Clunking/banging during acceleration and while boost building

[Sy Guy 0024]

I have a problem with one of my trucks during moderate acceleration, I get a loud clunking/banging from underneath. During easy accel, it runs fine with no noise. My first thought was a motor or tranny mount. Those appeared fine, and I could see no evidence of any drivetrain components hitting the body. I then decided to do a powerbrake test to see if the engine lifted towards the passenger side. No sooner do I get on the throttle than the banging starts up again, almost sounds like something has stripped out or let go and is thrashing around.

Could this be a busted transfer case? I put the truck in D and R, and it moved fine again in the driveway. Thoughts? Not sure what to check next.

 

[TY0618]

Re: Clunking/banging during acceleration and while boost building

possible craked flexplate?

 

[BoostedSUV]

Re: Clunking/banging during acceleration and while boost building

possible cracked flexplate?

Good thought! I've had a cracked flexplate do exactly what you are describing. It was actually flexing with RPM and hitting the bendix drive on the starter. Also loose torque converter bolts cause a rapping/clunking noise.

If the truck did it while it was moving I would suggest torsion bar mounts, but since it's more RPM/acceleration specific and you ruled out motor mounts I would check the flywheel, TC bolts or even the trans bell housing bolts. I've also had a cracked bell housing on the trans make noises as well.

 

[cloneman315]

Re: Clunking/banging during acceleration and while boost building

t case chain......

 

[Sy Guy 0024]

Re: Clunking/banging during acceleration and while boost building

Well, I dropped the propshaft and torque convertor cover, and everything looks fine. I'm leaning more towards the transfer case, as the sound seemed to be coming more from that area than towards the front diff. AFter I eat, I'm going to pull the plug on the transfer case and see what comes out...

 

[justbringit]

Re: Clunking/banging during acceleration and while boost building

check torshunbar mounts.

 

[Sy Guy 0024]

Re: Clunking/banging during acceleration and while boost building

Well, it looks like I've got metal shavings in the transfer case. Never a good sign.

 

[cloneman315]

Re: Clunking/banging during acceleration and while boost building

simple, check it all out, clean it, put in new chain etc,check the planet also,and the vc

 

[Sy Guy 0024]

Re: Clunking/banging during acceleration and while boost building

I figured you would suggest that, you've been a real advocate for rebuilding these things in all the threads I've read!

 

[cloneman315]

Re: Clunking/banging during acceleration and while boost building

i have done only a few,george blake did a good breakdown post.