CJ-5 Heater Fan Upgrade Questions

As far as I know the 72 and 73 motors are the same. If in doubt, figure I made a typo...

The NAPA part number 'might' be 455-1039 or 655-1039, but the person who posted these never came back to confirm the numbers. I got mine at Canadian Tire and got the right one first try.

The gasket is cut out of a chunk of 1/2" or maybe 5/8" foam. I have been careful on the 3 I have done and managed to reuse the old gaskets just fine.

I am not sure this is possible to do with the dash in place, even on the larger CJ7. Maybe if you take the seats out.....

For 'sure' nothing can be removed from the firewall side except the nuts holding the heater box in place and the hoses. The one nut dead center of the valve cover is an SOB!

Will it be obvious to my mechanic if the heater core

Not unless it is totally rotted. The cores aren't visible through the tubes I don't think.

If this is such a hard job, wouldn't

Yup. Costs less than a hundred.

Remember, this is a 1980 Jeep, but the core is

I use a garden hose and flush mine. It offers no restriction.

I have done the cutting from the inside so haven't needed to remove the tray.

Whatever one you can use the best! I have used the first and last. Although how to get a scroll saw in there?

I have a dremil tool with fiberglass reinforced cutting wheels that work well on that hole.

I know that a hole-saw will cut

Unless you have a right angle drill, it won't fit in there.

Good Luck.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 (More Off Road album links at bottom of the view page)

Thank you very much Mike !!

I will look for any other comments.

--james--

Take your old motor with you. The critical match is the shaft length, and the differnce will be obvious. The problem seems to be that someplace along the line -- probably from GM itself -- there was confusion about which motor was associated with which part number. Some suppliers will pull up the right part, some the other one (AutoZone, for one, will pull the wrong one using the web site's info). Considering the millions of parts available, one screwup isn't so bad.

Take your old one with you.

I managed to stretch my old gasket to fit, but it was tight. Go slowly, carefully.

You can't get the blower motor out with the heater box in place. You can't get the heater box out with the dash in place, but you don't have to pull the dash all the way off, either.

The heater core is kept in place by a metal panel held down by about a dozen coarse-thread screws on the forward face of the heater box. There is no way to remove it through the firewall.

Removing/replacing the heater box is such a pain in the arse. I recommend simply replacing the core now, while you have the damned thing apart rather than waiting until it leaks -- and it will.

Quadratec retails a new core for about 50 bucks.

Salvage your control cables, if you can. The replacement ones look better made than they are. I've broken two in as many years. Beware that the short cable that links (I think) the vent door with the cowl door is not in production.

You'll probably be happiest if you pull the tray and the right fender, but that's just me. Be aware that bolts will break when you try to get them off.

I don't see why the hole saw would only work from the dash side, but it does require building a jig. I did mine the hard way: Scribed a circle and used a die grinder for the rough and a file for the fine. Be prepared for a lot of trial fitting and revision. When you do the trial fit, leave out the heater core to reduce danage to the pipes.

It is well worth the effort.

-- "I defer to your plainly more vivid memories of topless women with whips....r" R. H. Draney recalls AFU in the Good Old Days.

James, I'm not sure if your still looking for advice on this mod. I just recently moded my blower motor. It's a fairly cheap upgrade but a pain in the ass to complete.

I bought the upgraded motor from Schucks, part # 35587 (that's the correct GM upgrade) I paid $30 for the motor, new.

You do not need to remove the dash or seats to get the heater housing out. I did it at 45 years old. However, you need be able to contort your body a little.

Getting it out is the easy part. 4 nuts and it's out.

Once out, unscrew the numerous screws on the back of the heater housing and you get to all of the innards of the heater hosing.

Absolutely replace the heater core (Schucks part # 399210 for $40.).

Replace your old blower motor and heater core.

Now the hard part. Lining up the flapper ducts and the heater housing and buttoning it up. That took a little finesse and time.

Now the really hard part...expand the hole to fit the new blower motor.

Read this and you will have complete success making the hole larger and it will look like a professional install;

I had to buy a 3 1/4" hole saw at Home depot for $20

Do not make the same mistake I made: I measured perfectly, and I made a perfect hole. However, I couldn't get the friggin heater assembly to fit back in. So, I absolutely hacked my beautiful hole into a jagged octagon using a dremmel tool (it looks like shit) but the assembly more easily fit back in.

As I look back on this I realized, I just needed to finesse the heater assembly to line up with the holes. Have patience (unlike me) and give it a good push and it will fit in nicely

Total Cost for the project, including the hole saw: $90 Total time...about 6 hours as I couldn't get it to fit back in. Have two or three friends help you line up the holes.

Just an FYI.

If you have the dash off, the cussing time will be cut in half at least 'And' the heater motor will fit straight through the nice new round hole... let alone how easy it is to hook up all ducts...

I think it is worth the 'extra' time to pull the dash.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail > James,

Mike, not having the dash off wasn't the problem (I agree it would be easier if it was off). My problem was the hard plastic duct that runs from the air intake on the hood down to the heater assumbly. It was this duct that caused my problems. You are correct though, it's easier to see what's going on with the dash off.

If this is a bigger motor too you need to consider changing the resitor strip that gives you speeds because the stock one may fail in time under the heavier current draw from a bigger motor.

----------------- TheSnoMan.com

I just clicked on something.... You have the backfire issue in the other group right?

The orange wire from the choke sometimes hits the exhaust manifold near the back which will cause that. The Ford coil connectors are pretty crappy and either could have been moved or dinged when you were in there trying to bolt the heater back on. Even a plug wire.

I also have posted a meter walk through for you to test your connections so you don't have to tear everything open on your alternator harness.

Mike

Anth> Mike,

The are both stock GM items. AMC used a GM heater setup with the same resistor pack which is why the larger motor fits right in and to the blower cage also.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 (More Off Road album links at bottom of the view page)

Thats cool, I just thought I would mention it.

----------------- TheSnoMan.com

Thanks Mike. Yes, I do have a back-fire problem. I forgot to add that my CJ-7 has a Chevy 350 w/ Edelbrock 600 cfm carb (Manual Choke), and an MSD ignition.

I either have a timing/timing chain issue or I may have inadvertently caused the problem. I have a leak on my Brake Booster, so I disconnected it and sealed off the vacuum. The other day I took the Jeep on the highway and (So I would have more responsive Brakes) I reconnected the leaky booster. After about 10 miles down the hi-way...BOOM...it backfired and the entire Jeep shook. So I pulled it over and it died. I did re-start the engine and after about 30 seconds...BOOM. So I shut it off and had it towed to a garage. Again, I'm not sure if the leaky booster caused a problem w/ Vacuum e.g vacuum advance/lean condition..or, my worst fear is the timing chain broke/slipped.

Where did you post the Meter walkthrough?

Thanks Mike and SnoMan

The resisters blow off power as heat and just act like a basic voltage regulator to slow down the motor.

The motor only has one set of wiring in it so it needs different volts for different speeds.

Mike

Anth> What's up with the resistor strip? Why do we need it? I thought the

The blower switch just routes current through different portions of the resister for different fan speeds. It's the resister that actually does the work of varying voltage to the motor.

True and the voltage and current dropped across them is converted to heat and airflow in duct keeps them for toasting most of the time.

----------------- TheSnoMan.com

Are we talking thru carb or exhuast on this backfire problem because this narrows down possible causes.

----------------- TheSnoMan.com

SnoMan, I'll be honest, I wasn't paying too much attention as my Son was in the back seat and I just wanted to get off the hi-way after I heard the Bang (I didn't want to be stuck in the middle of a four lane with a child in the back seat) I thing it was thru the carb, but not absolutely sure.

When it is through the carb it is usually (not always) from a leaning out conditon. When mixture gets too lean it does not fire properly and the mixuture is dumped into exhaust manifold where it starts to ignite and then the flame travel back into cylinder and into intake during valve overlap. You may have a weak pump or plugged filter that is causing it to lean out under high demand periods. I sticking or burnt valve can cause this to but if it is a burnt valve it would be consistant. I have also seen a worn cam lobe cause this but it too was also consistant and predictable.

----------------- TheSnoMan.com

Bad news !!!!! The shop did a block check ($75) and there is exhaust getting into the cooling system. Not much, he's getting a hydrocarbon reading in my radiator/coolant. Mechanic says it's probably not the head gasket, but rather, a cracked head. That's gonna hurt.