1985 K5 350 with air. It was leaking through the firewall into the carpeting the other day. I checked the hoses and the one on top was swinging left to right, so I'm guessing the inlet is cracked at the core??? Anyways, I disconnected both hoses, zip-tied the ends ( hope this is safe ) and sure enough the top was cracked. So, on a scale from 1 to 10 ( 10 being the hardest ), how hard, or easy, is it to replace a heater core??? THANKS!!!

 

about a 0.4 as far as heater cores go. especially if you dont have a/c its crazy easy. the non ac one is like 4 bolts holding the box to the firewall, a couple cables and you can take it out the entire box and swap out the heater core on a table (im sure i might be missing a few other small details). a/c if i remember correctly is basically the same thing but a few of the bolts are harder to get at.

BUT you also run into the joy of rusted bolts or spinning nuts in the box causing you a big headache. had a s10 that did that and ended up just torching the bolts out which ended up catching the interior on fire lol. was a $100 tuck so no biggie. but yeah dont do that

 

Sweet!!! My rig does have ac ( 2-75 ). I'm having second thoughts about replacing the core. If I don't use the heater or ac, what's the use??? Both hoses are blocked, so is that gonna screw up anything?

 

the fluid has to flow what you can do is bypass it

get something like an elbow with 2 nipples and put the hoses together then clamp em or a nipple that both hoses fit on with 2 clamps


Edit: this should work perfectly

 

the only downfall to that is if you ever have a cold or raining day where you need to defrost your windows it kinda sucks blowing just room temp air at it. other then that people do it all the time.

 

Replaced the core. PITA!! No rusted bolts, had to drop part of the fender inner well to get to the bottom mounting bolt, tore out the original core, I'm in pissed-off mode, broke some plastic to make the replacement fit, wasn't paying attention, heater controls are shot, I get intermittent heat in the cab, at least it's not leaking, replaced both heater hoses, thermostat is next, I now have a slow leak from lower radiator hose...yada yada yada...

 

it is possible to get at those bolts without dropping the fender, i know ive done it somehow on my suburban. but yeah as far as other heatercores core this is still as easy as they come. other vehicles you have to tear apart the entire dash board

 

ya on some newer cars we have had in the shop you have to take the entire dash out of the car including the center counsel

 

Looking back at it, I guess it wasn't that bad. My heater controls are all jacked up, though-the cables came off and I'm getting heat all the time unless I manually reach underneath the glovebox and close it. Can't stand prosperity, or words to that effect..