983B crank seized, now what?

[tdoats]

@khansen - this is a pic while it was operational about 2 hours before it shut down... I have a video of it running, but not sure how to upload a video here - you can't hear the engine purring over the tracks coming down the road though... the point is that the engine was running smooth as silk prior to locking down. Now, I've got the bucket blocked up with boisdearc stumps, but it is not high enough to gain access under the arms. I had to take the hood off (300 lbs of steel) to expose the top side of the engine for access.

I have not rotated shaft yet between torque converter and transmission... that's on the "to do" list when I get back on site

@Queenslander - thanks, that's what I'm going for is the one off ideas that others have seen happen

 

[Heavey Metal]

The main thrusts are 1/2 s and loose held in by the main cap.

When they get enough wear slack in the crank or thrust a sudden jar ( like backing out of a hole or the torque ballooning) can cause them to double up

Or fold they will also get a ramp wore in them and jump up on the main cap.

Your symptoms ( especially no movement) indicate this or a galled main ( I would expect to see at least .05 end play)

Pulling the main cap will tell

Also the torque could have the end play in a bind as was mentioned ^^^^.

 

[Willie B]

I'd be very surprised if the crank is seized. Likely there is a piston melted in a sleeve. Once you get past the belly pan, and oil pan, assess the crank, and accurately measure its journals. pending its condition, & whether you must turn/replace the crank. Get new sleeves & pistons. Likely you can make repair in the machine.

 

[nicky 68a]

I'm still wondering what's in all the filters and screens that the professional mechanic that checked it over didn't cut open?

 

[Bob11x]

Well- how did it turn out?

 

[tdoats]

Check all rods for side to side movement, Then look for a spun main if the crank has no end play.
Later Bob

Crank not seized ... movement north and south slightly. All Main Caps move slightly, and all Rocker Caps move slightly, cam shaft moves... nothing appears to be locked in the engine

 

[tdoats]

Okay, a few years later. Finally had a "right sized" CAT big enough in the area to brute force push the 983B out of the ditch and up to level dry ground - Thanks # Jody Preas

Engine inspected by a sound CAT mechanic, bottom side all intact - nothing frozen, slight movement with every main and all 6 rockers, as well as CAM shaft reveal that it's not seized in the engine proper. All filters are clean from debris.

Rear #10 shaft turns freely, between Transmission and Torque Converter - so no problems in the rear trans. Lowered the access cover and drained the TorqConv - no debris and no noticeable breakage.

Attempted to back engine off with reverse force - no joy, no movement in crank - absolutely none.

Starter won't touch fly wheel, same as when it went down.

Now going up to the Hydrolic Pump - removed fluid, going to remove that pump from the fly wheel to rule out the back side of the engine.
Removed 30 Gal of HydroFluid, noticed screen intact in bottom of tank - so no debris went from "Tank" to high pressure "Pump" thru that screen... thinking something is wedged somewhere.
Once that's done / we will dismantel the front to see if the timing gears are ajar.

 

[tdoats]

I hope if you are working on that machine with the bucket up like that there is something very substantial I don't see in the picture holding it up!

Have you tried turning that drive shaft between the torque converter and transmission?

yes - turns easily

 

[tdoats]

I'am no mechanic, but a neighbour had a D6C present the same symptoms years ago.
Turns out the (output?) shaft of the converter sheared, the broken ends turned against each other, jacking the shaft apart and putting enough lateral force on everything to stall the motor and lock it up completely.:beatsme

Thanks - good idea.

 

[Queenslander]

If the shaft turns freely, I think you can safely disregard my theory.

 

[wrwtexan]

After thinking back on my 3208 seizing to the point it wouldn't move at all and finding a piston locked in a sleeve (but with obvious lower bore damage), I am wondering if maybe one has galled on the topside and without any visible damage below it in the sleeve. I am awaiting a bore scope that might be poked down an injector hole if possible. Not being familiar with this engine, I don't know if I can as is possible on my 3306, 342 or 3208.
I don't want to start doing a bunch of exploratory surgery without some reason for doing so.

 

[petepilot]

is there any further news on this thread am really curious what if anything has been determined ?

 

[Dave Neubert]

Are you sure you did not drop a valve i have seen the valve imbed in the piston freezeing it in the cyl.

 

[wrwtexan]

Most recent work on this project was to drop all rod caps and see if crank would free up. All pistons are free in bores. I had to cut 2 cap nuts off but crank still won't budge at all. I'm afraid the next step will be disconnecting auxiliaries then going into the timing gear train. Being as big as it is and not being able to get to the engine from such an great access design (sarc!!) this will be a royal pain in the a$$.

 

[Dave Neubert]

Well if the pistons are free and the crank is free I would wonder if something in the flywheel housing has come loose and wedged between the flywheel and housing I would pull the hyd pump first and see if you have a problem there either way I bet the enging has to come out

 

[kshansen]

Just did a quick read through of this thread.

Did not see any mention of the starter being removed, it was suggested at on point but did not see it being removed.

Reason I mention this is one time a few years before I retired the 988H at the quarry failed to start after being shut down for lunch break. Starter was making bad noises and when removed reason was obvious as the "nose" of the starter was missing. That is a pretty big chuck of cast iron to have loose inside a flywheel housing and I could see it getting jammed in there and locking up the engine.

In my case we were lucky and after about three hours of poking and shoving various things in from either side of the flywheel housing we retrieved the nose and there were only a few little pieces missing less that a grain of rice!

 

[petepilot]

from what im reading here sounds like my next step would be to loosen all the main caps see if the crank would move then . this sounds like a seized main bearing , but could also be a crashed gear train in front , even with that the crank should move back and forth somewhat maybe only 8/12 thous. but should move 1`m asuming this is a 3406

 

[Birken Vogt]

from what im reading here sounds like my next step would be to loosen all the main caps see if the crank would move then . this sounds like a seized main bearing , but could also be a crashed gear train in front , even with that the crank should move back and forth somewhat maybe only 8/12 thous. but should move

I think he said it does move about that much.

 

[Dave Neubert]

He said he had end play

 

[petepilot]

from what im reading here sounds like my next step would be to loosen all the main caps see if the crank would move then . this sounds like a seized main bearing , but could also be a crashed gear train in front , even with that the crank should move back and forth somewhat maybe only 8/12 thous. but should move 1`m asuming this is a 3406

well guess i missed that part