Let's play "Name that engine!" (Help please!)

[brewern]

Please help me identify my boat engine!

Here's the deal. Last year, with very little understanding of boats or boat engines, and a small budget of $1500, we set out to find a runabout. After thousands of ads, we found a cool little vintage 17' Rinkerbuilt Runabout with an OMC Sterndrive (Wait moderators... don't move this post yet!). We had it out last summer several times. It always started right up and ran pretty well, but had a pinging noise at higher RPMs. I figured maybe it was valve lashing, and adjusted the valves. The noise stopped for maybe 15 minutes, and then it was back. Next I figured it was hydraulic lifters and that was right at the end of the season.

But wait, I remembered the original owner telling me it had a Mercruiser GM Chevy 3.0, 140HP inline 4 cylinder in it. Hmmm, I just stored that away in my mind, not really thinking too much about it, because I didn't know better. I also noticed the top of the valve cover said "2.5".... double HMMmmmmm.

So, I parked it in the garage and decided to do one more test. A compression test. The numbers were way off, and water shot out of the cylinders! :facepalm:
So, I decided to rebuild the engine. I have some great mechanic friend I can lean on for help, and so it went.

You can view my entire thread, from beginning to current, at the link below. Page 3, about half way down, begins the engine overhaul:
http://forums.iboats.com/boat-resto...erbuilt-renovation-paint-powder-579407-3.html

This morning I started a thread looking for advice on possibly just buying a new motor, in the OMC Sterndrive section. It was decided the previous owner pulled out the OMC engine, and put in a GM 2.5 I4. You can view that thread here:
http://forums.iboats.com/omc-i-o-inboard-engines-outdrives/where-buy-3-0-omc-sterndrive-594735.html

So, now I'm trying to get a definitive understanding of what's in my boat. When I start looking for parts, and rebuild kits, or possibly a replacement engine, what do I look for?

For the engine, am I correct that I should be looking for a 2.5 or 3.0 GM I4, pre 1990? Or should I look for an OMC Sterndrive engine, or what?
And if I need to work on the LU, I should be looking for parts for a Sterndrive SEI06?

Is my understanding that this boat has been Frankensteined together correct?

Any and all help would be greatly appreciated!

TIA,
Brewer

 

[Don S]

Re: Let's play "Name that engine!" (Help please!)

Do us all a favor and in this thread, just post a few pictures of your present engine and present outdrive so we don't have to try and read and understand two long threads to understand what you have.
That's all it takes.

 

[brewern]

Re: Let's play "Name that engine!" (Help please!)

Here's some pictures that might help.

Engine in the boat:

Obviously a Mercruiser right?

Serial plate on the valve cover, not above the starter where it belongs:


Lower Unit:


Engine removal:


Parts for eBay?

 

[dubs283]

Re: Let's play "Name that engine!" (Help please!)

judging from the photos i saw it looks like someone took an OMC long block assy and dressed it with mercruiser components, no big deal - happens all the time

the long block assy was manufactured by GM - they made longblocks for OMC and still do for merc and volvo

you will need to locate either a 2.5L or 3.0L GM longblock assy to replace the one you currently have, or simply have the current one rebuilt and paint it black

as far as parts, just order mercruiser parts, omc went out of business a while ago and parts are getting harder to find, besides the external component parts are all mercruiser

for drive parts just order alpha one parts, the se106 is a dircet copy of it, just make sure you dont order parts for a gen2 drive - its completely different

 

[Don S]

Re: Let's play "Name that engine!" (Help please!)

Is my understanding that this boat has been Frankensteined together correct?

You have an OMC engine, and a Mercruiser aftermarket drive, so yes, you have a Frankensteined setup.
What year is the boat, or the transom shield? Have a serial number on the transom shield, or a picture where we could see it?

 

[brewern]

Re: Let's play "Name that engine!" (Help please!)

I measured the cylinder diameter, and it's about 3.75 inches. As I understand it, this means I don't have a 3.0, and therefore must have a 2.5. Would you concur?

 

[brewern]

Re: Let's play "Name that engine!" (Help please!)

You have an OMC engine, and a Mercruiser aftermarket drive, so yes, you have a Frankensteined setup.
What year is the boat, or the transom shield? Have a serial number on the transom shield, or a picture where we could see it?

Here you go:

 

[Don S]

Re: Let's play "Name that engine!" (Help please!)

According to the model number in the picture below, you have a 1984 OMC 2.5L motor.

 

[Don S]

Re: Let's play "Name that engine!" (Help please!)

Transom shield is in the late 70's Mercruiser one drive range.

 

[brewern]

Re: Let's play "Name that engine!" (Help please!)

Let me try to put all this together, into a single set of specifications that makes sense. Correct me where I'm wrong:

Boat:
17' 1980 Rinkerbuilt Runabout

Engine:
1984 OMC 2.5L
4 Cylinder
120 HP ?
OMC Longblock
Dressed with Mercruiser parts

Drive:
Late 1970's (Boat is a 1980)
Alpha One parts or the SE106 (But not the Gen2)


Am I forgetting anything? Can anyone post link(s) to a proper master rebuild kit?

 

[Don S]

Re: Let's play "Name that engine!" (Help please!)

Let me try to put all this together, into a single set of specifications that makes sense. Correct me where I'm wrong:

Boat:
17' 1980 Rinkerbuilt Runabout

Engine:
1984 OMC 2.5L
4 Cylinder
120 HP ?
OMC Longblock
Dressed with Mercruiser parts

Drive:
Late 1970's (Boat is a 1980)
Alpha One parts or the SE106 (But not the Gen2)

Late 70's transom shield means it's probably a 79, not uncommon to have an older model engine and drive package in boats. The boat manufacturers buy the packages and use them, may be next years boat. Not a big deal.
So 79 transom shield in an 80 is normal.
The rest is correct.

 

[brewern]

Re: Let's play "Name that engine!" (Help please!)

Perfect, thanks!

Any ideas where to get a rebuild kit? I plan on having it bored if necessary, and possibly honed.

 

[Bondo]

Re: Let's play "Name that engine!" (Help please!)

Perfect, thanks!

Any ideas where to get a rebuild kit? I plan on having it bored if necessary, and possibly honed.

Ayuh,.... From yer Machinist...

 

[Howard Sterndrive]

Re: Let's play "Name that engine!" (Help please!)

now that we know it's a Mercruiser, a brand new 3.0L is another option:

not cheap - about $2500 once you buy the new flywheel and coupler, but then you'll have an extra 15 HP or so and a brand new long block with electronic ignition.

 

[Silvertip]

Re: Let's play "Name that engine!" (Help please!)

If you intend to rebuild the current engine, I hope you marked the rod and main bearing caps so they can go back on the matching rods and main bearings and the piston and rod assemblies so they go back into the same holes.

 

[brewern]

Re: Let's play "Name that engine!" (Help please!)

If you intend to rebuild the current engine, I hope you marked the rod and main bearing caps so they can go back on the matching rods and main bearings and the piston and rod assemblies so they go back into the same holes.

Was I supposed to do that? Uh oh! LOL, just kidding. Yes, I labeled everything in case I rebuilt it, but I've since decided it will cost way too much to continue this restoration. Instead, I'll be parting it out and looking for another boat. I'll be able to pay off what I owe, and make a little extra for the down payment on the next boat. Hopefully we'll have a nice upgrade for the next boat!