Engine/Transmission (1998.5 - 2002) Help finding engine knock

[J. Steve]

I've got a new engine knock after driving a couple hundred miles towing about 5,000 lbs. After much reading of posts and some engine experience I know there can be about 100 different things wrong, and none that are good. So with that, here are the details and hopefully y'all can help me find a place to start:



It knocks at every RPM and speeds up with RPM

It's loudest at the back of the engine and from underneath

Using a stethoscope didn't help isolate the knocking

There is no power loss or change in drivability and all gauges are normal

I haven’t done any mods in the last 10,000 miles or so and have had no recent problems

The truck is now at about 75,000 miles, with the original fuel pump

There is nothing else out of the ordinary about the truck (exhaust color, sound, etc. )



All ideas and questions are appreciated!

 

[J. Steve]

Sound clip

To help, i have digitally recorded the knock. Here are links to it in MP3 format and in WAV format (otherwise the same). The knocking is quite obvious and the sound is recorded from under the truck where it is the loudest. This clip is from idle after start up, rev up to about 1500, then back to idle, then shut down.



PLEASE HELP!!!



Sound clips:



MP3 Format



WAV Format



Edit: the clips should be 17-18 seconds long

 

[JasonCzerak]

Not a lose rocker?

 

[CHill]

Sounds just like when my torque convertor bolts started backing out and hitting the block.

 

[Nate]

Sounds like a lifter/rocker arm to me. Have you adjusted the valves?

 

[J. Steve]

JasonCzerak and Nate: Thanks for the suggestions, i was thinking that would be my first step so I'm going out to do the valve adjustment now, I will let you know if this helps.



CHill: I will also look into this. I probably wouldn't have thought of this, and it's possible since it wasn't too long ago since i replaced the torque converter



It's sure nice to start getting responses so soon to this problem, I will keep all updated. Any other suggestions at this point?

 

[J. Steve]

So:



The torque converter bolts were all snug and looked good (darn, almost an easy fix if no damage was done)



The valves (intake and exhaust) are all in spec and visually (with out removal and inspection) the rockers, pushrod socket’s and crossheads look intact and feel snug on the rocker shafts. Is there anything more specifically I need to inspect under the valve cover if everything I mentioned is in this condition? Should I look somewhere else? Is it time to consider the unmentionable? Thanks again y’all for your help, and in advance for any more that is available!

 

[nps]

Sounds like it might be time to drop the pan and look at the bottom end. If you don't want to go there, then hHave you drained the oil and looked for impurities? If you have the time, you could send an oil sample off for analysis of wear metals to rule out a spun bearing.

 

[DMannon]

I have an '01 with the exact same noise. Had the trans serviced, no problems there. Had the valves done a couple of weeks ago and asked the mechanic, who has been a good friend for years, what he thought. He said all the lifters seemed to working properly, that it might be one of the piston wrist pins. .



I put five gallons of biodiesel in a half full tank yesterday, and it seems to run quieter, but you can still here that tapping. It's most pronounced from the cab.

 

[azpete]

Hi Steve. Sorry I can't help you with that noise but also think an oil test would be a good idea. Used the Kenworth dealer once and they were really slow. The Cat shop off Aviation Hiway north of Price was good. Hope all works out.

 

[Evan A. Beck]

Downloaded the sound clips, and it is exactly the noise I was not hoping to hear. It's going to be a scored cylinder, most likely number 6. The noise you are hearing is the combustion event leaking into the crankcase. Chances are, something has plugged up the piston cooler nozzle in the main bearing journal. Seen one that was plugged due to main bearing failure, but that is pretty rare. Seen plenty of plugged nozzles from bad oil filters though. Definitely not a wrist pin or rod bearing failure. If it is, I will be very surprised. I am 99% sure its going to be scored cylinder/bad rings due to lack of oiling.



A compression test will probably not tell you much since the knock is not very loud yet. Oil test may show some high levels of iron and aluminum.



Next step is going to be to pull the head and inspect for damage. Until then, its hard to say if it can be fixed in the truck (in-frame) or not.



Best of luck to you...

 

[DMannon]

... It's going to be a scored cylinder, most likely number 6. The noise you are hearing is the combustion event leaking into the crankcase. Chances are, something has plugged up the piston cooler nozzle in the main bearing journal. Seen one that was plugged due to main bearing failure, but that is pretty rare. Seen plenty of plugged nozzles from bad oil filters though. Definitely not a wrist pin or rod bearing failure. If it is, I will be very surprised. I am 99% sure its going to be scored cylinder/bad rings due to lack of oiling... .

Evan, educate me a little here... how did you pin this down to #6 and the scoring? Mine sounds exactly like JSteve's, so I took into the local Cummins service center today and they said, yep, it was #6.



They said before they pulled the head, they wanted to disconnect the injector to that cylinder, said the knock could be caused by a stuck open injector. Also said if it was scored or a loose wrist pin, it's a bad thing; engine out time... I got a bad feeling about this. Until it warms up, mine sounds like somebody tapping with a ball peen hammer...

 

[Evan A. Beck]

DM, a simple compression test is all it takes, IF the problem is bad enough. If it is just a slight knock, then it may or may not show up on a compression test. I would say that 9 out of 10 piston/cylinder problems are in hole #6. Two reasons... One, its farthest away from the water pump and has less coolant circulation. Two, its fathest away from the oil pump, meaning it sees slightly less flow/pressure to the piston cooler nozzle.



I have seen plenty of knocks due to stuck injectors, but thats rare. Usually a stuck open injector is accompanied by plenty of white smoke. If it is stuck closed (even more rare), then the knock you hear is actually fuel being forced back into the injection pump.



If the cylinder is deeply scored, then yeah, engine out time. If it is only slightly scored, it can be honed and repaired with the engine in the chassis. Granted, the trans has to come out, but thats not really that big of a deal. Easier to do that than pull the engine out!

 

[keimmmo]

I have no way to listen to your sound clip. But, a sticky injector DOES sound a lot like a rocker arm noise. The 01. 5 gets to knocking like that once in a while. A good dose of injector cleaner and/or ATF will clear it up rather quickly. Also, the fact that Bio changed the knock would point me toward an injector... more lubricity in the Bio and a change in the knock.



Steve Keim

 

[ThrottleJockey]

Jesus, quit driving it.

 

[ata]

My money is on Evan Beck. 1. He's worked on a lot of these little 5. 9's. 2. Any time you get a knock in an engine and the knock doesn't get louder when you keep driving it. It all most always turns out to be a bad wrist pin in a gas motor or a scored cylinder in a diesel.

 

[CAROLINA CUMMINS]

Hello,



I'm with Evan too. I just finished a complete rebuild of a 5. 9 in a 97; that scored #5 because of a plugged oiler. It was so loud it hurt to crawl under the truck and listen. When I would crack the injector line to #5 the knock would all but go away. Hope it ain't, but it sure sounds like it.





Steven

 

[DMannon]

OK, so I have it in at San Luis Truck, which is the local Cummins service center. He started it up today and checked cylinder temps. #6 is running 50-60* COOLER than the rest.



He pulled the injector and it seems to work OK. Pumped it up to 250-ish bar and said the spray pattern looked as it should. He's got a call into Cummins to find out the exact bar it's supposed to open at.



Tomorrow AM he'll check the compression compared to #5. He's skeptical about the scored cylinder, said he'd expect some significant blow-by out of the breather with a score or bad rings. There's none of that... .



Any input? I'll update as I hear more. Maybe I should take some bets on this, see if it'll help pay for the repair.

 

[DMannon]

Well, they got the pan off yesterday... all the rod and main bearings were scored. Good news is the crank, cam, wrist pins are all OK. None of the cylinders were scored and it had even compression across all of them.



They said they found what looked like green plastic granules in the oil. Also, that an oil analysis would've shown the babbit material and some copper from the bearings.



After seeing the bearings, it surprises me that it had good oil pressure.



Should have it all back together this PM.

 

[J. Steve]

One solved, one to go! I haven’t been able to post about my problem for a few days, I’ve been in and out of town a lot with work this last week, but hopefully hearing all these suggestions and DMannon’s resolution I can make some headway. Thanks for all the help and I’ll know more tonight/ tomorrow.



DMannon: do you have any idea about the source of your green plastic granules? Is there any way to get all of these out before putting it all back together to prevent a reoccurrence or a later plugged main bearing journal resulting in a scored cylinder?