Jake brakes very rough

[Cowboyup148869]

I have a 2015 isx 15 550. Cpl 4585 and when the Jakes are engaging it feels very rough. I assume they are oil driven. I thought maybe oil pressure to them might be a cause but would really like some advice. This is my first post on here and I’m getting used to these motors coming from a cat background. Thanks

[Magard]

Does it seem like it’s working good. Should be around 30 psi on boost if system is right. There is two solenoids to make setting 1 and 2. Setting 3 is vg turbo tightens up. If one solenoid isn’t working it will have lower boost and vibrate really bad as the rpm drops. Oils be other things I guess but mine did this so...

[Cowboyup148869]

All 3 work. And boost is around 30. I can push the peddle a few times and can get them to smooth out. Is there a check valve to keep oil to them?

[Magard]

I’ve heard of this but don’t know why. Someone else will chime in on this.

[Cowboyup148869]

All 3 work. And boost is around 30. I can push the peddle a few times and can get them to smooth out. Is there a check valve to keep oil to them?

[Chamberpains]

This may not be what is being described. But I'm throwing my experience in to the mix.
My CM870 does this fairly often. I current engine has brand new solenoids, overhead is done recently, the engine is reman'ed Cummins 200,000 miles, turbo is YTS new, jake harness wiring checks out and no oil in the pass through connector. My last engine with from 750,000 to self destruction at 1.1 million did the same.

As long as I've ran an ISX it has always done this. Especially after long low boost cruising. I've come to just live with it. Its choppy maybe better described as fluttery til I cut them out with the throttle and let them come back on, then it smooths out. If I let it stay choppy and keep "jaking" it'll smooth itself out but feels funny till it does. I've always taken this as one of those "nature of the beast" things. I could definitely be wrong though. Maybe the engine gods have more insight??

[Rawze]

The main cause of the jake brakes being rough is fuel getting into the cylinders during jake operations.

On the CM870 and 871's is is usually worn down fueling(metering) actuators, or sometimes a leaking injector, where the timing circuit inside an injector is letting fuel into a cylinder. - Seen both of them plenty.

On the newer engines,... it is very common too, because of leaky electronic injectors.

so...


Start by doing an injector leak test and see if it passes a leak-down test.

[Cowboyup148869]

I’ll see about a leak down test. Last time I checked it was good. New injector cups too. And new #1 injector.