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RobM626

Vibration that 2 mechanics and Mack dealer can’t figure out

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6 minutes ago, Rob said:

With the pan dropped, did they check the crankshaft for twist which will show up as runout in the center of the crankshaft most times. This needs done at each main bearing crankshaft journal with an indicator as the crankshaft is rotated. Rebuilt a couple of engines where the crankshaft was not straight in the center from torsional stress and exceeded yield of the forging.

It's damned hard to be at the mercy of the mechanic; especially if they are on the wrong track. The small and "old time" shops tend to work with a customer if what they installed turns out to be incorrect or doesn't fix the problem. Very frustrating to "eat" what was misdiagnosed 100%. We are human and make mistakes and I always ran my business(s) with that thought in mind.

The last guy that worked on the truck pulled the pan and pulled every set of mains he said he couldn’t find a problem. He was also the one who found the burr and had his machinist smooth it out. It’s almsot impossible to do a full analysis if crank is bent with it still in no?

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It is easy. You pull one main cap at a time, set up an indicator on that exposed journal and rotate the crankshaft by hand noticing the deflection, (which is twist) while it is still installed. They usually do this prior to snapping/breaking and is usually a result from "dumping" the clutch while heavy.

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I am absolutely astounded the engine was not run without the transmission installed.

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1 hour ago, Rob said:

It is easy. You pull one main cap at a time, set up an indicator on that exposed journal and rotate the crankshaft by hand noticing the deflection, (which is twist) while it is still installed. They usually do this prior to snapping/breaking and is usually a result from "dumping" the clutch while heavy.

He did do that. But he told me there’s a possibility that there can still be a problem with the crank that will go unnoticed with the crank still in the engine. 

They also ran the motor many times without transmission installed. It sounds better. Much better. You dont have the gears spinning and chattering when it’s not installed so it makes you think the problem is after the flywheel

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I had a vibration once in a 237, it was running but the crank came out in two pieces!     terry:MackLogo:

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Posted (edited)

I would be interested in the setup he used to measure the crankshaft deflection. 

Was a sustitute flywheel tried? Was the crankshaft flange face indicated and measured? Was crankshaft vertical play in the block measured? Was balance on engine flywheel checked when removed from engine? 

Edited by Rob

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2 hours ago, terry said:

I had a vibration once in a 237, it was running but the crank came out in two pieces!     terry:MackLogo:

I've changed two crankshafts in 237's that have been driven in and the crankshaft was busted. Both right at the thrust bearing.

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7 hours ago, terry said:

I had a vibration once in a 237, it was running but the crank came out in two pieces!     terry:MackLogo:

I’ve heard especially Mack’s will run with a broken crank from numerous people

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5 hours ago, Rob said:

I would be interested in the setup he used to measure the crankshaft deflection. 

Was a sustitute flywheel tried? Was the crankshaft flange face indicated and measured? Was crankshaft vertical play in the block measured? Was balance on engine flywheel checked when removed from engine? 

I wish I knew the answers to those questions but unfortunately do not

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3 minutes ago, RobM626 said:

I wish I knew the answers to those questions but unfortunately do not

Can you ask? There are seemingly many avenues that were not tried or evaluated in the course of trying to repair this truck; all at your expense.

I don't mean to be belligerent but you have been through the mill on this and it's exactly the kind of "Bitch Problems" I always got stuck with when working trucks.

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4 minutes ago, Rob said:

Can you ask? There are seemingly many avenues that were not tried or evaluated in the course of trying to repair this truck; all at your expense.

I don't mean to be belligerent but you have been through the mill on this and it's exactly the kind of "Bitch Problems" I always got stuck with when working trucks.

Ill try and stop there one day and see if anyone remembers the details

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Was there ever a FIX to the original problem

inquirin minds need to kno

WotSezU?

cya

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On 9/26/2019 at 8:10 PM, Swishy said:

Was there ever a FIX to the original problem

inquirin minds need to kno

WotSezU?

cya

Sorry for the late reply, I haven’t been on here much lately. I ended up doing some work on the suspension . Changed springs and insulator pads and bushings and it tightened things up in the back. I’m pretty sure my problems are coming from the frame . I got a lot of flex going on throughout. Area behind cab where hoist for dump body sits as well. 

We were supposed to sell this truck and the 06 granite and buy a new truck to replace the 2, but the 06’ sold and the 00’ didn’t so we ended holding the 00’ and not buying the new truck yet. Dumbest decision to date. Don’t even get me started   On that lol. Gonna see how much longer we can get out of it. We slowed down a lot the past year. We lost 2 of our main contracts and don’t really have the work to warrant a new truck at the moment. Hopefully things turn around soon.

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Triaxles tend to have a good amount of twist/flex to them going down the road, simply because of how long they are.

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