84 Sundancer 26 foot engine mounts

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kevink1955

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Joined
May 25, 2007
RO Number
26446
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31
I recently helped my son install a rebult 5.7 mercruiser engine in his boat. While reinstalling the engine mounts I found the lag bolts that hold the steel engine mount (2 bolts) to the platforms are striped.

I removed the mount from the engine and did some poking around in the platforms and find nothing there to receive a lag screw, the only thing there is about 1/2" of fiberglass. Thinking that there may have been wood in there that roted away I poked around somemore and did not find any evdiance (chips or wood residue)of any wood having ever been there.

With a 3" drywall screw I did find some wood and thought that it may have originly been at the top and glassed into the platform so I tryed to pull it up but it did not move.

Anyone know what was originaly in there, like I said before there is no evdiance that it rotted away. The outdrive shaft alignment is perfect but the engine is just siting on the platform with the lag bolts floating loosly in the holes.

How do I fix this??
 
I wish I had an answer for you but unfortunately I don"t and also unfortunate that this is a Holiday weekend and alot of the informed guys and gals on here that would normally be able to help you quickly are probably out boating for the weekend etc. Hang in there though....I'm sure that as they start coming home after the weekend you"ll get some real answers quickly.
 
When you say "platform", do you mean the stringers that the engine mount is bolted to? Typically, a boat from that year would have wood stringers fiberglassed over. If you now just have a hollow fiberglass shell with nothing inside and this is what's holding the motor mounts, doesn't sound right. Sounds like the wood completely rotted out, but can't be sure from the info you've given. Post a photo if you can.
 
blueflew

I for the lack of a better term called them platforms, they are a rectangular "platform" about 4 by 6 inches that the right and left engine mounts sit on. the rear of the engine is supported by the gimbal mount of the bravo sterndrive.

I was able to probe the platforms with a long 3/8" threaded rod and find no evdiance of any wood ever being there. From the top, down 3 inches they are hollow. I did find some wood at 3 inches that I sunk a screw into about 1 inch and it was firm. I did not want to drive it further as it is down in the bottom at the hull and I did not want to drive it thru the hull.

Any Ideas ??
 
Yeah, I have a 1980 26 Weekender. Also a replacement 5.7 - although I didn't put it in. That construction was solid wood covered in fiberglass. The lag screws went throught the fiberglass and into the wood. Rot is a common problem in those stringers, and it sounds like yours is pretty rotted. The wood turns to a substance that looks like dark mud. In those days they put plenty of fiberglass in there so it seems to support the engine. However, it doesn't firmly attach the lag bolts so it doesn't keep the engine down.

Sometime in the mid eighties Searay put limber holes in those stringers to let water drain down to the bottom of the bilge. But those holes also provided further access for the water into the stringers. Not sure if they did that on the 26.

Mine had some rot on one side but not the other. The water actually goes in where the lag bolts are fastened and the rot starts there. You can take a drill with a quarter inch bit and drill holes along the side of the stringer. Where there is good-looking sawdust coming out of the drill hole, you still have good wood. Where you get mud out, well .... Of course, you will have to seal those holes when you get done.

Many people will say you need complete stringer replacement. IE: remove engine, grind out the stringers and rebuild. (BTW, this can extend to the transom as well). But you may find other solutions. First, I would determine the extent of the problem. You should get your engine fasted down firmly. Also, you will need to get your engine aligned - even after what you've done so far. Otherwise, you could create problems in your outdrive. You'll probably want to go to a service center for that.
 
I did not even find "Mud" in there probing from the top down 3 inches. Right now shaft alignment is perfect but I could see that the engine could move around and screw that up. He has been using the boat and has not encountered any problems yet but I feel we need to do something even if it's only a tempoary fix for this season.

Anyone have any ideas for a tempoary fix, I was thinking of sloting the top of the platforms and sliding a piece of 1/4 thick 2 wide steel flat stock under the platforms. I would prepair the steel with threaded holes to bolt the engine mounts. It would wind up working from the bottom up as steel - fireberglass platform - fiberglass spacer - engine mount. Anyone think this would work? Right now the engine is sitting on hollow platforms held by gravity!! As an alternative for this season, how about filling the platforms up with some sort of epoxy?

I do not want to burn up the coupler or worse yet hit a wake and have the engine come crashing down thru the fibreglass platform.
 
I wouldn't weaken the fiberglass by cutting it too much. Those stringers may be plenty strong since they overbuilt them. Some modern techniques have a metal piece on the outside of the stringer. It may be a simple angle iron with one bend, or it may be three-sided with 2 bends. You may be able to get something like that over the stringer, then bolt it through the stringer. You'd have to find mounts to attach. There may be whole systems for this.

You should try drilling the small holes I suggested previously. It can tell a lot.
 
From your description,sounds like at least half of the wood is rotted out. Another idea would be to cut just the top of the fiberglass and leave the sides intact. Then you could clean out all the rot and epoxy in new wood over any existing good wood and epoxy it to the fiberglass sides as well. then laminate new fiberglass over the top of the wood, extending it down the sides at least half way. You could then bolt new motor mounts in place. You may be able to do this with the engine in place by placing wood blocks and jackstands under the engine.
 
I've never heard that but I guess it could work. (Not the leave the engine part)! But if you go that far you're almost doing a normal stringer replacement. You're losing all the strength of the fiberglass and you'll shake it all loose cutting it out - so you're guaranteed to have voids. Might as well cut is out or maybe leave an inch. You'll have to do a complete fiberglass job anyway. The engine probably comes out fairly easily, so just pull the engine, clean the whole engine space, repaint and replace. Also a good time to check the oil pan, replace the engine mounts and clean up the transom hardware.
 
Thanks guys

You have all given me the things to look for and some ideas as to how to make a repair. I only spent a day on the boat a few weeks ago helping him install the rebult engine. I will be going back next week so I will do some pokeing and probing. Will report back with the findings
 
There is a product called "SEACAST" I think, that you can mix up and pour in to replace rotten stringers and transoms. Its an epoxy material made for the type of repair you are describing. I think George at Boatfix may carry it.
I'm thinking you could make a pour hole and a vent hole in each stringer and fill them with the material then glass the holes shut.

P.S. I have the same stringer setup in my Searay. My stringers are OK but I can see how they could easily rot.
 
Thanks Scorpio, the SEACAST idea is exactly what I am looking to do. Just want to get thru the rest of the season as we just droped the rebuilt engine in 3 weeks ago. Will give the SEACAST a look

Thanks
 
Got another look at it today and the thing I called a platform does sit on top if the stringer. The platform is about 3 inches high off the top of the stringer and still looks to me like it never had any wood in it. If you probe down 3 inches thru the platform with a 4 inch drywall screw I find solid wood (the stringer) that will hold a screw.There is no muck in there at all to indicate anything rotted away.

I think I am just going to bore a hole in the top of the platform and fill it to the top with Seacast and call it done.
 
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