Blazer Motor Upgrade

[Stodg73]

No, you do not have to pull the dash. There are 5 nuts in the engine bay and the heater hoses. Then you need to take the heater control cables off and the pull the whole heater box out.

The next step, is opening up the blower motor opening in the firewall.

Since you have the heater box out, you can refurbish it and possibly replace the heater core.

Then put it all back in.

 

[gr8dain]

Do you have to pull the dash for this upgrade?

You don't have to. I did not. But I did remove the glove box to give me some extra room to work. Removing the dash would provide more room, but I did alright with it in place. And as I have seen in other write-ups, even if you do take the sash off, you can leave stuff connected and just move the panel out of your way.

 

[tinhorn]

Wait a sec--what years does this fit? My blower looks different than yours.

Hey, would someone kindly measure the diameter of the blower motor that goes through the firewall? If it's the same size as mine, I'll risk the twenty bucks to experiment with upgrading mine. And I'll publish the results for posterity.

 

[gr8dain]

I just ran out and measured mine. It seemed like 4". I was measuring the part sticking into the engine bay. The part that went through the firewall. Hope that helps.

 

[Flex BT]

If yours is stock you'll need to drill the bigger hole in your firewall. The hole saw I used is 3 1/2 inches and the new heater motor barely fit through there. It sounds really scary but it was a quick job and that blazer motor frickin' gets it.

Edit:

Just saw you had a CJ5 , I think the upgrade wouldn't be exactly the same. If you look at Turbogus' pics last page it shows the electrical wire that also sticks through the firewall on the CJ7 , I think you'd need to drill that as well and run the wire. Make sure you get the big bushing that goes around the motor and the electrical connection as well. Someone with a 5 can probably give you more accurate info.

As a side question... after doing the blazer upgrade my fan motor doesn't do anything in the first of the 3 positions with my fan switch. The second position is like a low (that blows like a leaf blower) and the third is high (which makes the hot air feel less hot because it is blowing like a freaking hurricane). Is that normal or am I having a problem with my switch or motor?

 

[frhrwa]

If you have not done the blower motor upgrade, DO IT!

I found that out after I did it, the old motor was putting out the same amount of heat as the new one puts out on low.

Here are several part numbers for the motor:
NAPA 655-1039
Advanced Auto/Orielly's 35587
Siemens PM 102
Autozone PM 102


Just thought I would share these & this.

your lucky to even get that much air from the old one.. I changed mine also, and WOW what a difference, why I didn't do this back in '75 and on my '78.. living in Colorado, sure could have used some defrost ...

 

[frhrwa]

Hey, would someone kindly measure the diameter of the blower motor that goes through the firewall? If it's the same size as mine, I'll risk the twenty bucks to experiment with upgrading mine. And I'll publish the results for posterity.

its not the same size hole in the firewall, but worth every minute that it takes to make it fit!!! YOU will NOT be sorry!!!! the hole is approx 3 1/2", I put a strap across the center of the existing hole on the firewall engine side.. with a center guide hole in it.. then using a hole saw from the inside of the jeep, just took it slow and sawed a new larger hole.. and believe me, one of the BEST things I ever did to a jeep!!!

 

[tinhorn]

Heck, my motor is under the dash. I don't have to worry about enlarging a firewall hole at all. Just hoping the Blazer motor (said to be the same as a Wrangler, I believe) will swap into my oddball heater box.

 

[frhrwa]

Does this mod retain the original squirrel cage? The blowers I see at AutoZone and Advanced don't include fans although they're available separately.

uses the same squirrel cage.. no problem

 

[gr8dain]

Yep. As long as the squirrel cage can attach to the shaft of the motor you should be good.

I have been getting a good amount of airflow. But I have noticed this winter (first since the upgrade) that I get cold air if I am idling at a light for a few minutes. Then I rev it and hot starts again. It is like the coolant is not flowing when idling. Never noticed it before, but that is probably because I never noticed the heat before.

Is this normal or do I possibly have a water pump problem?

 

[72rtchallenger]

Yep. As long as the squirrel cage can attach to the shaft of the motor you should be good.

I have been getting a good amount of airflow. But I have noticed this winter (first since the upgrade) that I get cold air if I am idling at a light for a few minutes. Then I rev it and hot starts again. It is like the coolant is not flowing when idling. Never noticed it before, but that is probably because I never noticed the heat before.

Is this normal or do I possibly have a water pump problem?

I would at least flush the system , when you did your upgrade did you put in a new heater core ? but I dont think the heat should just drop off to cold at idle , have you got a good hot thermostat ?

 

[gr8dain]

I may flush it. Thanks. I did replace the core and the thermostat is new as of my engine transplant in July. Engine temp runs a steady 195 ish.

 

[IOPort51]

I would say this is very possible as this is a "passive" circulation situation. the water flows all the time but it is not forced. the increase in air flow would remove available heat from the heater coil faster and may even be capable of causing enough air flow to cause "cold air".

When this happens what fan speed are you using? You may need to try low rather than high??

 

[gr8dain]

I was probably on med or hi for sure. I will see if it is happening on low, but my guess it is.

 

[frhrwa]

check also the heater hoses going into the back of the heater core.. if they are backwards, you'll get an airbubble in your core and heat will be very sporadic..

 

[gr8dain]

I as thinking about an air bubble and was thinking about burping the system just in case.

 

[frhrwa]

I as thinking about an air bubble and was thinking about burping the system just in case.

if there is an air bubble, I'd bet the heater hoses are reversed.. check the flow and make sure you have them correct..

 

[gr8dain]

I will check it out. Thanks. Although I am pretty sure I got them on correctly, but with me, you never know.

 

[Flex BT]

Which is the send and which is the return on the core?

 

[Turbogus]

With regard to the heater core, so many of the Brass/Copper ones of old are being supplanted by the made in China aluminum ones, while the frame of these are the same size I've seen that the core itself is 1/2 the size of the conventional brass/copper. It has been remarked that these off little or no heat in other forums. Having to replace the heater core in "Easy Bake"

my '78 Ford panel van, my regular "go to" guys at NAPA only had the aluminum ones (China) available. Tried O'Reileys and while they didn't have it on hand they got both the HD (longer) and conventional core in 6 hours!
I think I'm gonna switch me "go to" auto parts guys.