BMW Blog

Bear with me as I'm a newbie. When I turn in the heat in my CJ5 ( 1st Jeep just bought 3 weeks ago ), I smell what I believe is coolant and smoke of some sort starts coming out of the heater assembly. I think it is the heater core, but need to be sure. How can I know for sure that is the problem?
You may have a leak, but you should be able to see coolant in either the floor board or on the firewall if it was leaking. You have coolant running through the core at all times so you should be seeing the leak at all times as well (i don't think the 5's have a valve that cuts the coolant off to the core) You may just be noticing it when the heat is on since the fan is pushing the odor into the rest of the Jeep. May want to look around under the dash and see if you see any leaks.
I see evidence of what looks like a previous leak, but nothing is wet that I can see. What about the smoke???
Thanks for your response,
Bob
Bob,
If you do have a leak, you should notice your coolant level slowing dropping, you should also have a small drain on the passenger side in the engine compartment underneath where the motor comes through (beneath the battery), I wish I had a picture of it for you. :brickwall Like bdmonist said, there is no valve between the engine and the heater core.
It could be what your seeing is steam, not smoke especially if the engine is warmed up. I just replaced my motor due to the old one freezing up. All that happened to mine was the plug on the back of the switch got hot enough to melt the plastic plug over a long time, but no smoke, although it could have been much worse. :rolleyes: Does that fan sound ok when running? If you have a voltmeter in your dash, does the voltage drop significantly when you turn in on? Just a couple things to check.

Rigor
The one I have now actually leaks on the engine bay side of the firewall where the tubes for the heater core come through the wall. So check there also.
http://i100.photobucket.com/albums/m1/bdmonist/Jeep%20Rebuild/HeaterCore.jpg
Will look into these tips. Thanks to all for your replies.
Bob,

I would surmise you have a leak somewhere, once you recognize the smell of antifreeze you will never forget it. There has been some great feedback here regarding your situation, there must be a leak in your system from what you have described.

Good Luck..........
I just got done replacing mine in my 78 CJ. The new core was only about 35.00. I had to take the dash partially off to pull the box forward far enough to come out but it was far less trouble than any other car I have done. The only problem was the foam on each of the vent doors was about gone. It took awhile to find a replacment but I found some at a craft store and glued it in place. I put in new cables and lubed up all of the pivot points. Just make sure you get everything put back exactly the way you found it. I put a spacer on one of the pivot doors on the wrong side and when I got the whole box put back in the door was stuck. I had to take it all apart and re-install it. While you're at it, go to a local auto parts store and buy a manual valve to shut off the water flow to the heater core. They are about 6 bucks and work well. Open the valve at the start of the winter and leave it off all summer. If you live in a mild climate you can just shut it off and replace your core when you get time. Here in Arizona it gets pretty hot in the summer so I take any step I can to keep the heat out of the drivers compartment. Have fun.
Bob, If you're in Richmond, Va, we have lots of clubs around with plenty of people with CJ experience. Check out http://www.va4wda.org/ for area clubs. I'm in Capital City. The best way to learn on a CJ is to dig in, take it apart and see what you find. People on these forums can get you through whatever you find and back together.
John N.. I am in Richmond , VA.. I'll try to be at the next meeting of Capital City. Looking forward to "digging in". :2thumbsup:
If the heater in question is in the 74 CJ5 that you've listed in your profile, the fan motor should be inside the tub.
http://i147.photobucket.com/albums/r320/HackFabrication/WiringHole005.jpg

Jeep used this style heater from 72-77. The 'drain' is a small hose located under the battery box. You probably have a bad heater core. Now the fun, digging it out of there without breaking the 30+ year old plastic heater box.
John N.. I am in Richmond , VA.. I'll try to be at the next meeting of Capital City. Looking forward to "digging in". :2thumbsup:

Good, we have a fair number of CJ's in the club.
It is on the inside. Looks exactly like the one in the picture. Is the hose to the left of the colored wires ( in the pic that turns up in front of the assembly and connects to the "funnel" that the flex duct runs to ) supposed to appear crimped like that? Mine is the same way & I assumed that it was collapsed and needed to be replaced. My fan works fine ( at least I hear it running ), but I get no obvious air flow from either the heat or defrost. I'm going to replace the cables along with the core. The knobs are stripped off and don't operate the cables ( pliers are required ).
Hack,
What is so different between a '74 - vs - a '76? In looking for parts, there seems to be a cut off at 1975. There seems to be anything you need for '76 on up, but a much smaller parts pool for the "Intermediate Years" ( '72 - '75 )
I searched for a pic of the drain, but I don't have one. It's under where the two heater hoses connect, IIRC. The three form a 'triangle' of sorts. It's just a small hose fitting, like 1/2". Again, I can't recall exactly.

This particular heater was used from 72-77. There isn't an abundance of parts in the aftermarket for these heaters. There is little, if any commonality with the 78-86 versions. The cables are different, although one of the later models will 'work', and another can be 'Hack Fab'd' to work. The biggie is the temp cable that is longer than the 78-86 versions.

The fan motor is 2sp versus 3sp on the later models. I converted mine to a 3sp motor when I rebuild the heater box. The squirrel cage is available when you need a new one. (you'll probably break it when you try to remove it from the motor).

The cowl grill is a different size than the later versions. The defrost duct is a cheapo cardboard thing that is usually rotting. A plastic version is available in the aftermarket.
Thanks for that picture Hack. I didn't realize their was that much different in those years, but its obviously enough to say "totally" different. You learn somethin' new every day!
Here's a pic of how the defrost hose is routed:
http://i147.photobucket.com/albums/r320/HackFabrication/JeepDefroster006.jpg

You can also see the drain that's attached to the fresh air plenum. Another part that ya can't get.

And one of the fresh air plenum (out of the Jeep):
http://i147.photobucket.com/albums/r320/HackFabrication/HeaterControls002.jpg

The fresh air cable is the only one with the 'grommet' on it. The defrost and temp cables mount with a 'clamp':
http://i147.photobucket.com/albums/r320/HackFabrication/ECMPlacement002.jpg

Disregard the spring in the above pic, it's used to hold the flap closed now.
Hack, I swapped the unit out today. The core had leaked some, but I think the real culprit was the mouse nest that completely filled up the plenum ( where the heater core actually resides ). Also, the duct from the cowl was stuffed full of leaves/ mud? so it is no wonder there was no air flow. It was actually easy getting the whole assembly out ( once the battery / platform was out ). There was of course the one nut ( center of the firewall behind the vacuum advance? ) that was a bear. I noticed you have new flex hoses on your unit. Are they readily available? Mine were crumbling to the touch and need to be replaced. Thanks for the feedback, I pulled the dash out of the way like one of the posts said. It made it much easier than it would have been had I not done that. I got the heater core from Advance Auto Parts. The screw holes in the core that lock it in place were too small and one didn't line up so I used a couple of 3/4" self-tapping screws in lieu of the originals and all was good.
Same with mine on the holes. I just took some self tapping screws to it as well.
to bad for me my heat is fixed and it is getting really warm out over here.