mndriver
curmudgeon extraordinare
In 2015, I was having issues with the alternator seizing on my tripac. I could use a 15/16" socket on the shaft nut and get it to rotate with a 1/2" ratchet, but once I let it sit for a weekend, fergitaboutit.
In September, 2015, I was finally able to replace the alternator with a new one. The truck sat all summer and was never used. I needed to make a new tension adjuster anyway, so I didn't worry about it.
Ran fine all fall and winter.
Come April 2016, in Houston on a 90+°F day, crank up the microwave, I toasted my brand new alternator.
Parts guy back home replaced on warranty.
Late April, toasted another alternator. Replaced it this time with a 120 amp system.
It started acting funny on me. Quit a couple times. Gave me "alt" codes. Replaced it with another 65 amp alternator. Also replaced all of my battery wires and main apu power feed wires and relocated the 75 amp maxi-fuse up where the thermo-king upgrade moved it to.
Was still getting an occasional "alt" fault.
On Monday, talked to a guy in peculiar Mo at the flyin'j. He mentioned that thermo-king had a larger pulley and a smaller pulley to slow the speed down to keep it cooler.
OK, I'll give them a call and get the skinny on that.
The guy was partially correct.
The 65 amp alternator has a 2" pulley
The 120 amp alternator has a 3" pulley to overspin the 65 amp to put out 120 amps and has a 120 amp regulator....
Good to know.
Explain the rest of this issue to the parts guy....
"Where did you get your alternator?"
Local Parts City. Why?
"You know the tripac alternator spins backwards don't you?"
I do now I am guessing from what you're about to tell me.
"Yop. The tripac spins CCW and needs a reverse fan on it to cool. Your cooking your regulators and they are doing a thermal shutdown."
Have you got any old fans around?
"Nope. But we can get a replacement fan. Let me go look"
Wait about 2 minutes.
"Yop, we have 5 in stock on the shelf. Cost is $14.78"
Great. I'll see you about 1:30 this afternoon.
The old fan and the new fan part number from the box.
The Ryobi 1/2" cordless impact is likely the BIGGEST and most used special tool I have on the truck. Talk about handy. With a 15/16" socket, all you need to change the fan/pulley for the alternator.
The old and new fan side by side.
Old alternator Fan still on the APU.
In September, 2015, I was finally able to replace the alternator with a new one. The truck sat all summer and was never used. I needed to make a new tension adjuster anyway, so I didn't worry about it.
Ran fine all fall and winter.
Come April 2016, in Houston on a 90+°F day, crank up the microwave, I toasted my brand new alternator.
Parts guy back home replaced on warranty.
Late April, toasted another alternator. Replaced it this time with a 120 amp system.
It started acting funny on me. Quit a couple times. Gave me "alt" codes. Replaced it with another 65 amp alternator. Also replaced all of my battery wires and main apu power feed wires and relocated the 75 amp maxi-fuse up where the thermo-king upgrade moved it to.
Was still getting an occasional "alt" fault.
On Monday, talked to a guy in peculiar Mo at the flyin'j. He mentioned that thermo-king had a larger pulley and a smaller pulley to slow the speed down to keep it cooler.
OK, I'll give them a call and get the skinny on that.
The guy was partially correct.
The 65 amp alternator has a 2" pulley
The 120 amp alternator has a 3" pulley to overspin the 65 amp to put out 120 amps and has a 120 amp regulator....
Good to know.
Explain the rest of this issue to the parts guy....
"Where did you get your alternator?"
Local Parts City. Why?
"You know the tripac alternator spins backwards don't you?"
I do now I am guessing from what you're about to tell me.
"Yop. The tripac spins CCW and needs a reverse fan on it to cool. Your cooking your regulators and they are doing a thermal shutdown."
Have you got any old fans around?
"Nope. But we can get a replacement fan. Let me go look"
Wait about 2 minutes.
"Yop, we have 5 in stock on the shelf. Cost is $14.78"
Great. I'll see you about 1:30 this afternoon.
The old fan and the new fan part number from the box.
The Ryobi 1/2" cordless impact is likely the BIGGEST and most used special tool I have on the truck. Talk about handy. With a 15/16" socket, all you need to change the fan/pulley for the alternator.
The old and new fan side by side.
Old alternator Fan still on the APU.
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