Volvo 5.7GI-B alignment and rear motor mounts

[WaveNAway]

Hello and thanks for reading. I have a 2002 Four Winns Vista with VP DP-SM out drive. I'm trying to align my engine to the gimble bearing and have lowered the front mounts as low as they will go. The alignment tool will go in all the way, but not smoothly, and still has heavier marks on top, indicating I need to lower the front of the motor more. When carefully inspecting everything I noticed the aft Starboard motor mount sits higher than the aft port mount. So now I'm guessing that my port side rear mount has let go and is sagging.
My questions are, is it common or likely for the rear motor mount to fail? And will I need to pull the motor to replace the mount, or are there any tricks?

 

[mklearl]

Either the front needs to go down or the back needs to go up. If one of the rear mounts let go then I think you know what the problem is. Once the rear mounts is back in place the front mounts should be adjusted properly.
With regards to the rear mounts... where did it let go? On the engine side or where the mount attaches to the boat?

 

[WaveNAway]

Ok, I think my suspicions where correct. The rear motor mounts have a large washer under the motor side, then there is about a 1/8" gap between this washer and the top of the rubber mount. The starboard side has this gap, but on the port side the washer is sitting right on the rubber. I just slid the motor forward (while supported with forklift) enough to remove the compressed mount. With no weight on it, the mount looks normal, but when reinstalled it compressed again. I just ordered two new mounts to try. Hopefully it is just a bad mount. I tend to worry that I could have stringer or transom issues causing uneven weight distribution on the mount. Hopefully thats just me thinking worst case scenarios.

 

[Dave-R]

Something seems amiss. On the rear mounts the engine does not sit on the washers. The engine sits on the square mounts first, this should align the engine. Then the large washer you mentioned sits on top of the bell housing into a recess that also aligns the engine. Check it out and see if you have it right. Dave-R

 

[WaveNAway]

OK, something is certainly amiss! I replace both rear motor mounts and still have the same issue. It appears that there is more weight on the rear port side mount, causing it to become compressed. I'm able to even out both rear mounts (height wise) by raising the front port side mount about 3/4". The alignment bar slides in with a lot of resistance with the front port mount up (rear mounts even) or with both front mounts bottomed out, and seems consistent everywhere in between. My guess is that the gimble bearing alignment is consistently off, and not much worse with one front mount raised 3/4", because the rear mount goes up in relationship with the front.
The only way I can explain what could be causing the issue is that the starboard stringer is bowing up (sitting on bunk trailer), or the transom plate is lower on the starboard side, in either case putting more weight on the rear port side mount. A rotten transom could be possible, causing the plate to drop down on starboard, but either scenario seems unlikely.
I provided a photo of the rear mounts. the large washed under the square nut is what the motor sits on. The smaller washers go on top of the motor bell housing bracket and fit into a recess. You can see a gap under the large washer, where the rubber is thinner. This gap is being compressed on my port side mount. I'm considering adding another large washer to the starboard mount to raise it up and even out the weight distribution. But I know that it's not normal to need to do this.
Any help is greatly appreciated!

 

[Dave-R]

I'm having a hard time understanding how the rear mounts could sag or fail. If you replaced both of them, they should have the right height then. There shroud be no adjustment there. I have always set the engine on these first, and tightened them. This determines the horizontal plane of the engine. Then you will adjust the front mounts to keep it in that same plane. Now that is not to say the the front mounts will be equal in height. As you said, the front mounts could be higher on one side and lower on the other. Keep the rear mounts happy first, as the shaft alignment depends on this being correct. Some mechanics bolt down the rear mounts first, then leave the hoist on the front of the engine, to move it up or down while using the alignment bar. I'm going to try that next time. Hope you get it right, and thanks for your post. Let us know how it turns out. Dave-R

 

[WaveNAway]

Thank you for the reply Dave. I will try lifting the front of the engine with the rear mounts tightened and then reset the front mounts as you described. Perhaps this is what that mystery 3rd lifting ring on top of the thermostat housing is for? I have been working under the assumption that the front mounts would have been set even on the stringers at the factory, and to be that far off something must be wrong. My front mounts are sitting on "L" brackets bolted to the side of each stringer. The starboard "L" bracket does appear to sit higher on the stringer, and this is the front mount that would need to be higher to cause the rear port side to have more weight on it. I may end up removing the front starboard "L" bracket, and mill out the bolt holes so I can slide it down more. I feel like I should not need to do this unless they screwed it up at the factory or something has shifted in the boat. This is my second year with this boat. I don't think the outdrive was ever removed before I owned it (it's a 2002), and last year I had to lower both front mounts about four turns to align the gimble bearing. It may have always had the uneven weight distribution causing unevenness in the rear mounts, but I did not notice before.

 

[Senior B]

Have you tried to align the gimbal bearing to the coupler? Often folks don't know that the bearing is able to move quite a bit in its housing. You get it fairly close to perfect then fine tune by moving the front motor mounts. In your case you would need to bring front mounts back up before attempting as they're already bottomed out. You may very well have the adjustment play you need if you haven't already done this. Good Luck.

 

[WaveNAway]

Hi Senior B, thanks for replying. Yes, each time I adjust the mounts I would align the gimbal bearing by tapping on four sides of the alignment tool with the tool inserted into the coupler.

 

[Senior B]

No SIr, what I'm speaking of is doing it before you slide the bar all the way in to the coupler. The gimbal bearing is able to move A lot up, down and left to right from with-in its race. you slide the bar in past the bearing and then move the bar up or down as required. That's why I say if you bring your front motor mounts back up and do the alignment of the bearing to the coupler as I speak of, you will have the wiggle room you seek to fine align the whole thing. Good luck.