Fan Belt Issue

MBI Houston

MBI Houston

Senior Member
I am trying to put on a new fan belt but having a problem. I can't get the belt to fit under the engine pulley. It will go into the grove half way around the pulley but will not fit into the pulley groove. It seems like there is not enough clearance between the pulley and the cross member under it.

The reason for changing the belt is that the old one was getting chewed up by something. Could there be something obstructing the clearance under the pulley which is making it difficult to get the new belt on and chewing up the old belt? Any ideas? Or is it normal to have trouble getting the belt on the engine pulley?

Thanks for your help.

Marshall
 
On occasion, I have had to jack the engine up slightly to get the belt on the pulley. Just put a block of 2x4 on your jack toward the front of the oil pan and raise it up slightly. Usually 1/4 to 1/2 inch is all that it takes.
 
I usually remove my generator pulley bolt & generator pulley, then place the belt in the generator pulley groove & finally re-install the pulley with the size belts offered by Model A vendors.
 
CarlG said:
On occasion, I have had to jack the engine up slightly to get the belt on the pulley. Just put a block of 2x4 on your jack toward the front of the oil pan and raise it up slightly. Usually 1/4 to 1/2 inch is all that it takes.
Click to expand...

Same here
 
There should be enough room to get a fan belt in there. The engine should slope upward toward the front by about 3 degrees. (If it's right, the intake manifold carb mounting flange will be level). Could be your front engine mount springs might be collapsed or sagging, or the yoke is drawn down too far into the cross member from the nut below. Loosen the rear mount bolt on the frame (not the big ones from the mount to the engine, but the smaller ones that attach the mounts to the frame). Then loosen the nut under the cross member that holds the front yoke mount, and see if the engine rises up toward the front.
 
Engine pulley clearance is a seperate issue, but I always install the belt on the engine pulley first, then over the fan, and always make the generator the last because it has the least amount of belt wrap.
 
I have experienced this same problem. There was not enough clearance between the pulley and the forged type front motor mount (not the cross member or auxiliary spring). It was necessary to twist the belt when installing it on the pulley and then force it past the motor mount. The stamped type front motor mount provides more clearance. It would help to remove the mount to front timing cover bolts and then jack the engine up slightly.
 
With the belt off, ck under the pulley to see if anything stuck there that might have chewed your old belt up??
Paul in CT
 
If any pulley has rust in the groove, that will chew up a belt very quickly. I found that out the hard way when I only got 3 miles on a new snowmobile belt. Every year after that I would sand the rust off the pulley before the first run of the season.
 
Thanks for all the help. I checked the clearance and it was ok. By twisting the belt towards the engine I was able to get the belt onto the pulley. I will watch the new belt very carefully to look for abnormal wear. Again thanks for the help.

Marshall
 
Herewith some lessons learned about replacing the fan belt on a Model A:

1. Obtain a replacement belt (see Note 1).

2. Loosen the generator/alternator mounting bolt sufficiently to remove tension from the old belt. Slip the belt off the generator/alternator pulley, off the fan/water pump pulley and then pull it off the crank pulley. The old belt can then be fed over the fan blades and removed (see Note 2).

3. Spin the generator/alternator and fan pulleys and examine for burrs, rust and/or distortion or wobble. Rotate the crankshaft and similarly examine the crank pulley. Also, visually check for alignment between the running faces of the crank, fan/water pump and generator/alternator pulleys (see Note 3).

4. Feed the new belt over the fan but not over the fan/water pump or generator/alternator pulleys. Place the fan belt as far onto the crank pulley as possible and pull on the belt to seat it. If it does not readily seat in the crank pulley, lubricate the belt – in the area in contact with the crank pulley – with a little bar soap or, as noted above, slightly raise the engine to provide additional clearance at the bottom of the crank pulley.

5. Feed the new belt over the fan/water pump pulley and the generator/alternator pulley, and wedge the generator/alternator back from the side of the engine sufficiently to tension the new belt (about 1” “freeplay” in the section on the passenger side between the crank and fan/water pump pulleys) while tightening the generator/alternator mounting bolt.

6. Crank over the engine a few times to ensure the new belt is properly seated and re-check the belt tension (sometimes new belts take a “set” from the packaging and may give a false indication of being properly tensioned when first installed).

7. Remove the radiator protection and engine jack (if used). If serviceable (albeit worn) keep the old belt in the trunk/seat pan/toolbox for an emergency “spare.”

8. Take your Model A for a spin and monitor the ammeter to ensure the belt tension is sufficient to properly operate the generator/alternator. In my experience, the tension does not need to be extreme and in fact too much belt tension can be detrimental to water pump and generator/alternator bearings.

Notes:

1. NAPA 25-20426 (also try NAPA 5L430 or the 5L440 which is 1" longer) or, for an alternator, you might try a TR22425 industrial cog belt; it will fit around the smaller pulley better.

2. While some may consider this to be overkill, I slip a piece of heavy cardboard – cut to the proper size – between the front of the engine and the radiator, both to protect the radiator and avoid skinned knuckles.

3. I find the easiest way to judge crank-fan/water pump-generator/alternator pulley alignment is to look closely at how the new belt tends in the pulley. If, for example, the generator/alternator is mounted too far aft – even by as little as 1/16” or so – a properly tensioned new belt will appear to engage the front face of the generator/alternator pulley more than the aft face and will wear prematurely.
 
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