Mercruiser alignment issues

[tank1949]

I have performed Chevy V8 motor/alignments at least a dozen times in my life but now I am experiencing issues. I was careful to torque flywheel and coupler to specs after making sure that there was NO contamination on mated surfaces. I raised or lowered engine to where I could freely insert and remove alignment tool. The grease indexed spline tool marks uniformly on alignment tool (top and bottom). But, then I spun motor over 180 degrees and tried inserting alignment tool. It was difficult. None of the manuals or videos suggest rotating motor like I did, but I figured that the tool would easily go in and out. Obviously, something is not perfect. I worked making sure that I have a happy medium but not perfect either way. Have any aligned using my method of spinning over motor after checking it? Maybe this is not necessary? THX

 

[alldodge]

Going 180 is good, most try to do 0, 90 and 180 for overall verification.

Going in good then not so good after turning means something is out of round. The first thought is the coupler. Is the coupler new?

Also have an engine serial number?

 

[tank1949]

Going 180 is good, most try to do 0, 90 and 180 for overall verification.

Going in good then not so good after turning means something is out of round. The first thought is the coupler. Is the coupler new?

Also have an engine serial number?

I don't think coupler is new. It had a spot or two of rust, but not much. I indexed existing crank to existing flywheel and then existing coupler to existing flywheel before removing in order to mount motors onto stands. I made sure dampeners were where they needed to be and torqued. I had to remove bellhousing and flywheel, etc. I had to replace rotten transom. Before, motors exhibit no vibration. The motor's serial numbers are hidden by heat exchanger and its mounting hardware. Casting numbers indicate 4 bolt main 350 and mfg in Mexico. I have never rotated any motor before. Maybe I should have? THX!

 

[alldodge]

Your probably ok, it may have just sat in one position a bit long. If you can get it in/out with minimal effort, and your sure it cannot get any better, then give it a go.

Only concern is you where able to get it real smooth at first, so wonder if its the coupler or even maybe the rear mounts

 

[tank1949]

Your probably ok, it may have just sat in one position a bit long. If you can get it in/out with minimal effort, and your sure it cannot get any better, then give it a go.

Only concern is you where able to get it real smooth at first, so wonder if its the coupler or even maybe the rear mounts

I'll pull motor and spin it over w/o plugs in it and no load. Then, I put dial indicator on alignment too, flywheel, etc. You don't happen to know acceptable runout on flywheel? I'm guess .0010 on edge? There is a possibility of trash on mated surfaces, but I thought I was very careful not to install it with any. If it spins over with alignment tool in coupler and I notice wobble, then something is OUT. THX

 

[achris]

.... Have any aligned using my method of spinning over motor after checking it? ...

Checking alignment at 90 degree intervals is the Merc preferred (and recommended) method.It does sound like something is out of spec.Pull the engine and check for flywheel runout.

Chris...

 

[muc]

might want to look at this service bulletin
MerCruiser Bulletin No. 2009-11
Improved Service Procedure for Engine Coupler or Drive Plate Replacement

 

[alldodge]

View attachment Bul 2009 11 coupler-install.pdf

 

[tank1949]

I wasn't far from max runout but didn't do the tapered 3/8 x16 bolts. I never heard of that!!!! Former owner has alpha 3 bolt coupler installed and not 6 bolt coupler specific for bravos. I understand the centering aspect of the procedure. Thx!!!!! I have printed bulletin. THX!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[tank1949]

I have never centered flywheel to crankshaft bolts either. I am wondering if I need to find some 7/16 fine thread V (tapered) bolts too and perform centering of flywheel as well? THX!

 

[alldodge]

I have never centered flywheel to crankshaft bolts either. I am wondering if I need to find some 7/16 fine thread V (tapered) bolts too and perform centering of flywheel as well? THX!

No IMO, the flywheel is indexed and taper screws would have no effect

 

[tank1949]

No IMO, the flywheel is indexed and taper screws would have no effect

Thanks...bought dial this morning including magnetic base. Live and learn!

 

[Mikey N.C.]

Did you replace gimbal bearing ?

 

[Mikey N.C.]

I'm a seasoned mechanic for many years on gas and diesel engines. Old Cummings big truck , bell housings would have to be dialed in to flywheel. By drilling bigger dowel pin holes.
I'm at a loss , why would you need to dial indicate flywheel ? Flywheel does have roll pin or dowel pin correct ? Rear of crank does have a boss that flywheel fit's on rite? And dowel or split or roll pin rite. So how can it be out of round , if rear main brg. and seal are not shot.
And if it's say. .015 out want it break crankshaft. ? And be vibrating like crazy.?
please infor. Me. I would like to know , how flywheel can get out some issues before.
I've seen back in the day rubber viscous dampeners slip and break crankshaft.

 

[Mikey N.C.]

The reason I asked about gimbal brg. We bought 4 or 5 from Sierra last year , and had trouble getting lower units back in. Low and be hold it was sorry mfg. bearings the center race in gimbal that pivots were seized up. Now I just talking about removing out drive not motor.

 

[Mikey N.C.]

Sorry for rant , did not read hole thread .if transom was rotted then stringers are rotted to . so motor is tilting.

 

[alldodge]

Might of missed something but didn't read anything about transom or stringer problems.

So far as the flywheel, the dial indicator is used to measure flatness. Have not found one on a boat which was not flat, but still as a good mechanic not bad idea to give it a quick check

 

[achris]

The reason I asked about gimbal brg. We bought 4 or 5 from Sierra last year , and had trouble getting lower units back in. Low and be hold it was sorry mfg. bearings the center race in gimbal that pivots were seized up. Now I just talking about removing out drive not motor.

In general, aftermarket parts are of a lower quality and tolerance. This is why I only buy OEM. That does not mean only Merc parts. If it's for the engine, I usually buy the parts from GM, and bearings in the drives, from a bearing shop (usually SKF or Timken)...

Chris........

 

[muc]

The reason I asked about gimbal brg. We bought 4 or 5 from Sierra last year , and had trouble getting lower units back in. Low and be hold it was sorry mfg. bearings the center race in gimbal that pivots were seized up. Now I just talking about removing out drive not motor.

If you use a alignment tool after replacing a gimbal bearing, you will find that it’s much easier to get the drive back on.

 

[tank1949]

Did you replace gimbal bearing ?

Not replaced gimbal bearing. Gimbal is smooth and no rust but not new. +- 4 and 1/2 thousands run out at end of flywheel. So, flywheel appears to have gone on w/o crap between crank and wheel. No noticeable wobble. I'll center coupler tomorrow with tapered 3/8 bolts and also measure runout with MC spline tool inserted. Coupler splines look good.