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+--- Thread: ISX 870 Jake brake is weak (/showthread.php?tid=2078)
ISX 870 Jake brake is weak - DKenworth - 08-27-2017
[b][font=Times New Roman][size=large] Here is my story... jake brake became very weak. Overhead set was done like 150k miles ago. Was holding very good but lately i noticed that position 2 doesnt do anything and turbo boost is no more than 5 psi. Used to like working on and off. Last month local shop was fixing front of engine oil leak that i had for a quite long time, so they changed all guskets there. They had pulled all 4 gears out as you know. Everything is fine now, no leaks. So at that time i changed jake break wires and checked my solenoids, they seems ok. So, i dont know but it become very weak after they done front engine job. Should i done overhead set again or any thoughts? Where to look? Thanks guys. Engine is isx 870 with almost 1.1 mil miles, runs good. mpg is over - 7mpg. All cool except that jake break.
RE: ISX 870 Jake brake is weak - marek4792 - 08-28-2017
Was the timing set properly with the timing wedges and the crank pin when reinstalling the timing gears? Does the engine sound any different after the job then before? Does the engine brake work normally in no. 3 position?
RE: ISX 870 Jake brake is weak - DKenworth - 08-28-2017
(08-28-2017 )marek4792 Wrote: Was the timing set properly with the timing wedges and the crank pin when reinstalling the timing gears? Does the engine sound any different after the job then before? Does the engine brake work normally in no. 3 position?The guy who did work on my engine works for cummins dealer, it was his sidejob ill say. Engine does sounds a bit louder to me , but u can hear it only outside. I have 2 position jake brake so when i switch to 2, it stayz the same.
RE: ISX 870 Jake brake is weak - Rawze - 08-28-2017
(08-28-2017 )DKenworth Wrote: The guy who did work on my engine works for cummins dealer, it was his sidejob ill say. Engine does sounds a bit louder to me , but u can hear it only outside. I have 2 position jake brake so when i switch to 2, it stayz the same.
This means I would trust him about as far as I could throw your engine across a room. Cummins 'certified' mechanics who work for the stealershits/Cummins are some of the WORST mechanics I have ever met out there. There is one in particular who does "side work" in the So.calif region who butchers engines so badly, that I get phone calls, questions, and complaints very often from s$it not set or done right. The guy is a complete engine butchering nightmare, and he IS cummins certified and IS working for cummins, and IS doing work on the side for people. -- COMPLETE SHAME!.
Hopefully you are not another one of his victims!
The engine cover has the correct timing wedge numbers on it. Ask the guy what timing wedges he used and then go look at your engine cover. - NEXT, get Insite and look to see what program the engine has in it. THE OFFSETS AND PROGRAM NEED TO MATCH WHAT YOUR ENGINE SERIAL NUMBER REQUIRES!. I don't work on 870's but it is my understanding that when they were making the CM870's, they were still playing with mechanical timing + matching programs per serial number range. Not all of them are set the same and this can have a big effect on things like the jake brake and how well the engine runs overall if not 100% correct.
Engine brake problems can be many. Start with the basics like verifying your engine static timing. Have the wedges placed in and see if the static timing is still in proper alignment. Make sure the programming is correct, re-flash it with the right factory program using the "wearther-pack" harness out on the engine and test it. If it is not mechanical or electrical, many times it is just bad programming on them, especially if someone has tried to "delete" it and did a s$itty job.
There are other ways to test the engine brake solenoids, etc. with procedures on quickserv. Maybe do those tests too. Also check your detent clearance on the engine brake rockers. Make sure one of the rocker shafts is not out of place. (reference: http://rawze.com/forums/showthread.php?tid=1106&pid=9466#pid9466 ).
RE: ISX 870 Jake brake is weak - DKenworth - 08-28-2017
Thanks a lot Rawze for advice, Im on the road right now, so you know cant do nothing. Uctually, just droped off load in Florida and would really apreciate to take my truck to your place over weekends if you have time.