Belt and C frame pin.

[Blademaster]

Howdy folks,
I have a later model 450C crawler dozer. I had an issue last winter where the hood fell into the fan. After 2 tries I got a fan that was bent in the mail so they sent another from the vintage warehouse in Milan IL. I got it into position only to find it was 1/2" too big. It would've hit the fan shroud. I took it back out and took my old fan to the machine shop and they straightened it. It looks pretty good so I bolted it up and checked my clearance all the way around the shroud. It was close on the left side but fit. I put the alternator on and wound the belt and tightened everything up and the fan hits the belt a good 1/4". I double checked everything and can't see where I did anything wrong. The belt is in all 3 pulleys and the belt is seated as it should be. Does anyone have any ideas? I'm rapidly heading towards throwing the hair dryer in my bathtub.

[Jim B]

Fan blade on wrong side to?

[Blademaster]

No I took a video of taking it apart so I could look at it before I put it back together. I'm taking it back off and I'm going to check water pump, alternator shafts to make sure they aren't bent or pulleys are cockeyed. The alternator and water pump were new last year. John Deere guy might be up this week. I had the service manager on the phone for an hour and didn't get much accomplished. He's in his thirties and is pretty handy with these old tractors because he grew up on one. You don't see that much with these young guys these days. We did have one idea I'll run by you. We're thinking of taking new fan to machine shop and trimming off a half inch or so. What do you think of that idea? If he machines the blades all to uniformity there shouldn't be an issue with balance?

[Jim B]

Trimming uniformly should work, but I can't say what the effect will be for certain, only a rebalance would confirm 100%. Can you or the shop compare the offset of the blades to mounting flange? The damage could have affected that offset at the center mount area, which might not be seen in the straightening of the blades. Just a thought.

[Blademaster]

So I took the belt off and spun the fan slowly both directions. I had zero uniformity - no 2 blades cleared the same. I checked the shafts/pulleys for play or wobble and everything spun like it should. I took the top radiator hose off which made getting the new fan in much easier.
I got it in and semi mounted and spun it. It cleared the shroud there were a couple dents in the shroud. I corrected those and tightened the fan down and put the belt on. I put everything back together and fired it up and shut it off a few times, then just let it idle for 20 minutes and gave her more fuel up to 1800 and all was well. However, when I raised the blade I got a clatter like a mini gun firing. I put the blade down and shut it off thinking I wrecked the fan but nothing was wrong there. I started it back up and got the same results again and cannot figure out where exactly its coming from other than its definitely up front.
Note the bottom pin is out that holds the draw works to the frame. It hasn't gone askew but it's off 3/4 inch. I was trying to raise the blade and tilt it so I could get that thing lined back up. It only makes this gunfire noise when blade barely up. What do you think?

[Jim B]

Could the pump drive coupling be about to fail and is starting to slip by the shaft splines. That would be down low, right in front of the engine and might only happen when the hydraulic pump is loaded.

[Blademaster]

Thank you, when I put the new belt on I discovered that I have the spring loaded shaft that I simply had to pry back to get the belt on as opposed to the direct drive shaft that has 4 bolts that are a bitch to get off. I must not have the right alignment. Ill be on that shortly. I didn't even think about that.