2012 Paccar?

Ding ding ding.... we have a winner.

You answered your own question correctly.

 

Hello @spsauerland, I noticed you mentioned the fan belt tensioner on this engines likes to "twist" down. I just picked up a 2014 t680 with mx 13 and have gone through 2 of these tensioners, first we had to replace because it was twisted sideways and crooked compared to fan belt. a week later The new tensioner would twist down and the belt would become loose. when I checked the puller by applying pressure to remove belt the tensioner remained in the down position and didnt spring back which is what cause the belt to go loose. so we purchased another brand new one from the dealership and still the same thing happens. Any help would be greatly appreciated. this is driving me nuts.\

ps: if i loosen the screw on the tensioner pulley, as if to remove it for example, the tensioner pulley does spring back. but i mean loose like almost just hand tightened which i dont think its supposed to be like that.

 

The fan belt tensioner on the EPA 13 had an update pretty sure. Did you order a Paccar tensioner? Should be updated to come with the base too.

 

Yep. Both from kenworth dealers. And the new bracket came with the first one. I didnt install because mechanic said they were the same. They look the same to me as well. I put the new one side by side the one on it now and the little holes line up. Should I just install the new one?

 

Yes, I would

1918442?

Dont remember repeat failures after the update.
How long did it last?

 

1956632PE its the base where the small knob on tensioner inserts.

Installed new last Thursday. Belt jumping Tuesday. Installed another new today. If i tighten bolt it twists down and doesn't spring back up. If I losen bolt then it comes back up tensioning belt.

 

You have either a part or assembly issues, not being there its hard to tell which one.....

 

I think one of the updates on the EPA13 was on the accessory belt for A/C compressor clutch bearing life.

 

Post last eight of vin so we know exactly what we are looking @.