Bell B30C artic dump truck- vibration

[Oldboy]

Hello, I have just acquired a 2002 Bell B30C ADT with about 17,000 hours on it. It has a Mercedes Benz V8 engine which seems to run perfectly. possibly a ZF transmission.
It has a very serious vibration when you rev the engine to or above low + revs. In neutral gear or driving its the same.
You notice it in the cabin as it starts to shake.
I have no mechanical history on it, other than the manager from previous owner said he thought it was torque convertor issue. I hope to make a start on diagnosing the problem in next couple of days, has anyone else had a similar problem?
thank you Michael.

 

[Nige]

So it vibrates even when it's not moving if I understand you correctly.?

 

[Oldboy]

Hello Nige,
yes its there when the truck is stationary or moving, definitely related to the engine or what is hanging off it. Could be harmonic balancer maybe ( assuming they have one)? its a pretty severe vibration more a shudder, when the revs are increased even slightly. Fairly calm at idle.

 

[Nige]

The fact that it does it with the truck stopped and in neutral removes everything South of the torque converter such as transmission and drive shafts.

I know nothing whatsoever about these engines, but does it have a vibration damper fitted to the front end of the crankshaft.? It ought to be pretty obvious if there is one. Check it for damage and leaks, also check the condition of the engine mounts.

 

[mg2361]

 

[Oldboy]

The fact that it does it with the truck stopped and in neutral removes everything South of the torque converter such as transmission and drive shafts.

I know nothing whatsoever about these engines, but does it have a vibration damper fitted to the front end of the crankshaft.? It ought to be pretty obvious if there is one. Check it for damage and leaks, also check the condition of the engine mounts.

thanks Nige, we will look in this direction and see what we find. ill report back in a while, cheers Michael.

 

[Oldboy]

View attachment 211518

View attachment 211518

Hello MG this is very helpful, we will check it out and Ill let you know what we find, cheers Michael.

 

[Nige]

MG, is the torque converter coupled directly to the back of the crankshaft or is it remote-mounted.?
If the former, then getting at the damper will be a major project.
Maybe better to concentrate on the engine mountings first.

 

[Cmark]

Also have a look at the fan. A plastic fan blade with a piece missing will cause an amazing amount of vibration. Try temporarily removing the belts to see if that gives you any direction.

 

[Oldboy]

Also have a look at the fan. A plastic fan blade with a piece missing will cause an amazing amount of vibration. Try temporarily removing the belts to see if that gives you any direction.

Thanks Cmark this will be getting a good look over too then. cheers Michael.

 

[mg2361]

is the torque converter coupled directly to the back of the crankshaft or is it remote-mounted.?

There is a driveshaft between the engine and the ZF transmission and getting to the torque converter would involve tipping the cab.

Oldboy, like Cmark and Nige mentioned I would start with the fan and the mounts. If those items are not the source then the driveshaft would be the next item to check since it would have to come off to get to the dampener.

 

[Oldboy]

Finally an update on the Bell dump truck. We found the problem to be very simple. We replaced the flange that fits onto the torque convertor as the spline was worn. the TC shaft was not worn, as I expect the flange was sacrificial being made of a softer material. So when we fitted the new flange it was a tight fit the the problem was over.
Thank you Nige and Cmark and MG for your assistance, you guys are a great resource.

 

[Nige]

We replaced the flange that fits onto the torque convertor as the spline was worn. the TC shaft was not worn, as I expect the flange was sacrificial being made of a softer material. So when we fitted the new flange it was a tight fit the the problem was over.

I'll be you any money you care to wager that the output flange was not designed to be sacrifical........
At the end of the day you fixed the problem. Happy daze.

 

[Bigbert]

Hi Oldboy, good to hear you fixed the issue. The vibration damper on flywheel is fitted to protect the propshaft to t/c from torsional vibrations. Frankly speaking never heard about issues of wrong flange material or machining. Please make sure the flange bolts are properly torqued and secured with Locticte 262 or similar.