475 cat with NXS serial ?

We have 7 NXS and 2 MXS engines in our fleet. Not a bad engine as far as emission era engines go. IMO, their biggest issue is with injector harness's and intake valve actuators. The harness's are not easy to change, the IVA's a pretty simple though. Many times IVA's are changed when the real problem is the harness, so you need to diagnose properly before throwing parts at them.

So far, other than the injector harness's and IVA's, here's common problems that we run into:

Rocker studs breaking, there are updated studs that eliminated the problem, make sure that it has the updated studs.

Compressor inlet hoses failing and intake fitting pulling the threads out of the compressor head. They have an upgrade that replaces the steel tube & hose with a braided line. We haven't had any problems with the new set up.

Intake actuation pressure sensors failing. We go though 3-4 a year on our 9 Acerts, they are easy to change, but are about $130.

Exhaust manifold and turbo studs breaking. No more common that any other cat motor, but with the 2 turbo and pre-cooler setup, it's a longer job to fix.

We had other issues, like injectors, ECM's, water pumps, etc., but no more common on those than most other engines.

 

Just to add to that, CAT sells IVA connector kits with pigtails, including crimps and heat shrink, for about $20 each. I know it's better to just replace the harnesses when those connectors start to go bad from getting brittle, but that's a cheap and very easy fix on the road.

 

That pretty mutch covers it all with the mxs / nxs I have seen a main bearing pick up and damage the crank recently, no warning at all with oil samples taken every 20,000km

 

We have 2 ISX's too. They are about the same, considering the EGR valves and turbo problems. Different problems, but about the same aggravation level.