banging noise

[angie1015]

26 foot 1982 larson with an omc stringer drive... i was driving the boat last year and bang all of a sudden the motor is knocking like crazy... when I pulled the boat out of the water and ran it the noise actually sounds like its coming from the drive.. i drained some oil from the drive and its looks clean. no metal at all.. im confused so this weekend I am going to seperate the drive and the motor and run the boat.. that should help me figure out the problem spot.. the question is how?? what is the easiest way to pull the drive off so I can run the boat for a second and find out if its the motor or the drive.. or maybe something in between.. its sounds like a rod in the motor however im not about to pull the motor out till im sure its not the drive.. thanks for the help..

 

[angie1015]

Re: banging noise

also my insurance covers the motor and the drive however the adjuster wont come to look at the boat till the problem is diagnosed... its at my shop now.. do I pull the boot off??? are there bolts there.. how do i get this drive off..

 

[chiefalen]

Re: banging noise

http://forums.iboats.com/showthread.php?t=275061&highlight=how+to+remove+ball+gear+shaft

 

[angie1015]

Re: banging noise

ok i read the post... the difference is my noise has never went away and my boat WILL go in gear... it does however vibrate like crazy which makes me feel like its not the motor.. also the banging didnt start quiet and get louder.. it was just loud and never changed.. i didnt drive more then 5 min at idol speed after the noise started..how can i diagnose this??? drive? motor? something else?

 

[chiefalen]

Re: banging noise

You asked how to remove the drive. Then you want to run it to see if the noise is coming from the drive or the motor.

Your gong to make me type it all out again with 2 fingers.

Looking at the drive from the back of the boat, you see the 2 pivot points, under the rubber bumpers, they are trunions, you would know that cause you bought a manual. Gently pry off the rubber bumpers and mark them so they go on exactly the same side and the right way each side.

There are 2 bolts each side, before you do anything put a flat piece of wood under the skeg thats the fin on the bottom of the drive.

And crank the bow up till the skeg just touch's the wood then remove the trunion caps on both sides, then have someone crank another inch up the bow and the drive will come off, just slide it or pivot the whole drive to the port just enough to expose the ball gear, the ball gear looks like fingers. Mark the trunion caps so you know what side they came from and put back exactly the way you removed them.

Tie up the drive to the swim platform or whatever is handy and be careful with the cable.

Now all you have to do is put water to the long hose that goes into the t-stat by removing the hose from the transom and tape push whatever the garden hose in the hose that goes to the t-stat.

Start the motor and diagnose away.

 

[angie1015]

Re: banging noise

great advice thanks!! took about 3 minutes.. started the boat and the noise is gone.. good news for the motor bad news for the drive... the boat still goes it gear no problem however the whole boat vibrates and bangs like crazy... how do i figure out this problem now?

 

[chiefalen]

Re: banging noise

So it's the drive correct ??

Did you check the oil in the drives,all 3. When you drain them do it into clear containers.

My guess what it is, or do you want to wait to see what the oil looks like ?

 

[Silvertip]

Re: banging noise

Ball gear tooth chipped, gone, jammed, loose. Is the vibration present in neutral or does it only vibrate in gear?

 

[angie1015]

Re: banging noise

it only vibrates in gear.. i have some pics i am going to post.. drained the oil and its clean however when i took the the drive apart i found chunks of metal..

 

[angie1015]

Re: banging noise

i hope this works i tried to send pics

 

[angie1015]

Re: banging noise

ok so I pulled out the water pump shaft and it was fine... its hard to see however the pic on the left which is the top of the drive after taking 5 screws out.. there was huge chunks of metal in there. i guess thats the problem but what is the next step. i found a local guy that has used drives for 500 bucks...im thinking i should just replace the whole thing unless i can somehow fix these gears.. and where do i get the replacment parts..

 

[angie1015]

Re: banging noise

i would rather fix it.. this way i know the gears are new and they should last for years.. also i do not want to replace the shift cable...

 

[mthieme]

Re: banging noise

The parts are going to run more than the used drive.

 

[chiefalen]

Re: banging noise

I don't know why to didn't tilt the drive up 10-15 degrees so it would be easier to access the upper, and tilt the bow all the way down.

Ok rebuilding can be done and the gears are available.

But are you up to using the special tools that would have to be built or bought?

Gears i believe at ebasicpower.com are 350 dollars i think. But i don't see the water pump shafts, ball gears, any thing else in the drive.

What does the upper look like is that where the problem is?

Or is it the lower?

You ain't giving me no info.

So 500 for a good complete drive ain't bad. Now to the question of what motor you have, the drive got to have the proper gear ratio.

Post the motor hp i'll give you the proper gear ratio.

This is a fully mechanical shift drive correct?

 

[angie1015]

Re: banging noise

the boat came with a 305 2 barrell carb so i would imagine the horsepower was about 150ish.. it now has a 350 with a holly 4 barrell. at least 300 hp now. .. im assuming its the upper cause it was the pic on the left.. the top which has metal chunks in it..

 

[chiefalen]

Re: banging noise

So what was chewed up in the upper?

Upper 21:16

lower 14:26

total 71

overall 1.41

 

[Howard Sterndrive]

Re: banging noise

i drained some oil from the drive and its looks clean.

you might want to raise your standards....
looks like gray mucky sludge in the pic

Water intrusion into the upper gearbox likely the root cause of the failure. Not much lubrication for the gears or bearings running in that gray muck.

Stringer uppers are difficult to keep sealed. they should be checked frequently. Hard to do on a 26'er but I would get the boat on a hoist or trailer at least 2 or 3 times a season for drive lube checks.

or....at the marina where I worked as a kid, when it got busy, we used to just back OMC equipped customer boats up onto the beach. We would take the drives off the boat and carry them up in a wheelbarrow to the shop.

Put a plastic plug in the cable hole so water didn't wash in.

don't try that with a Mercruiser

 

[angie1015]

Re: banging noise

i think your right.. it looked like there was some water mixed in when I looked in there. What do I do.. I see Ebay has a complete seal kit for 50 bucks.. should I buy that and reseal the whole drive to assure this wont happen again anytime soon?? the question is now what? buy the new gears for 400 bucks or so.. replace the seals and be on my way.. is it hard to replace the gears?? how is it done? all advice has been good.. I need to know what to do now..what kind of tools to I have to buy or Make??

 

[Howard Sterndrive]

Re: banging noise

If you are putting new gears in it, you definitely have to replace all of the seals.
There isn't really a "whole drive" kit. The upper and lower are 2 different seal kits.

Someone on Ebay might be putting them together as a pkg. I suppose.

Unless you have the tools to shim and preload new gears and bearings, I would leave assembly to the pros, ... accidentally get the preload wrong or the backlash too tight, and you won't make it down the lake once and all the new parts will be scrap iron.
Or just look for a good used upper locally... then pressure test it and reseal as necessary.
Your upper housing may not have survived the failure either. If run to destruction (knocking), often the failed rear bearing cone grabs the cup of the rear bearing and spins it loose in the aluminum housing.
The housing is then scrap unless the right tech./machinist knows how to fix that bore. There is a technique to repair the bore and drill the new race and use a setscrew to lock the race in the repaired bore.

There are a few OMC shops that have a mail in- mail back program where they rebuild your drive.

You can also buy a brand new aftermarket upper unit from GLM. They still make new complete uppers.

 

[chiefalen]

Re: banging noise

I know we would love to help you, but we do not know what the gears look like, the shafts look like. What does the lower oil look like. The other problem we are having is you don't seem to know what to call things, that could only mean you don't have a MANUAL.

DO YOU HAVE A MANUAL ????????????

Can you tilt up the drive a bit and take pictures of the water pump shafts laid out on a table and the inside of the upper. Take clear pictures, so we can see the gear.

There are 4 housings on the outdrive. The lower, the upper, the intermediate, ande the tilt clutch housing.

That means 4 different kits. All available thru Ebasicpower.com.

Now i bet right now you need a upper, however what do the ball gears look like they are the gears that look like fingers can you take a pictur of that also, they make kits to install and reseal the ball gear shaft.

Manual, manual, manual, guy on ebay has them and in a pinch the seloc omc Stern drives 1964-86 Repair manual #3400 is what i have.

lets see whats wrong before i give anymore advice.