Problems with my Cummins QSD 2.0

[Bronson]

Hello everyone, I'm new here on forum and I need your help.
I have a Cummins MerCruised QSD 2.0 that knock at 1450 -1500 rpm. At the last service, they have completely overhauled the engine, replaced one injector, replaced the camshaft on the valve train. Still have the same exact noise as before and the men from service said they found no damage in pistons, pins, cannot figure it out.
Somebody told me to use a dish tool to cut out injectors,and if i need to isolate the cylinder that has the knock, it sounds like an injector causing the issue once I can isolate swap the suspected cut injector with another cylinder, all injectors should be changed at time of overhauls. Or I'll risk damage to the overhauls engine. I know that an injector only has a life span of 500,000 miles.

Do you think is too difficult? What you recomend me, to buy the service manual for my truck [TradeBit.Com] and to save money by repairing it myself, or you recommend me to go on a proffesional service and to solve this problem.

Thank you for your attention!

 

[Seastoke]

If they have overhauled it surely you need them to carry on

 

[B58]

How many hours has the engine run, have you had any previus issues with the engine like diesel bug, water etc.... Injectors may last 500,000miles on the road but in marine conditions that can fall rapidly!
Take the injectors to a Bosch diesel specialist they can tell you if they are faulty? Do not under any circumstances try to test each injector by cracking the nut whith the engine running!
The other knock could be caused by injection timing, the type of injector you have will inject upto 5 times per cycle, if the timing is wrong it could cause injector knock
I you have replaced injectors in the past, you need to input the injector IMU code into the ECU the IMU code is read from the top of the injector, it contains information about the manufacturing adjustments, on this engine you can input the code using CDS (computer diagnostic system) any Mercruiser petrol or diesel dealer can do this.
Can you pull WOT 4000rpm+ underway does the knock go as the revs rise?

 

[lynall]

Im no expert but assume its a common rail motor? if so I would say injectors are firing to soon/early, most modern engines try and fire injector as soon as possible and have knock sensors to detect when its to far advanced, just an idea and maybe an avenue to look at?

 

[Latestarter1]

Forget Bronson, post stinks.

Repeat of previous post here and take a look at what was posted on another site..........

'Hello everyone, I'm new here on forum and I need your help.
I have a Cummins QSD 4.2 that knock at 1450 -1500 rpm. At the last service, they have completely overhauled the engine, replaced one injector, replaced the camshaft on the valve train, clearance checked the timing gears (all within specs), new head. Still have the same exact noise as before and the men from service said they found no damage in pistons, pins, cannot figure it out.'

Somebody is is up to something.............