77 120 OMC front engine mounts

[noreneb]

Hi guys/gals -<br /><br />We have a 77 Fiberform with a 120 OMC I/O - you help us on the last problem - replaced starter - runs like a dream. We had her out today - ran her slow to break her in - opened her up for a while then decided to shut her down (middle of the lake of course) and take a look at the motor just to make sure all is well. Well, all wasn't well - we opened the engine compartment and the front motor mounts (where you can adjust trim) one bolt was out of the hole and bent back and the other was almost out of it's hole. Any idea what can cause this? Too much stress when lowering engine - too much stress on traveling on the trailer. Looks like it's a minor repair we are going to do ourselves - bolts didn't sheer off, just came up - one still intact and one bent. Needless to say - we limped our way back to shore and home. The fiberglass the mount sits on is solid so it doesn't seem that that is the culprit........thoughts?

 

[Boatist]

Re: 77 120 OMC front engine mounts

I would suspect rotted stringers. If the bolt comes loose on either side could bend bolt on other side. Even a 3/8 inch bolt on each side should hold it down if rear motor mounts are also good.<br /><br />If you hit something with the outdrive while backing or outdrive hit something while sliding off the trailer could pop the front motor mounts out.<br /><br />Most likely your stringers are rotted not holding the bolt on one side or the other.

 

[Boomyal]

Re: 77 120 OMC front engine mounts

Ditto! Take the bolts out and probe the sides of the holes with some kind of a pick. The Mfg's never seal the bolts when they screw them in. As the years go by, water just follows the threads into the holes. Maybe the stringers are ok but the wood immediately around the holes have rotted and/or the lag bolt threads have rusted half away. You also want to check the rear mount bolts.<br /><br />If the wood appears solid, you could could fill them with epoxy and insert soaped up bolts. That would enable you to remove them later, if necessary.

 

[noreneb]

Re: 77 120 OMC front engine mounts

Thanks for the help guys - we took your advise and modified just a little - we treated and mounted a piece of oak over the old piece lag bolted it down then bolted the stringer to the oak piece then sealed it all up - took her out yesterday and she purred like a kitten until......I will be posting a few other questions in another topic.........