Leaking heater - easiest way to R&R?

[CCCC]

The heater is leaking coolant into the cab - 1970 GMC factory air setup. Wishing to get the heater section apart and deal with the core and/or connections in easiest/simplest way. Have looked it over carefully under the hood and in cab - looks like the heater section of the in-cab unit may come away from the rest. Is this the case? If so, best way?

Anyone done this job and have info/advice for a first-timer?

[special-K]

It's been quite a while since I've done one. IIRC,the core has to come forward. I drop the inner fender to remove the cover.

[CUSTOM/10]

I believe this depends on whether you have A/C or not !

No A/C it comes out from the engine compartment.
A/C it comes out from the interior.

I'm not 100% sure on this, others I'm sure will comment !

Gary

[67ChevyRedneck]

Haven't dealt with an A/C cab, but on heater only trucks you have to either drop the inner fender like Tim said, OR you have to remove the hood hinge. I removed the hood hinge because my truck wasn't "pretty" at the time.

[john]

Originally Posted by CUSTOM/10

I believe this depends on whether you have A/C or not !

No A/C it comes out from the engine compartment.
A/C it comes out from the interior.

I'm not 100% sure on this, others I'm sure will comment !

Gary

custom/10 is correct. the heater core is inside on A/C truck.

[Sammy]

Non A/c truck I have removed the passenger side hood hinge (secured with a wood block)n dropped the inner wheel well to rest on the 15 " tire. All for the bottom bolts.

[Orange Truck]

I have a 1969 Chevrolet C10 in the shop at the moment to completely replace the heater coil as it leaked coolant fluid inside the cab. I can offer more information on Tuesday of next week in case you do not receive an answer. From what you describe, I am of the opinion that it is the heater coil...incidentally there is a difference in the heater coil as to Air Conditioned or not Air Conditioned.

Originally Posted by CCCC

The heater is leaking coolant into the cab - 1970 GMC factory air setup. Wishing to get the heater section apart and deal with the core and/or connections in easiest/simplest way. Have looked it over carefully under the hood and in cab - looks like the heater section of the in-cab unit may come away from the rest. Is this the case? If so, best way?

Anyone done this job and have info/advice for a first-timer?

[CCCC]

Thanks for the replies. This IS a factory AC setup. Have been hoping for some step-by-step info from someone experienced - just to avoid some foul up that would cause more issues.

From what has been posted so far, I am gathering that the way to access and R&R the heater core assembly is by removing the right (pass side) panel covering it inside the cab. That seems to require removal of the glove compartment box (the cardboard) to get at all mounting screws. In addition, there are at least two smaller screws into that heater housing itself. Anyione know what those are and if they should/should not be removed before unscrewing and pulling back the panel covering the core?

Anyone know of a manual diagram or explanation of this little mess?

Thanks for your reading and assistance.

[Bigdav160]

It's not that hard. But yes, I pulled my glove box AND inner fender.

I also removed the heater vent, s duct and diverter from the inside.

Aftermarket heater cores look like the originals but do not fit like the originals. Be prepared for some bending.

[Hutch]

CCCC
This link is for a non ac unit but does give some idea of what is involved

http://67-72chevytrucks.com/vboard/s...ad.php?t=69812

[mikey531]

The easiest way is dump in a small can of ground pepper. make sure the heater is on high and the fan working. It will stop the leak for years ! You can still enjoy the rest of the summer and pull it apart in the winter. It really does work, I have done it myself.

[Daner]

I've heard egg whites work as well. Another stop gap would be to bypass the core. :P

[CCCC]

Long ago I inserted a shut-off valve in the heater feed hose and also now have bypassed the heater core so I can run the truck as is for the summer. But need to get this job done while the cab floor is bare and BEFORE I install the new liner/carpet/seats/etc. It is a 1 ton with nice utility bed and Alaskan camper - and I want to use this thing for a deer hunt this Fall.

I might try the "stop-leak" stuff if the situation were otherwise, but this truck has been in process too long and needs to be completed.

Got most of the heater box bolts out today - have dropped the inner fender - now need to figure out the remainder of the removal. This job is more complicated with factory AC setup. I am wondering if the actual heater core is the same as non-AC heater - I have a spare one of those.

Any further helpful info and good short-cuts will be appreciated.

[Hutch]

The heater cores are different
With A/C
http://www.rockauto.com/catalog/more...069&cc=1033603
Without A/C
http://www.rockauto.com/catalog/more...026&cc=1033603
Once inside the box you will see the difference

There is also some mounting hardware along with some seals that may need replacement
http://www.lmctruck.com/icatalog/cb/full.aspx?Page=64

[Orange Truck]

Just had the heater core on my 1969 Chevrolet C10 without A/C replaced by a local shop. Access was from under the hood. This was the original heater core with leak determined in changing the coolant fluit and flushing the system.

Originally Posted by CCCC

The heater is leaking coolant into the cab - 1970 GMC factory air setup. Wishing to get the heater section apart and deal with the core and/or connections in easiest/simplest way. Have looked it over carefully under the hood and in cab - looks like the heater section of the in-cab unit may come away from the rest. Is this the case? If so, best way?

Anyone done this job and have info/advice for a first-timer?

[Bigdav160]

The A/C heater core is removed from the passenger compartment..

[special-K]

I've never had to replace a heater core on an a/c truck. I'm glad I red this thread in case I need to. I've done a few on non-a/c trucks and was going to mention removing the hood hinge. I remember something about that but wasn't sure so left it off. I guess it's one or the other and I've done it both ways.

I don't have manuals handy but wouldn't this be covered in a shop manual? How about an exploded diagram like in LMC catalog. Might be enough to go on.

And yep,the cores are different between a/c and non

[67chevy_hotrod]

Just did this on my A/C truck Easiest way too attack it is rip out the glove box and glove box door and drop the inner fender well. A wobbly socket extension made my life easier use it if you have one. Also DOUBLE CHECK it doesn't already leak some new ones have been beat up through shipping and the necks from the core to the hater hoses crack. Also specify that it is in fact an A/C truck otherwise they will give you the wrong one. Good Luck! And honestly it is pretty straight forward just keep track of all your nuts and bolts(i.e. Fender Well, Glove Box, the nuts and washers that come off of the shafts that go through the firewall, and most importantly the 4 little screws that go into the box that hold the brackets in place to hold the core itself.) A step by step i would say drain some of your coolant to avoid making a mess then. pull out your glove box, then drop your fender there is bolts that go to the battery tray and somewhere else i don't know what it goes to exactly. I didn't remove my hood hinge i didn't care that it hurt my hands lol. Undo the diverter box from the box that the core is in just a few screws and leave the diverter box. then undo the heater hoses and slide them off the necks. then undo all the screws that are on the shafts that go through the firewall one is next to the necks in the middle of the little like area there. then you have some wiring that goes to the A/C relay i believe?(correct me if i am wrong) it goes into the box with the heater. gently pull the heater core box from he inside of the cab it will hit the dash its going to don't panic its just a tight fit. once you negotiate the core box out of there boom there is the core. undo the four little screws holding the brackets on and you can pull out the core. the brackets are tricky on the re install though. The inside one you put on the core before you put it in the box. After that the rest is really straight forward just do it all again backwards. I don't know about how bad your leak was but i had to gut my interior and wash the rug and my heat proofing insulation. Again Good Luck! any questions just reply on here or message me i am glad to help! like i said i literally did this last week and i am doing my dads non A/C truck too!

[CCCC]

I have it out and have ordered the new core. Looks as though there was a good flex seal in there once - need to check that.

The above post (#18) by 67chevy hotrod is an excellent play-by-play - I just finished the same process. Dropping the inner fender well seems a must. Getting that grommet/wire out of the heater box is a pain, and that one exterior body nut under the inboard side of the AC box is another - it will be interesting getting that one back in - as well as the grommet/wire in the box. The fit of the heater box is TIGHT against the interior face of the glove box frame - not sure how I am going to get that aligned and in and get those heater core inlet/outlet tubes through the firewall withut damaging them.

Also need to figure out how to rebuild the edges of that cardboard glove box liner. Rough before I started - a mess now - and need to find/replace some of those air handling tubes tha run around under the dash. Anyone have a source for those - or a better substitute?

Can't remember your screen names right now, but thanks for the heads up on checking the new core for leaks, thanks for the web adresses for parts, and - yes, there is a decent writeup in the factory manual but makes this sound simple - it leaves quite a bit to your ingenuity. But, don't we all need that if we are going to do our own work on these trucks?

Thanks to all. I will post a final after I get it working - don't hold your breath.

[67chevy_hotrod]

hahah thanks like i said i just battled through this last week! and those necks of the core are tricky to get in and so are the hoses with the way the a/c is set up in the engine bay good luck again and hope your back on the road soon!!

[67chevy_hotrod]

in regards to new air hoses i am in desperate need of those as well.. my dryer vent tubing only lasted a winter of defrosting lol. i got a new cardboard glovebox from LMC and it is fine just make sure you have all the little clips and screws, and specify that it is A/C there is a difference there as well.

[CCCC]

Thanks again for the info and those suggestions. Got thiis done, but 'tweren't easy at times. Tha factory air setup sure complicates heater core replacement. Issues:

Drop the inner fender for certain to get at some mounting stuff, and have a few nice moments getting the unwieldy thing all lined up to re-bolt.

The heater box only will come out past the front steel frame of the glove box with interference - there will be some scraping coming ou and going in.

The grommet/wiring through the heater box was a pain going back in - can't quite reach and get leverage from here.

Biggest issue was that the new "factory replacement" core (Rock Auto - little lesson there) ) turned out not to be the same depth dimension as the original (1/2" less deep). I had to move forward and couldn't wait for a return/turnaound so had to fabricate shim type cusions so that the original factory clips would hold the core secure inside the heater box. No - they did not send proper clips with the new core.

Actually, the re-install went more easily than the removal - the wire/grommet issue and getting the in/out tubes through the firewall were the slow steps - so the takeout experience sure helped with put back. It seems to be working and leak-free.

Thanks again for the support.