OMC Guru's need some help/specs

[BowTieGuy]

I got a boat from my friend that has a 140 hp OMC in it. He over heated it and cracked the block from what I can tell. He thought it was the head/head gasket and replaced both of them and it still gets water in the oil and blows it out the dipstick. It has to be craked. The model #is 990237E1 and the serial # is W550030. The Casting number on the block is 2770087.
Here are my questions
1. Why is it called a GM motor and an OMC motor? What parts are used from a GM?
2.I can get my hands on a 2.5 L from a car. Is there anyway to make this engine work?
3.How expensive would it be to drop a 350 in its place. I know I would have to buy the manifolds for the exhaust, but would it bolt to the stern drive? Thanks for the help!

 

[BAproject]

Re: OMC Guru's need some help/specs

The block is a standard GM block I believe

 

[zbnutcase]

Re: OMC Guru's need some help/specs

The entire longblock is from GM, and was never used in a car or truck app. And unless that car 2.5 you can get your mitts on is from a 62-70 Chevy II Nova, forget it, the late 2.5's are a totally different engine. And forget the V8 swap too, the drive wont take the power

 

[LAC_STS]

Re: OMC Guru's need some help/specs

He same reason its called a chevy motor and not a GM motor. The boat engines might be KVM engines but they are marinized. They have different gaskets and parts on them.

You CAN use a car wont but it WON'T last long.

 

[zbnutcase]

Re: OMC Guru's need some help/specs

You CANNOT use a car motor to replace a 140, unless it came out of a 62-70 Nova, and most of those didn't have 'em, most came with sixes. And you would be losing .5 of a liter

 

[4Winns2]

Re: OMC Guru's need some help/specs

You CANNOT use a car motor to replace a 140, unless it came out of a 62-70 Nova, and most of those didn't have 'em, most came with sixes. And you would be losing .5 of a liter

You are correct sir. My father's boat is a 1987 120/2.5 L Chevy Nova block from that era.

 

[BowTieGuy]

Re: OMC Guru's need some help/specs

Oh Ok. Thanks for the info guys. What if I dont know what car the 2.5 engine came out of? How can I tell if its the right block? If that engine wont work what would be the cheapest way to get this thing running again? Can I resleeve these blocks, because I am assuming it cracked a cyl. wall.

 

[BowTieGuy]

Re: OMC Guru's need some help/specs

Anyone know if these 3.0 blocks can be re-sleeved?

 

[Howard Sterndrive]

Re: OMC Guru's need some help/specs

Anyone know if these 3.0 blocks can be re-sleeved?

sleeving doesn't fix the block cracks you have....

that's why these boats are free every day of the week....there aren't many options

You buy a used engine (cannot buy new- the OMC coupler won't fit the crank on a 3.0 made after 1990), or push it out on the lawn with a "free" sign
or part it out - worth much more in pieces than as a whole.

Wait until you research the reputation of your electric shift OMC drive before investing in the engine....
If you don't have several thousand $ to throw at this scow and love wrenching, pass it on.....

 

[Howard Sterndrive]

Re: OMC Guru's need some help/specs

What if I dont know what car the 2.5 engine came out of?

I really doubt there's too may of those Chevy II engines in the world anymore... if there are, they're still in the chassis and rusted to destruction

here's one for $300 in pieces:
http://www.stevesnovasite.com/forums/showthread.php?t=157127

 

[zbnutcase]

Re: OMC Guru's need some help/specs

Yes a 3.0l can be sleeved, as can most engines by a good machine shop.

 

[BowTieGuy]

Re: OMC Guru's need some help/specs

Well i will tear the engine apart and see what damage is done to it. Another question- I found a mercrusier 250 6 cyl from a 69 boat. Anyone know off the top of their head if this engine woould be able to replace this 140 OMC? That merc. also has the stern drive on it so i could use that if it would fit in the old OMC hole. thanks for all the info and help!

 

[Howard Sterndrive]

Re: OMC Guru's need some help/specs

i could use that if it would fit in the old OMC hole.

2 and a half of them will fit in the hole... no good.

Your drive cannot handle the torque of a 6 cyl. (doesn't really handle the 140HP all that well, truth be told...)

You can rebuild the transom with plywood and cut a new Mercruiser hole. But then you'll need a shifter, gauges, steering etc.. all Merc compatible.

easier to just go shopping for a different boat

 

[BowTieGuy]

Re: OMC Guru's need some help/specs

Well that merc is actually a whole boat that I would buy just for the engine so i would have all the controlls and other parts. I dont think i want to try and fill the hole with plywood so i think i will scratch that idea.