The Mystery Knock...

Written By Lance Drivon
With a Bottle of Melrose Merlot 2006

:spend:It all started out in that nice May evening in 2010 installing my new plate, gauges and exaust. After installing them all and about to take off on her maiden voyage after startup I draw in a tip off a Snap-On pick that the previous owners mechanic had broke of in the inercooler boot that I wasnt aware of. BANG BANG BANG BANG.....I went cold. The riveting noise of that hollow clock clock clock noise.... SO I take it to a Mechanic who works on Big Rigs and light duty Diesel trucks. They pull the head,drop the pan. Head gets milled and magnufluxed. New genuine cummins parts gets put into engine. They said the engine looked virgin. New Piston. Cleaned cylinder. All back together and ready to seat the rings on the #1. I run it nice for about 2000-3000 miles and then start working her.So within the last few months I notice a noise.

So I had accidently brought her to :nono:1600* 2 times for 4-6 seconds each time but didnt notice any noise after.(:thumb1:I was showing my dad My 96 could kill his 01...and it did.) Not the transfercase rattle:nono: but another noise. So I fix the transfercase rattle and now I can hear it beter.. Hours with a stephascope under and over the engine. I replace the following just to get rid of the common little things people always neglect to do..


New Liftpump...
New Overflow Valve...
New Fuel Filter....
Injectors Pop tested and adjusted by Oregon Fuel Injection...
Adjust Valves...
Pull all return lines and supply lines away from cab...
Adjust valves...just incase the first time was wrong...

The noise is still there. When I brought it back to the Mechanic they said they hear something but its nothing they reconize. I take it the next day to another diesel mechanic and its not there at idle this time. At 65 you can hear it claping away like a hydraulic lifter but softer. Some days its louder. Somedays its hardley noticeable. It has become more noticeable at idle cold sometimes.. Sometimes not.. Your really have to squint and listen to it sometimes and sometimes you can hear it just over the combustion noise of this loud critter and its crazy injection pump.

Things I am thinking starting in order of what I think..

Piston Melted from hot pulls at 1000-1100* and the few short times of 1600*?

#1 wristpin boss in piston cracked and making noise acording to heat or cracked piston?

Exaust valve hitting piston because a thicker head gasget not used when put back on?

P7100 pump #1 plunger getting hit by its cam causing a clap knocking sound. The reason I say this is that the #1 injection line will make your ears bleed and the rest of them sound the same to each other. Your ears will be numb a little and ring after listning to the #1.

rod bearing but unlikely with the noise. Its not getting louder and louder...It comes and goes in volume. Seemes louder when colder <sometimes>.

The truck runs smooth. No white smoke. Starts great in cold mornings. 35 psi boost and I adjusted the afc with a regulated air supply to get the settings close. I am thinking of buying a bore scope and inspect the pistons. I found out From Moparman1973 the injector nozzels are 9/32" so i found a bore scope for $100 with a 5.8 mm head and shaft I can use to inspect them. I have to order it but I need some input on will a injection pump make a noise when the plunger is getting stuck or if a piston is melted or cracked smacking the head or cylinder.

Hope someone has had something like this before and I am starting to warm up the old knuckes for some finger bleeding work here.

Thanks in advance guys!

My wife is convinced I have gone mad but she has a 2001 2500 and she understands whats its like.....VP$$.......:evilgrin:i mean VP44

Did you run a magnet across it to see if it ferous or non-ferous metal?

It's non. Magnet didn't touch anything.. picked up sample bottle today..

Narrows it down to piston or bearing/bushing. Hard to see in the videos, But it looked too shiny for either so It could be chrome off cam lobe or follower. Can't remember right off if the lift pump has a lever or roller that rides on the cam if roller it could be chrome from it as well.

The lift pump has a tappet. Solid rod with mushroom end that rides on cam.When I went to go start her to heat the oil up to take a sample I noticed it did Something it never did before and it seemed to have a slight miss.. not bad so I am thinking that cylinder is starting to loose compression and not firing. After a few seconds she smoothed out besides that noise... Took a sample.. off to the mail tomorrow to cat for the verdict.

Well considering when your talking to Mr Wizard when your talking to CAT and having them check your oil. The saw an increased amount of Al that would be normal but nothing to do but watch whats going on..I said "Watch"? I can hear it...They filtered it and called back. They said the sample contained too-big of Al to make it into their graph,chart.ect. He said yup alot of Al. tin-0 silver-0 copper-1 lead-0 bearings look good on ppm...SOOO Money and decisions...head comes off...look for carnage...

Dont forget the pics:hyper:

Motor pressure washed. Injector lines off, wire harness removed. Intake off and valve covers loosened. Tomorrow push rods,return line exhaust manifold and whatever else gets in the way...Ok one note: upon Psi washing I covered the BHAF. NOTE NOTE NOTE: DO NOT FORGET TO UNCOVER IT AFTER WHEN YOU MOVE TRUCK INTO SHOP. IT WILL ACCORDION AND COLLAPSE! My wife had the giggles after I puled it out to show her.... I reminded her that her Vp-44 is still bad and she promptly continued doing other things

--- Update to the previous post...

Head off and I found......Notaphuckingthing..I Did place a 6 pack sequential in a row that looked awesome but promptly drank them.I'm wondering now... Aluminum.... How many aluminum parts are in a p7100

--- Update to the previous post...

The p7100 IS aluminum.......hum... Wondering if something is tearing up in pump... Pulling it off and sending to oregon fuel injection to be tested and inspected.

my truck has a similar knock as well, i would dare to say it is a timing knock.it will be noticeable as it gets worse, (if it is)i know that my vp-44 has a fuel leak and the fuel is leaking into the engine oil, and as a result the truck hard starts when cold and has high EGT's all of this started right after i had the skinny pedal down for the count.In the process of avoiding an accident my trucks rpm's went from 1,200 to 3,000 rpm's in a flash, and the engine never acted the same ever again.

Pump is off. Decided a change of venue. I called Industrial injection and they will test and calibrate it for about $150. They also have new head bolts and head gasget for $189. Cummins Parts. I have fingers crossed that they will find something that doesnt seem right. I will keep updating. Now just need to find enough foam and a box to pack this thing into and send it off.

Pump is off. Decided a change of venue. I called Industrial injection and they will test and calibrate it for about $150. They also have new head bolts and head gasget for $189. Cummins Parts. I have fingers crossed that they will find something that doesnt seem right. I will keep updating. Now just need to find enough foam and a box to pack this thing into and send it off.

Nothing against II but I hope you got that figure in writing as they usually charge more for repairs than they do to sell you a different pump, I know of this happening with them on several occasions.

Thank you for the heads up. Trying to save money. Its about $100 more sending to OFI. Anyone else have any sugestions to help me out on where to send it? All input welcome!

You can still send it to II just make sure you specifically let them know that the price they stated will be stuck to. If they do make repairs make sure you talk to them and discuss pricing before the repairs. I know of people sending in VP44 pumps to repair thinking that it would be chaper and when the final bill came they could have bought a reman from the a lot cheaper.

The pump tested good. They adjusted the plungers and timming. Will be installing soon.what would a single exaust leak sound like say the #1 exaust manifold gasget leak sound like? Would it be louder than a 460 or a 454 exaust leak... Louder and perhaps metalic due to the amount of exaust coming out from it because of higher compression? The noise did quiet down when it heated up... This would be embarassing if all it was is a exaust leak.

It didn't sound like an exhaust leak, I got lots of leaks down my exhaust and my forsake exhaust valves never sealed, that was more of a choking backpressure sound.

I did order new head bolts and head gasget from cummins, The head was milled .010 last year but the gasget they had on it was stock. I ordered a .010 over gasget..

you do have a interesting though here.i have suspected for a long time i had a exhaust leak up by the engine, because of the smell of exhaust gasses, but with the excessive leaks on my tail pipe line i always figure they came from there.

Injecton pump balanced and timed.Timming set for 15.05.New head bolts and .010 head gasget.Valves adjusted to .08 and .18Noise is MIA. The normal noises are there but not the one that was there.Clutch started slipping and found that #6 valve cover was leaking oil so I gave it a simple green bath and Psi bath and now its fine.The torque procedures for this engine are interestingly different than what I expected and I was able to time the pump in the first shot.

Glad you got it fixed!

I highly recomend everyone to pull your inectors and pump off to be recalibrated. My truck runs smoother, quieter and makes the fuel plate,afc smoke screw and pre-boost starwheel so much different that my truck set at 15 advanced has made me very happy along with the new over flow valve and lift pump.200k mile small investment...