521 Heater

[DanielC]

I have been working on some heater boxes for my 521 trucks.   I am just starting this post, I have around 50 pictures, and probably need to take some more.

I cleaned and painted two heater boxes, and a plate that goes over the hole in the cab above the transmission in January 2020.

 

You will need to clean paint and primer out of the threaded holes to reassemble the heater.  A good way to do this is the chase the threaded holes with a tap.  I found this tap and drill set at a hobby shop.

I have used all five of the tap sizes in the set, and as a bonus, you get the drills that are the right size for the taps.  It is hard to get the proper size drills for the taps.   The drills are not a normal fractional size.

 

I cleaned the squirrel wheel fan, using a mixture of a few drops of Dawn dishwashing detergent in a spray bottle of water.

 

I used these brushes and tools to clean the fan.  The squirrel wheel fan is 50 year old plastic.  be gentle with the fan.  I scraped dirt off the motor with the knife.  Do not scrape on the fan.  I sprayed the Dawn and water on the fan, gently used the tooth brush and the paint brush to remove grime.  I wrapped a paper towel around the wood stick to wipe each blade of the fan, both sides.

 

Before cleaning.

 

I also gently used the rounded point of an old test light to remove crud from the root of the fan blades.

 

This is after cleaning. 

 

The fan motor has three thick rubber grommets to hold it in the heater box.   Most of the rubber grommets are deteriorated, hard, or just fall apart when you touch them.

I found new rubber grommets, and 1/2 inch rubber washers with a 1/4 hole at Ace Hardware store.

 

In this picture, a new grommet is put in the mounting hole of the fan motor.  The new grommet is not as thick as the old rubber grommet was, so I put a rubber flat washer on each side of the grommet.  in the picture, from right to left is the #10-32 screw, a thin metal washer, a rubber flat washer, a brass bushing, and on the left side of the fan mounting hole with a grommet, another flat rubber washer.

 

I put all three new grommets in the fan motor mounting holes,

 

then I put the brass bushing in the grommets.  I pushed the bushing toward this side of the fan motor, so they stick out on this side.  See upper right corner in this picture.  Then I put one rubber flat washer on each brass bushing.

 

To seal the back side of the fan motor,  put some foam weather strip tape in the heater box.

 

The fan and motor can now go in the heater box.  Put the motor wires through the hole in the top of the heater box,

 

Then you can carefully put the screws in.  This is actually the third screw I put in, it is the most difficult because it goes in the narrowest place.  By putting the other two screws in loosly, it alighns the hole in the fan motor with the heater box hole.

 

Now I am tightening the fan screws.

 

This is what the fan screws look like when tightened.

 

with the fan and motor in the box, I tested the fan motor with a 12 volt battery.

Another picture test, with flash off the camera.  The fan was spinning in both pictures, but with the flash off, the exposure of the picture was longer, so the fan is blurred.

There is a more coming on this post, but I now I am tired.

 

 

 

 

Edited May 15, 2020 by DanielC

[Greaser2]

Daniel, do you have any extra heater cores that are good?

[DanielC]

I do not know if I have any good heater cores, except for the two that are in Dragon, and Ratsun.  I have two painted and assembled heater boxes, I need to finish this thread, but the only way I can test the heater cores in the assembled heaters is to replace the heater on either of the two trucks.

[Draker]

I have one from a 520 if interested I’ll pull it and test it.

[Greaser2]

Sure, I bet the core is the same.