6.5 knock? Piston slap? Fuel Delivery issue?

[smillysmil]

Posted on Facebook and the comments I got were "normal", "possible injection pump", "run 2 stroke oil in fuel", and "use ATF in the fuel". Wondering what steel soldiers think.

A while back I made a post about a smoking exhaust. I ended up doing all the glow plugs, all injectors, and fuel filter. Thing runs like champ! Except 1 thing. I have some kind of piston slap or something and it's loud and annoying until it warms up, where it is still there but hardly noticeable. I had this issue beforehand but assumed it was a clogged injector or something.

All original glow plugs and injectors were intact (it was a reman engine so paint was chipping off as I took plugs out). I have not done a compression test yet.(money is tight sry) Only smoke is on cold start (little puff). There is absolutely zero blow-by. No oil burning, No misfires, and no effect to performance.
Oil pressure is 60psi cold and 20ish warm

Just wondering if anyone has seen this before. Because I cannot find this same sound/issue on the interwebs.

Video 1 is coldish idle and video 2 is 220f idle
https://youtube.com/shorts/FHXKLt2Ie8Y?feature=share, https://youtube.com/shorts/31vn3lia6-0?feature=share

Edit 1: I've ran 2 tanks with Diesel Kleen. Also, The noise is almost gone with any throttle input.

 

[Mullaney]

Posted on Facebook and the comments I got were "normal", "possible injection pump", "run 2 stroke oil in fuel", and "use ATF in the fuel". Wondering what steel soldiers think.

A while back I made a post about a smoking exhaust. I ended up doing all the glow plugs, all injectors, and fuel filter. Thing runs like champ! Except 1 thing. I have some kind of piston slap or something and it's loud and annoying until it warms up, where it is still there but hardly noticeable. I had this issue beforehand but assumed it was a clogged injector or something.

All original glow plugs and injectors were intact (it was a reman engine so paint was chipping off as I took plugs out). I have not done a compression test yet.(money is tight sry) Only smoke is on cold start (little puff). There is absolutely zero blow-by. No oil burning, No misfires, and no effect to performance.
Oil pressure is 60psi cold and 20ish warm

Just wondering if anyone has seen this before. Because I cannot find this same sound/issue on the interwebs.

Video 1 is coldish idle and video 2 is 220f idle
https://youtube.com/shorts/FHXKLt2Ie8Y?feature=share, https://youtube.com/shorts/31vn3lia6-0?feature=share

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I can't swear to it, but I can't help but wonder of you don't have a leaky injector. A leak in an injector could cause you to have an "early fire" condition where the explosion inside the combustion chamber sounds like a "rod knock".

You mention "little smoke on startup". That could point to the leaky injector as well... Removing the injectors and having them tested might be a good place to start.

 

[smillysmil]

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I can't swear to it, but I can't help but wonder of you don't have a leaky injector. A leak in an injector could cause you to have an "early fire" condition where the explosion inside the combustion chamber sounds like a "rod knock".

You mention "little smoke on startup". That could point to the leaky injector as well... Removing the injectors and having them tested might be a good place to start.

That could be the case. I just never imagined that would be it since I’ve put in all new injectors. But maybe the line was clogged before hand.

 

[Gcelevator]

It is hard to hear in the video but it sounds to me like cold advance is stuck on, and i might be totally wrong but thats what i pick.
If not, try disconnecting one injector at a time and find the culprit. Good luck.

 

[smillysmil]

It is hard to hear in the video but it sounds to me like cold advance is stuck on, and i might be totally wrong but thats what i pick.
If not, try disconnecting one injector at a time and find the culprit. Good luck.

I have a feeling I know which cylinder it is. Tried the disconnect injector trick but not for long and kinda hard to hear when the engine is sputtering. Every time I try to record a video of it, its hard to hear over the motor running. But caught this video where you can hear the clatter at about 5-6 second mark. Coolant temp was 180. https://youtube.com/shorts/bQNa06kEMWs?si=Qu0QHT6IYfpr2b7G

 

[smillysmil]

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I can't swear to it, but I can't help but wonder of you don't have a leaky injector. A leak in an injector could cause you to have an "early fire" condition where the explosion inside the combustion chamber sounds like a "rod knock".

You mention "little smoke on startup". That could point to the leaky injector as well... Removing the injectors and having them tested might be a good place to start.

I was thinking the smoke on start up was a normal thing. I then started thinking maybe some kind of injection pump timing issue. Because I sometimes experience kinda like a blueish smoke while the engine is cold and I'm accelerating down the road for approx 20 seconds. If I smash the accelerator the engine will come up to a high RPM and starts to sputter and smoke like crazy until it finally wants to shift into second/third gear. So I thought throttle position sensor is off but multimeter reading doesn't look too bad.

Took a look at injection pump and the timing grooves don’t align. Could this be apart of my problem?

 

[Mullaney]

I was thinking the smoke on start up was a normal thing. I then started thinking maybe some kind of injection pump timing issue. Because I sometimes experience kinda like a blueish smoke while the engine is cold and I'm accelerating down the road for approx 20 seconds. If I smash the accelerator the engine will come up to a high RPM and starts to sputter and smoke like crazy until it finally wants to shift into second/third gear. So I thought throttle position sensor is off but multimeter reading doesn't look too bad.

Took a look at injection pump and the timing grooves don’t align. Could this be apart of my problem?

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That timing mark being like that isn't a problem - most times. You can put a mark with a center punch so you can get back to where you were BEFORE YOU MOVE the pump. You can align it to "center" and see what happens.

Also, have you looked at the Cold Advance yet like Gcelevator suggested?

What about the injectors? You mentioned new. Did you drop one while installing it? Not trying to insult you, just trying to look at all the options...

 

[Gcelevator]

I have a feeling I know which cylinder it is. Tried the disconnect injector trick but not for long and kinda hard to hear when the engine is sputtering. Every time I try to record a video of it, its hard to hear over the motor running. But caught this video where you can hear the clatter at about 5-6 second mark. Coolant temp was 180. https://youtube.com/shorts/bQNa06kEMWs?si=Qu0QHT6IYfpr2b7G

Yes, now i could hear a metal clanking in this video.

 

[Mogman]

Have you gone through everything bolted to the engine, all the mounts like the alt etc?

 

[smillysmil]

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That timing mark being like that isn't a problem - most times. You can put a mark with a center punch so you can get back to where you were BEFORE YOU MOVE the pump. You can align it to "center" and see what happens.

Also, have you looked at the Cold Advance yet like Gcelevator suggested?

What about the injectors? You mentioned new. Did you drop one while installing it? Not trying to insult you, just trying to look at all the options...

Although the timing mark is off I doubt that's my primary issue.

A while back I checked the cold advance for continuity and I thought I had something. I couldn't find any of my multimeters so I did not test continuity or voltage. One of my AM General Manuals says to turn to run position, disconnect both wires, connect A to B, and listen for an audible click, which I did not hear. So might end up buying a new cold advance for shits and giggles.

I do not recall ever dropping an injector.

 

[smillysmil]

Have you gone through everything bolted to the engine, all the mounts like the alt, etc?

I have gone through everything I could think of. Mounts, brackets, etc and I have not found anything out of place or loose. when I get under the truck while it's running you can practically pinpoint where it's coming from. It resonates from the side of the block and when the truck is cold it is loud.

I am almost entirely convinced it is a Piston Slap. It acts exactly like one too. As soon as I bring up the idle with the throttle lock, you cant hear the noise at all. Anything past an idle you can't hear it. idling while hot you can barely hear it. Idling while cold just sounds like a marble bouncing in a sealed glass jar (almost).

I just have to decide if I should let it ride like that until it blows or just pull the motor now.

 

[ikoinu]

Any luck on your diagnosis?
Bad injector or lifter?
I've got the exact same issue.

 

[smillysmil]

Any luck on your diagnosis?
Bad injector or lifter?
I've got the same issue.

Not much luck with the diagnosis. One of the first things I did was the injectors myself which helped it run better than when I got the thing but I have no change in the primary issue. I've driven it 1200 miles, (according to the odometer) I've run a few bottles of diesel Kleen and it runs great but still has that slapping sound.

My theory is they ran it low on oil and the piston carved up the wall leaving too much clearance and the piston is slapping the walls. Again just my theory.

It's a deep loud noise that I hear more from the side of the engine than the top. I took it to a reputable (to me) auto shop so they could compression test it or something. They ended up just joyriding it for a week and telling me this employee’s old man worked on them in the late 90’s and said it sounded fine. I was not happy.

I currently drive these daily in the military so I can tell you this engine is not okay.

 

[ikoinu]

Thanks for the update.
That's unfortunate. Shop certainly sounds questionable. Certainly not normal operation.

My unit went dead due to old fuel clogging the fuel shutoff valve in the high pressure pump.
Cleaned the system, freed the valve, bled the injectors and got it running. Now have the knock. Sea Foam through the intake and in the oil at idle has not cleared it up (yet).

Will test the injectors to see if that's the issue.

 

[smillysmil]

Thanks for the update.
That's unfortunate. Shop certainly sounds questionable. Certainly not normal operation.

My unit went dead due to old fuel clogging the fuel shutoff valve in the high pressure pump.
Cleaned the system, freed the valve, bled the injectors and got it running. Now have the knock. Sea Foam through the intake and in the oil at idle has not cleared it up (yet).

Will test the injectors to see if that's the issue.

For sure yeah. I’ve been working with that shop for almost 10 years and I just couldn’t believe it. It’s whatever.

So you had the truck before it made that noise? Mine came from the auction like this. I’d be interested to hear what yours sounds like. I guess in theory it would make sense a lack of fuel or a clogged injector would create some kind of noise. But I am not a Diesel mechanic.

I did injectors shortly before my new fuel filter showed up so hmmm. Maybe new injector is clogged. I don’t get misfires, performance is not effected, and I have no blow by. It’s just that sound.

 

[ikoinu]

Quality of service is not what it used to be unfortunately.

I've had it for 6 years now. Was a daily driver, but California has cracked down on rights and it has been parked for a few years with battery charging and weekly starts.

So, sound is gone. Started it today a few times, no lifter knock or injector noise. Business as usual. The sound was a hard clack, sounded like a stuck lifter up top.
Running a 16oz container of Seafoam into the crankcase and one through the intake (in small amounts) and letting it idle for a half hour did not seem to fix it very well that day, but after sitting for a couple more it appears to have cleared up.

Might be worth a try for you.
Now to change my oil.