Isx15 2250 engine brake issue

[Samvelm83]

Has anyone had this problem with engine brake?
So, when the engine oil is cool (up to 170F-200F) 3rd stage works perfectly but when it gets hot (220F-230F) the engine brake gets very weak and the engine starts vibrating. Using Rotella 15-40
Changed both solenoids but didn't help.

[Rawze]

could be engine brake solenoid starting to fail when oil gets hot.

[Samvelm83]

(05-22-2026 )Rawze Wrote:  could be engine brake solenoid starting to fail when oil gets hot.

Thanks for your feedback.

I thought the same way, replaced solenoids but didn't fix the problem.

[Rawze]

(05-23-2026 )Samvelm83 Wrote:  ...
Thanks for your feedback.

I thought the same way, replaced solenoids but didn't fix the problem.

Do injector leak tests on it when cold, and when hot. It could be leaky injector causing cylinders to partially fire when hot...

info: https://rawze.com/forums/showthread.php?...3#pid75483

[Samvelm83]

(05-23-2026 )Rawze Wrote:  

(05-23-2026 )Samvelm83 Wrote:  ...
Thanks for your feedback.

I thought the same way, replaced solenoids but didn't fix the problem.

Do injector leak tests on it when cold, and when hot. It could be leaky injector causing cylinders to partially fire when hot...

info: https://rawze.com/forums/showthread.php?...3#pid75483

Can it be from the jake brake check valve or the spring ?

[Rawze]

(05-23-2026 )Samvelm83 Wrote:  ...
Can it be from the jake brake check valve or the spring ?

It can as well ... but you said you already replaced them in post #3 above. Those components are internal to the jake solenoid units on a CM2250.

It can also be worn out rocker shafts letting too much oil past them as the oil gets thinner. This can be checked by pulling the valve cover off it and running the engine without valve cover, and then manually activating jake solenoids one at a time and watching for excessive oil flow from places where it should not be.

I would do the injector leak tests first though, as mentioned above, because it does not involve taking anything apart unless there are issues.

[Samvelm83]

(05-24-2026 )Rawze Wrote:  

(05-23-2026 )Samvelm83 Wrote:  ...
Can it be from the jake brake check valve or the spring ?

It can as well ... but you said you already replaced them in post #3 above. Those components are internal to the jake solenoid units on a CM2250.

It can also be worn out rocker shafts letting too much oil past them as the oil gets thinner. This can be checked by pulling the valve cover off it and running the engine without valve cover, and then manually activating jake solenoids one at a time and watching for excessive oil flow from places where it should not be.

I would do the injector leak tests first though, as mentioned above, because it does not involve taking anything apart unless there are issues.

Thanks for the input. Sure will run tests to see what's the problem.