Has anyone in the group had experience with a rattling BMW MKII sterndrive
unit or an early Volvo which is similar. Mine rattles loudly after a run on
the plane when you come down to idle speed. It wont rattle in neutral till
you get the revs up to about 1800 then the rattle comes back.

It has no decernable rattle under load, just idle after a planing run. The
unis and gimbal bearing have already been replaced. When I dont use the boat
a few days and start up it is quiet at first, but always comes back.

Anyone?

Thanks
Cam

"Grant" wrote in message
...
Has anyone in the group had experience with a rattling BMW MKII sterndrive
unit or an early Volvo which is similar. Mine rattles loudly after a run
on the plane when you come down to idle speed. It wont rattle in neutral
till you get the revs up to about 1800 then the rattle comes back.

It has no decernable rattle under load, just idle after a planing run. The
unis and gimbal bearing have already been replaced. When I dont use the
boat a few days and start up it is quiet at first, but always comes back.

Anyone?

Thanks
Cam

A flex plate can do that. Might be worth checking.

Dan

On Feb 19, 9:32 pm, "Danlw" wrote:
"Grant" wrote in message

...

Has anyone in the group had experience with a rattling BMW MKII sterndrive
unit or an early Volvo which is similar. Mine rattles loudly after a run
on the plane when you come down to idle speed. It wont rattle in neutral
till you get the revs up to about 1800 then the rattle comes back.

It has no decernable rattle under load, just idle after a planing run. The
unis and gimbal bearing have already been replaced. When I dont use the
boat a few days and start up it is quiet at first, but always comes back.

Anyone?

Thanks
Cam

A flex plate can do that. Might be worth checking.

Dan

I was thinking the same thing, But I wonder if the engine actually has
a flex plate (like an automatic trans) or if the ring gear or is
pressed on the flywheel (like a manual shift)?

Most marinized engines use a regular flywheel. A flexplate is typically
used with an automatic trnsmission and in that case the torque converter
acts as the flywheel weight.

"Tim" wrote in message
ups.com...
On Feb 19, 9:32 pm, "Danlw" wrote:
"Grant" wrote in message

...

Has anyone in the group had experience with a rattling BMW MKII
sterndrive
unit or an early Volvo which is similar. Mine rattles loudly after a
run
on the plane when you come down to idle speed. It wont rattle in
neutral
till you get the revs up to about 1800 then the rattle comes back.

It has no decernable rattle under load, just idle after a planing run.
The
unis and gimbal bearing have already been replaced. When I dont use the
boat a few days and start up it is quiet at first, but always comes
back.

Anyone?

Thanks
Cam

A flex plate can do that. Might be worth checking.

Dan

I was thinking the same thing, But I wonder if the engine actually has
a flex plate (like an automatic trans) or if the ring gear or is
pressed on the flywheel (like a manual shift)?

Stern drive boats do indeed have a flexible coupling between the engine
flywheel and the intermediate shaft which attaches to the universal joints.
In the BMW it is a flexplate with a spline. The Mercruisers have a rubber
coupling.

Cam

"James" wrote in message
nk.net...
Most marinized engines use a regular flywheel. A flexplate is typically
used with an automatic trnsmission and in that case the torque converter
acts as the flywheel weight.

"Tim" wrote in message
ups.com...
On Feb 19, 9:32 pm, "Danlw" wrote:
"Grant" wrote in message

...

Has anyone in the group had experience with a rattling BMW MKII
sterndrive
unit or an early Volvo which is similar. Mine rattles loudly after a
run
on the plane when you come down to idle speed. It wont rattle in
neutral
till you get the revs up to about 1800 then the rattle comes back.

It has no decernable rattle under load, just idle after a planing run.
The
unis and gimbal bearing have already been replaced. When I dont use
the
boat a few days and start up it is quiet at first, but always comes
back.

Anyone?

Thanks
Cam

A flex plate can do that. Might be worth checking.

Dan

I was thinking the same thing, But I wonder if the engine actually has
a flex plate (like an automatic trans) or if the ring gear or is
pressed on the flywheel (like a manual shift)?

"Grant" wrote in message
...
Stern drive boats do indeed have a flexible coupling between the engine
flywheel and the intermediate shaft which attaches to the universal
joints.
In the BMW it is a flexplate with a spline. The Mercruisers have a rubber
coupling.

Cam


And, I have seen them with slots instead of holes due to wear. Thing is, if
you can hear it in the boat, that is usually where the problem is, though
can be upper gear case
as well.

Dan

Dan,

You saying the rivets let go and flex plate components start to come apart?
Could be it. You suppose there is a way to check that before I lift the
engine out or remove the leg again? The noise is definately inside the boat.
Inside the transom housing or bell housing that is. Maybe I should swing the
prop and see if the flywheel wants to move, or not.

Cam

"Danlw" wrote in message
. ..

"Grant" wrote in message
...
Stern drive boats do indeed have a flexible coupling between the engine
flywheel and the intermediate shaft which attaches to the universal
joints.
In the BMW it is a flexplate with a spline. The Mercruisers have a rubber
coupling.

Cam


And, I have seen them with slots instead of holes due to wear. Thing is,
if you can hear it in the boat, that is usually where the problem is,
though can be upper gear case
as well.

Dan

On Feb 22, 12:12 am, "Grant" wrote:
Dan,

You saying the rivets let go and flex plate components start to come apart?
Could be it. You suppose there is a way to check that before I lift the
engine out or remove the leg again? The noise is definately inside the boat.
Inside the transom housing or bell housing that is. Maybe I should swing the
prop and see if the flywheel wants to move, or not.

Cam

"Danlw" wrote in message

. ..





"Grant" wrote in message
...
Stern drive boats do indeed have a flexible coupling between the engine
flywheel and the intermediate shaft which attaches to the universal
joints.
In the BMW it is a flexplate with a spline. The Mercruisers have a rubber
coupling.

Cam

And, I have seen them with slots instead of holes due to wear. Thing is,
if you can hear it in the boat, that is usually where the problem is,
though can be upper gear case
as well.

Dan- Hide quoted text -

- Show quoted text -

Don't know about the volvos but I would not call the merc piece a flex
plate. The later ones are a steel triangle with a rubber hub on the
center that bolts to the clutch pressure plate holes of a standard
flywheel. Early mercs had a much smaller coupler that bolted in the
center using the same bolts that held the flywheel to the crank. In
the parts catalogs they are both called couplers. Loose bolts on the
coupler could cause a rattle but I would expect it to be there all the
time. I tighten the crap out of mine when I have occasion to r&r it.

I would have to think that volvo has something pretty similar and that
theirs bolts to a standard flywheel as well. You need some weight at
the end of the crank. From you comments I'd guess that the volvo one
doesn't have the rubber component? The rubber in the merc one
compensates for a less than perfect outdrive to engine alignment.
Volvo must do a better job of aligning the outdrive to the engine
then. Otherwise I would expect an increased input shaft bearing
failure in their outdrives. Then again maybe that's your problem.
Does it have an additional carrier bearing in the transom housing
along the input shaft between the engine and the outdrive like a
merc? They can rattle as well.

No just the one bearing. Its about 2" long situated in the transom housing.
The inboard end of the shaft sits inside the middle of the flywheel and the
shaft is driven by a splined flex plate secured with about 7 bolts round the
outer circumference of the flywheel.

Cam

"jamesgangnc" wrote in message
oups.com...
On Feb 22, 12:12 am, "Grant" wrote:
Dan,

You saying the rivets let go and flex plate components start to come
apart?
Could be it. You suppose there is a way to check that before I lift the
engine out or remove the leg again? The noise is definately inside the
boat.
Inside the transom housing or bell housing that is. Maybe I should swing
the
prop and see if the flywheel wants to move, or not.

Cam

"Danlw" wrote in message

. ..





"Grant" wrote in message
...
Stern drive boats do indeed have a flexible coupling between the
engine
flywheel and the intermediate shaft which attaches to the universal
joints.
In the BMW it is a flexplate with a spline. The Mercruisers have a
rubber
coupling.

Cam

And, I have seen them with slots instead of holes due to wear. Thing
is,
if you can hear it in the boat, that is usually where the problem is,
though can be upper gear case
as well.

Dan- Hide quoted text -

- Show quoted text -

Don't know about the volvos but I would not call the merc piece a flex
plate. The later ones are a steel triangle with a rubber hub on the
center that bolts to the clutch pressure plate holes of a standard
flywheel. Early mercs had a much smaller coupler that bolted in the
center using the same bolts that held the flywheel to the crank. In
the parts catalogs they are both called couplers. Loose bolts on the
coupler could cause a rattle but I would expect it to be there all the
time. I tighten the crap out of mine when I have occasion to r&r it.

I would have to think that volvo has something pretty similar and that
theirs bolts to a standard flywheel as well. You need some weight at
the end of the crank. From you comments I'd guess that the volvo one
doesn't have the rubber component? The rubber in the merc one
compensates for a less than perfect outdrive to engine alignment.
Volvo must do a better job of aligning the outdrive to the engine
then. Otherwise I would expect an increased input shaft bearing
failure in their outdrives. Then again maybe that's your problem.
Does it have an additional carrier bearing in the transom housing
along the input shaft between the engine and the outdrive like a
merc? They can rattle as well.

"Grant" wrote in message
...
Dan,

You saying the rivets let go and flex plate components start to come
apart? Could be it. You suppose there is a way to check that before I lift
the engine out or remove the leg again? The noise is definately inside the
boat. Inside the transom housing or bell housing that is. Maybe I should
swing the prop and see if the flywheel wants to move, or not.

Cam

"Danlw" wrote in message
. ..

"Grant" wrote in message
...
Stern drive boats do indeed have a flexible coupling between the engine
flywheel and the intermediate shaft which attaches to the universal
joints.
In the BMW it is a flexplate with a spline. The Mercruisers have a
rubber coupling.

Cam


And, I have seen them with slots instead of holes due to wear. Thing is,
if you can hear it in the boat, that is usually where the problem is,
though can be upper gear case
as well.

Dan

Well, you will have to pull the motor to get at it. Now, the
"flex plate" on a boat is different than the auto version. Most of the time
it gets worn due to a lack of proper alignment, particularly on the Mercs.
I would guess that would be true for the others as well, though I have less
experience with them. Yes the rivets in the plate itself can wear, as well
as the bolts that fasten it to the flywheel. Pulling the engine isn't to
bad--I think it is faster to unbolt the mounts from the stringer and leave
them on the engine rather than the other way. Gives you a good starting
place to align when re-installing.

Hope you get it fixed OK! Dan