heater core replacement

[stepside454]

I need to replace the heater core in my 75 with air. Do you need to remove the entire box from under the hood ? If so, are there bolts underneath ? do you have to drop the inner wheel well ? how much fun am I in for ? John

[76sierraclassic]

I just recently changed mine out in my 76 GMC with air, and no, you do not have to take out the box under the hood (I assume you are referring to the evaporator core). There are 3 nuts on studs coming through the firewall from the heater/ductwork box. When looking from the front, one of them is on the top right of the box that has your evaporator core in it, one is on the bottom just to the left of the one on the top, and the last one is kind of on the left, and it's a pain in the butt to get to. I couldn't get to it with anything I had without dropping the inner fender. Fortunately that is not a difficult task. I just removed the tire and then droped the inner fender enough to get to the bolt. Then, if memory serves correctly, there was one bolt going through from the inside. I did wonder if there were other bolts because it was fairly difficult to get the ductwork out, but it was just being stubborn. I just had to yank a little harder. I think it took me somewhere in the neighborhood of 5 hours to change out my heater core.

BTW, I don't know if you have one or not, but my Haynes Repair Manual was not a real big help on this particular project. I don't know if Chilton's would be better or not.

Hope this helps...

Mike

[stepside454]

Thanks Mike, I appreciate it. John

[76sierraclassic]

Originally Posted by stepside454

Thanks Mike, I appreciate it. John

No problem. Glad to try to help. Hope it goes well for you.

Mike

[76bonanza]

Just did my 76 one week ago and Mike was right on mine was the same I was able to drop my inner fender enuf with out removing my wheel.

Was not as bad as I thought good luck.