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Ntc 300 big cam. Spun wrist pin bearing

chris allen

Senior Member
Joined
Feb 11, 2014
Messages
372
Location
georgia
Occupation
Feild tech
did an In frame few yrs ago in our old
Kenworth low boy. Did basic inframe job everything went well , So now my driver has noticed a knocking sound again. So I looked it over An sounded like it was from top end. Dropped oil pan An started pulling rod caps off an wiggle each rod. I though maybe it had spun wrist pin on number 2 or 3. Well I noticed rod 3 was Lil tite to wiggle. Pulled the number 2 head off An pulled piston An sure enuff the wrist pin was blue An bearing done turned an1/4 turn in rod an seizing up. Also noticed liner an piston both had scratches up An down them An bottom of liner was cracked An leaking coolant in pan. I looked over spray jets An looks to still be in tack an not stoped up. So do I just replace the one liner rod piston an bearings for that one hole. Would like to know what caused this cause don't wanta see this again with this truck
 

Truck Shop

Senior Member
Joined
Dec 7, 2015
Messages
16,535
Location
WWW.
Plugged piston cooler. Did you remove the piston cooler to make sure the oil rifle is clean? Did you find any coolant in the pan? If every thing else checks out then just replace
the one hole. Make sure that cooler isn't cracked.
 

chris allen

Senior Member
Joined
Feb 11, 2014
Messages
372
Location
georgia
Occupation
Feild tech
Tryed litely to get spray jet off. Does it tap in or does it screw in. It seems as if it's one per cylinder an not 2 made into one An bolted in like on other Cummings
 

td25c

Senior Member
Joined
Feb 14, 2009
Messages
5,250
Location
indiana
Tryed litely to get spray jet off. Does it tap in or does it screw in. It seems as if it's one per cylinder an not 2 made into one An bolted in like on other Cummings

Holding bolts for the oil jet are on the outside of the block passenger side .

I would replace all 6 jets as they get brittle over time .
Agree with Truck shop on replacing one hole if it all checks out .
 

DMiller

Senior Member
Joined
Feb 21, 2010
Messages
16,424
Location
Hermann, Missouri
Occupation
Cheap "old" Geezer
The original equipment used to be steel, the replacements nylon and there is a oring that likes to adhere to the block once installed so taking a small bolt(can't remember if 1/4 uss or 5/16 worked best) to the nylon ones and threading into the recess at the mounting face sometimes can get a small slide hammer to drag out. Not seen many stop up except with gasket material dropped in during overhaul. Most common cause of wrist pin roll is the bushing was not aligned properly when installed and dried up where the oil port was rolled on install and missed or the rod was crap. Usually with a choked piston cooler nozzle you end up with a piston failure. Any nylon nozzle you pull, pitch and replace.
 
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