Jake Brake RPM Issue

Does the engine fluctuate also or just the tach?

 

Sounds like you are saying it only happens with the jakes and the motor sounds like its missing. If its not missing and its just the tach jumping, just deal with it. My tach is jumpy with no engine miss. Annoying yes. So its fine otherwise? Other than that, sounds to me like one of the jakes might have a loose solenoid wire causing one of the jakes to intermittantly cut off and go back on in a fast sequence giving that feeling of a miss. If its not a loose wire, your gonna have to check the ohms at the wires down at the computer for the jakes. IF they arent in spec, you will have to check the ohms at the solenoids to rule out internal and external harness. IF all that checks out, its time to rebuild those old jakes. The jake kit for your motor is 160 bucks from cat and i have the part number for you if you need it but ill have to get in morning. it comes with all parts to do all 3 jakes. After the install of the kit, you will need to run your overhead. Once all that is done, you will be going through the windshield when you put the jakes on.
Forgot to ask, when was the last time an overhead was done on the truck.

 

if thats how long it has been since the valves and jakes were adjusted, its time to run the overhead. To have a shop do it, it doesnt cost much. If the shop that did the overhaul has any sense, they were supposed to rebuild the jakes as well and install new solenoids along with replacing internal wire harness but you never know these days.

 

Jakes sending you through the windshield on a cat, this I have to see. lol

Collie, what kind of manifold pressure are you getting with your jakes?

 

Don't confuse the jacobs bouncing around for being just too light overall gross for the job.

 

#### i cant remeber looking. only thing i remmber is the turbo screams pretty good when jaking. im not driving yet till i pull this trans again and then put another in.