Mercruiser front mounts

[littlebookworm]

Hi, all: Getting ready to drop in my Mercruisr 5.0 into my SunRunner. I decided to used the engine mounts from the replacement engine because the old mounts were shot. At home, using a come-along and a garage rafter, I lifted the engine off the dolly slightly and swapped out the mounts. Went to the marina to install the "new" mounts and was surprised that the lag bolts wouldn't fit through the holes in the base of the mounts. The "new" mounts used a3/8" lag bolts rather than the 1/2" bolts on the old mounts. Took the mounts home and drilled out the base holes to slightly over 1/2". I had planned on preinstalling, loosely, the mounts into the engine bay, and then later dropping the engine onto the center bolts and rear mounts. After reading one of the other posts, I'm not sure whether or not I should do it that way or if I should install the mounts on the engine and deal with aligning the mounts' bases, blocks, and stringer holes to screw in the lag bolts. Any suggestions?

 

[ziggy]

Re: Mercruiser front mounts

The "new" mounts used a3/8" lag bolts rather than the 1/2" bolts on the old mounts.

that, to me, sounds like someone, perhaps a previous owner, was trying to compensate for mushy stringers.....

 

[tkrules19]

Re: Mercruiser front mounts

I am having a problem with getting the right engine alignment when using to types of motor mounts. I dropped the engine in on the rear and front mounts and using an alignment tool began aligning. But with the front mounts completely bottomed out it is still not aligned an needs to go down even further and i must now try to find the right upper motor mounts. Lift the engine and replace them? I put the motor mount bottom half on the boat and then the upper bracket on the block. Then as u let the engine down slowly back down the nuts until you reach the right alignment just hope that the new motor mounts have enough room to go down.

Tom

 

[littlebookworm]

Re: Mercruiser front mounts

The thing is, the mounts that were on the boat were not drilled out to take 1/2" lag bolts, nor were the blocks under it. They seemed to have been put in when the boat was built, though, obviously, I can't be certain. When I checked the stringers, they were, and are, solid. There just seems to be two different number mounts, one with 1/2" base holes and one with 3/8" or 7/16" base holes. Not much of a difference but enough to give me an extra trip to the marina, 15 miles away, to get things done. I'm going over to the marina in about an hour. I'm going to premount the mounts and blocks so I can line up the lag bolt holes. I'm then going to tape the mounts and blocks together with some masking tape. I'll take them home and mount them on the engine. Hopefully, when I drop the engine in, I'll be able to use an alignment bar (punch) to line up the mount holes and the holes in the stringers. To be continued. Hy

 

[wca_tim]

Re: Mercruiser front mounts

If you look at the two mounts in the picture, the one on th eleft is the kind that has an upper mount that goes lower, the one on the right is a 1988 version of the non-balance shaft 4.3 mount to reduce vibration and although the upper mount isn't shown, it is shorter to make up for the taller lower mount. (Tom, there's your picture, I have the uper half of the mounts on the right as well... presumably they'll achieve what you need).

On aligning, when i recently repowered with a different engine and mounts, I had to also add to my stringers and shim the mounts so to make sure everything was going to work right I attached the entire motor mount s to the engine, and lowered it down on the shimmed stringers / new engine pillar mounts and then got the drive alignment close to be sure it gave me plenty of adjusting room both ways. Then i drilled the holes for the lag bolts, etc... probably overkill, but after drilling the holes, I moved the mounts out of the way and bedded the lag bolts in epoxy screwing them almost all the way in while it set up (I put mold release agent on the threads to keep them from sticking). One of the places where I had water damage when I started was from water leaking down the sides of the lag bolts...

Hopefully this is helpful...