replacing heater core only and/or assembly on firewall

[dutchman]

I browsed all of the tech forums and was surprised I didn't see any threads on replacing heater cores on full sizers (or maybe I missed it?)

I have a 1970 Wag with Buick350 and the heater core assembly looks more or less exactly the same as AMC era Wags. As a former Jeep parts guy, I seem to recall that the heater core and heater core shroud part #'s from the Willys Kaiser era superseded to AMC era parts and that they are retrofittable.

So my first question is if the heater core on Kaiser era wags is the same or close to the same as AMC era heater cores? (since I don't access to Jeep parts microfiche anymore (and since no parts guy at any Jeep dealership will bother looking into the old parts fiche)

second question:

the heater core assembly is more or less the same size and shape as AMC era wags but I'd rather do whatever is easiest in terms of replacement so is there a way to replace the whole shroud assembly or do I need to open up the shroud and replace the actual core itself?

Does anyone have a step by step how-to?

NOTE: I have a another used Kaiser era heater core and shroud assembly I can buy for parts that doesn't leak so I am not concerned with buying new parts

I am the 2nd owner of this fine automobile and am finally up to 117,000 miles (bought her at 82,000). She runs like a top other than this new leaking heater core issue. I have the heater core bypassed at the moment so she is 100% driveable

[Tad]

There a few different sizes of heater cores as I recall but they all fit in the same box size.
I got an '85 heater core into my stock '70 metal box without too much hassle.
Things line up correctly for the most part, IIRC the hose size was different, I just shoved them on.
The clamps inside my box were toast so I just tweaked the '85 ones to fit.
Been fine since '02 or so like that.

EDIT:
For the step by step stuff look for a post by Gambler68.
As I recall he did a writeup on his.

[jaber]

I know on the AMC version, theres 2 nuts on the fire wall next to the box and theres 2 nuts on the inside of the fire wall. Then theres a bunch of screws around the outside that reveal the core.

Not sure on the Kaiser...

[dutchman]

overheated buick / busted heater core,,,and my afternoon adventures

"I know on the AMC version, theres 2 nuts on the fire wall next to the box and theres 2 nuts on the inside of the fire wall. Then theres a bunch of screws around the outside that reveal the core. "

yeah, it's pretty similar if not the same

I was pretty sure you could retrofit a newer core into the old Kaiser shroud assemblies and you just confirmed that for me

you rock - thanks buddy and happy holidays

---

I am sad to report that from the time I posted earlier to right now I had to drive 10 miles across town to see my brother. I had bypassed the heater core since it's leaking so bad and steaming up the inside of the jeep (like Cheech and Chong Up in Smoke type action) I had assumed (wrongly) that when it blew the core a few hours ago and puked up some coolant from the core that it only leaked a small amount of coolant overall so I assumed I'd be fine bypassing it and checking the coolant level tonight when I got to a parts store.

Nope.

10 minutes into the drive my oem guage started reading much warmer than normal (slightly past 1/2way between cold and hot) and I figured it would be OK until I made it just a few more miles. Then the engine started sounding rattly and I could tell the fresh 20W50 oil change I put in last week was getting overheated...of course I was in the worst rush hour south Denver traffic of all time with nowhere to pull of the road...uh oh!

the engine rattles then got real loud and then I knew I needed to pull off the road NOW and let her cool down. I made to the first intersection and got ready to turn left onto a side street...of course it was the worst traffic ever with no way to turn until traffic cleared. I'm nervous at this point, I know my engine and this sounded bad. Then as traffic clears and I'm ready to turn with a break in eastbound traffic, it stalled and wouldn't restart...it would still turn over but with major difficulty...This is not good. I had my buddy jump out and we started pushing through the intersection trying to get her across during the break in traffic...

for those of you new to FSJ's, they are no fun to push in traffic and mine has no power steering...we barely made it but were almost clipped by some eastbound grocery getting Honda driving maniac who I guess didn't see the enormous 2 ton green 4x4 slowly getting pushed through the intersection...we were missed by a mere 1 foot...I saw my life flash before my eyes...

anyhow, heading back to the jeep now the engine should be cooled off

I fear I scored the rings and did some engine damage based on the noise, extreme overheating, and difficulty in turning over the engine when I tried to restart it...bummer. Hopefully, it just got real hot and it's still ok. I left it on a side street and am going back in a few with some water to add to the radiator -

let's all hope it just got hot and that it's alright. I pray the engine is still ok. I do not want to have engine swap this time of year

be safe out there everyone, don't be in a rush this holiday. even if the jeep's Buick engine is toasted, I'm glad my friend and me are alright. This afternoon could have been my last!

[gasman66]

stay safe and good luck!

[Gambler68]

Not sure about the actual core, but the boxes are different..hard to tell by looking at them but the holes for the fan are different/heights they mount off the firewall.

sorry to hear you ran your engine that hot :/

[dutchman]

engine won't start

went back and engine was all cooled off, added water to radiator (will flush it all later), just wanted to start er up. The radiator was pretty low as I added about 2 gallons - sadly, now it won't start

if I'm lucky it's just head gaskets and not cracked heads (or the block) - oil will definitely need changing but I first need to get it started and see if it's burning white smoke or not (sign of busted head gaskets)

it was dark out now so I'll look at her in the daylight tomorrow since it's in a safe place on a neighborhood sidestreet

[lkmarsh]

Obviously you have bigger concerns than a heater core now, but, for what it is worth, the Jeep heater core swap was the easiest I've ever done. It's not under the dash, like my Chevelle, and there is nothing but screws holding it in.

[Elliott]

Somebody here is building us some stainless boxes....

[dutchman]

I ain't skeered

I might get outta this on the inexpensive side since the old Buick 350 has an iron block and iron heads I may just have to replace the head gasket set up and be cool - odds are I may not have to machine the heads

there is a chance the block may have cracked and that would suck - hello engine swap

but the old Buick 350's are pretty bullet proof engines and I didn't run her in the red too long and I was roughly cruising 1200 rpm's so it would (hopefully) be unlikely I cracked the block

I'll know tomorrow when I look her over in daylight and see if I get bubbles in the radiator fluid (water for now) when I turn her over. I'll obviously be draining my oil and checking for coolant/water sometime thereafter I tow her out.

Absolutely worst case scenario, and I mean worst case scenario is that my old buddy owns a Willys Kaiser '71 with 4 barrel 350 he is parting out and I could make him an offer for his motor/heads/intake/4bbl carb

I hope NOT to go down the engine swap road so let's all hope it starts tomorrow with some starting fluid and blows white smoke (blown head gasket)

--------

My same old buddy who is parting out his Kaiser '71 also has an aftermarket Summit Racing Heater Core / Blower Motor assembly which totally rocked when his SJ was still on the road so odds are I'll be making him an offer and installing that and throwing that "piece of crap barely works in the winter time anyway" OEM shroud and blower motor assembly in the trash - maybe then I can finally change the spark plugs on the passenger side rear cylinders!!! (all you Willy's Kaiser SJ guys know what I'm talking about)

Oh yeah, I looked at the OEM heater core shroud set up and there are some super tricky bolts to get at...seems to me removing the blower motor housing makes getting at the shroud a little easier?

But really since my old buddy's SJ is heading to the crusher anyway, I think I'm gonna try to get his Summit Racing heater core set up and get rid of that awful and in the way OEM shroud assembly once and for all

I refuse to scrap this Jeep - this is the car I always wanted growing up - and it's one of the last left on the road ya know?

PS, everyone always thinks it's an International and have no idea it's a Jeep - ha!

[Gambler68]

Wobble socket T-bar takes all the hassle out of that rear plug FYI

Good luck! May as well just swap the pig out if your buddy has a running one. Perfect excuse to spend Xmas weekend in the garage

[fulsizjeep]

Not all replacement cores are a drop in fit. We replaced the core in Krista's 77 Waggy 9 years ago with a new NAPA part. It had the inlet and outlet swapped around and we had to do some slight metal work to the box to make the inlet/outlet fit without rubbing against any sheet metal. Now that I think about it, I am pretty sure the newer heaters in a fiberglass box have the heater core inlet/outlet swapped around from the older ones in the metal box.

[Lindel]

It's easier to put a newer heater core into an older metal box. I've done this twice now, when the fiberglass box was a religious artifact (it was holey... )

[jaber]

I'll know tomorrow when I look her over in daylight and see if I get bubbles in the radiator fluid (water for now) when I turn her over.

Being in Denver, I hope your water dont freeze, causing other problems....

[dutchman]

its in the 50's today and all, no freezing issues for now

thanks for your concern