Rear Heater Fan Rebuild

[BRShap]

Since buying my FJ40 with my brother (@dshap) a few weeks ago, we've begun to work on the few small problems. One of the problems was that the rear heater fan wasn't spinning. The rear heater core would get hot and the inflow and outflow pipes would get hot, so it seemed to be that the only thing wrong with the heater was the fan. Today we pulled out the fan and photographed the work done.

First we removed the center console and the two bolts that hold the rear heater to the tub.

Next we removed the black metal housing that holds the inflow and outflow hoses next to each other.

Then we had to figure out how to remove the whole heater assembly from the truck. The pipes attached to the heater core are short, and connected by rubber hoses to the inflow and outflow hard lines. There are hose clamps at both the heater and hard line ends of the rubber hose, so four clamps in total. They all needed to come off.

We had to cut off the rubber hoses that connect the heater core to the hard lines. They have probably been there for 20+ years and couldn't be wiggled out without risking damage to the heater core.

3 screws attached the fan to the base plate. Based on the rust and peeling paint I assume there was a leak at some point. We flushed out the core with water and diluted vinegar until it ran through clear. Not too much debris came out, mostly murky water during the first few flushes. The core appears to be in good shape.

Next we pulled apart the motor. First remove the fan set screw and pop off the fan. Then remove the two screws on top of the motor housing. The outside of the motor was rusty and dirty but inside was mostly clean.

 

[BRShap]

Next we cleaned the brushes, shaft, and commutater with some 600 grit sandpaper.

(Before photo)

(After)
The housing had rust and dirt in it so I cleaned that out as well with some dish soap and a toothbrush.
Its not perfect but he magnets and bushing are clean.

 

[BRShap]

Finally we oiled the top and bottom felts, bushing, and shaft with 3in1 oil.

We buttoned it all back up and.....

Sucess! The fan works again!

 

[BRShap]

So now some questions.

The motor works but you need to give the fan a flick with your finger to get it started. When turning it by hand its not all that smooth and feels like theres more friction than there ought to be. Ive never played with another fan so I'm not sure how its supposed to feel.

Is 3in1 a good oil for this application or is it too thin?

If anyone has any suggestions please post them up. I would love to get this thing working perfectly.

 

[Helipilot]

Good write up on your rebuild. I did the same thing to mine and used white lithium grease (use sparingly but get a good lube established) instead of 3-in-one oil which will be too thin for long term use since it will evaporate over time and become "gummy". There is probably some binding somewhere in your rebuild. Check for any grit in the assembly and proper alignment of the shaft in the housing. I am sure you will get it figured out since you did a good job so far.

 

[BRShap]

Just to update this thread incase it helps anyone in the future: White lithium grease worked like a charm. We disassembled, cleaned and regreased. The fan starts right up with no flick required and runs stronger than before. Thanks for the tip @Helipilot

 

[Helipilot]

You're welcome bud. This is a great forum for info and tips and I need a bunch of those.

 

[Captn Conch]

Just an FYI, It looks like your felts are missing around the top and bottom bearings..grease may not be the best lube for this application, the felts are supposed to be a reservoir for holding the oil and they soak up quite a bit, Coolerman used 30w which I did on my rear heater motor, but I'm going with a synthetic 5w30 maybe 40 on my front motor, should last forever. The 30w is probably ok but thick with sub cold temps..OK after the heater is running and all is hot. Somebody used pool table felt as theirs were missing or cooked off and they said that worked good to absorb and hold the oil.

 

[sggoat]

Next we cleaned the brushes, shaft, and commutater with some 600 grit sandpaper.
View attachment 1196541
(Before photo)
View attachment 1196544
(After)
The housing had rust and dirt in it so I cleaned that out as well with some dish soap and a toothbrush.
Its not perfect but he magnets and bushing are clean.
View attachment 1196542
View attachment 1196543

You still have gunk in the commutator slots--need to get that out or the brushes will arc--motor will eventually fail.

 

[Jetlander]

I had the same issue when I rebuilt mine. Get your cordless drill out and clamp it onto the fan shaft, and spin/drill away! It took about 5 minutes of lubing and spinning, but it freed it up nicely.

 

[adavis]

I realize this thread is very old but because its the best tech thread I could find regarding the rear heater motor I figured I'd ask this question here.

I'm very fortunate in that the rear heater in my 1973 FJ40 is as close to mint as a used heater can get, however the fan doesn't work. I decided to figure out why last night and when I pulled the motor out to inspect I was amazed at how it literally looks brand new but I could immediately tell that the problem is that the oil has completely dried up and the motor is difficult to turn. I carefully started to disassemble the motor and ran into a problem.....I can't get the rotor out of the stator housing. My question is, do I just use a small punch to tap the rotor shaft out of the stator housing or am I missing something? I just don't want to mess up this beautiful little motor by doing something incorrectly....

 

[B y r o n]

Were you able to get it to spin at all? If not the frozen shaft is what is keeping it from coming apart. Use some penetrating oil and get things to spin and then it should come apart without the need to beat on anything.

 

[adavis]

It does turn but doesn't "spin". It turns smoothly but is stiff. I pulled the fan and end plate off so I just have the rotor shaft to pull out, but its not coming. I used some penetrating oil (FreeAll) and it didn't do the trick. I figure I can just use a small punch and lightly tap on the exposed end of the shaft to drive it out but figured I should ask on here before I break something.

 

[Fast Eddy]

If it spins, it sounds like you're just not pulling hard enough. It's held in there by the force of the permanent magnets.

I'm assuming you already have the end bell, magnet assembly off. Pics would help.

 

[adavis]

I will definitely get pictures posted tonight or in the morning. I'm probably way over-thinking this. Thanks.

 

[adavis]

I got it apart last night by using a small punch to gently tap on the end of the shaft. When I got the shaft out I discovered the issue. There are little "fingers" that hold the felt disk in place as well as the "ball" on the end of the shaft. Lightly tapping the shaft pushed it through those fingers and allowed the shaft to slide out of housing.

I soaked both felts with 10w-30 oil and added a small amount of lithium grease to the "ball" before installing. The motor still has more resistance than I would've expected when turning by hand but it will spin freely for a quarter turn now. I hooked back up the power and it works great in both high and low speeds.

Thanks for the information and advice. Now onto the next item on the checklist.

 

[Jadavm]

Reviving this old sub for more technical support. I am trying to refurbish my rear heater as well, and followed everyone's steps, but I am unable to get the motor to spin still. I ran test plugs to the fan directly from the battery, but it will not spin. I ran the the fan with a multi meter for a continuity test which shows 4.1 to 5.6 ohms. I also tried bench testing and I am getting nothing.

Unfortunately, in I snapped the brown cardboard? which holds the brushes, but super glued it back together (let me know if this is a no-no)

Seeing as this isn't the most common or aftermarket supported part, I am curious if folks have creative ideas on how to work around this thing...

I can post pictures as well, but it looks exactly like everyone, with exception to the broken part that holds the brushes.

 

[cruiserkev]

Mine was seized up a long time ago. I tried to repair it but had the same results as you, no spin. A local rebuilder of starters and alternators saved me. They rewound the core, installed new brushes and cleaned everything. Still working great years later. Good luck!