Possible Cooling Fan Issue

[fireman5214]

Hello all, Our M35A2 started making a weird rattling/scraping sound all of a sudden going about 20-25 on our way back from a mountain fire at 300am. We are thinking it is a fan issue but unsure as we had to leave and go to work today. The truck was on a stone/dirt road and never got onto the mountain hard rock/rough terrain. We are going to look at the truck this weekend but the truck drives and shifts fine and the sound gets noisier on hills and when you step on the gas. Could this possibly be a fan issue and how hard would it be for us to fix ourselves? I have searched on here and saw people dropped the transmission and all of that and was not sure if we needed to go through all of that. It is a 1977 American General, any help would be appreciated.

 

[cattlerepairman]

From your description I find it difficult to point to a particular issue. Gee whiz...a Deuce making rattling noises....who knew!

If you suspect that the fan is an issue, check the fan. It should not feel loose when you try to wiggle it. You can take a wrench and check the mounting bolts of the fan to see that they are tight. Tilting the rad forward makes that a lot easier.

 

[fireman5214]

From your description I find it difficult to point to a particular issue. Gee whiz...a Deuce making rattling noises....who knew!

If you suspect that the fan is an issue, check the fan. It should not feel loose when you try to wiggle it. You can take a wrench and check the mounting bolts of the fan to see that they are tight. Tilting the rad forward makes that a lot easier.

We are going to look at it tonight and I will report back and no this was like a quiet normal ride to a loud obnoxious grinding type sound the whole 2.5 miles back at 20-30 mph because if you went over that the noise got increasingly louder and we never heard that noise before. Checked the tac, all other gauges to make sure everything was ok right away.

 

[fireman5214]

So it was the cooling fan and it was hitting the bolt from the alternator as the bolt from the water pump housing sheered off and the alternator is leaning slightly into the fan. We used a red wire to feel if the bolt was still in the housing and it is so we will have to replace the housing

 

[cattlerepairman]

Wow, lucky. If that bolt bends a fan blade, you HAD a radiator!



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[LowTech]

Wow, lucky. If that bolt bends a fan blade, you HAD a radiator!



Sent from my SM-G991W using Tapatalk

Been there, done that on the She Beast. Fan pulled the whole impeller section forward and ate the rad.

 

[fireman5214]

Wow, lucky. If that bolt bends a fan blade, you HAD a radiator!



Sent from my SM-G991W using Tapatalk

Luckily the fan blades were only bent in the area where it was hitting the center bolt on the added 12 volt alternator as the blades were spinning with the angled area toward the bolt and not the stiff 90 degree end.