Jump to content
RobM626

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

Recommended Posts

Hello

A few years ago we had a truck come in with heaps of ongoing problems. It was a R model OSHKOSH, CAT 1674, RR gearbox, 4 speed SPICER on 55000lb ROCKWELLS.

The fan vee belts would turn inside out, was always breaking fuel injector pipes, and the owner was about to remove the gear box as it was ready to blow up.

Anyhow I can't remember what we were doing but were talking about all these problems and he said some one back into him many years previous and had to get a new radiator made. The boss said about the crankshaft, fan and crankshaft damper to which he said were all OK. We removed the damper and it looked OK, but suggest to replace it.  

We cut the housing open as it was a viscous type and was dry as a bone. Well the truck was completely different, i.e. all the problems disappeared and drove better.

I do remember you have replaced the damper but is it the right one? Vibrations are black magic and to control them is another science, but many thing generate them, i.e. engine components and adjustments. Timing and fuel rates.

Gar

Share this post


Link to post
Share on other sites
14 hours ago, RobM626 said:

I have an EUP motor (6 individual electronics unit pumps) . There still is the possibility the cam gear is not times perfectly. A lot of my symptoms do point to that. As far as the lines go. I had the cam dialed about 9 months ago and the lines were in spec but the cam had scratches scuffs on it. After I did the cam the truck ran differently. I thought it was going to run better but doesn’t. After I get the truck back from dropping the tranny I’m going to pop the valve covers and do some checks . Or leave the truck in the south Bronx somewhere with the windows open and keys inside with a sign saying “take me I’ll be glad to be your problem”

Were do these injectors get the signal from on the motor of when to fire ?

There must be a sensor that picks up the position of the crank, were and what is it ?

Paul

Share this post


Link to post
Share on other sites
8 hours ago, GaryMac said:

Hi

May be of interest

Check 45-sb212025.pdf 

MACK new damper/mounting 2002

Gary

The link isn’t working. There was a service bulletin a while back that changed the size of the vibration damper for E-Tech engines the old damper was a couple inches smaller and had 6 bolts. When I went to Mack and gave them my vin number they gave me the new larger damper and it has more bolts but they said I can use 6 because I’m not changing the hub. I asked numerous times if it was right they said yes. I should’ve put a vibratech. I think it may have even been cheaper and they’re supposed to be really good

Share this post


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

Were do these injectors get the signal from on the motor of when to fire ?

There must be a sensor that picks up the position of the crank, were and what is it ?

Paul

The EUP’s are cam driven by rollers and there is a cam position sensor on the front of the motor and crank position sensor on the fly wheel housing. I changed both sensors. No change. I changed all 6 eup’s. The cam and the rollers. 

There is definately a misfire going on and it sounds like the cylinders are not firing balanced 

Share this post


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

The link isn’t working. There was a service bulletin a while back that changed the size of the vibration damper for E-Tech engines the old damper was a couple inches smaller and had 6 bolts. When I went to Mack and gave them my vin number they gave me the new larger damper and it has more bolts but they said I can use 6 because I’m not changing the hub. I asked numerous times if it was right they said yes. I should’ve put a vibratech. I think it may have even been cheaper and they’re supposed to be really good

http://hr.mckenzietank.com/maint/bulletins/45-sb212025.pdf

Share this post


Link to post
Share on other sites

This post is so dam long I don't want to read thru the whole thing so I will ask this and sorry if you posted it already have all the injectors been removed check and  tested ! you mentioned the Eups had been done,were all the cal codes installed on the off chance this could make a difference!

Share this post


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

This post is so dam long I don't want to read thru the whole thing so I will ask this and sorry if you posted it already have all the injectors been removed check and  tested ! you mentioned the Eups had been done,were all the cal codes installed on the off chance this could make a difference!

I was told the injectors were pop tested when the eup were changed but they could have lied and the injector lines were not changed . I was also told they put the cal codes in but that could have been bs too BC I know they didn’t bring the truck to the dealer. I’m gonna check all that stuff out once I get it back. The guy that has it now is taking forever. It’s a week already

Share this post


Link to post
Share on other sites
6 hours ago, RobM626 said:

The EUP’s are cam driven by rollers and there is a cam position sensor on the front of the motor and crank position sensor on the fly wheel housing. I changed both sensors. No change. I changed all 6 eup’s. The cam and the rollers. 

There is definately a misfire going on and it sounds like the cylinders are not firing balanced 

So this all started after the cam was changed I'm pretty sure you said a few pages  ago

And since then in a attempt to fix the problem caused by someone changing a cam there has been just about everything else changed from the front to back the back of the truck 

If it was mine I would be looking at the timing and all of this stuff that is driven from the timing

I find this almost impossible to believe that this has gone on for this long without people going back to when the problem started and finding the stuff up back then

 

Paul 

  • Like 1

Share this post


Link to post
Share on other sites

Well in  one small defense of the the guy/s that did the job I have had and personally seen where after a  cam job several times where the engines had an  erratic surge or pulse at idle and could find no reason for it a variance of 25 -50 rpm with in a few seconds @5 second intervals very annoying how ever the engine ran fine otherwise! The only thing that was replaced was the cam and lifters which would lead one to believe it has some thing to due with the cam grind! just saying!

How ever none proven!

Like I said I AM Tapped     Check the Snap-on truck see if the back ordered magic wands have come in yet !☹️

Share this post


Link to post
Share on other sites

I doubt it will be  the cam grind , diesels arent as susceptible to cam shaft grinds as petrol 

But you are saying there is a sensor driven from the cam ? perhaps thats a place to start

Perhaps these newer motors are cam sensitve and the cam isnt the right one or installed right 

Think about it this way , if the timing is out two tenths of sweet stuff all then the sensor will be out of time with the crank and the injectors will be out of time with crank and the cam sensor 

As I have said already, I would dial in the cam like I would have as young bloke chucking a hot cam in a car motor, not just make sure its timing marks are lined up but make sure the lobes are rising and falling in the correct position to the crank and to the sensor 

I would also make sure the crank sensor reads at the correct time and matches the timing of the cam sensor

This is what I would do, I doubt most young blokes would even know what Im talking about at any truck dealers so I would think this is something I would do at home over a weekend

I think you also find most people in modern work shops have little to no idea on fault findint and rely on work shop manuals and what the lap top says  and anything unusual just gets guessed at not thought out 

Just some thoughts 

Paul

Share this post


Link to post
Share on other sites

I have a lot of stuff to check. I wish I had a real E-Tech guy that can go thru this stuff with me. The last guy that put the injectors in thinks my crank is bent and that’s what’s throwing my timing off. There’s so much weird shit going on with this truck it’s drivig me crazy.

Share this post


Link to post
Share on other sites

If crank was bent I think you would’ve seen results from oil analysts & bearing wear. Like I’ve said before the adnormal clutch wear has got me stumped. If it was just missing is 1 thing; but I don’t see the miss causing the clutch wear. I’ve seen trucks with broken cranks drive to the shop. I’ve seen guys drive trucks with misses. Never heard of clutch wear like yours. I feel for you & hope you find the problem. You’ll have to keep it forever to get your money back that’s for sure. No disrespect intended.

  • Like 1

Share this post


Link to post
Share on other sites

It all seems to go back to when the Loader Backed into you.... I'd be getting some string lines out & making sure the Chassis is Square & parallel ...

If It was My truck (which It isn't) I'd be taking It to the nearest Ritchie Bros yard, Cleaning My gear out of It & let some else deal with It.

The down Time & repairs will (or should I say IS keeping) keep you poor trying to Figure It Out...

  • Like 1

Share this post


Link to post
Share on other sites
22 hours ago, Hayseed said:

It all seems to go back to when the Loader Backed into you.... I'd be getting some string lines out & making sure the Chassis is Square & parallel ...

If It was My truck (which It isn't) I'd be taking It to the nearest Ritchie Bros yard, Cleaning My gear out of It & let some else deal with It.

The down Time & repairs will (or should I say IS keeping) keep you poor trying to Figure It Out...

Then we would be trying to help that fellow out; unless you made it clear that it has a problem. Kinda what this messed up world is in all about. Just my opinion 

Share this post


Link to post
Share on other sites

How could a bent crank effect the timing???

The cam is driven off the front of the crank  so even if the crank was bent it would have effect on the cam posistion to the crank , so it would have no effect on timing

Paul 

Share this post


Link to post
Share on other sites
21 hours ago, mrsmackpaul said:

How could a bent crank effect the timing???

The cam is driven off the front of the crank  so even if the crank was bent it would have effect on the cam posistion to the crank , so it would have no effect on timing

Paul 

I think that was Rob's point.

  • Like 1

Share this post


Link to post
Share on other sites
18 hours ago, 1965 said:

If crank was bent I think you would’ve seen results from oil analysts & bearing wear. Like I’ve said before the adnormal clutch wear has got me stumped. If it was just missing is 1 thing; but I don’t see the miss causing the clutch wear. I’ve seen trucks with broken cranks drive to the shop. I’ve seen guys drive trucks with misses. Never heard of clutch wear like yours. I feel for you & hope you find the problem. You’ll have to keep it forever to get your money back that’s for sure. No disrespect intended.

I think the abnormal clutch wear was from the flywheel being cut wrong so the clutch’s were never seating right.

Share this post


Link to post
Share on other sites
13 hours ago, 41chevy said:

I posted that a while back for the chassis being out of square or bent from the loader hit. The engine could be out of line  and when the trans was R and R'd it could not go back in square. Only takes a few degrees mis alignment.

It makes sense. Gonna ask them to start measuring

  • Like 1

Share this post


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

Well I just got my truck back after 2 weeks in the shop and it’s 100 times better than it was. They dropped the oil pan and pulled the bearings to look for any breaks in the crank and found nothing. They did however find a burr on the end of the crank where it meets the fly wheel. The machinist cleaned it up the best he could. They also found the flywheel housing had some runout so they brought it in a little to be within spec. I can instantly tell by listening to and sitting in the truck that it calmed down a lot . That studder that I had when the motor was returning to idle also almost completely went away. I don’t feel the clunking when I press and release the accelerator either.

i still have a slight miss in the motor and am gonna pull the valve covers and  do a cylinder cut out test to check it out. 

I haven’t ran the truck with a load yet. That’s where the problems used to really show themselves. But if the truck stays the way it is now I would really be happy. 

Thanks for all your opinions and ideas guys. Just wanted to give you guys an update

All of which could be caused by the chassis being out of alignment. I would still check chassis if nothing more then peace of mind.

  • Like 1

Share this post


Link to post
Share on other sites
4 minutes ago, 41chevy said:

All of which could be caused by the chassis being out of alignment. I would still check chassis if nothing more then peace of mind.

What kind of place should I bring it to check that out? A body shop or alignment place?

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.

×