1978 FJ40 front and rear heater core questions - what is rear made of ? (1 Viewer)

[edwards_rljr]

Due to a leak at my water pump, following a coolant flush, and my OCD, I'm now going though my whole cooling / heating system in my 1978 FJ40 and have everything taken apart and have a few questions.

I've read a few threads on here concerning heaters and cores but haven't found one that talks about what the rear core is made of. Does anyone know what the rear heater core is made of ? I assumed that it was brass/copper and had just been painted silver or pewter or whatever from the factory but when I got it apart, there seems to be some rust on it, not a lot, but some on the fins, and they do seem more sturdy than copper. The cover wasn't really very rusty so I didn't think that the rust on there was just stains from that but I don't know. The pipe nipples don't even look like brass, even on the inside. At first I thought it looked like brass inside but now I think that was just rust and coolant crud in there looking kinda brassy but I'm not sure. I'm wondering because the guy I talked to about boiling it out and pressure testing it said he couldn't do it if it wasn't brass/copper... specifically, he said he couldn't do it if it was aluminum. It really feels too heavy to be aluminum. Is it steel?

I took both and rinsed them out, the rear seemed fairly clean, only a few small dark particles came out when I put water in it, shook it around and poured it out several times. The front core was harder to get water to go in it and when I shook it and poured it out it was harder to get the water to come back out and it was rusty and nasty looking every time so I figure it's really clogged up with crap. I put vinegar in them, and let them sit overnight 3 times and the front still seems clogged and has dark rusty crud come out and I think it might even be leaking. The more I have thought about it, it seems like I remember seeing a little coolant in the floorboard last winter and wondering where it came from but just wiped it up and then didn't see anymore and ended up forgetting about it.. I know that sounds dumb but it wasn't gushing out and I never saw any more in the floor so the issue just went to the back of my mind.

I'm wondering if it's even worth fooling with having the front one boiled out and pressure tested. I found one on Advance Auto Parts website for $55 (Ready-Aire?), called them up and they say it is a brand new heater core and made of brass/copper... the radiator shop guy told me it would be about $20 to boil out and pressure test mine and then if it leaks and can't be fixed, I'm just out $20 and have to buy one anyway... seems kinda pointless... has anyone on here bought one of these Ready-Aire cores before? Wondering if they are just as good as the OEM one.

I'm going to be rebuilding the heater and blower with those kits from AATLAS1X.. having the heater parts blasted and powder coated... might as well have a new core in there if I can I guess... just hope the rear core is ok.. I don't want to have to take this stuff back apart again.

Does anyone know if it's possible to put some kind of shut off valves on the pipes to the rear heater in case something happens with it ?

yes, that's a big dirt dauber nest in the bottom of my heater... wtf? how they found their way in there, I have no idea.. that thing could've been in there for years...

rotten foam

core didn't look as bad on the outside as I thought it might

still not great though...

Can someone tell me what this hose on the bottom of the blower is for ? it's never been attached to anything since I've owned it.. just hanging there. Is it supposed to be attached to something?

 

[numby]

I never really payed much attention to the rear core but now that you point it out it does "appear" to be steel rather than brass. Touch a magnet to it. If it sticks it's ferrous. It's unlikely that it's aluminum if original.

The rust in your front core is probably a combination of sludge and rust out of the block and maybe a bit of electrolysis.

The tube from the bottom of the blower is for drainage in case of condensation, leaks, etc.

 

[Degnol]

Both are copper cores with brass tanks, I believe. The hose you picture is just a drain tube, not connected to anything on the bottom.

 

[edwards_rljr]

rear core update

ok, I'm an idiot, I didn't even think of a magnet.. took one from the fridge and tried it... it sticks to the fins but not the nipples or little tanks... so I guess the fins are steel... I knew they felt a lot more sturdy than the copper ones on the other one... question now is, are the tubes that run between the tanks likely to be brass too since the tanks are? the fins are too close to get the magnet between there.

 

[fj404life]

I had the local rad shop clean and test both heater cores out of my 69 40. Also had the same rad shop repair numerous aluminum dirtbike radiators. Id find a better shop that can deal with anything you throw at them!

Dont see any reason why you couldnt add a valve for the rear heater if you wanted to.

 

[srgould41]

My rear heater had what looked like a factory shut off valve in the feed hose when I bought it. The valve was frozen open and didn't look like it would last through a repair so I chucked it. There are plenty of shutoff valve options available on the Internet or your local hardware store. I've been thinking of adding one on each hose because my son likes to step on the heater while climbing into the back. One of these days I just know it will blow apart on me.

When I tested my cores two years ago the rear flowed fine and didn't seem to have any gunk in it. The front was another story. The first time I had it out I just kept flushing with a hose, one side then the other until it was clean. When I put it all back together, after a heater box rebuild, the heater would get cold at times. I figured it was still blocked. A few weeks ago I used a trick suggested by others, such as Coolerman. I poured a mixture of muriatic acid and water into the heater and let it sit. Then flushed it out and repeated a couple more times. When I ran a hose to it the core flowed like crazy. I couldn't believe the before and after difference. I bought a small container of acid that was only a couple bucks or so. You might give that a try yourself before taking the cores to a shop.

 

[bikersmurf]

My rear heater had what looked like a factory shut off valve in the feed hose when I bought it. The valve was frozen open and didn't look like it would last through a repair so I chucked it. There are plenty of shutoff valve options available on the Internet or your local hardware store. I've been thinking of adding one on each hose because my son likes to step on the heater while climbing into the back. One of these days I just know it will blow apart on me.

When I tested my cores two years ago the rear flowed fine and didn't seem to have any gunk in it. The front was another story. The first time I had it out I just kept flushing with a hose, one side then the other until it was clean. When I put it all back together, after a heater box rebuild, the heater would get cold at times. I figured it was still blocked. A few weeks ago I used a trick suggested by others, such as Coolerman. I poured a mixture of muriatic acid and water into the heater and let it sit. Then flushed it out and repeated a couple more times. When I ran a hose to it the core flowed like crazy. I couldn't believe the before and after difference. I bought a small container of acid that was only a couple bucks or so. You might give that a try yourself before taking the cores to a shop.

As a precaution, add one shutoff to each line. If your heater core fails, turn both off and you're good ot go. The ball valves I used were $5-6 each at the hardware store.

 

[edwards_rljr]

DIY heater core flush/boil out

After reading some other threads on here, and trying the vinegar, I considered trying the muriatic acid myself but I don't have the ability to pressure test them so I would still have to pay someone to do that. When I get done with this, I want to KNOW that I have good cores because I hope I don't have to take them back out for a LONG time. Nothing would make me sicker than to do the muriatic acid method myself and think everything was ok then hook it all back up and then find out there was some tiny pinhole in the core that I didn't notice because I don't have the ability to pressure test it myself.

So, I'm guessing nobody has any experience with the 'Ready-Aire' front core that I found at Advance Auto Parts for $55 ? Seems like a steal if it's any good. Unfortunately, when I called them, I didn't think to ask them where it was made. Maybe I should call them back and find out if it's made in China - LOL

Concerning the shut-off valves... seems like a good idea to me. I was just wondering about the best way to do it and if anyone else had done it. Seems like some good brass ball valves would be good. The big question I have is how to attach them and where. My first thought is to put them where the heater pipes come in through the firewall and T off to the rear. I really think it wouldn't be a bad idea to have shut offs to both cores just in case either one ever leaks... shut that one off and still have the other one to run? Not sure if that's possible though since the blower would still be putting air through there if the front core was shut off and you would be getting cold air blown on you from the front if the core was shut off. I'm also wondering if there's enough space there since the sections of rubber heater hose between the metal pipes are pretty short. The rubber between the metal pipes and heater core nipples is only 2-3 inches so it seems like it would be tough to put a valve between there. Basically, there was very little space between the metal pipe and the core nipples on both of mine. Most of the rubber hose was what was covering the ends of the pipes and nipples... And you have to consider the hose clamps being there... would have to have 2 more clamps on there if I put a valve in there.. I guess I'll look at the hardware store and see what kind of valves I can find.

If nothing else, it seems like it would be good to have them so that if a core started leaking, you could shut it off and keep driving and not be stranded or have to have it towed. I'd be interested in seeing pictures and/or detailed descriptions of what you did.. type of valves.. where you installed them... etc.

Another question about putting shut-off valves in is, does the engines cooling system depend on the return from the heater lines in any way ? I'm not even exactly sure which direction the water flows. I just know that there is the line that T's off from between the 2 lower radiator hoses and goes back to the heater valve. Then the other heater line comes from the back of the head ... so , whichever direction that heater water is flowing, does the engine cooling system depend on this loop in any way or is it just a way for the heater water to be returned and the other coolant from the radiator will continue to circulate without the heater lines in the loop?

 

[edwards_rljr]

I had the local rad shop clean and test both heater cores out of my 69 40. Also had the same rad shop repair numerous aluminum dirtbike radiators. Id find a better shop that can deal with anything you throw at them!

Dont see any reason why you couldnt add a valve for the rear heater if you wanted to.

sounds good in theory.... but I couldn't even find a radiator shop around here... every mechanic I talked to said that nobody works on radiators here anymore.. everybody just installs new ones... it's just like everything else now.. I'm sure they make more money installing a new radiator than fixing one. I ended up talking to one guy that said there was a rad shop in another town about 30 min away.. ended up going over there with the cores.. older guy with a old shop .. probably been doing this stuff for years... will probably get better service from him than any of these fast-food drive through auto service shops that are on every corner anyway.. we'll see what he says about the cores tomorrow.

 

[waiting for time]

When they pressure test it they just put a solid cork in one hole and one with a hole for the compressed air gun in the other. Put 20 to 25 psi on it and hold it under water. if there are bubles it leaks. You can do this very easy yourself. Buy a botlle of wine with a cork, drink it and cut the cork in 2. Cut to size and drill a hole in one of the halves,.....think you can fill in the rest.

for $20 you can get a decent botlle of wine.

 

[numby]

The big question I have is how to attach them and where. My first thought is to put them where the heater pipes come in through the firewall and T off to the rear. I really think it wouldn't be a bad idea to have shut offs to both cores just in case either one ever leaks... shut that one off and still have the other one to run? Not sure if that's possible though since the blower would still be putting air through there if the front core was shut off and you would be getting cold air blown on you from the front if the core was shut off. I'm also wondering if there's enough space there since the sections of rubber heater hose between the metal pipes are pretty short. The rubber between the metal pipes and heater core nipples is only 2-3 inches so it seems like it would be tough to put a valve between there. Basically, there was very little space between the metal pipe and the core nipples on both of mine. Most of the rubber hose was what was covering the ends of the pipes and nipples... And you have to consider the hose clamps being there... would have to have 2 more clamps on there if I put a valve in there.. I guess I'll look at the hardware store and see what kind of valves I can find.

Some years had shorter brass lines form the firewall to the rear heater. The ones I've seen (got a set around here somewhere) have about a foot of hose for the last bit to & from the rear heater. While not super accessible due to the location under your seats and console it's a better option for locating the shut-offs than at the firewall. Maybe somebody here knows which years had the shorter hard lines.

 

[srgould41]

I put a cable operated valve in the engine compartment on the feed side of the hose. That way I can adjust the temp or shut off the normal operation completely. Doesn't help for leaks, though.

What I might do, just as an idea to others, is buy three more manual valves. One would go into the return line in the engnine compartment. This will shut off everything. Then two manual valves in the hoses to and from the rear heater core. This won't allow the rear heater to be used if the front goes bad, but then the rear core doesn't put out all that much heat anyway. I am mostly worried about the rear because the hoses are so long and run along the floor. I can see them easily being cut or holed.

 

[edwards_rljr]

heater pipes

Some years had shorter brass lines form the firewall to the rear heater. The ones I've seen (got a set around here somewhere) have about a foot of hose for the last bit to & from the rear heater. While not super accessible due to the location under your seats and console it's a better option for locating the shut-offs than at the firewall. Maybe somebody here knows which years had the shorter hard lines.

oh, ok, didn't know that... that would certainly make it easier to install shut-off valves... mine is a 06/1978 and the pipes practically meet the core nipples.. there might have been about a 1/2 inch of space between there when I was trying to figure out where to CAREFULLY cut the hoses without scarring up the pipes.. the hoses did not want to simply slide off the pipes or nipples of course and I didn't want to bend anything trying to manhandle it... nobody else has offered up any pictures or anything of valves so far... we'll see if I can figure out how to put some shut-off's on there I guess... I'd like to have them just in case.