Cankshaft

[TBusclas]

Four weeks ago got in truck and started and with clutch depressed sounded like throw out bearing shot, about 30,000 on Southbend 1947-OFEK. Disappointing but not the end of the world, had to drive that day so limped along little clutch usage as possible and after half dozen or so shifts noise quit. When got truck home again shut it down and little later had to move it and when went to start starter locked up, well my first thought then was starter, grabbed new starter and put on and rattle/metal contact returned but not as severe so I went back to my original thinking of quirky throw out bearing or something coming loose in the clutch. Now long story short, have changed out clutch, pressure plate, flywheel and swapped out three starters and still have the metal contact when clutch depressed. Called Southbend and they are telling me more than likely the thrust bearing is shot and that is sounding right to me now as approximately 57,000 miles ago had a high spike in metals on oil report, steel (iron) and brass/bronze (copper) parts. At that time I was seeing/knew of nothing external going on so we changed out oil ran 2000, changed out again at 5000 and increased change out intervals as lab results dictated and metals have now returned to normal the last 15,000 miles. I am out and don,t have access to manual right now and can someone give me the max end play for this motor. If mine is out of tolerance, as I now suspect, going to drop the pan and depending on condition of crank roll in a new thrust at a minimum. Anyone else ran into this or have some insight?
Thank you,
Tom

 

[cerberusiam]

I think the crank end play is .006 to .012, if you have more that .012 then the thrust bearing like broke off and fell out, fairly common failure on the factory thrust bearing.

 

[EricViviano]

.003 - .017 is what the 2004 FSM says

If your going to go to the trouble of rolling in new bearings on the bottom end, I would do them all, crank and rods.

 

[DavidC]

I think the crank end play is .006 to .012, if you have more that .012 then the thrust bearing like broke off and fell out, fairly common failure on the factory thrust bearing.

WHAT!!!!!!!!!!!!. 100 years building diesels and they cannot make a thrust bearing. Now that is very disappointing.

 

[Ozymandias]

WHAT!!!!!!!!!!!!. 100 years building diesels and they cannot make a thrust bearing. Now that is very disappointing.

Good for the ones with AT Trans, no force on that Bearing.

 

[DavidC]

Good for the ones with AT Trans, no force on that Bearing.

Well that's good news. Losing a thrust bearing after the 53 episode would not make me very happy.

 

[TFucili]

Wouldn't it still see thrust one direction under acceleration, and the other under decel with the TCC locked, especially with an exhaust brake, no??

 

[DavidC]

Wouldn't it still see thrust one direction under acceleration, and the other under decel with the TCC locked, especially with an exhaust brake, no??

Tom, don't ruin my feel good at the moment with practical logic

 

[cerberusiam]

WHAT!!!!!!!!!!!!. 100 years building diesels and they cannot make a thrust bearing. Now that is very disappointing.

Yes, yes it is.They used the cheap 2 piece bearings in the factory builds. Clevite has a 1 piece pretty much every one updates to because the OE ones break off and rattle around or fall out.

Happens on automatics all the time also. The torsional harmonics beat the crap out of it.

 

[Ozymandias]

Wouldn't it still see thrust one direction under acceleration, and the other under decel with the TCC locked, especially with an exhaust brake, no??

Nope, not an ounce. The TC catches that all as it is just slides into the Trans.
The manual clutch kills the trust bearings, always so.

The Engine itself doesn't produce sideload on the crankshaft.

The AT itself has also Trustbearing(s) in it, so no pushing against the engine.

 

[GCroyle]

Oz,

Clutch at release pedal on floor every action has an equal and opposite action, right? You're applying maybe 450-500 lbf to the clutch to hold it released. Thrust bearing has to deal with it. Foot up, no more force applied. The OEM G56 SAC has a lower release load.

But doesn't a torque converter in lockup have pressure applied into it to force the piston to lockup? That force has to be reckoned with. Now, i'm just throwing that out, i know nearly doodley squat (nearly nothing) about AT's. I admit it. But i've seen the internals of a few torque converters and they have friction material on the engine side side of the lock up piston and oil pressure pushes the piston and locks it up. At least the ones I had in my hand did. Nearly clueless about current stuff.

TDR, fire away.

Gary

 

[DavidC]

The million dollar question. If it is known to be a problem why would Cummins continue to use it ?.

 

[TFucili]

https://www.google.com/url?sa=t&sou...Vaw1Xsdhgep24gy1oTe1m64Cl&cshid=1565829420330

 

[Ozymandias]

GCroyle that piston is internally in the TC, just the fluid goes into.

 

[dieselshadow]

A TC contains that pressure on both sides. It’s not “pushed” one way or the other during lock or unlock. Quite simply it’s nothing like a throwout bearing pressing against a pressure plate (which in turn pushes against the crankshaft.)

Think of it this way, you can hold a hydraulic cylinder in your hand. If it’s maxed out, your hand would feel any pressure unles you pressed it up against something. The TC is on a splined shaft and held solid by being bolted to the flywheel. The engine or the trans “feels” nothing when the TC goes to lockup.

 

[cerberusiam]

Question that has been asked many times, only answer that seems viable is $$. It isn't an epidemic thing but it is known issue.

The clutch or TC put very little over all strain on the thrust bearings because it isn't a constant force. there will be loads both front and back depending on whether the engine is under power. Theoretically it should balance out most of the time with the torsional thrust and beveled gears. The only real problem with a manual is when someone rides the clutch all the time under low loads. Not only does it mess up the throw out bearing it is constant pressure on the backside of the thrust bearing which normally takes the least load.

TCC is all internal in its application, it just locks the TC components together.