So #7 injector went out and my buddy drove his truck for a while with the injector sometimes coming back on and then going out again so we changed it with a new injector and granted the new injector has a much louder click than the old injectors but I don't think this knocking noise we're hearing is the injector. I'm pretty sure it's something else but I wanted to get input from the diesel gurus.
What do you think of this knocking noise? What do you think it is and what should we check?


When we changed the injector we drained the oil rail so that it wouldn't drain into the cylinder but I'm sure we still got a little in there. I did stick a cloth down in the injector hole with a grabber of some sort that my buddy had so we could wipe up the oil in the injector hole and keep as little as possible from getting into the cylinder.

We however didn't have any tools to press the injector back into place so we pushed it in as far as possible and set it in using the bolts that hold the injector down and torqued it to about 10ft lbs.
Could it be the injector isn't seated all the way?

 

Dont forget that you have to put some miles on the truck to work the air out of the system. When I do injectors I dip them in clean oil and presss them in by hand, I them take a rubber mallet to tap in in the final amount needed. If you have doubts at all that the injector is not seated properly then by all means check it.

Have you run any tests with AE to buzz the injectors etc with the new one in?

 

Sure did' buzzed real nice. #2 and #6 are sounding a bit worn but are working, #7 is now very pronounced.

A rubber mallet is kind of hard to get on number 7 and 8, how did you managed to get any sort of momentum back there?

 

It may be that the solenoid on #7 is much stronger thus opening and closing the injector with more force.

It was not easy but a few short "taps" and they pop in for me. The last set was on Platinum Petes truck and I used the same method.

 

humm, well it almost sounds like a mechanical knocking noise. It doesn't sound healthy. Should we remove it and reinstall it?
We didn't pre-lube the injector before putting it in as it already had some oil on it from packing.
My buddy says it almost sounds like a bent rod. I have to agree, it doesn't sound good, mine doesn't knock at all like that.

 

I would remove and check the o rings for sure. I take a can of clean oil and dip them in it. I use a small pump to go into the GP hole to suck out as such oil as possible, then cover the GP holes with rags, remove the fuse for the pcm and then turn the engine over to purge any oil that may remain.

When you first started it after the install was there any chance that there was oil or fuel in the cylinder and she may have hydrolocked? Or did she turn over freely and fire off as normal?


I have to run to work now I will check back later.............

 

It didn't act hydro locked but it did sound like a GP or two may have ignited some fuel in a cylinder or two when trying to get it started.
When we turned it over there wasn't any resistance in the starting that I noticed, neither did my buddy.
We had to turn the engine over a LOT to get it to start once it was all back together. I was pretty sure it was because there wasn't any oil in the oil rail and we just had to fill it back up but we turned it over so much that we ran the batteries down and had to charge them back up.

 

I listened to it really closely and to me it just sounds like cackle fro me etrained air, I think I would put 30 miles of varied rpm driving on it than give it another recording for us to listen to, but I'm honestly not concerned at this point And Monty didn't even ***** an ear!
Jim...& fat Monty

 

Try just driving it and see if it quitens up. Also if you think it may be the injector, remove the valve cover and unplug it. See if this noise goes away. How much have you run it since the r&r?

 

Just a thought, but are you 100% sure that you have the correct injector?
I once installed an injector that I bought online for a spare. It knocked alot louder than the rest did, but the truck ran fine.
Turns out that the company sent me a "AA" injector by accident instead of an "AB"
AA's are single shots and are noisier than twin shots.

 

I can hear the knock and I agree, doesn't sound healthy.

My $.02 is that your injector isn't all the way in there. A loose injector can make a knock sound. It's best to lube the injectors really really well prior to installation because the o-rings can get damaged easily. What I do is hook the injector clamp over the top bolt and then use a short wooden dowel (about 1" dia) and a hammer to lightly tap the injector down in place. I place the dowel on the lower portion of the injector clamp where the second bolt goes. You will hear and feel a solid thud then the injector hits home.

I always turn the engine over by hand with a breaker bar before attempting a start after injector replacement. Seems like good insurance. I just lay the valve covers in place and turn the engine over about 8 or 10 times by hand with the glow plugs removed.

If it were my engine, I would pull the valve cover on that side, start the engine and see if the noise increases. A loose injector or broken glow plug will be obvious at this point. If you pull the injector, check the copper washer, if the injector was loose then that copper washer will probably be burned or gone.

Good luck!

 

Am am VERY sure it's the right injector unless the wrong cover was put back on it because it was marked AD and the injectors in the truck were marked AD.

 

Got it' thanks, I will report back, we're pulling the inject again tonight.

 

Check to see if you left the old copper washer in the injector cup

 

Take a straight edge and lay it across the top of the injectors. If #7 isn't seated all the way it will be obvious.

I've never had much luck diagnosing noises on the internet, but I don't think you've got a bent rod. Take the truck for a spin and get up to highway speeds, then let off the go pedal so the injectors go quite. My guess is the knock goes away when you do that. You can hear a little of it at about 1:19 in your video when you rev up the motor and then let off. Mechanical noises don't go away as long as the motor is still spinning.