Any one knows the real cause for PACCAR mx13 injector knocking?

The claim is carboxilate buildup on a disc inside the injector itself. There are revisions and improvements being made as well as a software revision. Push back thru your purchasing dealer to get all 6 injectors replaced.

Running the Grey bottle diesel kleen helps keep the problem away. There’s also a new White Bottle Power Service most dealers should have on hand.

 

If the truck has a symptom audible symptom of fuel knock that is present at the time of service. An injector can be tested and deemed out of range and replaced. If the truck is still knocking after flush procedure will be to test and replace the out of range injectors. The dealer will have to push on reps to get all 6 replaced at once. But if you’ve had continuous issues and multiple visits, this should be easy.

I would try a different dealer. Keep in mind the MX engine can be serviced under warranty at both Peterbilt and Kenworth dealers if one or the other is better in your area.

Also Paccar has extended the warranty on injectors in the 21 to 23 models to be covered under 10yr 435 mi emissions due to the issues customers are experiencing.

 

I want to add to what Goodysnap said about trying a different dealer. Talk to the service manager if you have not already. Ask for the General Manager. Call Paccar and tell them the problems you are having and ask what they can do to help you get service. About US | PACCAR

 

A call to Paccar about dealers that jack you around seem to get instant results.

 

Just to follow up and for completeness: The warranty was also extended to the '24 model year. A new, updated design for these injectors has become available as of the end of November. After 65,000 miles of with to the dealer about every 6K miles, and several replacements and injector shuffles, I have an appointment for six new injectors on Tuesday. Fingers crossed.

 

I don't believe Paccar can fix their own motors.
Money pits ......