Tested 3 of the ISX we have, one CM 2250 and two CM2350 isx. The 2014 cm2350 failed the pressure test immensely, dropped from 29k to 21k in a second and down to 300 PSI in 30 seconds. The 2013 dropped gradually about 8000 PSI in 1 minute as posted previously, but the cylinder cut out test revealed nothing to me (back 3, front 3 ran fine, each piston ran fine too). Wanting to buy injector leak test kit, should I go with OEM from Cummins or does this one from Amazon do the job (or other places). Also if it’s dropping that much on the cm2350, any guesses?
3164001 Fuel Injector Leak Test Check Kit Alt. for Cummins ISX/Signature Engine
https://amzn.to/3rTAP38
Cheers.
The injector leak test kit you have listed there is only for the older Dual-Over-Head-Cam (DOHC) CM570, CM870, and CM871 ISX engines. It will not do squat for test on a common rail CM2250, CM2350, etc. engines.
BTW: none of those engines should drop more than 4,000 psi in one minute.
To find the issues...
FIRST, start by replacing the high pressure relief valve at the front end of the main fuel rail if it is more then 250k miles old. use the Quickserv procedures to see if it is leaky otherwise.
NEXT, re-torque all the Quell tubes to cumins spec that feed the injectors and do the leak-down tests again. For all you know it could just be something simple, and not an injector intself.
If it still fails leak down tests, then start by capping off injectors, front 3, do tests again ... then back 3 ... and isolating what injector(s) that is causing the issues that way. Cummins makes fuel line caps for this test on the common rail engines.
If you find that it is more than 2 injectors are leaking like that, it is highly likely that some damage to them has occurred at some point. A 6-pack is not out of the question at that point. If, say, only one or 2 is leaky, replace only them.
It's easy enough to test the rail relief valve before replacing it. Check quickserve, I believe it's allowed a certain amount of drops per 30 or 60 seconds under the high pressure leak test.
Worth checking, they are a pricey item to just throw in.