Engine knocking LDS-456

[Oerthedge21]

I had kinda figured this noise was normal, as I've had some other diesels that made a similar noise, but after asking a few people who said that doesn't sound right for a deuce, I got a little concerned. I searched on here some and I found an old thread about somebody's LDS (my truck also has an LDS) with a very similar noise which ended up having a melted piston. My truck is a 68 that was rebuilt in 89 and had an LDS dropped in which according to the tags was also overhauled that same year, and only has about 25k on it now. I was poking around at it while it was cooling down after I got home, and I noticed that although you don't feel anyhting by touching the block, heads ect in various places, injector lines #2,3 and 5 feel like someone is tapping on them with a hammer, while 1,4 and 6 just vibrate and shake with the rest of the engine. The difference in feel is very noticable. The knock is definitely louder when cold, and as far as I can tell is present no matter what rpm the engine is at. Anyone ever heard of something like this before? And which set of tests do y'all think would help me most here? I was gonna start craking lines and try a compression test too but I don't wanna get too far in yet since I'm relying on this truck as my daily driver for the week while I pick up another car. I'll try to post up a video of the noise soon, I don't have great internet right now so my phone isn't too keen on loading a video into here

 

[frank8003]

Use the heat temperature device thingie First to compare cylinder to cylinder.
It is a huge internal compression engine.

 

[cattlerepairman]

As for the injector lines: They are all different lengths, so will vibrate differently. Are they all tied together in at least two places?

I am with Frank...take a laser thermometer and check each cylinder (exhaust). Is there one cold one among all the hot ones?
What does your blow by look like when you open the oil cap? If it is puffing smoke, it is an issue. If there is just a bit of lazy haze...not so much.

Maybe you can shoot a short 10 second video with sound and share it?

 

[Oerthedge21]

Ill try to get my hands on one of those thermometers tomorrow, along with a video. In regards to the injectors lines, I'm not sure I'll look tomorrow, I just found it strange how fierce the difference was. The blowby looked somehat heavy for what it should be, and I checked the oil again a little while ago and it looks like it's been slowly making oil so my hopes are pretty low already, really sucks.

 

[cattlerepairman]

Well, thinning out the oil because of one of the internal fuel leaks (well known....do a search....FDC, hydraulic head, flame heater are the most common culprits) would certainly make it get louder....less lubrication, less "cushioning", more blowby. If it is only that, it is a few O-rings and an oil and filter change, in the absence of any real damage! Better than a hole in a piston. You did not mention "milkshake" so I figure it aint coolant in the oil.

 

[Smokindodge]

As for the injector lines: They are all different lengths,

Nope. Absolutely not. Dead Wrong.

Every mechanical pumped Diesel engine has injection lines of the same length. Otherwise the injection timing would be off. Even most of the common rail diesels have similar length lines.

To the OP: pull the oil fill cap while it’s running, see if you can feel a definite “chug chug chug” of air blowing. Also don’t be scared to crack an injection line a 1/4 turn loose while it’s running on each cylinder to see if any of them make a difference. Once you identify a problem cylinder diag gets easier from their.

 

[frank8003]

Nope. Absolutely not. Dead Wrong.
Every mechanical pumped Diesel engine has injection lines of the same length. Otherwise the injection timing would be off. Even most of the common rail diesels have similar length lines.

Duh on me, I never even thought about equal length and why but that is why some line are looped around a few times. And the multiple bracket fuel line keepers need to be there. Thanks.
View attachment fuel system best picture.pdf

 

[Oerthedge21]

Oil is all clean, just a little dark. The FDC was already bypassed when I got it, so sadly I know it won't be that easy. The flame heater has also been disconnected. I'm gonna try cracking the lines later today when I get home, as well as checking the exhaust manifold temps. I'll try to get a video up here of the blowby as well as the noise. I had noticed too, but never really bought much of it, if the truck is cruising around 45-50mph, so around 2k rpm, it'll seem to kind of skip and hop around at times. The best way I can describe it is like when you got a real rough part of the road and your foot bounces around on the throttle and the engine gets kinda choppy until you smooth your foot out. It'll do the same kinda thing. As soon as I let off or give it more/put it under load however, it will immediately stop doing such. K was hoping it was maybe a HH related type issue but wouldn't that produce symptoms all around the rpm range as well as power loss issues too? The HH or a bad injector are kinda my last hopes here

 

[cattlerepairman]

Oerthedge21, your suspicions have not yet been proven wrong. Still on the rule-out list. Does your oil smell of diesel fuel and appear to have thinner viscosity? How does it drip off the stick? Motor oil should "stretch" and coat the dipstick. Oil with diesel in it tends to "bead" more (water-like), making big drops. Wow, super scientific....
If your truck is "making oil", it does have fuel (less likely, coolant) leaking into the crankcase.

 

[Oerthedge21]

It doesn't look too thin yet, but the level has definitely risen since I changed it. It doesn't smell either. For the exhaust manifold temp check, should I drive the truck around and get it hot before checking it, or should i just start it up and see which cylinder ports heat up quicker and reach a higher temp? And what exactly am I looking for as indication of an issue, a cylinder with a lower temp or one thats hotter than the others?

 

[cattlerepairman]

Start, let idle, check manifold at each cylinder, back and forth. You will see the temps rising at each cylinder - unless it is not firing. At those, the manifold will stay noticeably cooler. It will all warm up somewhat but it will not get the same heat as with an operating cylinder.
I would not drive the truck until the issue (or issueS) is/are identified, simply to avoid unnecessary wear and tear on bearings and moving parts.

 

[Oerthedge21]

Ok so I'm looking for a cylinder that's cooler than the rest. Will do, I'll report my findings/test results later today

 

[Jeepsinker]

You need to change your hydraulic head o-rings and probably the boost pump seal too. Need to stop the fuel in oil contamination first and foremost, then move forward. Running it with fuel in the oil is hard on bearings and cylinders even if not under a load.

 

[Jeepsinker]

https://youtu.be/w7svtxE4AwM

 

[Oerthedge21]

So you think it's coming from the IP then? And I know, I drive it as little as possible but I have to get to work and this truck is all I have right now. I'm in the process of picking up a car this weekend, but until hen sadly I have no choice.

 

[swbradley1]

Duh on me, I never even thought about equal length and why but that is why some line are looped around a few times. And the multiple bracket fuel line keepers need to be there. Thanks.
View attachment 773400

You and I both learned something new.

 

[Jeepsinker]

So you think it's coming from the IP then? And I know, I drive it as little as possible but I have to get to work and this truck is all I have right now. I'm in the process of picking up a cat this weekend, but until hen sadly I have no choice.

Absolutely coming from the injection pump. Replace the hydraulic head o-rings and the boost pump drive seal and you'll be good to go until something else breaks.

Your knocks could be cylinder liners that are coming apart. That's what happened to my LDS465-1A, which is why I've spent so much effort installing a Cummins.

I surmise that the cause of many windowed blocks is actually the bottom of the liner shattering, catching the piston, and then blowing the rod out the side. Mine didn't window the block because it locked when I was starting it and it hadn't even reached idle speed.

 

[Oerthedge21]

I guess I'll order up the IP seals then. I'm gonna do the exhaust manifold test before I leave work today anyway since we have one of those IR thermometers here. Hopefully they come out similair and the HH is what's giving me all the trouble

 

[Oerthedge21]

https://youtu.be/IyIvpZ7acHs
It's quiet from the engine bay, much more noticeable in the cab.
https://youtu.be/lfqlYC_jsL8

I pulled the fill cap while it was running, engine hot, and the smoke does puff out, if you out your hand over the hole you can feel the gasses pulsing out which I'm pretty sure is a bad sign.

 

[Jeepsinker]

Yup. Start looking for an engine or planning a swap. You have damaged pistons and/ or liners. These engines really aren't worth the cost to overhaul anymore for their average lifespan ( 40-50K miles)