350 Mag Engine/Trans Alignment

[Eric LX]

I am getting ready to align the engine in the boat for spring and I thought I would throw this out for any last minute advise before I start.

I just purchased my Response last fall from a dealer that is now in jail (a story in itself). When I was winterizing it I noticed that the lockplates and lower nuts under the tranmission mounts were loose and spinning. I purchased a set of the OEM Merc service manuals that has the specifications for aligning the front and rear mounts and setting a .003" gap between the output coupling and the prop shaft flange at 90 degree intervals.

Once these adjustments are made should the prop shaft spin with ease when the packing is dry? Also, any other suggestions for a first timer on this job.

As Always - Thanks!

[eyepeeler]

When aligning the couplings, try for .000" if you can. Don't worry about your propshaft spinning freely as the propshaft bearing is water lubricated.

[Eric LX]

When aligning the couplings, try for .000" if you can. Don't worry about your propshaft spinning freely as the propshaft bearing is water lubricated.

Thanks, I will see if I can get there. I am going to see how close I am now before checking any adjustments and then I plan to strart with the front mounts and then work my way back.

In a few weeks I plan on filling the bilge with water to make sure that the pump works correctly and then I can see if the shaft turns smoothly with some lubrication.

[eyepeeler]

Eric, the lakewater lubricates your strut bearing underneath your boat.

[Eric LX]

Eric, the lakewater lubricates your strut bearing underneath your boat.

Thanks for the clarification. I am learning about this boat one step at a time!

[Woodski]

Eric, there are two styles of rudder bushings, one is a rubber bushing with a brass outer sleeve and the other is a white plastic (vesconite) version. The rubber bushings require water lubrication to allow easy rotation of the shaft, the vesconite units will allow the shaft to rotate freely w/o water lube. Your boat came with the rubber units from the factory.

As you do the alignment, since the bolts are all free the vertical location of the engine might have shifted. So ensure that you get that position correct as you proceed, make sure you have the coupling centered in the bushings as you proceed. Since there is some weight to the shaft and coupling, it will try to droop as you go through the process. You will have to lift it slightly to get the correct position. You will want to carefully check all three axis for alignment as you go. There might be some witness marks on the bolts to help guide you with the original position. The other bit of advice, be patient, get a good light for visibility and take your time doing that job. Also a good time to nut and bolt the entire engine compartment, there are probably other items not to spec. Hose clamps are a potential opportunity for trouble.

The .003" gap is referring to that amount our of perfectly aligned. As noted in the thread, the closer to spot on you can get the better.

[Eric LX]

Eric, there are two styles of rudder bushings, one is a rubber bushing with a brass outer sleeve and the other is a white plastic (vesconite) version. The rubber bushings require water lubrication to allow easy rotation of the shaft, the vesconite units will allow the shaft to rotate freely w/o water lube. Your boat came with the rubber units from the factory.

As you do the alignment, since the bolts are all free the vertical location of the engine might have shifted. So ensure that you get that position correct as you proceed, make sure you have the coupling centered in the bushings as you proceed. Since there is some weight to the shaft and coupling, it will try to droop as you go through the process. You will have to lift it slightly to get the correct position. You will want to carefully check all three axis for alignment as you go. There might be some witness marks on the bolts to help guide you with the original position. The other bit of advice, be patient, get a good light for visibility and take your time doing that job. Also a good time to nut and bolt the entire engine compartment, there are probably other items not to spec. Hose clamps are a potential opportunity for trouble.

The .003" gap is referring to that amount our of perfectly aligned. As noted in the thread, the closer to spot on you can get the better.

Thanks for the clarification. I still have the rubber bushing, thus explaining the stiff turning of the prop when I was inspecting it last fall. It took some force to get it started then it turned easier like one would expect it the rubber was holding it.

For the alignment, my thought is to first check the front motor mount location per the measurement that is shown in the service manual. I think that it is still close since the bolts are tight. I feel that the trans mounts are loose due to the trans being replaced right before I bought it and the not torqued correctly. I am hoping that it all makes sense as I am going through the steps and the majority of adjustment is with the trans mounts.

I want to learn to do this myself since it is something that should be checked from time to time.