This swap has been written up in several Jeep-related sites on the net, but I though I'd add my own experience with it to the collection. Basically, the heater motor in '87-90 YJs and '78-86 CJs can, with a little effort, be replaced with a considerably more powerful motor from an early 70's Chevy Blazer. Here's something another fan (heh heh) of this swap once said:
"Michael L. Courtenay" <mlc@midcoast.com> writes:
On 11/11/99 6:00 AM, David Curbow at bnsf69@hotmail.com wrote:
> A friend of mine has
a heater in his 75 CJ-5 that puts out allot of heat and
> the heater in my 78
CJ-5 seem weak. Could there be some reason why I freeze
> my a** of in my Jeep
and sweat up a storm in my friends? Are some heaters
> known to be week?
Is it the blower? Are there after market heaters that put
> out more heat. Any
help would be nice.
I bet he just has a good
core and a clean heater box (no leaves, mouses'
nests, etc.) Here
is how to beat him:
Do the Blazer heater
motor swap previously mentioned. It's a PITA, but only
costs $20 in parts and
is ABSOLUTELY AMAZING.
With this swap, I can
practically get burnt by the air coming out of the
box. I can defrost
the windshield in December with no top on, and keep all
the glass clear with
the hardtop on. It is absolutely amazing.
One time, in the summer,
the electric fan under the hood quit with no
mechanical backup (mud/bearings).
With this swap I was able to turn the
heater on full blast
and get the Jeep out of the woods without having the
temp gauge go through
the red, using practically just the heater core to
cool the motor.
True story. I have since become an evangelist for the
Church of the Blazer
Heater Motor. Glory be!
- ------------------------------------------------------------------------
Michael Courtenay
1979 Jeep CJ-5
Warren, Maine
USA
1976 Jeep CJ-5 (wife's)
mailto:mlc@midcoast.com
1948 Jeep CJ-2A (project)
Vice President, Overland
Jeepers of Maine 1987 Jeep Grand Wagoneer
- --------------------
http://www.midcoast.com/~jeeps
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Without getting into needless detail, the only "modification" required for this swap was to enlarge the heater motor hole in my YJ's firewall by 1/8"-1/4" all around, to a new diameter of 3-1/4". I used a die grinder, but a hole saw would have been a little cleaner. Of course, before I could do this I had to drain the rad, unhook the heater core hoses, unbolt the heater box assembly, unhook the flapper cables, and unplug the electrical connectors. A new '73 Blazer heater motor cost me about $30 CDN ($22 US) at the local Lordco, and it bolted right into the heater box. There was a vent hole in the side of the motor housing that I plugged with a plastic cap (included with the motor). The squirrel cage blower from the YJ's motor bolts right on to the new motor's shaft.
With the new motor installed in the heater box, I reinstalled the box, and plugged the motor wire and resistor wires back in (the motor wire terminal is the one in the engine bay, and the resistor cable is the 3-wire one that plugs onto the box in the passenger side footwell). I did this upgrade when I had the fenders and engine removed, so I had plenty of access. It's still a very doable mod even if you don't have your engine out, though...
Now that winter's here, am I ever glad I did this swap! The new motor kicks out plenty of heat, and the three speed ranges all work like they used to, and the top (hurricane-speed) setting is enough to defrost even the most frozen of feet!
Questions? Email me!