D2 5U fan belt adjustment

[quote="laurencen"]Running the crawler today we noticed the belt bouncing at idle, the fan can be turned by hand with the motor off with little resistance, looking at the fan pulley by removing the short bolt and key the nut side should turn to tighten, at this time both parts are tight and likely rusted

what is the best way to loosen these parts, I have used wd40 and diesel on them with the hope I can turn the nut side, was there any special tool to do this job? if all is good how easy to turn the nut side?

Thanks[/quote]

Since you have loosened the pinch bolts, removed the keys, and used the loose juice, the last thing is to tap the nut side with a brass bar and a hammer to get it moving. The nut side has pockets on the backside formed by the gussets, use the bar in the pocket.

2 bolts with lock keys to be removed
Then the best way to turn the back flange of the pulley is to find something like a deep socket or short extension, a bolt etc that will span the gap between the webs of the pulley and a convenient protrusion on the front of the water pump. Usually it will be a bolt head or the casting knob under one. You want the length of this piece to result in it bracing itself securely when you pull on a fan blade. You can develop some good leverage pulling on a fan blade! I have had to heat the rear flange to break it loose and have tapped on the webs too, but once you get it moving, I would wire brush any exposed threads and then relube it before backing it off as far as possible so you can clean the threads under the belt and lube them.

Finally use your tool in the opposite direction and run the flange back forward to tighten the belt. It should not need to run very tight, I think it should have around 3/4 to 1" deflection at mid span with firm pressure.

The fan belt doesn't have to be all that tight in order to turn the fan. My belt bounces a little at idle and you can turn the fan by hand (not easily but it can be done) but no cooling problems.

the belt bounces around at idle, I figured there was a tool other than the brass punch, anyway sprayed a few days with wd40 and diesel fuel, with the bolt removed it does move maybe half inch either way, sure is tight so will try every few days and get more movement each time.

the starting motor uses the same coolant as the main motor, what would be the duration one can run the starting motor without issues of heat

[quote="laurencen"]the belt bounces around at idle, I figured there was a tool other than the brass punch, anyway sprayed a few days with wd40 and diesel fuel, with the bolt removed it does move maybe half inch either way, sure is tight so will try every few days and get more movement each time.

the starting motor uses the same coolant as the main motor, what would be the duration one can run the starting motor without issues of heat[/quote]

If your cooling system is not stopped up in the usual places like in the pony heads,pony water jacket, flywheel housing under the pony block, you should be able to run it indefinitely without over heating. One objective of running the pony is to make heat in cold weather. It does help to turn the main engine for water circulation as the pony doesn't have a water pump.

good information regarding how long it can run, the goal is to start turning the main engine once the motor runs smooth without choke.

this machine is close to 70 years of age and doubt the unit has been taken apart so likely has the typical blockages, there a way to check without taking parts off?