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RobM626

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

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is this a mechanical or electronic engine? I know the mechanical engines suffered from worn throttle return springs and governor issues that made the engine surge but this was only when running down the road. if its doing it when parked I would look at engine related such as flywheel,clutch, or possibly internal parts or timing issues. 

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Has anyone mentioned the flywheel housing itself?  If ever removed or replaced it needs to be dial indicated/centered to the crank when installed. Most of the time they are within specs but I remember the old timers having to drill and re-pin some. I'll look in the manual in the morning 

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7 hours ago, Lmackattack said:

is this a mechanical or electronic engine? I know the mechanical engines suffered from worn throttle return springs and governor issues that made the engine surge but this was only when running down the road. if its doing it when parked I would look at engine related such as flywheel,clutch, or possibly internal parts or timing issues. 

Etech. Does it while parked

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4 hours ago, turckster said:

If the flywheel is out of balance the issue should show up as soon as the the engine is started. You can unbolt the clutch and pry it back from the flywheel, start the engine and if you have a vibration then it could be a flywheel issue, crank issue or so forth. If it runs smooth as silk your issue is else where. Most people do not check flywheel housing run out  on the e-tech engines because they are a fixed dowel. Older Mack flywheel housings could be adjusted but not e-techs. If the flywheel housing is out of round then it must be replaced. 

An out of round flywheel housing can cause many issues like premature clutch failures, input shaft seal/bearing failures, spigot bearing failures and etc. 

I’ll ask the mechanic tomorrow

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Out of curiosity how would the housing get out of round or flatness if it was never touched ?

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1 hour ago, RobM626 said:

Out of curiosity how would the housing get out of round or flatness if it was never touched ?

It may have been bad before, then parts got worn or replaced it made the vibration show up.

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3 hours ago, Mack Technician said:

2000 = fixed dowel

I wondered that. It seems your right after looking at the manual. It was 30 years ago that I saw the guys drilling and re-pining them so that would be about right. The manual still shows you checking run-out though. But if its over .010" it dont tell you what to do about it. 

Edited by Mackpro

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As I recall it was popular for the engine (steel) to fret the bellhousing (aluminum) and cause a leak at joint-point where engine, oil pan and bellhousing meet. The aluminum becomes the sacrificial metal in that stress battle. They went to a steel bellhousing and discontinued the aluminum. You can only buy a steel bell now.

12 years I never saw an aluminum bell replaced for anything other than fretting at the aforementioned 3-mate point. They're well built. The spotted fretting was minimal and accounted for less than 5% of actual engine-to-bell mate surface. It was an oil leak issue really. Only silicone is sealing that motor together (sleeves, block housings, bell, etc.) it relies on perfectly machined trueness of mate surfaces.   

IMO....... Mack bellhousings don't die, they are murdered. If someone let half the bolts fall out of the transmission and it started torquing around your going to kill the mate surface or crack something. Turkster is right on, its a "boots on the ground" inspection and diagnostic. Go see if a magnet sticks to the bell.   

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I would like to have a fix more than anyone... in the meantime my mechanic hasn’t checked out any of the ideas you guys gave me BC they have been busy working on my 2012 mack... they told me “just drive the truck, it’s at 95%” 

its really sickening to me that that’s the reply I get. Especially since Everytime I keep driving the truck I have to end up replacing something else. I think he really doesn’t want to drop the tranny again to check the flywheel/ bell housing and flywheel balance. I’m gonna keep pushing though... he said he definitely will check the crank endplay and runout . Hopefully today... 

i wish I could find a better mechanic around here. The sad part is, when it comes to every other truck except this one they actually do a very good job. They’re one of the only shops in the area that do a shit ton of in-house work... I guess this all goes back to my luck, or lack of luck... if it was raining pussies I would get hit with the only cock.

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another thing to look at is crankshaft runout. I've seen the flywheel mounting flange non perpendicular to crankshaft centerline due to wear; (bent crank). An indicator on the crankshaft flange will readily reveal this as the crankshaft is slowly rotated through 360 degrees of rotation. Dirt/rust buildup precluding the flywheel from mounting squarely onto the crankshaft hub/flange will also appear to be an unbalanced condition but this can be seen before the flywheel is removed from the crankshaft. Only time I've really seen flywheel housing wear is when the bolts were not adequately tightened after a clutch change, or missing bolts altogether allowing things to move when they shouldn't.

I don't know but it certainly appears, ( to me at least) there have been a lot of variables overlooked in favor of swapping parts on your nickel.

to find vibrations which are so deep seated I use a set of glue on transducers/accelerometers and monitor each with a portable oscilloscope individually. This works well but is expensive.

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2 hours ago, Rob said:

seen

I think it definitely is the crank. The more I listen to it and feel the noise the more I’m convinced so. I went back to the shop 3 times and asked him to check it out for me and Everytime he told me he was busy... yesterday he was in the middle of a valve adjustment and said that if he messes that up the motor could blow... I said well my motor definitely is going to blow... I’ve been running the truck for a year and a half like this because the mechanics keep telling me “ just run the truck “ or “ I can’t have everything perfect , the truck is 18 years old”

i have a feeling my crank and block are going to be shot and unusable for a rebuild. And mind you I did an inframe on this motor like 4 years ago

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12 hours ago, Rob said:

if it were me, (and it's not) I'd get the pan off the engine and transmission out. Using two hydraulic bottle jacks, force the crankshaft up into the block and remove the back four main bearing caps. Then plastigage those bearings for clearance. This sounds like the crankshaft is "wollering" around in the bearings from what I've seen in the past. Usually running like this results in crankshaft breakage and hopefully you are not to the fatigue stage yet. Ensure the bearing clearances are even and there is no scoring. Would be a good idea to roll a new set in if nothing bad or out of tolerance is found. After the main caps are reinstalled, pry the crankshaft side to side at the rear main as there should be virtually no movement. If side to side movement is detected, set up an indicator to ascertain how much there is. Then pry the crankshaft fore and aft in the block again looking for movement, or "walk". Fore and aft movement is usually "shimmed" to tolerance.

Gets expensive when you have to pay for the labor; especially labor that is non productive. Far too many "swappers" out there whom read a computer to tell them what to change than good qualified mechanics these days. Your problem seems be into the dynamics of what make the machine operate which are not being evaluated deeply enough.

It feels like I have excessive walk. Everytime I press and release the throttle I feel a slap in the transmission. And with time it just keeps getting worst and worst... it’s eating up my clutches and a transmission. 

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16 minutes ago, RobM626 said:

It feels like I have excessive walk. Everytime I press and release the throttle I feel a slap in the transmission. And with time it just keeps getting worst and worst... it’s eating up my clutches and a transmission. 

has thrust on crank been checked?   terry

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3 minutes ago, terry said:

has thrust on crank been checked?   terry

No..they told me they were gonnna check it when they replaced my vibration damper and when they did the clutch and never checked it .. and last 3 times I went to shop over the past week they didn’t have time

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15 minutes ago, Rob said:

Get under the truck and remove the dust cover on the bottom of the flywheel housing. Pry the crankshaft with a bar or large screwdriver to the rear. Mount an indicator on the crankshaft pulley/dampner/ balancer and block, then zero the indicator. Pry the crankshaft forward in the block till it seats and note the deflection of the indicator. If this is out of tolerance for crankshaft "walk", you could have either a worn out thrust bearing, or a worn thust surface on the crankshaft.

Any shop that would tell me they don't have time would not get any of my business.

Thank you... gonna try to get a dial and check it myself

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don't think you'll have a 1/2 hour of your time wrapped in this before finding something positive in reference to a solution.

Block can be align honed back to new condition if not destroyed. Crankshaft if bent or suffering from fatiigue will need replaced. I don't favor inframe overhauls on off road trucks citing the damage, (twisting usually) a crankshaft can suffer from the severe duty they endure. Kind of difficult to thoroughly evaluate a crankshaft if it remains in the block during engine overhaul.

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52 minutes ago, Rob said:

don't think you'll have a 1/2 hour of your time wrapped in this before finding something positive in reference to a solution.

Block can be align honed back to new condition if not destroyed. Crankshaft if bent or suffering from fatiigue will need replaced. I don't favor inframe overhauls on off road trucks citing the damage, (twisting usually) a crankshaft can suffer from the severe duty they endure. Kind of difficult to thoroughly evaluate a crankshaft if it remains in the block during engine overhaul.

I agree completely... who knows what the condition of crank was during the last inframe. And after the inframe oil pump was bad that wasn’t replaced and camshaft as well... this thing is a money pit

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Ifthe enginehas had a overhaul then who knows it may have some pistons mismatched.

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