wondering if i put too much in - creating to much pressure on the old heater

the amount of antifreeze won't affect the pressure, too much just won't cool as well, consult the label and add the amount called for to get the protection you want, the system holds about 16 qts [about 15 liters] .... by looping I meant remove one hose altogether, run the other one back to the vacated fitting, same as blocking but easier

Bill

well red aren't you clever.That would have been much easier and cheaper. Anyway I got them blocked now so I will leave them that way till I figure out how to get the heater out of the cab. I'll save that question for another day.
Thanks everyone
Rick

So, if I recall correctly, you discovered a stuck thermostat that was installed upside down and crooked. If it had been in straight, there would have been over heating and some boil over. Since it was in crooked, there was free flow and the proper operating temperature was never reached. Now that the new thermostat is in, you should have a good operating temperature and some increased pressure which probably affected the heater core. Your heater core was probably ready to fail.

Yes truckernix I imagine you are right. I was replasing al the hoses belts just to be safe cause I didn't know how ol they were. I actually discovered that that old thermo was busted from its casing . That is why it looked weird to me. Anyway I got the 2 heater hoses plugged. Just trying to burn off (steam)all the anti I spilled on the rad

Generally a radiater shop repairs with solder I believe, but believe it or not we just fixed a heater core with J.B.Weld. Block off one end of the core submerge it water with a little air pressure, find the leaking area try to open it up a little bit sit it on a warm wood stove and inject with a plastic syrenge some good ol STRUCTURAL j.b. weld. I'll let it set fo about a day or so than submerge it back in the water bucket for about an hour at 7.5 lbs. looking for leaks if she does I go back over it again until she holds, we've done a few of them like this.Some people say this could be dagerouse because of the weld softning up and giving off fumes B.S. J.B.weld doesn't even soften up on exhaut manifolds.For $7.50 she's worth a try

Well I had this issue as well and I had to take it around to shops getting Quotes. Think it was around $300 to recore it cause it was a honey comb or something of the sort. Anyhow, I was broke at the time and installed a universal heater and have still not got around to recoring it.

Good luck