Demolished 3B Piston Sleeves- what caused this? (1 Viewer)

[Sykoslug]

For all of the engine failure sleuths out there, I have a great mystery for you to help me solve. I finally got around to stripping the head off of my most recently failed 3b and can see the condition of the cylinders, bearings, gasket, etc. It's very interesting and I hope someone can tell me why they think this happened.

A short history of this engine. Purchased to replace a similarly failed 3B, no real history on mileage or condition, only that it had been a running engine before being pulled, then it sat in a storage shed for some time, then was installed in my cruiser. I had a shop doing the install for reasons I can elaborate on later. Once installed the engine displayed a lack of power, barely able to run because of low oil pressure (the shop simply adjusted engine idle to make it stay running), but no other obvious problems. I decided after I took possession of the vehicle to test compression with a massively inaccurate pressure gauge (Harbor Fright), leading me to conclude that I needed to refresh the motor.

With the engine in the truck I lightly honed the cylinders, installed new rings, and con-rod bearings, had the head tested for cracks, valve grind with new seals, and installed fresh pre-cups and new MLS head gasket, per FSM. *Of note, when removing the oil siphon from the bottom end I observed finger-tight banjo bolt on the oil-pickup line, perhaps the cause of my low oil pressure...

Having assembled the engine (took me about 6 months to finish the job) I started it up and began the break-in process. Oil pressure was great, power was mediocre. As this is running a turbo, I played with fuel and wastegate to get it tuned, but it never really improved to what I used to in my first turbo 3B nor to what I have heard others report. One of my last attempts to find the sweet spot in thing was to install a small FM air-air intercooler and have the injectors rebuilt (apparently fuel had varnished in them). After a few miles of driving around with these updates, the motor went BANG!!!!!!!!!

3rd gear, flat ground accelerating modestly. Fuel and boost were on the high side, and sadly in hindsight, I believe my boost gauge line was cracked and not registering correctly so I'm not 100% on boost but it was as high as 15-20PSI. Of note, it had the power I felt like it had been missing right before the failure.

Pulled the oil pan to find large chunks of metal...

Today, I know to what those chunks once belonged: the #1 Cylinder Sleeve, Compression rings 1 and 2, and the Piston Skirts. Also noteworthy are the cracks forming around the tops of the the number 3 and 4 sleeves... What's interesting is that the exact same thing happened on the previous motor and that one had been fully rebuilt at great cost by a shop and lasted about 1.5 years or 10K miles. I have yet to read of this happening in other 3b's.

Here are some dismaying images:

 

[gerg]

lots of cylinder pressure from turbo and extra fuel with increased heat from ring friction during initial break in = ring ends touching and seizing on cylinder?

 

[Sykoslug]

Greg, that seems possible. What I find interesting is the fracture pattern on both engines around the very top of the sleeves where the block ends - very little support there.

I wonder if all of this was because a cracked boost pressure line led to a leak and mistakenly thinking boost was far lower than it actually was and the resultant turning up the juice. What's worse than no info? Bad info.

 

[roscoFJ73]

Those bearings look a bit worn and worn unevenly, maybe its the pic.

Something not right with the parts, badly fitting or incompatible parts from another engine possibly. It needs a full rebuild with all parts checked closely for spec

 

[gerg]

Extra air from your turbo doesn't do anything catastrophic to the engine. Piston skirts breaking off.....have pics up close of the piston and its ringland? The affected cylinder also looks like it has severe glazing compared to the others. Really high temps in there? I have to say ive never seen liners fail in that way either. Very weird stuff.

 

[Sykoslug]

Those bearings look a bit worn and worn unevenly, maybe its the pic.

Something not right with the parts, badly fitting or incompatible parts from another engine possibly. It needs a full rebuild with all parts checked closely for spec

Agree on the bearings. That's 600 ish miles on those bearings... Crank was also similarly marred. The engine looked like it's had a previous rebuild. The con-rods and caps have stamped #'s. One set of stamped numbers match 1-1, 2-2 etc on one side of the units, the other numbers don't match. I'll take pics and load up in a later comment.

 

[Sykoslug]

Extra air from your turbo doesn't do anything catastrophic to the engine. Piston skirts breaking off.....have pics up close of the piston and its ringland? The affected cylinder also looks like it has severe glazing compared to the others. Really high temps in there? I have to say ive never seen liners fail in that way either. Very weird stuff.

I honed all 4 in the same fashion. The #1 sleeve is totally absent. Completely shattered and missing. Is that the one looks totally glazed?

 

[gerg]

Wow, my mistake sorry. I guess it's just the block I was seeing. I wonder if your liners were hammering? Only thing I can think of to explain the one that's partially cracked up top.

 

[roscoFJ73]

Agree on the bearings. That's 600 ish miles on those bearings... Crank was also similarly marred

Is there any end float on the crankshaft?

Any ideas about the injection pump ? Just wondering if it was part of the original problem

 

[Sykoslug]

Is there any end float on the crankshaft?

Any ideas about the injection pump ? Just wondering if it was part of the original problem

I'll check the crankshaft end float, that wasn't checked in the refresh.

The IP might be the smoking gun. It was transplanted from the previous engine that had experienced the same failure on the same cylinder. The only modifications to it were a new gov diaphragm back in 2009, Mercedes 240D Spring (which I no longer advocate), Max fuel adjustments, and slight timing retard.

 

[FJBen]

When you did the refresh, did you happen to deck the head or make any changes there?

Almost sounds like wrong liner protrusion which could cause the top lip to crack and liner to bust apart.

 

[ceylonfj40nut]

^^^^ this. FSM has specific run out tolerance on liner protrusion. Milling will affect this. As will a gasket that is not the proper thickness for the new milled tolerance.

 

[Sykoslug]

In short, nothing was done to the block/liner relationship. The liners were only honed in place. The head wasn't milled or decked - just cleaned, valves ground, and pressure tested. The one variable that changed was use of an MLS head gasket from Engine Australia vs the fiber-type gasket that was in there before.

I have read in other build threads and in FSM that when new liners are installed, special care must be taken to ensure the protrusion is correct and that the tolerance is very fine. It is a consideration for when I rebuild this engine.

 

[gerg]

Liner protrusion is critical and easily overlooked.

 

[FJBen]

In short, nothing was done to the block/liner relationship. The liners were only honed in place. The head wasn't milled or decked - just cleaned, valves ground, and pressure tested. The one variable that changed was use of an MLS head gasket from Engine Australia vs the fiber-type gasket that was in there before.

I have read in other build threads and in FSM that when new liners are installed, special care must be taken to ensure the protrusion is correct and that the tolerance is very fine. It is a consideration for when I rebuild this engine.

So yes you are correct, you absolutely have to get that block/head/liner relationship correct.

#1 there could be different MLS gasket thickness available, if you have the wrong size on, thats bad as @ceylonfj40nut alluded to. I know on the 13BT was showing 1.5 and 1.6 thickness, not sure which part number you got from Engine Australia.

#2 the head and the block must be much smoother for an MLS gasket vs regular head gasket for it to work correctly. I know some have gotten away with that, but any warpage or too rough of a head/block can cause issues

#3 Liner Depth/protrusion/headgasket: , here was the info from my 13BT rebuild from the machine shop, (per my rebuild thread link in signature)
The block was shaved down 2 thousandths so that the liner protusion would be correct as 2 of the cylinders were out of spec and sitting too low.
From there you have to set the counterbore so that the liners are the correct depth and equal.
The liner protrusion (not the ridge) needs to be .4~.39 of a thousandths ( close to 1/2 a thousandths) or about the thickness of a piece of paper.


Liner protrusion is how far the liner (not ridge of liner) sticks above the block. This is important because if the liner is too low, the liner can actually move up and down causing the liner to break, and most likely a failed headgasket or worse. Too much is bad as well as you won't get a good seal, which pretty much guarantees a leak and failure. Both are bad and don't allow the headgasket to crush seal correctly.

I will say, my 13bt even "out of spec" made it 485,000kms until a blown coolant hose caused a blown headgasket and piston/liner scoring necessitating the rebuild. They are tough and forgiving.

Unless there is something terribly wrong with the IP/injectors causing a meltdown in that same cylinder, I'm leaning towards that headgasket/liner thickness relationship.

Lastly, here is some good info I found:

WRONG CYLINDER HEAD GASKETS
The wrong gasket can introduce angled force action into the flange, either because the diameter of the combustion chamber border is too small or the gasket has the wrong thickness.


PROPER MEASUREMENTS MUST BE TAKEN
Make sure that proper measurements are taken. Otherwise, it will get expensive: a broken liner will move gradually in the direction of the crank shaft after the engine is started. When the location of the liner break is level with the first piston ring in TDC, the piston ring springs open above the break location. At the next downward movement of the piston it pulls the cylinder liner downwards. The rotating crankshaft can shatter the liner, piston and connecting rod.



hope some of this helps:

 

[gerg]

I didn’t think liner protrusion influence the liner as far as movement. However, It will have dramatic influence on your head gaskets seal and lifespan.
Never seen a 13bt gasket up close but if there is a .1mn difference in thickness I doubt it would allow for piston to cylinder head contact. I do think if it did contact it would be evident on the piston itself.
In the past I’ve retorqued fiber gaskets and then later replaced it and found that The liner contacted the cylinder head in some spots. It is possible for a fiber gasket to compress enough to allow the liner to contact the cylinder head and not have piston to cylinder head contact. If that’s the case then I doubt a difference in .1mm would be a problem.

 

[grayjs]

I don't have as much technical info to add compared to the diesel guru's above, but a similar scenario happened to me when I rebuilt my 3b a few years ago. Toyota decided they would sell me a B head gasket rather than the 3b in which I needed. Went ahead and installed it without realizing. Was not able to turn my engine a full revolution by hand. Thankfully I had not tried to start it yet. So I pulled the head and found the pressure from the wrong head gasket had broken the liner protrusions on all cylinders. Ended up pulling the engine and doing a full rebuild...

 

[roscoFJ73]

The IP might be the smoking gun.

I was thinking it may have been related to the poor power, rather than the engine damage

 

[Sykoslug]

FJBen, I can attest to the damage done when the liners come apart from the ridge and allow the liner to creep towards the crank....I don't know if that is precisely what happened in my case, but based on the broken material and the evidence of other liner ridges in the early stages of cracking...I think that's what went wrong.
Here's an image of the number one piston damages. Noticed it's naked piston...no skirt on it!

 

[Sykoslug]

I was thinking it may have been related to the poor power, rather than the engine damage

Oh that's a good point, but the IP was working great on my first motor so I brought it over to the replacement. I did have to get my injectors rebuilt, so the pump may have also been varnished after sitting so long on before going into the replacement motor.