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Another issue... Noise (clang) coming from motor under acceleration Mercruiser 3.0 with Alpha One

T

thecca

Member
Hi... I went on the water yesterday and noticed a strange sound coming from engine bay under acceleration / trying to pull a wakeboard/tube out of water. Sound is pretty weird, it's like a rattle and I can compare it to pieces of change in your clothes dryer, it clangs, like if there was some metal parts in the motor/transmission that were broken and flying around, but the motor does not lose any power and runs smooth like usual. Sound started saturday randomly and wasn't there before even with 6 people in the boat and a wakeboard in the back.

What do you guys think? Someone at the marina said the motor probably needed to be changed, but I doubt it? I mean, it happens only on accelerations. I checked oil and it's still clear and full. It doesn't heat and the oil pressure is good. Checked for some lose parts and everything seems fine... Once it's at cruising speed and on idle motor runs fine.

Transmission / Drive gears are fcuked up? Motor can't withstand pressure (acceleration)? Could it be the timing or a broken flywheel dust cover?...

Thank you.
 
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I will take a video tonight and post it. I switched from 91 octane to 87 octane (owners manual said motor was built for 87...) but I doubt this could be my issue since the noise is really loud.
 
The grimble bearing was changed in february. The U-Joint seems OK since it's not making any noise when I'm turning and no water is getting into it (well, as far as I know). I've tried pulling the trim up and it didn't solve the problem. Put some octane booster and it didn't help either. Sound is really coming from the flywheel area.

See video here : You can clearly here something wrong around 1:45 : http://www.youtube.com/watch?v=mFnLCR086d4&feature=youtu.be
 
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I will have to remove the entire drive for this. I think I'll do it myself, but could someone explain me why a cracked flywheel cover would do this? I mean, I don't understand...

And also, will it hurt the boat more if I continue riding it in this condition? I fear it might get worst and break something else...
 
nothing gets removed, inside the boat look at the thin metal cover just below the oil pan. It covers the flywheel
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I have to put my head in the hole or take a mirror? I mean, this is located in the back of the engine, I don't think I can get there unless I remove the drive or if I'm a contortionist
 
Ed put up the diagram, what i do is lay on my face on the starboard side with my head up against the back and stick my hand under the engine... and run your hand on the flywheel cover. Yank on it and see if there are any screws in the bilge. I think 8 of them should be holding the cover.

Me i snap off the ear it gets in the way when i install a starter in a 3.0l.
 
I fear I might hurt something else by continuing to use the boat... If it's an easy part to fix, I don't want to damage other expensive part. What do you think?
 
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Allright I will check tonight! But what could ''rationally'' explain this sound when a broken flywheel cover occurs? Wouldn't it just do the noise all the time even not under load?

Thanks again for your answers, you're helpfull! PS : What's the ''ear''? English isn't my first language so I sometimes have trouble understanding all expressions...:)
 
A piece of metal or trash touching the flywheel ring gear. The clear fuel filter is not my favorite type...they can break open. Use a solid metal type.
Put some octane booster and it didn't help either.
Click to expand...
That crap will foul the spark plugs.
 
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Also, I've noticed the fuel filter isn't full of gas even when running. Is this normal or it's supposed to always be full with no air in it?
 
Anybody has another suggestion?

I will look tonight for :

1) Broken flywheel cover
2) Spark plug color
3) Bad rockers (after valve cover removal)
4) Exhaust flapper (I doubt they're broken since the issue happens under load, not at idle)
 
If you don't have access to a mechanic's stethescope use a broom handle or section of 1/2" PVC pipe and place one end near the noise and your ear on the other...you'll know where it is very quickly. As was stated lay down and place your hand on the back flywheel cover and feel around it for the vibration.
 
Just went at the marina and checked a few things.

Opened the oil cap, sounds OK.
Checked the flywheel, the dust cover (that is in plastic) is intact and the metal cover also. Everything is tight in there. Sound doesn't come from flappers/shutters either.

I'm starting to think it's a bearing somewhere... (may-be a bearing around the flywheel/in the drive, but the gimbal bearing is brand new...)

I will contact a mecanic and bring him on water to see what he has to say, I'm exhausted and don't want to waste my summer finding this issue.. I'll keep you posted guys. Thanks.
 
Use your smart phone or digital camera and make a SHORT video recording the sound and post it to youtube and then post the link here..........
 
Sorry missed it..


Motor needs to come out and the bellhousing assembly needs to come aprt and see where all the metal scrapings are and are coming from.....

definately sounds like somthing scraping.....something loose or broken and scraping.

my opinion....
 
Just came back from the marina and did a ride with the mecanic there (who is an expert, according to a few people I've talked with...) He said that it's probably my timing that was off and fried the motor... They're gonna check with the light to see where it is currently and call me back.

Also, my engine is running at 175F on the gauge and it's supposed to be 140 (according to him). He said that I might have to change/rebuild my whole engine since it's probably ''fried''... I don't really know what to think, I'm a bit shocked here.
 
Mecanic also said said a bad timing could kill the engine if you run it a few months like this. He also mentioned something about loose pistons or something like that, that would create this sound. I'm thinking it's a rocker arm problem or a timing problem, he'll time it and check the rocker arm. I'll see after this...

I've also noticed that it makes the sound a lot more when I push the throttle WOT and I let it back. As soon as it stops accelerating, the rattle begins. (I think it's noticeable in my video)

Also, what's the correct timing? I think my engine is the 3.0LX (I have the audio warning system) and the year is a 2000

If I'm not wrong, it sould be 2 degree and 12 after base mode right?
 
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Some mechanic, just sayin.

Disconnect the battery make sure it's disconnected neg side first then the pos side.

Lay back down on your face on the starboard side and grab the starter. Shake it like your were shaking a cheating wife.

AGAIN LOOK FOR BOLTS IN THE BILGE.

Run your hand over every inch and the drain hole stick your finger in there.

Use a mirror make sure you eyeball the starter bolts.

Post back !
 
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I also just noticed that the timing cover was changed (probably for a car one), since the timing tab isn't even there anymore. How can someone time it without a freaking tab?

I'm starting to think my boat is a mess... Damn this ain't a good feeling.
 
Had time to check rockers tonight.

Put no.1 piston in firing position, checked the rocker arms.

Is it normal that they are a bit loose? (I can move all of them from left to right but not from side to side and I can, with a bit of strenght, spin the rods, except the ones that can't be adjusted in this position).
http://img690.imageshack.us/img690/654/n545.png

Guy in the DYI video tells to turn an aditionnal 3/4 turn, but if I do this, they won't be loose anymore like the ones that can be adjusted are right now?...

The other rockers that couldn't be adjusted with no.1 cylinder in firing position were all very tight EXCEPT the last one (exhaust valve of cylinder 4). Is it normal?

I will check timing tomorrow and go for a ride.
 
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You are doing this all wrong...........................


I dont care what the "guy" on youtube did.........the static adjustment is typically done when assembling for the first time in my opinoin....with a running motor in use I would do the following.


This is what I would reccomend as this engine has allready been running.

Take the valve cover off. Remove the carb linkage, cover area around the exposed head edges with rags to catch oil. This is a messy job!!

Start engine and allow to warm up so it will idle on its own,

start on the first rocker arm and repeat for all the rest.

Loosen the rocker arm nut until you just start to hear a clacking sound. As soon as you hear this sound tighten the rocker arm nut 1/4 of a turn to start.
do this 3 more times, 1/4 turn at a time and allow the engine to run and smooth out between each turn. Say 1-3 minutes....you may have to kick the idle rpms up a bit by hand also to keep it running... try to keep idle between 650 and 800 rpms... might need a bit more to keep it running.

The total amount of tightening should be 1 full turn ( 1/4 at a time) for each rocker nut after clacking has been detected.

Sometimes these 4 cyclinders can be a bit wierd so if one needs a bit more than 1 full turn it is ok to got 1/4 turn more.
 
Ok I'll try this today...

But are they supposed to be loose when the valves are closed or I should not be able to move them a little bit? (When cylinder is in firing position)
 
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