OMC engine replacement options?

First post, and first boat

I purchased a boat form my inlaws for very cheap, the only issue with it is the engine. The 17.5 foot came with a 3.0 Cobra 302BPRPWS, a 90's model. The Block is cracked and letting water in and compression out. This is from a bad winterizing job from a company the in'laws fought with for 3 years. Guess they couldn't afford a lawyer

Regardless the 3.0 is obsolete and I'm having issues finding a remanfacured GM 181 for a decent price. So, what do you think my options are here? From what I understand the bell housing bolt patterns are the same on the early year mercruisers and 4.3L cobra V6's.

The Mercruiser and V6 4.3 are a dime a dozen around here, but I just can't seem to find a decent 3.0 to put back in the boat. The 4.3 will need a new outboard and I think if I find a doner boat I can just use whatever it has graneted propper engine alignment with the different front mounting. Will a mercruiser require a different outboard? Wiring? head? Shifting cables? Throttle adjustment?

I'm mechanically competant and have lots o' time. I've rebuilt cars and thought I would try my hand at a boat. I know they arn't the same. But as far as swapping the engine goes, I'm a bit lost. Mainly due to the age of this block and.....well...it's a boat. When I look at it I feel like I'm hammering on a glass bottle.

Re: OMC engine replacement options?

the 3.0 is the most popular engine used in i/o's today. It is far from obsolete.

4.3 swap is do-able, but I wouldn't bother with a Cobra transom. Your thinking of Mercruiser transplant is a good way to go. Get the whole boat so you have all the helm wiring, gauges, shifter... it's all somewhat different.

As you know you'll need a new outdrive, so you might as well look for a complete V6 Mercruiser powered hull and do the swap from pulley to prop.

However, 9 times out of 10, while looking for a suitable repower package with all that, you'll just find a better boat with the engine and drive you want for about the same $ or less than buying a used engine/drive setup. Push yours to the curb or part it out and save $ and be out boating sooner.

For that other 1/10 , I'd probably just stick with a 3.0 and drop it in and go. You can buy a brand spanking new 3.0 for about $2000.

Re: OMC engine replacement options?

Howard Sterndrive said:

the 3.0 is the most popular engine used in i/o's today. It is far from obsolete.

4.3 swap is do-able, but I wouldn't bother with a Cobra transom. Your thinking of Mercruiser transplant is a good way to go. Get the whole boat so you have all the helm wiring, gauges, shifter... it's all somewhat different.

As you know you'll need a new outdrive, so you might as well look for a complete V6 Mercruiser powered hull and do the swap from pulley to prop.

However, 9 times out of 10, while looking for a suitable repower package with all that, you'll just find a better boat with the engine and drive you want for about the same $ or less than buying a used engine/drive setup. Push yours to the curb or part it out and save $ and be out boating sooner.

For that other 1/10 , I'd probably just stick with a 3.0 and drop it in and go. You can buy a brand spanking new 3.0 for about $2000.

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Most popular used in engines today? I'm sure it would take more than just drop and go for a newer block. cam gear, fuel pump, filter size, heads, etc... I would like to go down that route, if it would match the bellhousing mount for the transom. I don't know if the 3.0 will be underpowered for my 17.5 or not.

The only thing that puts me off for parting out is the quality of the interior and such is just to perfect to drop. No tears in the uphostry, bright vibrant colors, good plastics, and still has gel coat on the hull. Absoultly nothing has to be overhauled except for the engine.

The second thing keeping me from that is my space....it's in the drive way and I don't have a back yard. I can only imagine what my wife would say to two boats in the drive way LOL.

What mercruiser models do you think I should look for if the OMC isn't viable? I know mechanics won't work on the things because of them going out of buisness, but that's ok It's a pretty straight forward engine. The Sterndrive is just what throws me for a loop. That's wichcraft to me. But the bearings are good and it really looks hardly used from a mechanics perspective, but I really don't know everythign to look for.

I did find a junkyard that will deliver a 3.0 shortblock to my door $700 total cost, OMC but if it solve's my crack problem then that would be good to right?

Re: OMC engine replacement options?

ashc2025 said:

I'm sure it would take more than just drop and go for a newer block. cam gear, fuel pump, filter size, heads, etc...

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nope. nothing has changed.
If your engine is 90's as you say, then it has a 1 pc rear main seal so you can buy the same one new today.

http://www.michiganmotorz.com/base-marine-engine-19672012-replacement-p-67.html

includes head, and an upgrade to electronic ignition.
"Direct replacement for 1990-2012, 3.0L OMC, Volvo Penta, MerCruiser, etc."

Re: OMC engine replacement options?

I think this might be my affordable option?

http://pensacola.craigslist.org/boa/3259241712.html

The boat I have is a 91 OMC 3.0 Cobra. Do you know if I could just hot swap this engine? It's a 94 Merc. If at the very least just pull the block and get it overhauled? Sorry if I seem skeptical for the year differences.

Re: OMC engine replacement options?

ad says the engine is seized, but the basic long block (block and head) is identical to a 91 OMC.

doesn't look like much a donor candidate to me. If it was ever in salt water, pass on it.

Re: OMC engine replacement options?

Add was left up, said it was sold.

Unfortunately most boats down here are in the salt. So, I'm not sure what I'm going to do with that.

I did find a block from a 97 Bayliner, research shows me it's a 3.0L Mercruiser engine. Now, what I'm not sure on is engine rotation. I did find that the flywheel is a different size on these engines, but there's a conversion. I also have a machine shop that can basically overhaul the block. Not super expensive, after it's all said and done.

Refurb short blocks online are hitting the 1.5 - 2K, I'm not sure why people want gold for these blocks. *shrug*

Re: OMC engine replacement options?

ashc2025 said:

I did find a block from a 97 Bayliner, research shows me it's a 3.0L Mercruiser engine. Now, what I'm not sure on is engine rotation. I did find that the flywheel is a different size on these engines, but there's a conversion. I also have a machine shop that can basically overhaul the block. Not super expensive, after it's all said and done.

Refurb short blocks online are hitting the 1.5 - 2K, I'm not sure why people want gold for these blocks. *shrug*

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97 Bayliner 3.0 is same as 94 and 91... nothing changed from 1990 to 2012 - not sure how many ways I can tell you that. flywheel is not different.
1969-1989 3.0 flywheel is different, but 1990-2012 all use the same flywheel

don't worry about rotation - all 3.0 marine engines rotate the same way.. gm never made a counter-rotating 3.0

I don't know why people would spend $1500-2K on a rebuilt when you can get brand new for $2099 with a free $300 electronic ign upgrade.. people are generally not smart consumers I guess.

Re: OMC engine replacement options?

Howard Sterndrive said:

97 Bayliner 3.0 is same as 94 and 91... nothing changed from 1990 to 2012 - not sure how many ways I can tell you that. flywheel is not different.
1969-1989 3.0 flywheel is different, but 1990-2012 all use the same flywheel

don't worry about rotation - all 3.0 marine engines rotate the same way.. gm never made a counter-rotating 3.0

I don't know why people would spend $1500-2K on a rebuilt when you can get brand new for $2099 with a free $300 electronic ign upgrade.. people are generally not smart consumers I guess.

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Sorry man, I just keep getting all kinds of contradicting info on the net. Some say the fly wheel is different, some say the Merc bolt patterns are diff, and of course the rotation situation. Just have to understand that I'm a verry meticulous person, and when I do something I like to do it once. Redundant labor is dumb to me. If you jsut pay attention to what your doing and watch your specs it will turn out right the first time.

As it stands now I found a used short for $150. I looked it over and asside from surface rust it's all ok. The machine shop I'm working with said that worst case scenario a rebuild would be $800 but by doing that it would be a brand new shortblock any ways. Still 950 for a short block is excellent, compared to the prices I've seen anyways.

Thanks for your help Stern, I'll try to update this thread as I go with the rebuild.

Re: OMC engine replacement options?

Gettin my block back, alright.....I can't seem to find a gasket set above 1988. From what I can see the intake manifold gasket and the gasket for the bell housing seem to be the only special items.....by special I mean obsolete. Any suggestions?

Re: OMC engine replacement options?

Intake manifold gasket, right here on iBoats....http://www.iboats.com/OMC-Sterndriv...8178923--session_id.413416745--view_id.269177 EDIT: Maybe not....see here...http://bpi.ebasicpower.com/c/OMC5C-IB/Engine+Gasket+Kits+for+OMC+Inboards

Maybe someone else can help with the "bell housing gasket".

Re: OMC engine replacement options?

available at any Evinrude dealer

0914662 GASKET, Manifold to head. 302BMRPWS & 302BPRPWS Models 302BMRPWR & 302BPRPWR Models 1 $12.96

If by Bellhousing, you mean to mount the outdrive,

0911836 GASKET, Gear hsg. to pivot hsg. 1 $8.84

Re: OMC engine replacement options?

Manifold gasket popped up, thanks man. The bell housing gasket is the Flywheel housing gasket -

http://www.marineengine.com/parts/o...=Transom+Plate,+Flywheel+Housing+&+Mounts

Part 3 on here....

Re: OMC engine replacement options?

ashc2025 said:

Manifold gasket popped up, thanks man. The bell housing gasket is the Flywheel housing gasket -

http://www.marineengine.com/parts/o...=Transom+Plate,+Flywheel+Housing+&+Mounts

Part 3 on here....

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geez- never even knew there was a gasket there - I think I'd leave it out. If water ever did get in there, you want it to be able to drain out.

Re: OMC engine replacement options?

There's a drain hose installed at the bottom, I hope I don't get water in there or I have bigger problems.....I really can't think of a reason for it, there's a plate that goes between the block and housing, it's behind the flywheel too.....I suppose to prevent water from settling on the flywheel *shrug* I'm thinking gasket maker, just need to find a marine grade that can withstand salt/brackish water.

Re: OMC engine replacement options?

Got my block back, and I should be doing most of the rebuild this weekend.

Dissasembled my old block, any body know where a decent site, asside from craigslist, to sell these parts?

Re: OMC engine replacement options?

ashc2025 said:

...any body know where a decent site, asside from craigslist, to sell these parts?

Click to expand...

You might be surprised how effective Craigslist can be. I sold an old outboard a couple years ago on CL and the guy came from two states away to get it

Re: OMC engine replacement options?

southkogs said:

You might be surprised how effective Craigslist can be. I sold an old outboard a couple years ago on CL and the guy came from two states away to get it

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Man, that awesome. it's posted up. I'll just keep renewing the page unill i get some hits. Internal parts don't take up much room.

Re: OMC engine replacement options?

I was able to rebuild and install the engine over the weekend.Used the engine alignment tool, and installed the sterndrive too. Sealed everythign up, hooke dup water and turned the engine untill I pulled water to the riser. Primed the fuel and oil, and turned her over. Ran the engine at 2k for about 15-30 min. (Didn't time it). So far so good. No water in then oil either. Now, here are my issues so far.

Pushrod cover will not seal, new gasket and everything, 3rd attempt. It leaks from the bottom corners, I'm guessing it's warped. I tried another and it leaks from the same spot. Going to pop it off and see what I can do.

Had to replace the hydraulic lines on one side of the tilt arms. That was a PITA! Previously mice had chewed through the lines. So now it doesn't have any fluid. Nor does the pump spin it is holding pressure now, so that's good for the lines. Havn't checked the manual on fixing this issue yet.

Couldn't get the motor to idle, stalls and dies below 1k RPM. Opened the butterflies and I could see myself in the intake track. Egads that's a lot of fuel. Looks like a carb-rebuild is in order. Compression is good across the board, so I know my headgasket and rings are good.

So far not to bad price wise:
Boat: $1000
Engine rebuild: $1200

Market value for boat $4000 (high end)

Things left to do:
Rebuild carb ~$40
Bleed, fix trim pump ~???
Repair seat lumber ~$65
Drop her in the water and see what happens

Re: OMC engine replacement options?

I was finally able to get the boat in the water and Murphy's Law was in full effect. The boat took a little work to get running when I first pulled it out. after I had it idling for about 6 or 7 min on the trailor I was finally satisfied enough to pull her out. The steering was crap, but there was a current and I wasn't gassing it at all. The back end seemed really low to me, but I did have a lot of weight out of the boat. After I spun her arround in the bay I brought her to the dock and before I could slow her down the engine stalled and slammed me into the dock....now I have a nice little gouge in my bow.

Here's where it just goes down hill. I verified that my steering was working under load and I was good. When I got her home I was pretty low on fluid so I bled it and now I'm all good. The boat would not start up after the initial stall. There was backfiring out of the carb and lots of negative words threwn about. The engine acted like it was 180 out of timing. Once I checked it at home I was able to re-tighten the bolt and fix that issue.It was not 180 out only like 8. But it still took some to start. So now it will run out of the water but not in. and the engine is at a pretty extreem angle when I'm in the water, I'm assuming that's the problem. Any suggestions?