HARD KNOCK AFTER LIFT PUMP REPLACEMENT

[david85]

Did you try a power balance test?

You can slightly loosen each injector feed while the engine is running line to temporarily de-activate each cylinder in turn. A bad injector that is knocking can be taken out of the equation that way. I know it's not very likely that running the tank dry will cause immediate damage to the injectors or the injector pump, but old components that weren't in perfect condition to begin with could get pushed over the edge, so to speak.

CAUTION: keep fingers well away from the high pressure connections when you do this. Fuel pressure is high enough to cause "hydraulic injection injury" which results in poisoning of living tissue beneath the skin at the point of injection (invasive surgery is the only treatment). Its not very likely to happen in this case, but wanted to put that warning out there for anyone else that comes across this thread.

One thing I don't see here is a description of how the pump failed. Did it rupture and fill the crank case with fuel? Or did it simply stop working? Did you do any kind of inspection of the old pump to find any clues?

 

[Ian Rebmann]

I did try a balance test but it was the first time I did one. The knocking never went away and I held each open till the engine started to bog. The nut to loosen is the one on the Injector correct. Not the IP right? Not sure if I should give it another go? I did not inspect the lift pump but there was no fuel in the case.

 

[nostrokes]

Yes the one on the injectors. Might want to try it again and open them up just a little more so it doesn't just bog but starts to miss and run rough. That way you know for sure the injector isn't firing.

 

[Thewespaul]

If you have someone to watch the tach for you the rpm should drop the same amount with each injector, you shouldn’t have one that either doesn’t drop any rpm or drops enough to make it die.

 

[gerlbaum]

I can't help but I had a mechanical fuel pump die on me. After I replaced it I had the same knock. I chased it for months - new injectors, lifters, rocker arms, and push rods. Nothing changed. Everyone on here said my valve was going to drop. It never happened. Tick remained just like yours, went with rpms but past 1500 or so you either couldn't hear it or it would go away. I used a mechanics stethoscope and could not pinpoint. I just drove it for a year like that. Finally I rebuilt my entire turbo system and replaced my pump with a Omega moose to accommodate.

Hasn't ticked since and that was 9 months ago. Now I have no idea why but my theory is when these pumps get tired timing on an individual cylinders can be slightly off creating bad timing on that individual cylinder and therefore the tick. I had timed my truck with the old pump on it. New injection pump, same timing and no tick. I honestly have no idea but my theory is all I can figure.

 

[gerlbaum]

BTW I do not believe that running out of fuel caused the issue. I believe it may just be the old nail in the coffin on a tired pump, or at least it puts enough of a strain on it to finally case it to go out of spec enough.

 

[Thewespaul]

That sounds like a lot more than a tick to me, that’s a strong knock. If you’re seeing any smoke at all I’d say the issue is fuel related, but if the exhaust is clean you’re probably looking at a mechanical issue.

 

[hesutton]

Have you drained your oil since this happened? If so, was it thin and had a diesel smell to it?

These mechanical pumps can dump diesel fuel into the crankcase when they fail. If that happened.... you could have a damaged engine.

I'd change the oil just to be sure.... wouldn't hurt to do a used oil analysis on that oil as well.

Heath

 

[Ian Rebmann]

*UPDATE*
sorry i was finishing finals and had to focus on those alone.
i drained the oil just to be sure there was no diesel and i would say pretty confidently there was not. i also put water in the old pump and actuated it and water did not come through on the arm side. When I started her up with the new oil the knock got quieter. it didn't disappear completely and it came back to full volume with in 10seconds can someone connect these dots? another issue is the fact that there was sum metal particles and a few shavings in the oil that i found when i flipped and drained the filter.

as for the power balance test i had the same results. i even loosened the nuts so fuel was spraying upwards. I also decided to test 3 injectors at the same time and I thought she would of almost died but the bog was only slightly worse then with a single injector test. which makes me think the injectors are still getting enough pressure and fuel. the engine still sounds strong while testing every injector.

I wrote up to this point a few days ago and today I went to go tinker around further inspected all the glow plugs connections male (the glow plug itself)and female. Then I found a bad seal on a vacuum box above the OEM water separator also right in front of the steering wheel replaced that (there are vacuum lines that run from that line to the IP any body know the purpose?). I bought a general chilton manual and im not impressed Anybody have a good manual they use?. then when checking the oil dip stick it is very hard to read on one side it will be right above the add line and on the back its extremely high and vice versa depending on the direction in which you put it in. i have never had a dip stick have this problem to this extreme of a level. when i started her up the noise deafened completely but then coming back after another 10 seconds or so. I am thinking I will just add more oil but because of this dipstick error and I already put in about 11.7 quarts with filter replacement id like to see what you guys think?

 

[Hydro-idi]

Sounded exactly like my engine when I had a brand new hydraulic lifter that collapsed.
I would pull valve covers and see if you can depress any of the rockers with your hand. If you find one that depresses easily, bingo.
I think the lift pump change may have just been a coincidence, and not related to the engine tick that your having.

 

[Hydro-idi]

I’ve also heard both a valvetrain tick & an injector knock with these engines.
It sure sounds like you have a valvetrain tick listening to your vid.
Just my .02

 

[Ian Rebmann]

there was a mention in the past of MMO, any thoughts? i would have to let it run and most likely drive her for a considerable amount of time for there to be any effect right? ive never used MMO before its a dilution product right? you cant just fill the fuel filter with it? and do not feel safe driving her. I also have another can of lubro molly if any new readers have thoughts on that purge. I went through one can with out creating two separate fuel cycles so It went by pretty fast.

 

[Hydro-idi]

I’ve had great luck with the stuff. You could try a couple quarts in engine oil to see if that clears it up.
But.....I would strongly advise that you pull valve covers first to confirm a collapsed lifter if there is one.

 

[79jasper]

There are no vacuums lines on a diesel, minus the vacuum pump itself.

Sent from my SM-G892A using Tapatalk

 

[Ian Rebmann]

just pulled the cover on the side it seems to be coming from. visually everything looks great i couldn't get a rocker to budge with physical force. however the bolts holding the cover on were not tight obviously they were holding it down and oil wasn't seeping through to noticeably but could that be the knock? the cover seems like it could produce a sound like that if pressure is being released and pushing against it with every rotation. Im going to wait to throw the cover back on for a few minutes if you guys have any more tests or things to look for? ive heard of people running the engine with the cover off to see if that offers any more clues but that seems dangerous.