MerCruiser Rear Motor Mounts.

[Mkos1980]

Pic is from a 90 350 Mag with Alpha drive. The trouble I am having is a slight knock at full left turn. I have new U joints, and a new gimbal. When aligning I have to REALLY lift the back of the bar up to get it in and once it starts to go in it goes in all the way but its hard to take back out. I have to twist the bar while pulling out. All the marks are on top of the bar with only a tad on the bottom. Lifting the front of the motor up, I cant even get the bar in. Lowering its the same . I guess I just found a small sweet spot that I was able to get it in. Any thoughts? The fiber washer is about 1/4 thick and fills the gap between flywheel housing and transom plate perfectly. How can I tell if I have sagging mounts? Both sides are identical. Boat and engine only have 176 hours on it.

 

[dubs283]

Re: MerCruiser Rear Motor Mounts.

rotten transom? stand on the drive and bounce, should be very solid

are the splines on the coupler good, nice and flat, or pointy?

 

[Mkos1980]

Re: MerCruiser Rear Motor Mounts.

Splines are flat , not pointy looking. Transom is VERY solid. Boat has never been overnight in the water and always garage stored from the origional owner and myself. Bilge is bone dry all the time.

 

[dubs283]

Re: MerCruiser Rear Motor Mounts.

if the alignment bar is showing heavier marks on top the front of the motor needs to go down. try small increments on the adjusting nuts, same number of turns both sides. once it is as close you can get it with the alignment bar all the way in the coupler, hit the end of the bar with a hammer down, up, side to side, etc...not super hard but enough to get the point across. then check how well the bar goes in and out

 

[Fun Times]

Re: MerCruiser Rear Motor Mounts.

if the alignment bar is showing heavier marks on top the front of the motor needs to go down. try small increments on the adjusting nuts, same number of turns both sides. once it is as close you can get it with the alignment bar all the way in the coupler, hit the end of the bar with a hammer down, up, side to side, etc...not super hard but enough to get the point across. then check how well the bar goes in and out

X 2 you are also setting the bearing alignment. Grease the heck out of the bar and slide it in and out a lot of times and also keep turning the bar then slide some more and tap the end of the bar with something like a dead blow hamer up and down side to side. And keep greasing the bar up with spline grease, You will get it. It just takes some hard work is all If your bar has a hole at the handle end I some times will put a bar in the hole to make a T handle to help slide it in&out for a while till I get it smoother then I will retest the sliding in&out by hand to make sure I got it right.Here is a link to the hamer good for this job.http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=33906 Good luck with it.

 

[trumanlake]

Re: MerCruiser Rear Motor Mounts.

Sounds like mine. No matter how much up or down will not slide in easy. If you can contort your body enough to get a good look at the rear mounts you may even see that the space between the bell housing and the transom mount looks like a wedge. The starboard mount on mine is down slightly, and no the transom on the boat is solid. Hoping to limp her through the season then pull motor to repair. If by chance it fails before then ....... plan B. (fix it now)!

 

[WizeOne]

Re: MerCruiser Rear Motor Mounts.

...I got it right.Here is a link to the hamer good for this job.http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=33906 Good luck with it.

Great tool boat teck. I couldn't live without mine. I just bought on a whim a few years back, now I am always reaching for it.

 

[WizeOne]

Re: MerCruiser Rear Motor Mounts.

Pic is from a 90 350 Mag with Alpha drive. The trouble I am having is a slight knock at full left turn. I have new U joints, and a new gimbal. When aligning I have to REALLY lift the back of the bar up to get it in and once it starts to go in it goes in all the way but its hard to take back out. I have to twist the bar while pulling out. All the marks are on top of the bar with only a tad on the bottom. Lifting the front of the motor up, I cant even get the bar in. Lowering its the same . I guess I just found a small sweet spot that I was able to get it in. Any thoughts? The fiber washer is about 1/4 thick and fills the gap between flywheel housing and transom plate perfectly. How can I tell if I have sagging mounts? Both sides are identical. Boat and engine only have 176 hours on it.

Just went thru this with a friends boat although it was a much older 898/Merc I drive and he did not get the knocking you describe. But his alignment marks were as you describe. It was evident that the motor was sitting too low in the rear. The mount stringers were sound.

We ended up pulling the engine to find that someone previously had install the mount springs on the underside of the transom assy mount brackets instead of between them and the bellhousing mount arms.

This not only lowered the rear of the motor but was causing the torque side fiber washer to be extruded up into the bottom of the bellhousing mount bushing hole.

We pressed in new mount bushings and placed the springs in the right place and then got a real good alignment pattern on the bar.