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:
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: