Please help!! Merc I/O MCM 3.0 Inline 4

I desperately need some help. I have an 18 ft Bayliner with the above mentioned motor. Been trying to get er back working.At first wouldnt crank at all. Replaced starter. We are starting now, and are running on muffs. So I put it in the water, wont start. WTF.Back in the driveway starts, and runs like a champ. Pull the carb take it apart, clean the bejeezus out of it, put it back in. Starts right up. again. No surprise there. While its out, change oil, gear oil, spark plugs because why not. Still starting great. Get back into the water. Starts right up. Hot diggity daffodil we may be onto something.Throttle I rev up to see how it does. No problems. Starting to look up. Seas are a little rough for a sea trial because if I break down Im likely to capsize. Head back out couple days later, lake is like glass. In the water at the launch. Starts right up again. Looking good. Throttles up again. Looking better.Time to go out. Putting around no problems. Throttling up progressively no problems. I get up to about 60% full throttle and start losing power. Throttle to neutral immediately. Engine dies. Wont restart. Turn the key, starter engages, tries to turn over cant.Go to engine compartment. Oil everywhere. Check the dipstick, completely empty. Oil filter is about 1 inch unscrewed. I tightened oil filter snugly im sure of it, also have run it significantly since changing oil. Whatever, one problem at a time. So im literally dead in the water. Back in the driveway (thank god for sea tow) on muffs, refilled oil, same symptoms. Starter engages, tries to turn over, wont. seems locked up. So question is, am I completely effed or is there something else I can do?

Thanks in advance
Jonathan

Running without oil will seize the motor but pull the spark plug first to rule out a cylinder or 2 filled with water

I see no signs of water.

Try turning the engine over with the plugs out....while on the muffs....

No Joy

does that mean it wont crank over or it wont start or there was no water in the cylinders and it cranked over

If your close to nj I know of an engine

Pulled all the plugs. Sounds like it tries to turn over for about a half second then nothing. Don’t see any indication of water in the cylinders

Bt Doctur said:

If your close to nj I know of an engine

Click to expand...

south Louisiana. How much? Wonder how much it is to ship LTL

see if the engine will turn over by hand....if the rotating assembly will spin by hand, I'd think your high current wiring is bad....one or more bad connections will keep the starter from doing it job....

If the rotating assembly won't spin by hand, another engine is probably the best alternative at this point in time...

I had already tried turning over by hand with no luck. Instead of a new inboard, I wonder about converting to outboard. Enforce transom by running supports from stringers to transom, jack plate attached through hull to those supports. Local boat yard has a used 150 for $2500. I could sell the outdrive at that point. Lighter weight overall. Sell the inboard for scrap. Got a quote for replacing the motor at $4000.

Ok, so I’m just going to assume, that when the motor ran out of oil, it overheated and jacked up the entire engine. I found a reman long block assembly that I am 90% sure will work $2500 with 2 year warranty. Checking with the seller. Assuming all of the ancillary parts of my motor are good (carb, alternator starter etc). Should I be good to go? And is there anything I can do with the old motor? Take it to the junkyard for scrap? Find a guy to give me $100 to see if he can salvage any parts? Really cool centerpiece?

I'd be inclined to think replacing the engine would be cheaper than trying to convert it to an outboard....if the old engine is locked up, its block is likely scrap...reuse of the bolts ons is possible - without any history its hard to say...