Mercruiser left/right alignment

[metzgerb]

I've searched through a variety of the forums here and can't seem to find a full answer to my issue. I recently purchased a 1972 Signa with a Mercruiser 140HP (Motor SN 3247636, Stern SN 3287033) and after 3 times on the water, the engine blew up (intake valve failed causing hole burnt into piston). I came across a donor boat that I was told was a 140HP as well (Motor SN 2791722, stern SN 2794760). I pulled the original motor and installed the "new" motor. Originally I had a hard time getting the port side rear motor mount bolt in after I had the starboard one in. It appeared to be hitting the Transom Plate/Exhause tube. I ended up pulling the motor again and installing the donor boat exhaust tube from transom plate back. I was able to get the bolt in, however I am now having issues aligning he engine.

I bought he alignment tool and replaced the gimbal bearing while I had it apart. While trying to align it, the motor appears to be too far to the starboard side and needed to be adjusted. I removed the front motor mount bolts and the holes are not centered. The motor does not want to shift to the port side even with the rear bolts loosened.

Could their be an issue with the Transom Plate compatibility that I would need to install the "donor" plate? Any other ideas on adjusting the motor left/right?

Thanks in advance,

Brett

 

[achris]

If the transom is starting to rot you can get the alignment between the inner and outer housing vary, giving you what you are seeing. I would remove the engine and transom housings and measure the transom thickness. It needs to be 2" (+1/8" -0"). And check it for rot.

Chris...

 

[metzgerb]

The transom appears to be very solid. I removed the starboard rear motor mount bolt and moved it until it was lined up. it has to move a little more than 1/4". In talking with a local guy that had done the same thing, he said he ran into the same problem. His resolution was to slot the motor mount. He said he drove it for 2 years and never had an issue. Concerns of this?

Thanks,
Brett

 

[achris]

That is a band-aid, not finding the reason and fixing it. I would a)never do it, and b) never suggest or recommend it.

Another possibility is that the engine coupler is damaged. Turn the crankshaft 180? and recheck the alignment.

Chris.....