Heater Core Replacement

[ChaseDale3and8]

The heater core in my 86 K10 let go and dumped a bunch of coolant in the floor. Fortunately I wasn't far from home at the time so I limped her back home without overheating. I haven't put one of these in since back in 1995 so my memory is fuzzy on exactly what I need to do to replace it.

My truck has A/C as did the last one that I had to put a heater core in. The only thing that really sticks in my mind on the replacement is that it's a real pain in the ass on an A/C cab like mine. Seems that I had to drop the inner fender out, and take the glovebox out. I think that I may have had to remove the cable for the control and unbolt and drop the plastic box down to access it which is a real pain. Does this sound right?

Anybody know of an easy way to do this? I'm open to suggestions to make this as easy as possible. Need some step by step instructions so I can get this old girl back on the road. It figures that it would happen when I had some work for her to do and she decides to lay down on me! ...Joe

[TDS-MN]

The Haynes manual has a pretty good step-by-step actually. Especially if you've done it (or similar) before.

My truck does not have A/C, and I did not have to remove the inner fender at all. Access to the core housing bolts was from under the hood, but other wise the steps you listed sound about right to me. I don't recall any other real special tricks. I know my Haynes walked me thru the control cable disconnection. But again, my non-A/C is going to be different. I've read that it is a tougher task when you have the A/C system to work around.

[ChaseDale3and8]

Originally Posted by TDS-MN

The Haynes manual has a pretty good step-by-step actually. Especially if you've done it (or similar) before.

My truck does not have A/C, and I did not have to remove the inner fender at all. Access to the core housing bolts was from under the hood, but other wise the steps you listed sound about right to me. I don't recall any other real special tricks. I know my Haynes walked me thru the control cable disconnection. But again, my non-A/C is going to be different. I've read that it is a tougher task when you have the A/C system to work around.

I'm thinking that I had to drop the inner fender out of the way to access some of the bolts on the core housing since it's a lot bigger on an A/C cab. I think that the lower ones were hard to access with the inner fender in there. I just can't remember for sure. Maybe I'll take pictures as I tear it down and try to post them up.

If I remember right the core is held in the housing by a couple of sheetmetal straps. On my last one, one of them was rusted completely through, and I had to buy another one from GM. Hopefully I won't have that problem this time. I do have a repair manual somewhere around the house. I can never find it when I need it though. My wifey has a habit of reorganizing and putting my stuff away somewhere, then can't remember where she put it if it's been a while. Thanks for the reply. ...Joe

[TDS-MN]

Joe,

Yup, my wife tries to 'help me organize' my stuff the same way a lot of the times, LOL!!!

I think you are right about the straps holding the core in place inside the housing. That's how I remember too. I suppose it could be necessary to pull that inner fender to access some stuff. The nut heads to remove the housing are all accessed from firewall side, on my truck. Pretty sure there were only 3 of them, though.

Hope the repair goes well for ya!

[piecesparts]

Take the glove box and glove box door out of the truck. Take the heater hoses off of the core. There are bolts that go clear through the cab and the nuts are in the engine compartment. Take those off and go into the cab and disconnect the heater control cables and vacuum lines. Roll the heater housing downward and towards the floor of the cab and expose the heater core. Take the small bracket off of one end ot the core and pull from the housing. Re-install in the reverse order.---check all of your foam seals for condition to make sure the heater is sealed.

Put all bolts, hoses, and glove box parts back on.

[Prerunner1982]

Originally Posted by ChaseDale3and8

I'm thinking that I had to drop the inner fender out of the way to access some of the bolts on the core housing...

I have heard of people doing it but I replaced my heater core on my A/C cab without.

[piecesparts]

I have replaced a few heater cores on the mid eighties trucks, and I have not dropped a fender yet. I use a 1/4" drive ratchet, long extensions and a deep socket.

[ChaseDale3and8]

Originally Posted by piecesparts

Take the glove box and glove box door out of the truck. Take the heater hoses off of the core. There are bolts that go clear through the cab and the nuts are in the engine compartment. Take those off and go into the cab and disconnect the heater control cables and vacuum lines. Roll the heater housing downward and towards the floor of the cab and expose the heater core. Take the small bracket off of one end ot the core and pull from the housing. Re-install in the reverse order.---check all of your foam seals for condition to make sure the heater is sealed.

Put all bolts, hoses, and glove box parts back on.

Thanks for reminding me about the vacuum hoses. I had forgotten about that. That's why I asked about replacing it so that I could hopefully refresh my memory somewhat before I tear this thing down. I don't want to tear anything up taking it apart! Thanks for replying. ...Joe

[ChaseDale3and8]

Originally Posted by TDS-MN

Joe,

Yup, my wife tries to 'help me organize' my stuff the same way a lot of the times, LOL!!!

I think you are right about the straps holding the core in place inside the housing. That's how I remember too. I suppose it could be necessary to pull that inner fender to access some stuff. The nut heads to remove the housing are all accessed from firewall side, on my truck. Pretty sure there were only 3 of them, though.

Hope the repair goes well for ya!

Yeah, the wives sure are helpful alright, especially when they borrow tools that never make it back out to the garage for their little home projects! LOL ...Joe