Will heater core go in upside down?

[dave brode]

All,

I believe that I installed mine upside down in my '71. The 3/4" fitting is on the bottom, the 5/8" on top. My truck has a radiator with the return snout on the tank, which is for 3/4" hose.

I have it hooked up now, but it seems that the coolant does not flow through the core like it should. The flow from the engine goes to the top of the core, the bottom snout on the core goes back to the rad tank.

Do I have it upside down?

Remind me how easy the heater housing is to remove, please. I assume remove inner fender, and it'll come off. Will the blower motor clear the hood hinge?

Thanks much in advance. This is s great site.

Dave

[john]

Yes the factory had the 3/4 fitting at thr top.

[dave brode]

Originally Posted by john

Yes the factory had the 3/4 fitting at thr top.

Thanks, John. I did look at several threads in the FAQ and other areas. My truck is a hodgepodge [cadillac engine etc], and I could not be certain that the return should be 3/4". I did figure out that the return was on top, but I could not find verification that the 3/4" snout was to be on top for sure. Even if a thread did show a core with the 3/4" on top, I might wonder if that truck had it wrong too. I figured that someone here would know for sure.

I'll be changing it. I hope that I can remove only the inner fender, and not dink with the hood hinge.

Again, thank you.

Dave

[jeffspower]

Yep, you can put them in upside down. I've seen them work fine both ways, but I always install them the "correct" way with the small inlet nipple at the bottom. My reasoning is the core shouldn't plug as easily as the coolant flows up, leaving sediment & rust that won't pass thru in the bottom header tank. When installed upside- down, crud that won't pass thru sits on top of the core blocking off tubes.

When swapping out a blower motor, I leave the hinge on the hood and unbolt the hinge from the fender. You can slide it forward and it will sit on the fenderwell. I've never dropped a fenderwell to pull the housing, I don't like dealing with the rusted clipnuts that break loose and spin. Somehow I manage to get to the pesky screws with a 1/4" drive wobbly socket & extension.

[Dark Knight]

To remove the housing, you must take out the inner fender. There is one bolt that is in the bottom left hand corner that must come out. I think you also have to remove the hood hinge, but just unbolt it from the fender like jeffspower says.

[Stocker]

Originally Posted by jeffspower

Yep, you can put them in upside down. I've seen them work fine both ways, but I always install them the "correct" way with the small inlet nipple at the bottom.

Non-A/C truck? It's been several years since I replaced the heater core in my A/C truck, but I seem to recall it would only go one way....


I also recall it was very difficult to replace, but I did it without removing any body parts. Probably because I didn't know any better.

[dave brode]

Gents,

Done. I removed most of the inner fender bolts, left the front three in the fender lip and the ones on the rad support, just loosened the bolt in the bat tray. Did not have to remove blower motor, or hood hinge. It came out with the rear of the inner fender hanging down a bit.

Thanks all.

Dave

[stevewhitmore]

Dave,
Could you please walk me through the process you did, I need to replace the core in my non AC 69 Chevy.
I am new at all of this and could really use some help. Messing with the fenders worrys me a lot

[dave brode]

Originally Posted by stevewhitmore

Dave,
Could you please walk me through the process you did, I need to replace the core in my non AC 69 Chevy.
I am new at all of this and could really use some help. Messing with the fenders worrys me a lot

Steve,

I read posts everywhere from "no problem, just use a swivel, no hinge or inner fender removal" to "have to remove hood hinge" to have to remove inner fender".

Here's how it went for me:

I removed the big bolt holding the inner fender to the cab, and the bolts holding the inner fender to the fender on the rear half of the wheelwell. I removed the bolt holding the inner fender to the battery box. This allowed the inner fender to drop down enough to get a socket on the hard to reach heater box fasteners. I did not have to touch the hood hinge. Once the box was loose, I used a long screwdriver to pop the cable off of the little linkage pin inside the box. It was a tight fit wiggling the box up out past the hood hinge.

The wire brackets holding the core into the housing are a bit of a fight. It had been a few years since I "re-did" the truck, and I had forgotten about those. You might want to buy some "home store" foam weather seal mat'l in advance to place around the core to make all of the air go through it, rather than allow air to leak around it.

Once I flipped the core, reassembly wasn't too tough. Get the cable back on the pin, and stick the box back on the firewall.

The only problem I see in an old truck is the fender to inner fender bolts. I would soak the heck out of them for a day or two prior to doing it. Some of the holes have a nut welded to the fender. If any of those break loose [which they sometimes do], you'll have to grind the bolt heads off and try to position a new nut up inside there somehow. Some of the holes have nuts attached to spring clips, which can be replaced easily.

If you don't want to mess with the inner fender at all, I advise to try the "remove hood hinge" method, and buy one of those wound spring looking extensions for a 1/4" drive socket set.

Hope this helps.

Dave

[toddtheodd]

I think on mine, I never put that one bolt back that requires the removal of the fender well, so if I need to pull it again I don't have to mess with that PITA bolt.

[stevewhitmore]

Thanks a lot Dave, this is great. I plan on tackling this over the weekend, wish me luck
Steve

[Mike J]

I need to do mine as well, finally got the engine running last week only to watch coolant spray out of the heater box every time I revved the engine! Top tube is cracked.

[stevewhitmore]

Hey Dave,
Just wanted to say thanks again for the detailed instructions because I followed them to the T and it went great. I did have to grind the inner fender bolts off but other than that it went pretty smooth.
Thanks again
Steve