Cm870 tick

[Tyrone456]

I’m hearing a slight tick when the motor warms up (don’t hear it on cold start) it doesn’t do it when idleing or stopped only when I’m rolling and then let off accelerater here’s a video
https://youtu.be/MKEktYrGwG4

[Unilevers]

jake rocker detents? sounds like a few jake rockers slapping around in there.

[Tyrone456]

(10-05-2018 )Unilevers Wrote:  jake rocker detents? sounds like a few jake rockers slapping around in there.

As in rocker arm? Is this something i can check myself

[pearce trucking]

Unilevers is talking about your Jake rocker springs being worn out. I just reassembled my rocker levers yesterday. On the passenger side rocker shafts, the Jake rocker is the center rocker of each cylinder. There is a circular cap held in by a snap ring on the back of each one. That cap holds a spring that loads a pin which settles in to a hole in the rocker shaft when the Jake is in detent position. If the springs wear out, the pin won't hold in the detente position hole on the rocker shaft.
The springs are cheap and can be replaced by removing the snap ring and cap and installing a new one. If the pins are worn you should be able to pull them out with a magnet after you remove the spring.
The "pins" are called check valves, not pins fyi.

[Tyrone456]

(10-06-2018 )pearce trucking Wrote:  Unilevers is talking about your Jake rocker springs being worn out. I just reassembled my rocker levers yesterday. On the passenger side rocker shafts, the Jake rocker is the center rocker of each cylinder. There is a circular cap held in by a snap ring on the back of each one. That cap holds a spring that loads a pin which settles in to a hole in the rocker shaft when the Jake is in detent position. If the springs wear out, the pin won't hold in the detente position hole on the rocker shaft.
The springs are cheap and can be replaced by removing the snap ring and cap and installing a new one. If the pins are worn you should be able to pull them out with a magnet after you remove the spring.
The "pins" are called check valves, not pins fyi.

Is this a pricey fix? I just got the truck? It just started doing it in May. And put about 5k miles on it since it started. Doesn’t seem to do it on cold start

[Chamberpains]

I don't know if you'll actually "fix" it. My cm870 made the same noise's on the million mile engine and still makes the exact same ticking when letting off the accelerator and Jake rocker slapping on the new Cummins Cert. Reman'ed Long Block I had put in. I don't know if it's the nature of the cm870 or there is an actual problem. I've checked and adjusted everything on the overheads on both engines. Had the solenoids and detent springs replaced on the old engine. The new engine came with all brand new overhead parts and still the same noise's. If you get your's to stop please post what it took. I'd love to know.

The Jake rocker slapping, I can get to do it when the Jake switch is on and my foot very light on the accelerator pedal. It's almost like the Jake solenoid is getting commanded to engage slightly but not fully causing the slapping around. It stops and doesn't do it under idle and acceleration. Only coast and deceleration and stops after about 5-7 seconds of either happening.

[Tyrone456]

That’s exactly what it does. Sound like a light engine brake