As I see there are some other creative ideas being born here. Nothing wrong
with that.

As to the subject matter I have to say that I'm almost sure that coupler was
spun a bit (few sec.) although as I said looks like new after that. That got
me thinking : can the coupler survive a short slippage and be still OK?

My outdrive must have been somewhat misaligned as I was not able to put it
back in. It went in,caught the spline and jammed about 3/4 of an inch before
full insertion. Alignment tool that techs used was showing a position that
was close to good/or good yet the outdrive couldn't be installed. 2nd
mechanic somehow managed to push it a bit more so he could put on a nut and
used it (and other ones) to slide it in. Yet a thump could be heard when the
outdrive finally went in (while tightening nuts). This was a clear signal
that even though the outdrive was installed engine mounts were not happy. I
suggested removing it realigning the engine and heard only "it's gonna be OK
now". Well, it wasn't. As a result the whole engine had to be taken out to
find out that the coupler I had was a wrong one (there are two types A5 and
A7 and I needed the other one, a bit bigger). But with the engine out I
could examine the outdrive and was surprised to see that it was perfectly
fine, at least visually. I was wondering is this still acceptable or even 1
turn makes it useless.



"JamesgangNC" wrote in message
hlink.net...
You can run the engine without the outdrive. You can just hook a garden
hose onto the water line coming in from the outdrive and run water through
it. You just need a piece of plastic tubing to clamp the hoses to. I've
run mine that way. When you've got the outdrive on put some muffs on it.
If you don't have any muffs buy some, they are only about $15 and you need
them anyway. Even with a bad impeller you can usually get enough water
through the muffs from the garden hose pressure to keep it cool running in
the driveway. As others have pointed out the rubber exhaust components
will get hot pretty quickly and they will melt. They were not made for
straight exhaust, they were made for wet exhaust. And the lower unit
water pump is IN the exhaust stream going out the prop. It is plastic
too. Just no reason to not give it water since all you need is a garden
hose.

If you have burned up the coupler you should be able to see evidence of
that. Melted rubber, etc around the outside. It won't strip the splines,
the rubber will spin inside the housing. If it has spun at all then it is
shot. You're trying to transfer a couple hundred hp through the thing.
I'm guessing you burned up some exhaust rubber or the water pump impeller.
Or maybe the oil from when it was winterized last. Get some water in the
thing so you can run it for awhile then you can troubleshoot.

It is not odd for mercs to not be a 'perfect' fit even after being
aligned. Anyone doubts me just get yours perfect and then turn the engine
1/2 turn and you'll see what I mean. Merc couplers have no center
alignment bushing so they are never perfectly centered on the flywheel
anyway. Slightly out of alignment is not going to bother the u-joints or
make them 'catch'. They take far bigger stresses on turns and trimming.

"JIMinFL" wrote in message
link.net...
The water pickup is in the upper gearcase exhaust path and holds the
copper pickup tube that fits into the top of the water pump, by means of
an interfereance fit rubber bushing. The exhaust shutter is a stainless
steel plate with a rubber edge which helps it seal better. Those are at
the top of the Y pipe and directly in the path of escaping exhaust
gasses. You can tell when they have either melted or are worn out by the
annoying rapping noise they make. The noise is so alarming that you would
think your engine is self destructing. Those rubber hoses I spoke of
contain the exhaust gasses from escaping into the engine room and
causeing a fire. I will guarentee you that if you can't hold your hand on
one of those hoses for at least several seconds, the hose is charring and
will eventually rupture.

You may not have damaged anything, but the previous owner might have. I
think you said this boat is new to you.
Now that you have it all apart, you might as well inspect everything that
you can. Can you run the engine on a stand to make sure the engine isn't
making the noises? I understand the exhaust noise will make it hard to
hear anything else but maybe you could poke around with a stethascope and
listen to the various engine noises.

Do some troubleshooting and report back what you find.

JIMinFL



"Proxy" wrote in message
...
Appreciate the info on the coupler.
As to the dry run seems that you are ech oing same thing that I've
already heard. Let me repeat then, no engine or major engine part will
get hot within the time intervals that I'm talking about. Not even
exhaust. Exhaust shutters are made for high temp, and plastic water
pickup does not expel exhaust gasses, "those rubber hoses" you refer to
are made for exhaust, let's not forget, and under normal operating
conditions withstand very high temp.
As I said before, no need to cool if something is still barely warm. Try
it or you will never know. Nothing personal.




"JIMinFL" wrote in message
ink.net...
You have gotten a lot of good information so far. Here's some more.

Water is needed, not only to keep the engine cool, but also cools power
steering fluid, and those rubber hoses between the exhaust riser and
wishbone. The exhaust shutters, and plastic water pickup fitting in the
upper gearcase are also in the path of hot exhaust gasses. Also, the
engine should not be started with the sterndrive in the tilted
position. You risk tearing the u-joint bellow, damaging the gimbal
bearing, u-joints, and possibly the engine coupler. The u-joints, at
the very least will make a very unhappy noise if run at extreme angles.

Look carefully at the coupler splines and the splines on the sterndrive
yoke. If you had an allignment problem, you should see evidence on the
splines. To test for coupling, you will need an old yoke with the
u-joint removed. Hold the coupler in a fixture or mount it on the
engine. Put the yoke in the coupler and a 2' pipe thru the u-joint
socket. The coupler should be able to take at least 200lb torque
without slipping. One other test you might do is to check for runout.
I'll let you figure out how to do that.

You should take the top cover off the sterndrive and make sure
everything looks happy inside.
You should drain all the gear oil and make sure you don't see metal
filings or water.
You should install a new water pump body kit after finding and removing
all broken impeller pieces.
You should make sure the upper gear housing moves freely while feeling
for a bad bearing.Same goes for lower gearcase,except you need
to check for proper shifting.
You should check for propshaft runout.

I'm sure I left out a lot of details and would hope you have the proper
OEM service manuals to guide you.

Hope some of this information is helpful.

Good Luck
JIMinFL


"Proxy" wrote in message
news Thanks. At this stage I'm not even thinking about rattling/clunking
noise. When I put the engine together I'll have one more chance to
reexamine everything. I have the engine hanging on chains and wonder
how do I go about the coupler. The rest will come later. One thing I
know 4 sure that 2 mechanics have missed the alignment part (or
thought that it may be ignored for a while and both were wrong). Most
upsetting is that I pointed that out to both and from that moment
became an annoyance. They seemed to have no appreciation for other
point of view at the moment.

Now, I've had a look at the coupler and seen zero damage but.since
the idea of the coupler is to inject a weak point into the drive
system to protect crank and drive shafts I wonder where is the
breaking point for a coupler. If a spun coupler (for a few secs) may
still be usable or regardless of its look should be replaced anyway.
With other words, is this enough to spin it just one turn to break the
rubber layers bond or does it remain good until the spinning visually
separates rubber bushings (burned, melted rubber would be visible
then). Since the engine is stripped of exhaust I have to work
backwards, start with the coupler, put the exhaust, linkage,
electrical together and test yoke/u-joint play, engine alignment and
potentially outdrive issues. Just don't want to put it back together
to later have to dismantle it again to yank the coupler out. I don't
feel like going back and forth few times over.

As indicated impeller is just a cost of testing which I don't mind.
Otherwise I see no issues with running the engine dry as long as there
is sufficient lubrication. As I said I've done it several times on
different engines always successfully without any issues or signs of
trouble (no need for cooling something that is still cold). But that
issue is beyond the scope of this subject. Coupler is.
Btw. Cobra has the best setup allowing impeller removal in just few
minutes. Very handy, at least in my opinion.

My take is this: the engine was out of alignment which has caused
u-joint jamming momentarily and that has caused coupler to let go for
a moment (blue smoke from the engine compartment - back of the
engine - typical for coupler failure) and was immediately shut down.


"Mr Wizzard" wrote in message
...

"Proxy" wrote in message
...

damage except for impeller that I have written off anyway for this
experiment.

Ah, Ok, I didn't realize that you wrote off the impeller (I missed
that)
(but the rubber smell could be the impeller galling up down there)

So, you didn't say anything about the U-joints. And when
mechanic dude said the yoke "isn't right", whats that mean?
Wrong one, wrong size, or bad, or what?

have you peaked inside the outdrive? bled a little bit of
grear juice out the bottom of the lower unit to look for
shavings? You replaced the coupler, or said that there
is no visable damage, or difference between that one,
and the one that was given to you, so I can't see that
being the problem. Besides, think about it, there is
nothing really to rattle there - the spline is a very percision
fit, and nothing really to rattle. Things that can rattle a
connecting rods, pistons, U-joints, yokes, bevel gears etc.
Could they have missed the shift-shaft lever alignment when
putting the outdive on? - dog clutch caught between gears?
Its all a pretty solid chunk of metal down there, so noise
can be transmitting from anywhere.

Hate to be stupid here, but are you SURE its not the motor?
i.e. since your not worried about water, cooling, impellers,
can you pop the outdrive off, and try to run the motor wihtout
the outdrive ? And whats the gimbal bearing look like ?
The front input shaft bearing for the outdive unit itself ?

Keep us posted.