Brand new heater core leaking?
 

How could a brand new heater core be leaking? I purchased a new heater core for my truck since I was tearing it totally apart for paint, just got it all put back together and noticed antifreeze leaking inside on passengers floor just below heater box. I even rebuilt and painted the whole a/c - heater assembly with new gaskets as well. I doesnt leak all the time, but when I really step on the gas and accelerate it almost runs out. I checked the heater hoses on the firewall and they are tight, no leaks there. Anything else it could be?

Re: Brand new heater core leaking?
 

Sorry to here that it is leaking but I have learned to pressure test new heater cores with a garden hose on one end and a plug on the other because I have been burned twice and never again.

Re: Brand new heater core leaking?
 

I guess this is my first burn then. I will test every one I ever buy from now on. Thanks for the input. Not looking forward to the 5+ hour job on a freshly painted truck.

Re: Brand new heater core leaking?
 

i have seen some times that heater hoses are tightened too much and cause the flimsy nipples they attacth to deform in shape and cause leaks

Re: Brand new heater core leaking?
 

That is GREAT advice! I just got lucky, I guess. Put one in a couple years ago, and no problems.

One thing I did read about on this site: Most replacement cores (like anything else) will not fit EXACTLY like the original. So in one case I read about, one of the screws for the hold down brackets was just a tad too long. Long enough to slightly puncture the guy's brand new heater core. Of course, he didn't figure that out until after it was all reinstalled, etc...

So, you could check that also.

Re: Brand new heater core leaking?
 

I used original screws and brackets. Did I mention my truck has a/c? This replacement will not be fun.
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Re: Brand new heater core leaking?
 

I did the exact same thing when I installed my new heater core, ran both screws right into the tank. Fortunately I noticed it before I installed it and was easily able to solder the holes closed and get some shrorter screws.
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