OMC 800 hammering noise in bell housing area

[gojayo]

I truly pray someone will recognize my problem. I've had many boats, and now I have a 25' Sunrunner with a OMC 230 and a Stringer 800 mechanical shift outdrive. I have a terrible hammering noise in the area that would be a bell housing if it were a car. I realize that the stringer has an intermediate housing and an upper and lower gearbox, and I've looked carefully at the exploded view of the intermediate and looked carefully at the ball gears.

Last summer I moored the boat and the last time I started it before taking it out of the water I heard a low volume ticking/pulsing noise between my boat and the slip I was backed into. I didn't think I had heard it before, but it was quiet and I was on the way to my trailer anyway. No event on the way there, and I took it out of the water. I called a marine auto parts place where the owner knows something about the Stringer and he said that I'd need to put it back into the water to troubleshoot it further, so I waited until last week to stick it back in. I had previously drained and refreshed all the Stringer's 4 oil compartments...no metal in the old stuff. Some water in the small outdrive raise and lower gearbox, but that's not my current problem.

I ran the engine with water earmuffs on in my driveway and heard the ball gear noise, and thought that maybe the dry ball gears might be what I heard, so I greased them too.

At the launch I heard the ball gear noise and something else, but couldn't put my finger on it. All pressures and temps were Ok, so off I went. The noise was RPM based, no doubt about it, and was there regardless of whether I was in gear or not. I idled for about 10 minutes and I'm sure it was louder than the boat had been during last year's season, but thought I might be imagining it. I slowly brought the boat up to plane and drove it for about 15 minutes until the noise that I was trying to convince myself was my imagination suddenly got VERY LOUD and hammer-sounding, both over the transom and looking down at the ending under the hatch cover. Loud and knocking, and I'd swear it was no more often than once per revolution. I immediately reduced the throttle to an idle, and the engine didn't die, and was still in gear. The temp was fine, and it might have been my imagination to say that the oil pressure might have dropped a tad, but that gauge is terrible anyway so I don't trust it. For 25 minutes I idled back to the dock in gear with no problems...no heating up or the hammer getting worse. I worried that I might not be able to take it out of gear (fearing an outdrive cause of the noise) so I waited until the launch was clear. I got close to the dock and tried to put it in neutral but it wouldn't go. I turned the motor off and jumped to the dock, took the boat out and went home.

Back in the driveway with the water earmuffs on the noise sure sounds like it's in the bell housing area, and of course now the outdrive shifts in and out of forward and reverse just fine. Although it seems like the oil level is down a bit in the engine, there is no metal in the filter (I cut it in two and pulled the fan filter apart to be sure). No water or metal in the outdrive's oils. I thought maybe I had spun a main engine bearing, but with no metal in the oil filter I think that is now ruled out. The engine sits very low in this boat (below flush hatch covers) and laying ON the engine with flashlight and mirrors I can't see anything odd anywhere. I hate the idea of pulling the drive and all that mess unless I have to. I can't tell if the noise is engine related and being amplified through the flywheel or if it's telegraphing back inside the boat through the intermediate shaft, but it is definately loudest from inside the boat and out outside. I realize that the intermediate housing is just a shaft running into some spline I guess in the center of the flywheel, so I can't for the life of me believe that it's that...but what else could be going on?

If anyone has experienced this, please please help. If anyone just has wild ideas please suggest them too. The odd thing is that in the driveway, the sound is predictable and doesn't seem to be getting any worse. It's runs fine at idle and at about 2,000 RPM except for the hammering noise. I'm stumped, but I can't put it back in the water like it is. When the "event" happened, it felt/sounded like something "let loose"...something that was part way bad and then got totally bad, and that sound hadn't gotten better or worse since.

Thanks to the community, and sorry this is so long.
Jay in Seattle

 

[Manipulator]

Re: OMC 800 hammering noise in bell housing area

What do the ball gears look like? They can let go if worn enough. There isn't too much to the intermediate housing as you have explored. Engine, coupler, bearing and then ball gear. I suppose if the coupler went bad it would cause a bad noise. I think the best thing to do, to rule out the upper unit and lower unit would be to pull the drive off the boat. It's really rather simple. Then with the drive off, fire the motor and rev it up some and see if you still hear the noise. Watch your temp as the impeller won't be working with the drive off. It should be okay for a short time to see if you still hear the noise but don't run it long as it will overheat. If you hear the noise, then it's the coupler, the bearing in the intermediate or it's in the engine. At least this will help rule a few things out.

 

[fendersfender]

Re: OMC 800 hammering noise in bell housing area

Jay, I would start by removing outdrive, then run engine...this will tell you if the outdrive is the culprit....if its not the oudrive or ball gears, it may be a loose flywheel, in which requires the engine to be removed. worst case scenario is a worn out bearing.....wish you luck.....check every possible noise source before assuming the worst

 

[fendersfender]

Re: OMC 800 hammering noise in bell housing area

oops...manipulator beat me to it!!!

 

[Manipulator]

Re: OMC 800 hammering noise in bell housing area

Well one thing I didn't mention was the fly wheel as Fender did. Definitely a possible source. I've heard of them coming loose or even warping. Again, a possibility but lets rule out the drive first. Then we'll move on to the the rest.

 

[gojayo]

Re: OMC 800 hammering noise in bell housing area

Thanks for the replys. Questions:
Do I understand you to say that I should remove the upper and lower gearboxs on the drive but leave the intermediate in place? Does this allow me to NOT have to unthread the shift cables? If anyone has a link to a remove/replace upper and lower gearcases I'd appreciate it. I haven't bought a manual yet as I've been hoping to not need one!

If the flywheel was loose or warped, I imagined that the starter wouldn't engage correctly, but it does. I looked at parts of the flywheel through the starter attachment point (I have the newer small starter since 2 years ago) and from under the bell housing since there is no scatter shield down there on my boat. I didn't see any odd markings or broken teeth etc, but I guess that doesn't tell the story...the noise has to be coming from somewhere!

Thanks, Jay

 

[KaGee]

Re: OMC 800 hammering noise in bell housing area

Why not get a stethoscope and nail down the sound before ripping everything apart?

BTW, the drive is removed in one piece. And yes, you have to remove the shift cable.

 

[Manipulator]

Re: OMC 800 hammering noise in bell housing area

Don't need to separate the upper from the lower, just pull the whole drive off the intermediate (IM). You can leave the IM in. You might have just enough clearance to leave the cable in. You won't have much but it may be enough to where the ball gears aren't engaged. You'll need something that the drive can sit on. I just made a stand out of some 2X4's.

 

[gojayo]

Re: OMC 800 hammering noise in bell housing area

Thanks again. I've never used a stethascope (spelling, sorry) but this hammer is so loud that I'm sure it's radiating in all directions. I guess an auto parts house will have the stethascope that is used for these purposes?

As relates to whether the Intermediate needs to come off or not: I'm truly not an expert marine mechanic, but my skills and tool assortment is far better than the average guy...I have a forklift and torque wrenches etc etc...but I don't have a helper unless I rent one! Point being that if leaving the Intermediate is only a temporary troubleshooting step if the problem is indeed in the flywheel/coupler area...is it still worth just pulling the upper and lower IF it's possible without messing with the shift cables? I only say this because if there's one condition that can save work I'd rather go that route...like anyone would. If I remove the whole drive including the intermediate, does the power steering assembly have to come off too? What is the least list of stuff I'd need to remove to actually SEE the flywheel and the coupling for the intermediate shaft? If the hammer is coming from there I would think that visibly it would be obvious, right? Will using the stethescope allow me to rule in or out the coupling or flywheel being messed up vrs some other problem?

I appreciate everyone's time here. My summer clock is ticking...paying moorage now for the last month and a half without a boat is giving me heartburn. Here in Seattle, $250 per month for non covered moorage for a 25 foot boat is cheap...most pay over $350...man. What a sport we "enjoy", huh?

Jay

 

[Manipulator]

Re: OMC 800 hammering noise in bell housing area

My thoughts are you need to yank that drive. Either way, if it?s in the bell housing, the IM or in the outside unit (upper or lower) the drive needs to come off. You will have to tackle the shift cable; midis well just drive in and do it. Thinking about thins some more, there really isn?t much slack in that cable as it exits the intermediate (IM). If you start it, you run the chance of the upper unit making contact with the intermediate shaft ball gear, that wouldn?t be pretty. That?s if you decide to unhook the drive like we discussed earlier.

I would say the hard part is getting the shift cable through the intermediate housing (IM). The cable goes through a hole in the IM and many times gets hard to pull out due to sealer being around it. You will also have to disconnect the shift cable from the shift converter box. Don't be discouraged, it is really not that hard. Get a manual. Basically you push the cable into the converter box while holding the spring retainers with a screwdriver (there are on the bottom), then where the cable goes into the box there is a small hole you slide a cotter pin in to keep the tension off the cable, you could use a small nail. Take the top of the shift converter box off and remove the cables from the pulley and remove the cable from the box. There are two cables, a long one and a short one. Make note of where each goes (long cable goes around the pulley wheel). When putting it back together it only goes one way and you?ll get it as you look at it. I have pictures of mine apart if you need to see what I?m talking about. Before you do all this, and this is very important, remove your battery from the boat. If the shift cable hits the solenoids or any live areas it will destroy it. They aren't cheap either.

Disconnect the tilt quadrant, and then push the drive up as far as you can and tie it to some good ski rope and to the boat. Make sure it is good and secure so the thing doesn?t come down on your fingers. You will need to get next to the ball gear on the left facing the back of the boat in the IM. This black looking hose is the shift cable. There is a small bolt that holds a retaining clip here; you will need to remove it. Then you will want to try to spray some WD40 around the cable to help free it. Sometimes these things come right out but many times they do not. I pulled on mine for a while with no luck. I was about to cut the damn thing. Then I wedged a long 3/8 inch socket extension between the top of the cable and the IM and pulled down and it slid right out with a little muscle. After this, have a friend with or make a cheap drive holder. I made one out of some 2X4?s. Let the drive back down (remove the rope holding it up). Take the trunnion caps off (4 bolts holing them on and one on each side of the drive), then the pivot caps (one on each side with two bolts each holding them on) and the drive comes right off. Pull it away from the boat with the shift cable. Now you can fire the motor like I mentioned before. Again not for very long as it will overheat. Listen for the noise. No noise, then it?s in the out drive. If you hear the noise then you can remove the four bolts that hold the intermediate shaft and ball gear in place. There is a shim behind the retainer plate, careful with that, you can reuse it. Slide the shaft out, the shaft will come out with the bearing. Check the bearing and see if it?s trashed. Check out the bearing race which is still in the IM. Take a look at the splines on the IM shaft for damage. If all is looking good you can see the coupler with a strong flash light by shining it through the hole. Look for any debris in there that could suggest a blown coupler. If you don?t see anything start the motor again and listen for the sound. At this point if you do or do not hear the noise when running the motor if doesn?t matter, the problem lies there and the engine needs to come out and you need to take the bell housing off and check it all out. You can either pull the motor with the bell housing/ IM attached, which would require removing the back motor mounts, or you can unbolt the bell housing from the IM through the back of the boat (Transom hole) and pull the engine with it. I?m pretty sure you can do it that way. Pulling the motor mounts in the back you may run into things you just don?t want to know. Stripped lag bolts, rotten would etc. Glad to hear you have a fork lift handy. First thing, rule out the out drive from IM and coupler. Then go from there.

 

[gojayo]

Mr. Manipulator! Re: OMC 800 hammering noise in bell housing area

Mr. Manipulator! Re: OMC 800 hammering noise in bell housing area

Thanks so much for all your advise. Last immediate question: I talked to a local mechanic who said he knew the Stringer 800 well. He said that inside the coupler were springs and he referenced what he said was like a clutch plate or something. He said that sometimes the springs rot and cause trouble. Is there anything in that coupling that could cause the loud hammering sound I'm hearing?...in your opinion?

Oh...I lied...one more! If a rod bearing has gone out, would the crank transmit that sound back through the flywheel so the sound sounded like it was coming FROM the bell housing? I pulled each plug wire one at a time and each removal sounded the same from the motor missing a bit but no difference in the banging sound. Also like I said before, no metal in the oil filter. Again, in your opinion, do you think that sounds like a thrown rod or more like the coupling or ? I understand that I have to remove the outdrive now, and believe me I wish I didn't, but this group and you are the only way I'm going to enjoy this search if I can reconsile the probability of what I'm looking for. What do you guess I'll find?

Thanks again to you and all. Jay

 

[whywhyzed]

Re: Mr. Manipulator! Re: OMC 800 hammering noise in bell housing area

Re: Mr. Manipulator! Re: OMC 800 hammering noise in bell housing area

I talked to a local mechanic who said he knew the Stringer 800 well. He said that inside the coupler were springs and he referenced what he said was like a clutch plate or something.

That mechanic is full of ship. He's never had an 800 apart- If he had he would know that there is no clutch, no springs, nothing. DO NOT take your boat there!

 

[Manipulator]

Re: OMC 800 hammering noise in bell housing area

Full of sheeeeeeeeeeeeeeeeeeeeeeeit is right.

 

[gojayo]

Part way there! Re: OMC 800 hammering noise in bell housing area

Part way there! Re: OMC 800 hammering noise in bell housing area

Got the outdrive off and only broke 2 bolts! Pretty good. Ran the engine without pulling the shift cable without the ball gears being engaged, and no hammering noise from the bell housing or intermediate. Got the shift cable out without my torch and only small amounts of taquilla. I can turn the outdrive's ball gear by hand, both in neutral and in gear, and I get a definate clank and resistance once each revolution. Since it's each revolution of the ball gear, doesn't that point to the upper gear housing? So, is it wise now to just shop for a used upper gearbox with the right ratio NOW, or should I start tearing the upper gearbox apart?

Also, one other unrelated question: The drive that raised and lowers the outdrive: It had water in it when I last changed the outdrive's oil. I got worried about underwater seals etc, then remembered that my bilge had seriously filled up a year ago when I left the drain plug in when storing it outside. With that drive's motor sitting so low in the bilge of my boat, could that water have some from inside the boat via the bilge and not necessarilly from the outside?

Thanks to all. Jay in Seattle.

 

[fendersfender]

Re: Part way there! Re: OMC 800 hammering noise in bell housing area

Re: Part way there! Re: OMC 800 hammering noise in bell housing area

water could have gotten in from inside, but not likely.....those tilt housings are notorious for leaking.........as far as your upper gearhousing is concerned, it may not be as bad as you think....it just may be a broken water pump shaft (the are known to rust and twist the splines off)...if so, parts are still available.....and i would change impeller while your at it. a good source for parts is http://www.sterndrive.info/ ....hopefully this is your problem.....if not, worst case scenario is a trashed gearset, which will cost around $800 for gears, not including seals, etc. Get yourself a good oem service manual (they are still available on ebay)...good luck