Usually when this happens first, it will break the crank....you thinking that is what happened.

Every time I have lost thrust control it brakes the crank the exact same way....of course was it material failure that you lost the thrust brg or was it ……

Did you assemble the bottom end on this one...and if so how did you set crank thrust....

 

I haven't been through the bottom end on this one; it was a stock shortblock at the time. I'm honestly not sure about the stock tolerances; but its something I need to look into at this point. The complexity of this issue (I think) extends to metallurgical analysis that is far beyond my capabilities...

 

i have to go along with our admin. i also have seen many detriot and cummins engine snap the cranks just as yours when the thurst bearing surface on the bearing fails and allows the crank to walk back and forth in the block.
infact the boat that is in my avitar is one of the snapped crank motors.

in each engine i had to repair like yours, each was a goosed motor and each one snaped just as yours in the counter weight/throw area.

carefully check the block where the thrust bearing sits, as you may find the block is bad right there. look for scores and with a new bearing to be sure it is tight on the sides, by useing a micromiter and vernier. messure the inside of the new bearing between the thrust flange and the block thickness for the main bearing flange.it should be a very snug slip fit. if to loose junk the block. here even a few .000 is to much.

good luck man .

 

Checked the block; no galling or marking from the crankshaft (just some stuck -on bearing that came off with a dremel tool and a wire wheel). The new bearing is just as tight going on as any of the others I've worked with.

From looking at the old thrust bearing (or rather, whats left of it) it appears that for whatever reason one of the "ears" of it (the thrust portion) cracked and broke off into the oil pan. I know of no way to determine which failed first (the bearing or the crank). Any thoughts on this one?

 

bearing!. as that would allow the crank to move back and forth."to much end play" as shown in the snapped flex plate. that would cause the rods to bind up along with the pistons when they have to **** in the bores trying to move up and down. then when they bind snap there goes the crank.

i am thank full you that the block is Ok. esp as i have seen many damaged.

 

Matt, did you make sure that the torque convertor is not ballooned? I'm absolutely positive in your case that you have (or should have) installed an aftermarket TC, but anything's possible regardless of manufacturer. That will kill a thrust bearing and/or flexplate in short order. Just covering all bases, man.

Cody

 

Matt, send me some more pictures when you get a chance. I have seen more than a few broken cranks, that one broke or the crack started in the 7/8 throw. Which direction is the active thrust in the 6.0 twards the flywheel or the waterpump end? What did the radius of the main look like (whats left of the radius on the throw that broke, rod and main? As far as checking the block to see if the saddle is damaged, check the crush and the i.d. on the bearing without the crank in. When you get a new crank (or even a good used one) I would check the web deflection with the rods out, and then with the rods in. That main hole may be off location, and very capable of withstanding 400hp, but with the increased load, may have been enough to snap it. The easiest way to check the block main bore alignment is have a mandrel made to the size of a std. crank journel and the length of the crank. Have a good bevel on each end of the mandrel. It should slide through without hanging up and also turn freely with all bearings installed an fully torqued.


Now which happened first, the thrust left and took the crank with it? or Visa-versa. To break the thrust bearing like you are desrcibing it, I am betting the crank broke first and the shock or impact got the thrust.

 

Soooo, is this covered under warranty??





jk



https://www.ford-trucks.com/forums/5...ew-2007-a.html



VERY interesting read!

 

matt, you have any update on the broke crank? do you have the engine running yet?

 

any updates?

 

yea... you talk to cass yet????