Cat 3406B JAke adjustment...

What it does is keep the jakes from coming unless the throttle linkage is at idle position. It works like a reverse light switch. The ball in it makes contact between the pins to complete the circuit. It's designed to not allow the jakes to come on if you are on the throttle. It's normal for the jakes to come on at idle and kill the truck on a mechanical engine. You have to turn the switch off or just rest your foot on the clutch enough to activate that switch if you don't want to turn them off.

 

Wore out hit it right on head.

 

It's hard to kick the mechanic, most of my age have never worked on the mechanicals. They were retired as we started. Except where I come from we still think a 30 year old rig is pretty late model.

 

Get to know your old cat, mine is still painted white I do all my own work, it's just too hard to find a old school mechanic. I did have a clutch put in onetime at a freightliner dealer and after 18 hrs I had to finish the work myself because the mechanics couldn't figure out how to reconnect my shifter air lines. Truck was stuck in deep reduction and that's as high as it would go. In the mechanics defense he probably don't see enough of the motors anymore to remember the troubleshooting.

 

3406"A" block pumps had a jake switch opening that contacted the fuel rack, so if set correctly the rack moved further closed than idle when in deceleration cycle and activated the jake, at idle the rack moved back to a give enough fuel to idle and the jakes didn't stay on, but these were really fussy to set, I don't know if a B/C pump can be set like that or not , never tried,

 

That was one way we used to pick out the rookie drivers, "back in the old days", when they would come to a stop and their engine would go into a 3 cylinder shake fest, or just completely die out. Another way, was when they'd spin the engine with a Kysor shutdown system until it built oil pressure off the starter. Ahh, technology now has given them an edge. LOL.