The Old XUD DervBus Thread!

[darrenjlobb]

Its all stripped.....

As said before, AT THE TIME of failing, the oil was bone cold, i had only been driving for 5-10 minutes, hence i was totally off boost at the time.... And normally the oil gets to 90-100 ish and i lift off to let it cool down (oil cooler STILL not fitted....)

Anyway, onto the more interesting things...

Basically ill try to simplify the damage, because man i wanna know what is going on here, and ive got lots of theorys, but no idea what order / what cause....

But physical damage....

- Camshaft snapped in 3 places (and both left and center bearings caps snapped in half)
- Conrod no exsistant, (but this always happens as it flys around until the engine stops, and looking at the range of damage it has made, im certain the rod snapped at the LITTLE end....not the big end)(The big was was still fully attached, and spinning silky smooth)
- Piston smashed up on one side, but not enuf to let the wrist pin come out, so i think this is just damage from the flying rod....
-Inprints in all pistons from smashing valves
- All bearings throughout the engine looked in excellant condition, EXCEPT the big end bearing shells on the rod that broke, which have worn down to copper...so clearly an oil issue here....)

And obviously the obvious damage, like two gaping great holes in the block!


So lots of ideas....starting with the camshaft, after it broke the first time, its obvious that all the other brakes, are just from where it being stopped, and valves wide open, the other pistons have smashed up home on the valves, and just broke the camshaft in more places, you can see the inprints in the pistons....but what caused the first snap...did it happen by itsself, or maybe just the flying piston after the rod broke...who knows....

Obviously there must be some kinda oil issue, becos the rod bearing was worn very badly....but why just this one, blocked oilway in the crank?? but still seemed to spin really smooth, must have worn over lots of time, so even this to me, i cant see how that would make it throw a rod totally off load....

Wondered if maybe the cam could have snapped, number 1 fires, then the exhaust valve couldnt open, meaning insane cylinder pressures on the rods way back up....but then, thats if the cam broke first, which i think is unlikly...

Hm....confusion to say the least...some pics....

So anyway.....

Engine back out yesterday evening, 2 1/2 hours work, working alone:



Initial damage....pretty standard!













And the worn shell on the failing cylinder...