1977 OMC 175 hp questions

Hello everyone, I am new here and pretty new to boating. So I have a few questions. Last week I purchased my very first boat a 1977 Mark Twain with a 175 hp OMC I/O, and I love it! But I have had a few problems, which are to be expected, espically for a boat that is 30 years old. So here are my questions..... any help or advice would be greatly appreciated.

1.) What is everyones opinion on the Mark Twain boats.... pros / cons... that sort of thing

2.) My tilt has gone out and I talked with the mechanic at the marina at which I purchased the boat. I am fairly mechanically inclined so I took apart the gear set up on the outboard, and besides some water in the oil (which I replaced) everything looked to be alright. So my guess is that the tilt motor needs replaced. What are everyones thoughts on having the tilt motor replaced, or rebuilt. And if I need to buy a new one where is the best place to find one. Also how hard are those motors to replace... I know the boot must be removed to gain access.... Insert your knowledge here.\

3.) While out cruising today I happened to look in the engine bay and noticed that the engine has began to pull itself from its wooden "engine mounts" (for lack of better terminology) The wood which the engine sits on seems to have rotted away over the past 30 years and the bolts have basically pulled right out. How much is involved in replacing those mounts, is it possible work for me to accomplish myself, what all is included in replacing those mounts, and what kind of materials would I need?

Besides the problems listed above the boat is in great shape and the engine runs like new... Minor repairs here and there are to be expected and are apart of boating... any input is greatly appreciated and welcome, thanks for everyones help.

-Brian

Re: 1977 OMC 175 hp questions

Hi Brian- I also had a 1977 OMC. Tilt motor went out twice. Water seems to get into the motor. My stringers also rotted out. I kept using bigger bolts untill there was nothing left to screw to. Has your electric shift gone out yet? It will. Mine had to be rebuilt three times. I put a whole lot of money in that boat during the time I had it. I now have a mercruiser and it is like night and day. Not one major problem in the seven years I have owned it.

Re: 1977 OMC 175 hp questions

Mark Twains are actually good boats. Although no longer made, in there day they were considered a well built boat. At least I feel they are. Had an uncle that had one but he had an outboard on his. I believe it was a 1977. The tilt motor can be found fairly easily today, there are plenty of replacements. You could find quite a few on eBay. I would pull it, test it and if bad (depending on how bad) rebuild it. Typically the brushes wear out. What type of system do you have? The hydraulic system or the jack screw setup? Could be the solenoids for the tilt are just bad. I would rule out all other causes before I yank it. It is easier to get to if you remove the boot but you can get to it by going under the motor but it?s tricky. The motor could be fine, just a bad connection. On a stringer the only thing holding the engine in and pushing the boat are those engine mounts. The out drive does not push against the transom. This is something that needs attention soon! The rotted wood, if truly rotten can be a major overhaul. You can do it if you have a way to pull the engine. I redid my front mounts on my boat. My stringers were still in good shape. I had to re-glass part of the mounts. Then I just filled the old lag bolt holes with epoxy and re-drilled them. Then used new lag bolts. I did it with the engine still in and it was a major pain in the buttocks! I have some pictures if you want to have a look. My problem was I have the hydraulic system, it leaked for years and oil got down into the stingers and fiberglass. The fiberglass build up peeled right off the stringer. It all depends on how much you like the boat. If you really like it and plan on keeping it for quite a while you want to do it right. That would require yanking the motor, cutting out the rotted wood and replacing it and then re-glassing it all in with new fiberglass.

Re: 1977 OMC 175 hp questions

As for the bolts coming out of wood mounts. What I did was slightly over drill the existing holes and injected marine tex into them and then replaced with the same size hot dipped galvanized lag bolts. (worked like a charm)

Re: 1977 OMC 175 hp questions

I dont plan on taking out the whole engine, I was thinking of removing the back seat and jacking up the engine, removing the rotten wood from the front enging mounts, then resetting the engine back into correct allignment and replacing the lag bolts for the rear mounts and from what everyone is saying fill them with some sort of epoxy then putting the bolts back in. Anyone have any other ides on this?

As for the tilt I will definetly give it a good test and once over before I take it out... but im pretty sure it needs replaced... a few days ago my friend took the boat out and forgot to put the drain plug in and a ton of water was in the engine bay before he remembered to put it in.... luckily the bilge pump works..... and it is the screw/gear set up not hydraulic

Re: 1977 OMC 175 hp questions

Hi Brian! Hey, if you want to find out just about anything on your boat, check out: www.marktwainboats.org . I own three Mark Twains now, one of which is a '75 w/351 stringer drive. They are great boats and old up well. There are a few threads on floor/stringer replacement that are very helpful. My '75 had the entire floor redone, and I'm getting ready to do a partial on my '78 20 footer. Come on by and check us out!