Jump to content
RobM626

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

Recommended Posts

On 3/10/2018 at 5:36 PM, terry said:

Broken crank?

That is what I wondered.

If it happened after the dampener was replaced, is there something wrong with the dampener or the way it was done?

When watching the dampener/pulleys when the motor is running, is there any noticable wobble, out of round, or back and forth movement? 

The strange thing is, every time something is done to the truck it is okay for a while - and they are unrelated repairs.

Share this post


Link to post
Share on other sites

The damper was replaced recently after the problem persisted. I feel like the truck feels fine for a few days when they put new clutches in... then the vibration starts to rattle the hell out of the new clutch and then that slapping/clunking noise starts to come back Everytime the throttle is pressed and released. It’s not to noticeable if I run the more with just the flywheel on , BC I did that 2 times and figured maybe it’s the clutch.and they all look the same when I pull them . Uneven wear.

Share this post


Link to post
Share on other sites

I've purposely not went to the broken crank scenario yet. Usually with a broken crank if the engine continues to run it is significantly down on power, (due to timing issues) and tends to emit a strange but short "grinding" noise when either the starter motor is engaged, or the engine is shut down. This is from the pieces moving separate of each other. It also highly stresses the main saddles and webs of the cylinder block many times rendering them useless. The engines tend to break cranks towards the rear and this can allow the back part of the crankshaft to "woller" as mentioned earlier in the bearings. Pulling the pan and main caps will readily reveal this with a naked eye. One can also find it easily when checking the thrust clearance as when the crankshaft is forced to the rear of the block after being forced to the front, the front doesn't move which is a dead giveaway to a broken crankshaft. I think, (from memory which is fading) thrust is taken on main saddle #5 from the front in that engine.  

Systematic troubleshooting through proven tried and true methods is how you find, and engineer repairs that last. A real "shotgun" approach has been taken with this truck from the time of the inframe IMO. I mentioned I don't like inframe overhauls in a vocational truck citing the extreme duty they endure and I'm getting the feeling you are discovering why my stance is so strong.

Share this post


Link to post
Share on other sites
5 hours ago, Rob said:

I've purposely not went to the broken crank scenario yet. Usually with a broken crank if the engine continues to run it is significantly down on power, (due to timing issues) and tends to emit a strange but short "grinding" noise when either the starter motor is engaged, or the engine is shut down. This is from the pieces moving separate of each other. It also highly stresses the main saddles and webs of the cylinder block many times rendering them useless. The engines tend to break cranks towards the rear and this can allow the back part of the crankshaft to "woller" as mentioned earlier in the bearings. Pulling the pan and main caps will readily reveal this with a naked eye. One can also find it easily when checking the thrust clearance as when the crankshaft is forced to the rear of the block after being forced to the front, the front doesn't move which is a dead giveaway to a broken crankshaft. I think, (from memory which is fading) thrust is taken on main saddle #5 from the front in that engine.  

Systematic troubleshooting through proven tried and true methods is how you find, and engineer repairs that last. A real "shotgun" approach has been taken with this truck from the time of the inframe IMO. I mentioned I don't like inframe overhauls in a vocational truck citing the extreme duty they endure and I'm getting the feeling you are discovering why my stance is so strong.

All of the symptoms that you mentioned is exactly what the truck is doing. When turning on and shutting off... even when the motor is returning to idle there’s a studder before it reaches idle which I contribute to possibly being a timing issue. Like the sensor maybe be getting false signals from the crank not rotating straight...it just baffles me that guys on the internet  that haven’t heard, drove, or seen the truck can have a better idea of what’s going on that the people who actually had their hands on it... I woke up this morning fuming. I can’t wait to go to the shop today I have a lot on my mind I’d like to tell these guys

Share this post


Link to post
Share on other sites

Well I for one would like to hear the resolve to this issue if you do reach the fix for this please post it!

There has been quite a few posts lately that end up with no resolve!

And I also agree pulling the pan don't cost much and worth a look after you check the end play on the crank! could be a broken block  also who knows?  This is quite an odd senerio ! We had an  e7 with an od knock at idle presumed it to be injectors fuel knock piston slap bla bla bla ended up showing up as a cracked block after several months BEHIND the compressor! what we thought was a leaky compressor gasket!

Edited by fjh

Share this post


Link to post
Share on other sites

I feel this gent will keep us updated as he's been through the proverbial "wringer" with this truck. You are very correct about many signing up or logging onto a website to attempt to capitalize on other's knowledge to lessen their burden. Once their problem is resolved and gone, so are they. I tend to remember these type participants myself and am not quite so helpful the second go round.....

  • Like 1

Share this post


Link to post
Share on other sites

Yup I agree ! In my opinion that's what these forums are about! And I don,t mind sharing my experiences with people ! However its only polite to do the same back ! Alot of these guys have been nubies . The smoke one awhile back was a frustrating thread! Guy never posted what happened!  It may save some else grief at some point!There Ain't A big bag of money to be had in this game now ,Back 20 years or so a guy could make a buck NOW With all this Teck crap on the trucks your lucky to drive past a shop with out having to turn in to get something fixed or diagnosed !  

  • Like 1

Share this post


Link to post
Share on other sites

Well went to the ship again today and told them it’s getting worst everyday. Asked them to please put the dial on the crank and once again they told me they don’t have time that they won’t b able to do it until Thursday now

Share this post


Link to post
Share on other sites
1 hour ago, terry said:

I have seen thrust washers come out and you get a whole bunch of end play, and you do not a dial indicator on to tell if something is way out of limits, get a pry bar and get under and start checking yourself!   terry:thumb:

my 2 cents worth        I think broken crank can be eliminated for all that i have read it would have come unglued long ago  thrust washers out sounds more reasonable but not knowing mack engs. any better than i do i`m not sure they even have any . main bearings worn completelly out would create many of the symptoms described wrong size mains to begin with would do same .but would be an obvious oil pressure problem

  • Like 1

Share this post


Link to post
Share on other sites

Have you guys seen any cases where ur able to put in new bearings and it solve the problem? And have you seen bearings go bad in 4 years and pistons liners be fine?  I know it depends on if the crank has damage and if the block got damaged as well . I’m trying to look at the best case scenario.

the weird thing is, I have been doing oil samples every few months and besides the  on sample when I had fuel dilution because of leaking injectors all of the samples were great... no elevated metal levels. The notes stated better wear than universal averages. So I never got any signs of any bearing wear or top end wear from oil samples

 

Share this post


Link to post
Share on other sites
2 hours ago, Rob said:

I hate to say it but it's time to check your losses with this shop. Have another give a diagnosis in formal proposal and get the attorneys involved. You can do small claims yourself easily. If you can prove the work done as guesswork due to incompetence, you will come out quite well on reimbursement. Document everything and be prepared to present it to a judge. Not hard to do and with the funds expended over this ordeal, most likely worth the effort to right the wrong.

I really hate doing stuff like that but it’s really gotten out of hand... they had our 2012 granite in the shop last week for dpf problems. They baked the filter changed a couple sensors and a valve and gave us a bill for $5600. They did the same thing like 8 months ago and now again.now 3-4 days later I have a warning message come up saying dpf system fault. I keep telling them I think it’s a motor issue causing the dpf issue and they’re telling me no no no.

i just don’t think it’s right that we have to keep paying for incompetent guessing games when at the end of the day the problems aren’t solved

Share this post


Link to post
Share on other sites
47 minutes ago, carlotpilot said:

my 2 cents worth        I think broken crank can be eliminated for all that i have read it would have come unglued long ago  thrust washers out sounds more reasonable but not knowing mack engs. any better than i do i`m not sure they even have any . main bearings worn completelly out would create many of the symptoms described wrong size mains to begin with would do same .but would be an obvious oil pressure problem

I’m really praying it’s not as bad as I’ve been thinking. It’s hard to sleep at night with this stuff constantly going thru my mind

Share this post


Link to post
Share on other sites

                               The only thing I can add to this is a strange-odd issue I ran across years ago with a similar problem. Had a K100 KW with a Detroit 8V92 that had a clutch changed out

                                by another shop before it landed on our door step. Found the bell housing bolts were bottomed out but the bolts and washers were right up to the flat surface in

                                the bolt pockets on the bell and really no gap. But the bell was moving ever so slightly. Probably not your problem on this issue but thought I would bring it up.

                               

                                Truck Shop 

Share this post


Link to post
Share on other sites

When the truck is parked in neutral, running... when the vibration comes on and you push in the clutch does the vibration change or go away?

Share this post


Link to post
Share on other sites

The vibration stays the same but the clutch chatter eases a little bit

Share this post


Link to post
Share on other sites

besides putting a dial on the flywheel as suggested earlier  I was going to suggest getting under the truck and watching the flywheel spin in the inspection cover while running to see if its wiggling like the crank is bent. but if your oil samples have been good that kind of rules out any bearing slop you would get with a bad crank.  I know you said it has new injectors but one other test you can do fairly simple is to crack open each injector one at a time and see if the shaking goes away. I have never worked on Etec macks but if the injector is firing out of time because of a faulty ECM it can introduce a vibration. shuting down a cyl 1 at a time may be something to try as it don't cost anything.

 

Just throwing out ideas

Share this post


Link to post
Share on other sites

I dont think the truck is working tomorrow so I have a lot of stuff to try and some time to do it ... once again thank you for the suggestions

Share this post


Link to post
Share on other sites

I would bet the complete mains were never changed. Sounds like they popped in the lower shells and let the uppers stay.

Share this post


Link to post
Share on other sites
6 hours ago, macks in nigeria said:

These guys on the internet are the best brains you will find on earth when it comes to Macks,feel sad reading about your problems but also admires your tenacity to get this truck running perfect as a lot of us would have given up.Now that you are here be rest assured that the guys will walk you through the issue.Good luck

I know I can see that! So true... I really wish I came on here when the problem started...

im a perfectionist when it comes to cars, trucks, and guns lol. I like to take care of my stuff so it takes care of me

  • Like 1

Share this post


Link to post
Share on other sites
42 minutes ago, RobM626 said:

I know I can see that! So true... I really wish I came on here when the problem started...

im a perfectionist when it comes to cars, trucks, and guns lol. I like to take care of my stuff so it takes care of me

That's the one thing common to most on here also intolerance for lack of caring about results.    Paul

Share this post


Link to post
Share on other sites

I will also make a comment about R models in general . Some were rock solid and drove as smooth as other trucks. then you had some that felt like they spent more time in the air than on the pavement. Most 6 wheeler Macks I drove were well planted to the ground and were smooth driving and running with that extra weight of the dump bed took out any engine vibrations. A superliner with air ride cab was quieter than a standard R model with air ride cab etc...My experience it was the R model tractors was that would tend to vibrate more.  What im getting at is these R models all had more vibration than a modern day truck or one made of aluminum.  ones opinion of a "bad" vibration may be completely normal to someone else. And without one being there to see or feel it its best to get a few opinions on it. 

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Welcome to BMT!

...The world's best antique, classic & modern Mack Truck support forum! Founded in 2000, BigMackTrucks.com is the place to go for everything related to Mack Trucks!

BMT!

BigMackTrucks.com is owned and operated by Watt's Truck Center, New Alexandria, PA. This forum and it's contents are not affiliated with Mack Trucks, Inc. or Volvo Trucks North America.

×