loud bang!

[1archie]

i have a 1996 f350 powerstroke 4 x 4 auto trans, when i stop then get on the gas it makes a big bang or thud sound. sometimes when i get on it while driving it does it too. any ideas where its coming from? Hope its not the trannie, seems to shift good and strong. Torque converter maybe? Axle?? Any ideas what to check?
I just bought this truck a few weeks ago and this is my first diesel.

[mschn99]

first place to check would be U joints....take the whole rear driveline out...then check them. Sometimes the little bit of load from just holding the truck from moving can make a bad u joint seem good...

[1archie]

pulled rear driveline today, the u-joints were tight. Tightened up the lift stuff on the rear, took it for a test still a bang! I power braked it slightly to see what it would do, let off the gas stepped then stepped on it and thud/bang. could it be moter/trannie mounts? any other things i could try?

[MrJohnWayne]

yeah could be a tranny mount.

[1archie]

how would i go about checking the trannie mounts?

[fordnut85]

open the hood and have a buddy watch the motor while you powerstall it, or vicea versa and see if the motor/tranny flop around. Might want to check the yoke of the rear end also.

[pallentx]

have you checked the transfer case lately? Better question, when was the last time you changed it?

Use a good quality fluid if you deciede to change it.

[1archie]

yeh, i'm thinking its the transfer case or the rear end. checked moter mounts
look good. what noise does the transfer case make when it goes bad?

[pallentx]

well, once the transfer case chain gets loose, you can start to feel 'slack' (for lack of a better word) in the drive train. Going from drive to reverse can result in a delayed clunk. If you let off the gas...sorry accelerator pedal, then throttle again.....delayed clunk.

I have seen drive chains so loose that they wear holes in the transfer case.

Although if it is your rear end, it would be a louder clunk. have you set the emergency brake and placed the truck in neutral and grabbed the rear drive shaft (near the rear diff) and given it a good shake and twist? If yes and there is no slack or wiggle, I would l look again at the u-joints and xfer case.

[1archie]

man, i am having a hard time figuring this out. checked the motor/trans mounts, driveline and u-joints, axle, yoke, i even went through and tightened up the lift, shocks, sway bar, etc. I can feel the thud underneath my feet when i gun it off the start and sometimes it does it when i floor it going down the road, but when i take it easy it doesnt do it. i even grabbed a hold of the 4 wheel drive shift lever to see if i could feel anything but i couldnt feel anything there only under my feet/floorboard.
theres a big red 12 valve cummins down the street that keeps blowing smoke passing me. he is probably like ha,ha! i am to scared i might break something to get on it. i would really like to kick his a$%.