Pajero 4WD Club of Victoria Public Forum Pajero 4WD Club of Victoria Public Forum

Go Back   Pajero 4WD Club of Victoria Public Forum > Vehicles > Generation 2 Pajero

Generation 2 Pajero NH - NL Models 1991 - 2000

Reply
 
Thread Tools Display Modes
  #1  
Old 1 Week Ago
motorazr motorazr is offline
Member
 
Join Date: Aug 2018
Location: Adelaide
Posts: 105
Default Harmonic balance wheel problems

Well after only 5 months, the old girl snapped a second harmonic wheel balance bolt. At least this time I wasn’t 600klm from home and stranded. The first time was just out of Bacchus Marsh heading to Adelaide. This time at least I wasn’t doing 100 kph, and have the wheel fly off into the never never. I was only doing 60 kph and heard a loud clunk, lost power steering and battery light came on, I was able to recover the wheel which was resting against the bottom of the radiator.
New bolt clean snapped, again leaving a good part of it in the crank. Might there be any particular reason that this keeps happening? Talking to the towy on the way to the repairer the towy mentioned that perhaps two locating lugs could be placed on the end of the crank shaft similar to what are on high performance vehicles. Any thoughts on this?
Reply With Quote
  #2  
Old 1 Week Ago
disco stu disco stu is offline
Valued Member
 
Join Date: Dec 2018
Location: Wollongong
Posts: 506
Default

I guess the question is-what is actually causing the bolt to snap? I feel that 2 pins certainly wouldn't hurt, but I don't think it is your problem, as I don't think that in itself should snap the bolt
Reply With Quote
  #3  
Old 1 Week Ago
motorazr motorazr is offline
Member
 
Join Date: Aug 2018
Location: Adelaide
Posts: 105
Default

That was also part of the discussion in that why would the bolt snap? Possibly a pully out of alignment?
Reply With Quote
  #4  
Old 1 Week Ago
brw0513 brw0513 is online now
Member
 
Join Date: Apr 2018
Location: Brisbane
Posts: 168
Default

Could it also be that the blind threaded hole in the end of the crankshaft is full of crud? You might get to the desired tightening torque but not fully seat the balancer.

Another possibility is the thread form in the crank is damaged. Maybe run a tap into by hand to check?

Two broken bolts is a pattern that must have a cause.

Are you using genuine MM bolts with the right part number?
__________________
Ian B
1998 NL SWB 6G74 Manual
Reply With Quote
  #5  
Old 1 Week Ago
motorazr motorazr is offline
Member
 
Join Date: Aug 2018
Location: Adelaide
Posts: 105
Default

Yep, all genuine parts and on both occasions the new style was used.
Reply With Quote
  #6  
Old 1 Week Ago
Kaldek Kaldek is offline
Member
 
Join Date: May 2017
Location: Melbourne
Posts: 69
Default

For what it's worth when I'm tightening my crank bolt on my 3.0 NH Pajero, I use one of those large "cam sprocket holders" which come with pins that fit into the balancer. I torque the bolt down to 160Nm, dry. I make sure the threads are clean but I don't use lube and I don't use loctite.
Reply With Quote
  #7  
Old 1 Week Ago
brw0513 brw0513 is online now
Member
 
Join Date: Apr 2018
Location: Brisbane
Posts: 168
Default

Quote:
Originally Posted by Kaldek View Post
For what it's worth when I'm tightening my crank bolt on my 3.0 NH Pajero, I use one of those large "cam sprocket holders" which come with pins that fit into the balancer. I torque the bolt down to 160Nm, dry. I make sure the threads are clean but I don't use lube and I don't use loctite.
This is a very good point.
__________________
Ian B
1998 NL SWB 6G74 Manual
Reply With Quote
  #8  
Old 6 Days Ago
erad erad is offline
Valued Member
 
Join Date: Mar 2015
Location: Cooma NSW
Posts: 2,571
Default

Any bolt which is subject to vibration or cyclic loading requires a certain tension in order to overcome the fluctuating loads. By tightening the bolt to above the fluctuating load, you eliminate fatigue in the, bolt, even though the tension in the bolt is higher than the peak fluctuations. I would say that in your case, the tension was not enough to overcome the fluctuating loads and the bolts failed in fatigue. If you look at the failed surface, you may even see evidence of fatigue failure - typical is clamshell lines emanating from the final point of failure.

Why did the bolts fail? The tension in the bolt was not high enough. Maybe the torque was as specified, but as suggested above, maybe there was some crud in the thread, or maybe the bolt was bottoming out in the crankshaft. Did you have a washer under the bolt head? Any of the above may cause the bolt to bottom out before achieving the correct tension. I would thoroughly clean the whole assembly and lubricate the threads with light machine oil and tighten the bolt to the specified torque. In particular, check the seating face of the pulley against the crankshaft. If that is not clean, the pulley may settle at a later time, leaving the system with inadequate tension. Run the engine for say 1000 km and then go back and check the tension. Slacken the bolt off and then re-tighten it - do not simply try to tighten it up from its static position because that will not give you the correct tension.
Reply With Quote
  #9  
Old 6 Days Ago
motorazr motorazr is offline
Member
 
Join Date: Aug 2018
Location: Adelaide
Posts: 105
Default

Thanks for the input, it is appreciated. Will have a chat with my mechanic about the points you have raised.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Wheel alignment problems reciprovac Generation 4-3 Pajero 8 28-02-16 08:47 AM
nl wheel bearing problems paj-attack Generation 2 Pajero 1 30-10-12 11:49 AM
Harmonic Balance bolt woes mickymac Mechanical 5 09-08-11 04:46 PM
Harmonic Balance problem after front accident Anthonyo Generation 2 Pajero 4 30-03-10 08:26 PM
Harmonic balance taskrog Mechanical 5 14-09-08 08:08 PM


All times are GMT +10. The time now is 07:02 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.