Engine alignment help

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Apr 3, 2009
17
Pixel Perfect 33_77-83 Port Credit Harbor Marina
I have been trying to align my engine on my hunter 33 (1978). The engine is a Yanmar 2qm20h, and I have been fighting with it for 3 days now.

I have the coupling disassembled, and have tried using a thick pipe wrench levered between the engine block and the fiberglass stringer but i cant seem to get the mounts to move over a bit. All the mounts have been loosened but I think the 30 years of use has made the mounts stubborn.

I will try putting a jack under the engine to relieve stress on the mounts tonight and see if i can push the engine over that way.

Does anyone have any tips? I can see visually the engine flange needs to slide over a millimeter or two to port to line up with the coupling. The engine shaking I was having last season is undoubtedly because of this mis-alignment.

I have bought a flexible coupling (drive saver) between the flange and coupling. With this flexible intermediate plate, can I get away with the gap? or do I still need a .004 inch gap with the feelers (the coupling is 4" diameter).

Any help would be appreciated.
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Are you saying that you are loosening the lag bolts that hold the mounts to the stringers? And then trying to slide the engine to port? I wonder if the problem is that the mount holes are like mine and only slotted on one end? See picture.
 

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Apr 3, 2009
17
Pixel Perfect 33_77-83 Port Credit Harbor Marina
I have the Bushings Inc type mounts. Are yours the standard yanmar mounts because they look much more secure than what I have. This is the mount that I have : http://shop.torresen.com/ships_stor.../8"+Stud,+For+Engines+450-750#&sectionid=5159

I managed to get the engine much closer in alignment with many more hours of trying to find a safe place to pry the engine over with a wood board. I think another hour or two I'll have managed to get it in place.. hopefully.
 
Dec 2, 2003
1,637
Hunter 376 Warsash, England --
Questions and problems of engine to shaft alignment crop up so often that I made a diagram to show the pitfalls.
Both engine and shaft have to be in alignment with their axes absolutely parallel in both vertical and horizontal directions,
AND,
they also need to have the centres of both gearbox flange and shaft flanges aligned vertically and laterally.

i.e. no angle between shafts as well as no displacement.

Problems in achieving this means the engine must be moved bodily sideways, up or down and also tilted sideways and up or down as well.
I hope the attached diagram illustrates this.

Also make sure the shaft is as well centred in the log tube as you can get. Perhaps to within ± 1/8" if possible.

Normally the task of moving the engine and its mounts is not as great a problem as you appear to have and I wonder whether the anti-vibration mounts are already at the limits of the slots for the lag bolts. Slacking them off a fair distance will enable you to see this.

Fitting a flexible coupling will ease the angular alignment problem but you will still need to get the axial alignment right.

Keep us posted on how you get on.
 

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Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Donalex's illustration assumes mounting holes being slotted. Yours are and mine are not. My 2QM20 had the mounts that your link shows. Looks like those are slotted both ends. Seems like you are almost there.
 
Dec 2, 2003
1,637
Hunter 376 Warsash, England --
The picture in the link that "inquiztr" included in his second posting showed slotted holes. How else does one align the engine- or are there large holes in the engine's brackets and large washers.
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Thinking more about this issue I can see that my mounts, with one end having only a round hole, would still allow a certain amount of lateral adjustment.
 
Apr 3, 2009
17
Pixel Perfect 33_77-83 Port Credit Harbor Marina
Its seems that you are right, one of the mounts has reached the edge of the slotted clearance however I am almost there with the alignment.

The previous owner has a mish mash of two different engine mount types being used. One is the bushings inc brand mount I had linked to which I like and the other looks similar but doesnt have the cast iron casing around it so the rubber busing is exposed, and the base is just a steel plate. This brand doesnt have as large as a slot to move the mount over so I will replace it this weekend and I think that will solve my problem.

I dont have a clear picture of the other kind but you can see the one closer is the better kind.
 

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Dec 2, 2003
1,637
Hunter 376 Warsash, England --
Inquiztr

Been busy again with my drawing prog and updated the drawing in my original posting and added another to show side view as well.
Please note it is the location of the cutless bearing and the center of the log tube that determines the position of the engine.
If the shaft is not centred in the log it will bang against it at certain engine rpms and vibrations and scare you witless.
The flex hose on the shaft gland tends to hold the shaft where it has been for years and it is not possible to see the end of the log tube whilst afloat (without causing a flood!) So one needs to press the shaft hard fully down, flexing the hose, until the shaft contacts the inside of the log and then measure the distance of coupling flange off the hull using a steel rule across the face of the flange (measure to the top edge of the flange). Then pull the shaft firmly upwards and measure again. Take the average as the centre of the log and adjust the engine to suit.
Do it again in the horizontal plane also and you will have a correct setup.

Revised pics also shown below.
 

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Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Good explanation and nice work with the illustrations. I had the advantage of having the boat on the hard and installing a new engine when I lined up everything. Much easier that way. Even so it took a lot careful measuring before installing the mounts and then the engine.
 

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