engine help please!

[mindfusion]

hey folks I bought a 1978 fiberform boat 18' with a 6 cylinder merc and a OMC 120 outdrive. the back motor mount has rotted out and caused the back of the motor to sag. this caused the motor to bind up I think is this possible? and if so what kind of potential damage am I looking at? also is there any steps you all can reccomend to get the motor started and see if its even worth fixing? I plan on cutting the motor mount support out and fixing it, but would like to hear the engine run and possible see the outdrive shift before investing tons of time. thanks for your help in advance.

 

[Don S]

Re: engine help please!

It will destroy the coupler and splined yoke in no time. Along with gimbal bearing, ujoints and possibly the drive.

 

[mindfusion]

Re: engine help please!

so best to pull it apart? If I do what do I have to replace at a minimum? such as seals and stuff?

 

[Boomyal]

Re: engine help please!

Being a 1978 model, you have what is termed a stringer mount outdrive. The oudrive does not attach to your transom, except via the large boot. Your intermediate housing and motor are effectively one unit. As such you have no problem with alignment of the driveshaft and coupler because the whole package will sag as a unit.<br /><br />However, if you don't want your drivetrain rolling around inside your boat, ya better fix up your motor mounts, now!

 

[mindfusion]

Re: engine help please!

that is pretty good news it sounds like, now what would cause the motor to bind up? is trys to turn over but stops. the previous owner said it was running great and then the mount gave out and now the engine won't turn over.

 

[mindfusion]

Re: engine help please!

also from what you are saying, I should be able to separate the lower unit from the engine to check out whats going on and then bolt them back together with out the worries of having the two professionally aligned right? I have never had to do this, but am fairly mechanically inclined so any info you all can give me is only going to make things easier for me.

 

[POINTER94]

Re: engine help please!

Make sure you mark the teeth on the the outdrive connection to the engine, they have to go together in the same way they came off. Taking off the lower unit is not that tough of a job.

 

[Boomyal]

Re: engine help please!

I assume that you do have the big black transom boot around the outdrive? OMC was that way until some time in the mid '80's. If so, you have none of the outdrive alignment issues that all these poor Merc owners have. The outdrive simply pivots in two cradles at the back side (sticking outside the boot) of the intermediate housing. The outdrive is driven by a set of intermeshing ball gears located between the out drive and the outside of the intermediate housing.<br /><br />I can see no reason to seperate them 'just to see what's going on'. Make sure the outdrive is in neutral (try spinning the prop, to verify) and take a breaker bar to the crank pully nut and try to turn the engine over by hand. (clockwise if your facing the pulley, someone correct me if I'm wrong).<br /><br />If you cannot turn it over (360 deg) you have motor issues not related to your motor mount stringers.

 

[Boomyal]

Re: engine help please!

Originally posted by POINTER94:<br /> Make sure you mark the teeth on the the outdrive connection to the engine, they have to go together in the same way they came off. Taking off the lower unit is not that tough of a job.

Ditto on marking the ball gears, but to completely remove the outdrive and be able to set it aside, you would have to disconnect the shift cable from the converter box (inside the transom) and pull the cable out thru its passage hole in the intermediate housing.<br /><br />You really need to get a Seloc manual before you start tearing into things. But again, read my post above.

 

[mindfusion]

Re: engine help please!

boomyal, that sounds like my plan I will try as soon as I get home. I tryed to do that last night with limited visibility and a cheesy piece of flat metal and it just bent, but it was way to thin, so i may have to pull the front motor mount and get a breaker bar in there. provided the motor turns over, is it worth fixing the mount issue? the rest of the floor seems solid, and the boat is in nice shape. I just don't know that much about I/O boats

 

[Boomyal]

Re: engine help please!

As to whether you should fix the motor mount issue, YES! <br /><br />As to whether it's worth it, that I cannot say. You have to decide what the boat is worth to you. Here is a picture of my current project on the 1975 boat I purchased new. I love the boat and when I get done it'll last another 60 years.<br />

<br /><br />

<br /><br />Note the rebuilt motor mount stringers.

 

[mindfusion]

Re: engine help please!

that looks like the exact same boat, the motor mount stringers I don't think will be to hard to do if I buckle down and do it. I am running short of time (gotta move to north carolina in two months) so hopefully the crank will turn over and I can get it running, although when you said that nothing in the back should cause the binding, thats got me worried it must be the motor. also the lower unit is trimmed all the way up, could that have some effect? I couldn't get the trim motor to work last night ( i didn't try to hard, since it was dark and I had been driving all day), but the wires were unhooked so I plugged them in figuring they work on a reverse ground type switch? so it should have worked either way, maybe just backwards right? I am just trying to get as many ideas a possible before I get home, as I have a harder time getting on the internet there.

 

[Boomyal]

Re: engine help please!

Absolutely do not run the motor with the outdrive in the up position. You will break something. The outdrive tilt is not for trim, it is for raising the outdrive only.<br /><br />I am not well versed in the front mount trim system. My V8 does not have it. Again, a manual will be well worth the $$$$. Unfortunately there are no manuals for the boat itself. Manufacturers' should be required to supply a blue print with each boat.

 

[mindfusion]

Re: engine help please!

I think I'll buy a book. do I get one for the motor or the Outdrive or should they be the same book?

 

[Boomyal]

Re: engine help please!

Originally posted by mindfusion:<br /> I think I'll buy a book. do I get one for the motor or the Outdrive or should they be the same book?

This is what you want. Good luck and don't hesitate to post questions, progress and any points of special interest regarding your project. Pictures are always welcomed.<br /><br /> http://www.iboats.com/mall/index.cg...rent_category=repair manual&*******=817410331

 

[Don S]

Re: engine help please!

You did some editing of your first post that said you had a 6 cyl Merc engine and a 120 OMC Cobra drive, plus adding the 78 year.<br /><br />Sure makes people wonder what ta hell I was talking about.

 

[Bt Doctur]

Re: engine help please!

In-line 6 or V-6 hooked up to a OMC 120 sounds a bit strange to begin with.Even with the drive up all the way the motor should atleast turn over and not bind, try pulling the plugs to see what comes out of them.

 

[mindfusion]

Re: engine help please!

don S didn't change anything? what should I look for coming out of the plugs? unless the owner lied to me he said the motor ran great. obviously there is a problem though so might as well start somewhere. I think I will pull the plugs to get rid of the compression factor and make it easier to turn over the crankshaft. I also need to figure out how to get the lower unit lowered.

 

[cc lancer]

Re: engine help please!

Don S...you should have got a new crystal ball. <br /><br />Mindfusion:<br />Booyal is on the marks with his answers, everything hangs off the back of the engine, the boot just keeps the water out. <br />Your engine is notorious for bad electrical connections, clean all connections especially the battery ground to engine, then disconnect the plug, and check all to see if you have corrosion on any of the contacts [male plug].<br />If your engine will not turn over, repost, and we will walk you through getting it going.

 

[Boomyal]

Re: engine help please!

Hey CCL, where ya been. You never went back and finished our discussion on foaming the boat! You asked for a pic and I posted one for ya. <br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=26;t=002120