loose engine mounting nuts

[FishHog]

So I was changing the plugs last night on my 5.7L 1988 Mercruiser and the front mounting nut looked loose, so I tried to turn it. It was so loose I could turn it 3 or 4 turns by hand. Other side was also loose on further inspection. I tightened them both up and finished my plug change, but got thinking last night about this.

I already replaced the drive, and it was aligned just fine. Am I really changing anything by tightening up those two front mounting nuts. The mounting blocks look fine, the bottom adjusting nuts have not been moved, and the engine was resting on them, I just tightend down the top nuts. Not sure how they even got loose with the lock washer on there, but I will keep an eye on them from now on.

I guess I was just wondering if I perhaps changed an alignment by doing this and if that could cause me future problems.

Thanks for the help.

FishHog

 

[achris]

Re: loose engine mounting nuts

So I was changing the plugs last night on my 5.7L 1988 Mercruiser and the front mounting nut looked loose, so I tried to turn it. It was so loose I could turn it 3 or 4 turns by hand. Other side was also loose on further inspection.

I tightened them both up and finished my plug change, but got thinking last night about this.

Thinking is bad thing.

I already replaced the drive, and it was aligned just fine. Am I really changing anything by tightening up those two front mounting nuts.

Told you thinking was a bad thing. Tightening the nuts does 2 things. Firstly it stops the bottom nuts moving (and that would change the alignment) and secondly it stops the engine from twisting up off the bottom nut under hard acceleration (and that's a good thing).

The mounting blocks look fine, the bottom adjusting nuts have not been moved, and the engine was resting on them, I just tightend down the top nuts. Not sure how they even got loose with the lock washer on there, but I will keep an eye on them from now on.

Good choice... It's actually part of the annual service... Check for loose or missing parts.

I guess I was just wondering if I perhaps changed an alignment by doing this and if that could cause me future problems.

Thanks for the help.

FishHog

All good....

 

[zbnutcase]

Re: loose engine mounting nuts

No your fine-its the bottom nuts that matter.

 

[Don S]

Re: loose engine mounting nuts

I would pull the drive and recheck the alignment. Here is why.
Many times the lower nut can come loose on one side and drop down, since the engine is still sitting on 3 mounts there is no weight on the 4th corner. When you tighten it down, you push the mount down to the lower nut, thus pulling that corner down and pulling the mount up on the opposing rear mount. This also throws the coupler out of alignment AFTER you installed the drive. That is why I always recommend the alignment have a final check after all motor mounts have been tightened down.

 

[FishHog]

Re: loose engine mounting nuts

OK, thanks guys. I guess I'll error on the side of caution and pull the outdrive and double check.

appreciate the help.

FishHog

 

[bigskiohio]

Re: loose engine mounting nuts

i think you already knew the answer.