thumping outdrive help

have a 78 pre alpha drive on a 250 cu in, 165 hp merc. just recently replaced the ujoints as they were vibrating and noisy. reinstalled drive and did a water muff test. while the unit is in neutral and running, the drive is quite and doesn't jump, but kick it into either forward or reverse, it has a sporatic 'thump' and when it does this, the drive jumps sideways a little. adjusted the lower shift cable at the mount, but it still has the thump while running in gear. the prop locks into gear strong and the ratchet drag feels the same in both directions. tried listening to drive with a wood pole but inconclusive as to where the noise is coming from. by ear, it seems to be the lower area. drive wasn't doing this before the u joint replacement. did i screw something up? suggestions welcomed.

Re: thumping outdrive help

The only thing that doesnt turn when in neutral is the prop shaft.

Re: thumping outdrive help

Yeah, Reel poor is on to somthing. You can remove the prop... start it up, (with muffs), you won't need a runout gauge to see if the shaft is bent.<br />along w/ the shaft is the gear assembly inside, If the shaft is not bent, then I would say you are missing a tooth on a gear. <br />Drain the oil and look for metal.<br />There are many posts regarding metal in the oil and how it affects ALL of the drive. Do a search in this forum.<br />What happened prior to the Thump sound? was it hit, did you back into somthing? What is the condition of the prop, now and prior to the noise?<br />Did you let your teenager borrow it???...sl

Re: thumping outdrive help

thanks for the replys. prop is new. did not hit anything. shaft doesn't wobble. just strange that it didn't do this before i did the work and now it does, however, it runs great in neutral. think i will pull everything & give it a look. might get a stethescope and try it to better locate the source of the noise.

Re: thumping outdrive help

165 drives have hunting gears. did you reset them?