6.5 knock then goes away

[J Sonic]

This is the first 6.5 for me. It has 124000 runs like a bear. Went to Ohio to deliver a boat about 2500lbs. Lost 3psi of oil pressure on the trip. Went to pass a vehicle after getting back, a rapping sound developed. Took the foot out of it and it stopped. Didn't do it again till this weekend on 800 mi trip. On this trip the oil pressure dropped to 30psi from 40. Motor doesn't sound like it has a oil problem. Shut it off for a while pressure back to 40. While getting off the exit pushing down on the throttle it started rapping,backed out stopped again. I had the oil changed and held 40 the rest of the trip. Now it rapped one more time home. Could this be a injector or lifter going bad? I have never had a bearing start to spin and not finish itself. Also my temp won't go under 200. 215 on the highway. I am not familar with diesels.

 

[sweetk30]

i saw a 6.5 with a solid knock we all were 100% sure it was bottom end. thay removed motor sent out all remaned and reinstalled. fired it up and still knocked bad. called dealer and asked deisel mech what he was thinking it was. he said there was a recall on the injector pumps. the one we had was still under warrenty. sent it in and thay replaced it and bam no noises.

you might want to check that out.

 

[k204dr]

had a knock come and go in my 6.2, swapped all kinds of stuff looking for it. one day it came thru the oilpan. ended up being a wristpin. theres lots of different things it can be. loosen your injector lines carefully one at a time with it running, you can pick out which cylinder it is that way.

 

[jdemaris]

There are many things that can cause temporary knocks. Most common - with the 6.2 or 6.5 engines are - a bad injector, or a bad rubber-mounted crankshaft pulley. The latter is not the harmonic balancer- it's the outside pulley held on by four bolts.

 

[J Sonic]

Ok, well I guess will replace the injectors. The problem is it dosen't last but a few seconds. I am not sure but what would I be looking for, if I loosen the injectors. It wouldn't be knocking.

 

[k204dr]

if you loosen the injectors one at a time with it running, its like pulling the spark plug off a gas engine, it doesnt' fire on that cylinder. if the knocking goes away, you've found the cylinder it is.