help i have a 99 quad cab 5 speed hd when the truck is cold (sitting for 8 hours or more) when i drive i get a heavy Bang from underneath. already changed the fuel filter tore open the front and rear diff. checked the driveshafts t case etc. it lessens after the first 25 miles or so. it is only when the truck is slowing down (usually around 1900 rpm. ) i have the van akken cpc on it but, it does it weather its hooked up on not. any ideas on what i missed? it started about 800 miles ago and it is getting worse. the truck only has 42k on it. the truck will actually jump like i hit somthing in the road.<br>anybody have any ideas?

 

Check the trans mount at the frame and at the trans.<br>And stick your finger in the transfer case inspection hole to see if things are coming loose.<br> Danny

 

dan,<br>had the t case out and completely apart looks like new. the mounts are good not loose or twisted. any other ideas?<br>thanks,<br>bob

 

I work on these trucks everyday, try to explain the noise again<br>with a little more detail??

 

dan,<br>The best way to describe it is at about 1900 rpm there is a bang that comes from the front of the truck. when you first start it, if you back up then go foward 3 feet stop the truck put it in netural disengage the clutch rev it to 2200 and back off the gas it will bang without the truck moveing. you can feel the truck &quot;jump&quot; then as well. worse when moveing. more noticeable in 3rd 4th or 5th gear than 1st or second. it dosent smoke when it happens sometimes pushing the clutch in lessens it sometimes it dosent. the only parts i havent checked that someone told me might be related in the fuel supply, injection pump, or clutch. what do you think? we went thru almost everything else, we changed the trans fluid and opened up the trans pto ports and poked around but we didnt see anything. not hard to shift and it dosent do it on accrelation just on the slowdown the part that has us all miffed is it lessens after driveing 20-25 miles to almost non existent<br>thanks<br>bob

 

I don`t know?<br>Sounds to me like <br>Motor mounts<br>Possible clutch or flywheel sheard bolts<br>bell housing coming loose<br>other than that its hard without seeing it in person.<br>Good luck, let me know when you find what it was<br> Danny

 

dan,<br>thanks i didn't think about the flywheel or bellhousing.<br>will let you know when we finish ripping it apart. ;D

 

Boy that has got to have you miffed for sure!. Good luck!

 

[quote author=SFtopSGT link=board=13;threadid=6802;start=0#64319 date=1036817919]<br>Boy that has got to have you miffed for sure!. Good luck!<br>[/quote]<br>thanks i'm gonna need it. 2 different diesel mech. have no clue. :'(

 

well we found the problem today. the fuel supply pump was on its way out and the cpc box i have helped it along. I talked to ted at jre and also learned they are haveing problems with the box. it happens almost exclusively to the standard trucks and is more common in the 2000 and 2001. they dont know exactly what the problem with the box is but they are working on fixing it. it is also a problem with the b&amp;d plug and play. go figure. &gt; :'(