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cumminsdr, Mechanic
Category: Medium and Heavy Trucks
Satisfied Customers: 3653
Experience:  All types of Cummins applications
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I have an intermittent knock and its accompanied by what

Customer Question

I have an intermittent knock and its accompanied by what sounds like a spun rod bearing but the noise is coming from the top of the engine. Only lasts for 30 to 60 seconds, its an ISX in a 2008 IH pro star.
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  cumminsdr replied 1 year ago.

Did you check the camshaft lobes and rocker lobes for damage while you performed the overhead adjustment? You need to get Cummins Insite program and perform a injector cutout test to see if it is an injector failing and isolate the failed one(s). That is the likely cause since a failed bearing would be constant. But you can pull an oil sample and have a lab perform oil sample test and see if there is an internal engine problem . Or drop the oil filter and cut it open and check fro metal/bearing material. Injectors only have a life span of about 500,000 miles.

Customer: replied 1 year ago.
the rollers have damage and the lobes seem fine but have some scratches under a 16th wide so should be OK but it only makes the noise after you tack up the engine a few times and some times it will not do it at all. Could it be possible that the Jake harness could be playing a part in all of this?
Expert:  cumminsdr replied 1 year ago.

There should be no damage to the rollers this means they are breaking apart and will cause other internal damage as that metal passes thru the engine.. You must replace the rollers asap. This is a known issue with these engines. Cummins has updated the rollers and made theu wider to increase the strength and relieve stress causing the failure. The jake harness is plastic and if the 2 legs broke off that hold in in the head it too needs to be replaced.

Customer: replied 1 year ago.
Already did all of the stuff that you suggested I need more info.. Why would you charge me for the answers I already have...
Expert:  cumminsdr replied 1 year ago.

So you isolated the injectors with The Cummins Program? I see the pic and that is the start of something very bad for the engine. In the event that macrospalling is observed THAT YOU HAVE THE START OF, inspect the lubricating oil filter for metallic debris. If metallic debris is found in the filter, inspect and replace as necessary the main and rod bearings, camshaft bushings, turbocharger, lubricating oil pump and pressure regulator, and the lubricating oil cooler.An overhead set will not help a injector that is failing mechanically and accelerate the damage on the rollers The stated procedures are needed to determine the cause

Expert:  cumminsdr replied 1 year ago.

HI do you need more assistance? Please don't forget to rate my service

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