About two weeks ago I replaced the heater core. After replacing I’ve dried up the carpet twice. I haven’t notice any leaks except for one maybe two (drops not any big leaks) on the firewall behind the dash. Also out of the heater box right by the passenger floorboard where it meets there was a tiny leak but has seemed to go away. Haven’t noticed the vents leaking either. I’ve also put a heater hose on the drain tube. Pretty stumped at this point. Any thing to check out before I replace the heater core again?

 

Is it actually coolant? Or water??

 

I think it’s coolant. Not sure why it would be just water. Has a slight coolant smell to it. No signs of the heater core being bad besides passenger floorboard being soaked.

 

Might try tasting it, (but, not very much) to verify it is indeed coolant. If it is, then you have a leak somewhere. (yeah, no kidding....... Thank You Captain Obvious.......) It MAY just be where the soft lines hit the hard lines to the core, it maybe be the joints in the 'movable' heater core lines, if it has those, or, it may just be a bad heater core........

 

Thanks bud. I’m gonna try tightening up the clamps on the hoses and dry the carpet again. It is the heater core with the swivel ends on it.

 

That could be the issue... the swivel joint leaking.
I have avoided those like the plague, just for the potential of that happening.

 

definitely avoid these at all cost, good spot for a leak, oem style cores only, also good practice to use new heater hose just because its cheap and as this hose ages fiddling with could cause a crack in it or its just all hard and dried up and doesn't reseal well, if you didnt pull the hvac box out theres a very good chance the heater box is still full of coolant from the last leaking core thats slowly splashing out, also why i just use oem cores as you should pull the dash apart anyway and clean it out and clean the evap core as its probably plugged restricting air flow

 

Okay so I’ve pulled the dash let the truck run. No leaks that i can see come out of the end on the heater core. I have noticed that it doesn’t seem to have a leak until i drive it around. It’s been about 3 weeks since i have done the heater core but I’m guessing that it’s just water from the old heater core still leaking out. The only place I’ve noticed it coming down from is on the floorboard right next to the kicker panel. I have installed a hose on the ac drain tube so that can’t be the problem. How far should i be able to put a screw driver into the drain tube to see if its stopped up or not?

 

With the dash out of the way, pressure test the cooling system.

 

Ive had a leak on the drivers side also for awhile. I just soaked the windshield and found that my windshield seal is leaking about where the leak is coming from on the passenger side. So I reckon I’ll get that done if its still leaking then i will pressure test the coolant. I’m thinking this is the problem. Hopefully so at least.