3.0L driveline knocking noise...HELP!

[chargedstang89]

Hi all! I'm new to this site, but well versed in engines. My father owns a 1999 Bayliner Capri (19ft). It has the 3.0L Mercruiser with an Alpha 1 stern drive. The boat is making a knocking/clicking sound at idle and it gets much louder as the engine RPMs rise. There's also a vibration in the boat as well. Power seems to be fine. I used an aluminum pole while the engine was running on the lake and moved it around the engine. I hear a little normal valvetrain noise, but all of the knocking/clacking seems to be coming from down low, towards the driveshaft area. As far as I can tell, it's not coming from the exhaust/head area. Is it possible that the u-joints are junk and need to be replaced?

Late last season, he hit a log on the river, and tore the lower unit off of the boat. The boat took on a lot of water, and the insurance company took care of everything. It ran fine this year up until recently. They replaced the gimble bearing and bellows as well, but I'm not sure about the u-joints. It also doesn't make a difference if you turn left to right or not, as the sound remains constant.

Any help on this would be appreciated as I'd love to get the boat back on the water ASAP.

Thanks!

 

[Haut Medoc]

Re: 3.0L driveline knocking noise...HELP!

Welcome to iboats.....
I'd say it is the u joints......
Pull the drive & start the engine, if the noise is gone, that would be my guess......
Run the engine for no more than 15 seconds if you are not supplying water to the engine.....
I'd check the engine alignment & the gimbal bearing, too......​

 

[chargedstang89]

Re: 3.0L driveline knocking noise...HELP!

Thanks! How can i check the engine alignment? My father said that supposedly, the shop said they did this when they replaced everything and it ran fine so far this season until the past few times he took it out. I wonder if those u-joints got submerged in water in the accident last season and they didn't replace them. They put a new throttle cable on too, and the throttle is extremely stiff and notchy, so I'm not too impressed with this shops work so far. It's almost like the cable is kinked or rusted, but that's a different story...first thing is first...ha!

 

[Haut Medoc]

Re: 3.0L driveline knocking noise...HELP!

You need an alignment tool....
They pop up on ebay for 30-50 bucks.....
I'd be inclined to say that water probably got to the ujoints....
No reason not to believe they didn't check the alignment, but it is something that should be done as part of preventative maint. at least yearly.....​

 

[4winnsskipper]

Re: 3.0L driveline knocking noise...HELP!

Welcome to iboats.....
I'd say it is the u joints......
Pull the drive & start the engine, if the noise is gone, that would be my guess......
Run the engine for no more than 15 seconds if you are not supplying water to the engine.....
I'd check the engine alignment & the gimbal bearing, too......​

a

DO NOT run your engine without it being supplied water for ANY length of time. This eponentially decreases the life of the impellar, it's designed to be lubed with water, it's like saying well you can run your car engine for 60 seconds with no oil, but no more. sure it's PHYSICALLY possible, but you will have severe damage no matter what, there is no avoiding it.

 

[sabastianunf]

Re: 3.0L driveline knocking noise...HELP!

Raw water impeller will not be destroyed if outdrive is pulled. Could damage the circulating pump but probably not in 15 sec.

 

[chargedstang89]

Re: 3.0L driveline knocking noise...HELP!

You have to keep the throttle locked in forward gear when removing the lower unit, correct?

As for alignment, why couldn't you just use the driveshaft? Or is there something special the tool does? Just curious.

We are going to tear it down tonight. If the gimble bearing is good, which they should have put a new one in and aligned it, then hopefully we won't even need to worry about it. Guess we'll see...

 

[Haut Medoc]

Re: 3.0L driveline knocking noise...HELP!

You have to keep the throttle locked in forward gear when removing the lower unit, correct?
Yes......
As for alignment, why couldn't you just use the driveshaft? Or is there something special the tool does? Just curious.
There is a special tool, but if you have a new gimbal bearing, just spin it & feel it for roughness, I doubt that you need the tool at this time, however just because the input shaft goes in does not mean you are properly aligned, so to answer that question.....
No.... The input shaft is not enough to insure proper alignment....

We are going to tear it down tonight. If the gimble bearing is good, which they should have put a new one in and aligned it, then hopefully we won't even need to worry about it. Guess we'll see...

Good Luck!.......

 

[4winnsskipper]

Re: 3.0L driveline knocking noise...HELP!

Raw water impeller will not be destroyed if outdrive is pulled. Could damage the circulating pump but probably not in 15 sec.

DOH!!! forgot this was a mercruiser not a volvo, my bad.

 

[Modified]

Re: 3.0L driveline knocking noise...HELP!

Let me know if this is a one person job or not, I'm going to have to take my outdrive off to sand and repaint soon.

 

[Bondo]

Re: 3.0L driveline knocking noise...HELP!

I'm going to have to take my outdrive off to sand and repaint soon.

The Alpha Outdrive weighs in at about 80lbs,........

With some Blockng,+ Tools,..... It's easily a 1 man Job........

 

[chargedstang89]

Re: 3.0L driveline knocking noise...HELP!

We got it apart last night, and I pressed the old u-joints out and put the new ones in. We are going to re-assemble everything tonight and put the drive back on.

Here's my question... The u-joints felt smooth when they were in the driveshaft assembly. No needle bearings were damaged, BUT in several of the caps, what grease was left, was a rusty brown color...almost as if they got wet in the accident. Dad called the shop that did the repair work and the guy said that they probably didn't replace the u-joints unless they saw something obviously wrong with it, but that they did replace the gimbal bearing and did align it. He also said he didn't think it was the u-joints and then went into the whole "we'll have to dyno it, blah blah blah" talk.

So, do you guys still think it could be the u-joints or is there something else I can check while it's apart?

We did a quick dry fire. Put the gear shifter back in neutral, fired it for a couple of seconds. I heard a little lifter noise (boat has a lot of use on it) but couldn't hear that loud sound that used to be there. However, the sound of the exhaust could have easily drowned it out.

I guess we'll see tonight.

 

[Haut Medoc]

Re: 3.0L driveline knocking noise...HELP!

If there was any rust or crap in the ujoints, then I think you have solved your problem.....
Ya can't always tell if they are good or bad from the outside......​

 

[chargedstang89]

Re: 3.0L driveline knocking noise...HELP!

If there was any rust or crap in the ujoints, then I think you have solved your problem.....
Ya can't always tell if they are good or bad from the outside......​

The shafts on the inside of the u-joints that the needle bearings ride on were shiny and not rusted, but all of the little bit of grease that was left had a rusty brown color to it. The u-joints did wobble really easily and there was no stiffness like there are with new ones. Who knows...maybe the tolerences were worn just enough to allow some vibration that you can't tell while just holding the driveshaft and u-joints with no load being placed on them.

If this isn't the problem, then I have no clue what it could be.

 

[Haut Medoc]

Re: 3.0L driveline knocking noise...HELP!

Post back with the results.....
I think you'll be OK.....
Looking at it while sitting is alot different than 1000 rpm.....​

 

[chargedstang89]

Re: 3.0L driveline knocking noise...HELP!

Will do. Also, the instructions that came with the u-joint show a special spanner wrench type tool to remove the large, round, toothed nut that holds the driveshaft into the lower unit. I used a hammer and punch (without damaging the nut) to get it off. The book states that it should be torqued down to 200lb. ft. We don't have this wrench. Is this something I can put back on using a hammer and punch and hammer it until it just doesn't move anymore, or do we really, really need to get the tool. Let me know.

 

[chargedstang89]

Re: 3.0L driveline knocking noise...HELP!

We ran into a huge problem tonight. The prop is stuck in drive now that everything is back together when the shifter is in neutral. I just took the lower unit back off. What do I need to do to get it working right?

What position does that little silver lever on the lower unit need to be in? It moves if you move the prop. Please help as we are trying to get it in the water for this weekend. I would even be willing to pm my phone number to someone if they can walk me through it real quick tonight. Please help.

 

[Haut Medoc]

Re: 3.0L driveline knocking noise...HELP!

Do this simple test......
With the unit on the bench, turn the intermediate shift shaft cw while turning the prop ccw......
It should lock in foreward......
Turn the shift shaft ccw & the prop cw until it locks in gear.....
If it will do it both ways you should be OK.....
With the helm in foreward, the intermediate shift shaft should be facing directly foreward, it is impossible for the drive to go on any other way....
So, in order to put the drive on you must put the drive in fwd by turning the intermediate shift shaft cw while simultaneously turning the prop ccw until it locks into gear.....
You must keep the shaft in this position by applying steady pressure whether by a bungee cord of manually, if it does not stay locked in gear, you need to back it off & try again.....
To answer your question about the retaine wrench, is it mandatory?
No....
Should you use it ?
Absolutely....
You have no inkling as to how much torque is on the retainer.....
So, you are rolling the dice.....
It may be OK, maybe not......​

 

[chargedstang89]

Re: 3.0L driveline knocking noise...HELP!

Well, by coincidence, I tried basically what you said before reading your post, so I guess I accidentally did the right thing. I yanked the drive back off, and the prop would not spin ccw, so i figured the shift shaft had been moved at some point while it was off. Possibly by bumping the prop or something. Anyways, I turned the driveshaft while fiddling with the shift shaft and it popped in and started spinning the prop ccw as well.

I then put everything back together, and only rotated the prop ccw to get the splines to line up. once it was lined up, and the lower unit was bolted back up, everything was still in gear, and i could not turn the prop ccw, so hopefully that told me it is in gear in the right direction.

Put the shifter in neutral, and the prop would then spin freely in both directions. If I put it in forward again, it would the not spin ccw and if i tried to spin it cw, it would make a ratchet type feeling, so i'm thinking it's definitely engaged in the right direction.

Then I fired the boat up w/ water being fed to it, and let it idle for a minute, revved it up a little, and I heard some valve noise, but I'm not sure I could hear the loud noise that was there before. This is either because the exhaust out of the drowned out the sound, or the clicking/knocking sound was fixed. ha!

My dad is taking the boat out this weekend to test. Will post results after.

Does it sound like everything is engaged correctly?

 

[Haut Medoc]

Re: 3.0L driveline knocking noise...HELP!

Yes!......​