8V71 Forward Motor Mount

[Rob Dengler]

Need some help on how the forward motor mounts work on 8V71's (58' Yachtfisherman 1973)

There is a flat plate on edge that runs from the right to left side of the engine that hold the weight. Then to the bow and stern of this plate are angles with one hole that goes into the stringers. In between these angles and the flat plate is some kind of bedding/glue compound.

So the angles with the holes hold the motor secure from bow to stern, but what keeps the motor in position port to starboard, the glue? And what do you do when the glue fails and the angle is now free?

More glue and or what kind??? This set up seems very strange. So motor alignment port to starboard is dependent on glue???? What should I do now that those bonds are failing??

 

[oscarvan]

I am by no means a specialist, but I doubt the 3700 pound monster is staying put with glue..... Heavy rubber, maybe but not glue. And yes they can deteriorate and yes that can cause problems.

Someone will be along shortly to confirm that....... Ready to learn myself...

 

[Rob Dengler]

I have tons of photos but have given up trying to forward them to this site due to error messages. There are no fasteners between the flat bar bracket holding the weight and the angles with the holes. Don't understand how it stayed together this long.

 

[MadHatter53]

Something needs to be bolted to the stringers. There's too much torque to,glue down.

 

[johnjen50]

The front motor mounts are mounted to an aluminum rail that rides over and is bolted to the main stringers in the ER. The aluminum rail is mounted to the stringers with several bolts, and the motor mount is attached to the rail with 2 big bolts. There is no glue on mine. I have the 58 yacht fish too.

 

[johnjen50]

Are you saying that the aluminum rails are missing the bolts that hold them to the stringers?

 

[oscarvan]

If you want you can email me the best picture and I will post here....

oscar"at"noln.com

 

[oscarvan]

And here we are.....

 

[racclarkson@gmail.com]

Wow! And I can tell you it's no picnic getting those bolts out. I needed a 1" drive racket and someone else's back on mine.

 

[dsharp]

The rubber is “vulcanized “ to the metal. Not sure if that style of mount is still available. Some people bolt the three pieces together.

 

[MadHatter53]

What's holding things together?? The first pic looks like it's shimmed.

 

[Rob Dengler]

So in the process of trying to rattle loose the two large bolts that hold the motor to the aluminum rail with my huge air impacted, (were talking hours of hammering) the bond between the loose angle and the rest of the motor mount cracked and the angle just fell off. After that, I just starting cutting the bolts.

So, someone brought up just bolting the assembly together by drilling some holes through the whole thing. Does anyone have bolts through theirs? I wonder how much more vibration their will be because of more metal to metal contact?? Should I add 5200 in there??

Any thoughts???

 

[kelpy]

Your alignment must be way off now if that corner of the engine dropped down onto the engine bed plate even if just a "little bit".

How is the front of the engine adjusted left/right with that type of mount? Up/down can be done with shims but that would be a lot of work lifting and dropping the engine each time to add or remove a shim.

 

[Rob Dengler]

I'm in the process of jacking the motor up 12" to drop the pan and disconnect everything from the bottom for a rebuild. The last oil pan bolts under the pan and next to the marine gear are almost imposable for me to reach.

 

[dsharp]

You can bolt the whole assembly together. I don’t know if they still make Thiokal but it was a 2 part material that we used to bed struts to the hull. 5200 would probably do about the same thing. I would try to get bolts with a long enough shoulder to go through both sides if they are available. Did you cut the heads off of the motor mount bolts? There’s an aluminum plate on top of the stringer that the bolts tap in to.

 

[dsharp]

Never mind, I looked at the picture.

 

[Rob Dengler]

My bolts went through the steel angle and into a perch on the aluminum stringer bed. So basically they are through bolts. Only 2 out of the 8 came loose. All the others had to be cut.