• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Weird "thunk" during shut down. Ideas?

tanman_2006

tanman_2006

Just a farm kid...
Messages
5,694
Reaction score
935
Location
Seiling, Oklahoma
I am hopefully pulling my 2006 LBZ in the shop this afternoon but it has developed a pretty good "thunk" and a shake when I shut down the truck. Feels like our old volvo semi with a 350 cummins, when it shuts down it rocks the cab.

First thing I am gonna check is the exhaust since I installed the 5in diamond eye 2 weeks ago. Maybe something came loose.

My next thought was it feels like a balancer is out like when my 6.5's crank dampener came loose, or heaven forbid the flywheel is F'd up.

I would appreciate any ideas, the truck is running normal otherwise.
 
Last edited by a moderator:
Motor mounts?

Known to pull loose sometimes..
 
I'll check that out.

The exhaust was tight still.

I hadnt seen any threads of bad flywheels or balancers so I was wondering how common/uncommon they might be.
 
Ut oh. My clutched alternator used to make the truck stop with a thud at shutdown. I think it was due to the compression stoppage.
 
If the Alt is causing the noise does that mean it is bad? I am going to buy a new Serp Belt and check the tensioners and pullys for problems this weekend if I can get a time to shut the truck down for more than 1 hr.

On thing I recently added was a hydraulic bale bumper but I doubt that would cause this noise (wrong end of the truck) the only thing they touched would be wiring for controlling the system.
 
Pull the belt off and see what it does. Not sure if it more common on in inline engine, but my old 6bt and the newest 4bd shut down with a shake. I think due to the compression
 
If it's the LBZ you need to deal with the PITA secondary shroud to get the belt off. Secondary shroud... the one that's hanging on my shop wall.;)
 
Burning oil said:
Pull the belt off and see what it does. Not sure if it more common on in inline engine, but my old 6bt and the newest 4bd shut down with a shake. I think due to the compression
Click to expand...

Thats why I compared it to the Cummins in our semi.

I am about done hauling calves for the next couple Weeks so hopefully I can tear into it on Saturday.
 
Got it all cleared up now :thumbsup:.

First:
I pulled the serp belt and immediately noticed an idler was loose and tensioner was loose. Went to the dealer and they had parts on hand :cool:.

Fixed some odd vibrations at idle that I had waved off as being a part of a diesel truck, didnt fix the clunk.

Next:
I went back to the exhaust and had the gf shut down the truck with me under it, noticed the guy that installed my new bale bumper and B&W hitch had taken loose my exhaust from the delete pipe back and just didn't get it all tightened up right and my exhaust was hitting the brackets.
 
You must log in or register to reply here.
Back
Top