HELP! Seized Mercury v6 240 EFI

[Jeep_Creep_]

So here is my story, long time boat owner, just traditional Mercruiser I/Os. I really wanted a Seadoo Islandia Mercury 240 V6 EFI since it is a beautiful deck boat, with an amazing hull design, and much more affordable than say a Tahoe. I was very afraid to purchase it as I have read warnings about these boats failed oil pumps. This was a Marina stored, maintained, boat that the owner even had the Marina sell it. So I figured GREAT! This thing was SUPER clean for its ago, looked new, so I thought it was well taken care of. Well, I took it out 3 times for about an hour, putting around my lakes, and guess what, oil pump failed, engine seized according to shop. So all those pennies I saved for this expensive boat is now a pile of junk. So now I am broke being broke, had to borrow a few bucks just to get it shrunk wrapped for the season.
IDEAS?
1. Mechanic said to rebuild, it would cost him just as much about buying a newly rebuilt motor $4,800 on eBay
2. Mechanic also mentioned its kind of underpowered for a 22' boat, and he would look into bigger motor options? Anyone hear of this working or what to use?
3. I could attempt to rebuild myself but have read and heard from others that could have cracked block on top of damage etc so probably a waste of time, even if I could get out the pistons, the cylinder walls could be totally trashed.
4. Mechanic also said an idea, buy a trashed jet boat for $1,000 he sees them a lot for sale, and pull the motor out of the boat, then scrap the boat. He said Mirage jet boats are cheap with same motor, only thing I can find are Sugar Sand Mirages and they are 140 not 240, so I am not sure which boat he is thinking of. Only thing I have been able to find with a Mercury v6 240 EFI is another Seadoo boat, which is not cheap!

Does anyone know other boats that use the same motor as my 2000 SeaDoo Islandia?

Also can anyone explain the different to me what a (Mercury v6 240 efi) vs (Mercury v6 240 efi M2 Jetdrive) is? Are they the same motor?

 

[Tim75]

So here is my story, long time boat owner, just traditional Mercruiser I/Os. I really wanted a Seadoo Islandia Mercury 240 V6 EFI since it is a beautiful deck boat, with an amazing hull design, and much more affordable than say a Tahoe. I was very afraid to purchase it as I have read warnings about these boats failed oil pumps. This was a Marina stored, maintained, boat that the owner even had the Marina sell it. So I figured GREAT! This thing was SUPER clean for its ago, looked new, so I thought it was well taken care of. Well, I took it out 3 times for about an hour, putting around my lakes, and guess what, oil pump failed, engine seized according to shop. So all those pennies I saved for this expensive boat is now a pile of junk. So now I am broke being broke, had to borrow a few bucks just to get it shrunk wrapped for the season.
IDEAS?
1. Mechanic said to rebuild, it would cost him just as much about buying a newly rebuilt motor $4,800 on eBay
2. Mechanic also mentioned its kind of underpowered for a 22' boat, and he would look into bigger motor options? Anyone hear of this working or what to use?
3. I could attempt to rebuild myself but have read and heard from others that could have cracked block on top of damage etc so probably a waste of time, even if I could get out the pistons, the cylinder walls could be totally trashed.
4. Mechanic also said an idea, buy a trashed jet boat for $1,000 he sees them a lot for sale, and pull the motor out of the boat, then scrap the boat. He said Mirage jet boats are cheap with same motor, only thing I can find are Sugar Sand Mirages and they are 140 not 240, so I am not sure which boat he is thinking of. Only thing I have been able to find with a Mercury v6 240 EFI is another Seadoo boat, which is not cheap!

Does anyone know other boats that use the same motor as my 2000 SeaDoo Islandia?

Also can anyone explain the different to me what a (Mercury v6 240 efi) vs (Mercury v6 240 efi M2 Jetdrive) is? Are they the same motor?

The Merc 240 efi is the powerhead portion of the Merc M2 jet drive system.

The Merc 2.5L outboards are basically the same engine. Except for the crankshaft splines to the driveshaft.

Your only option for more power is the 3.0L Optimax engine. 250 hp. Not even a 10% gain. Again- it would need to be for a jet drive.

There are several people here that have rebuilt their engines. Dr. Honda has pictures here about his process. Including a 1x2 inch hole in the block.

How do you know the oil pump failed? They don't actually fail often. They get a lot of blame, but frequently it is the engine that overheats (sucked up weeds in the lake?), the the oil pump shaft seizes from being overheated. I know- ultimately the same result- your wallet exploded. You won't know for sure until a close inspection. Maybe even after removal.

 

[Tim75]

The Merc 240 efi is the powerhead portion of the Merc M2 jet drive system.

The Merc 2.5L outboards are basically the same engine. Except for the crankshaft splines to the driveshaft.

Your only option for more power is the 3.0L Optimax engine. 250 hp. Not even a 10% gain. Again- it would need to be for a jet drive.

There are several people here that have rebuilt their engines. Dr. Honda has pictures here about his process. Including a 1x2 inch hole in the block.

How do you know the oil pump failed? They don't actually fail often. They get a lot of blame, but frequently it is the engine that overheats (sucked up weeds in the lake?), the the oil pump shaft seizes from being overheated. I know- ultimately the same result- your wallet exploded. You won't know for sure until a close inspection. Maybe even after removal.

I remembered something else that has been reported here in the past.

An owner was driving his boat in shallow water and it seemed that the engine seized. The starter would not turn the engine. Could not turn the flywheel by hand. The clue here is shallow water. He picked up a rock and it jammed tightly in the impeller-wear ring.

Did that happen to you? A close inspection from the nozzle and up into the intake tunnel. It will cost less than $4800.

 

[Jeep_Creep_]

The Merc 240 efi is the powerhead portion of the Merc M2 jet drive system.

The Merc 2.5L outboards are basically the same engine. Except for the crankshaft splines to the driveshaft.

Your only option for more power is the 3.0L Optimax engine. 250 hp. Not even a 10% gain. Again- it would need to be for a jet drive.

There are several people here that have rebuilt their engines. Dr. Honda has pictures here about his process. Including a 1x2 inch hole in the block.

How do you know the oil pump failed? They don't actually fail often. They get a lot of blame, but frequently it is the engine that overheats (sucked up weeds in the lake?), the the oil pump shaft seizes from being overheated. I know- ultimately the same result- your wallet exploded. You won't know for sure until a close inspection. Maybe even after removal.

Ahh, that makes sense with the whole 240 EFI and M2 Jet Drive.

Well maybe I can find a deal on a boat having a Optimax 3.0L engine, not sure if it's same quality, I know Mercury / Mercruiser big in the business.

I will look for Dr. Honda's pictures and rebuild, I would like to try it myself to save a ton, or maybe at least strip it down a bit and have maybe a machine shop do it, as far as the piston removal, boring, and any machining that I really probably wouldn't do near as half a good job of.

I don't know that the oil pump failed for sure. However when I was talking to the mechanic I did mention it started beeping randomly even when the key was off and just away from it. Talking to the mechanic he states that is a low oil pressure to the primary or secondary pump. I don't remember which. My fault for not thinking that was the issue, I thought it was low on oil. When it stopped running I was at low RPM like 10mph all day, and it just randomly stopped, I don't think I sucked up anything but I need to double check now. Mechanic said he could not get the motor to budge manually moving it.

 

[Jeep_Creep_]

I remembered something else that has been reported here in the past.

An owner was driving his boat in shallow water and it seemed that the engine seized. The starter would not turn the engine. Could not turn the flywheel by hand. The clue here is shallow water. He picked up a rock and it jammed tightly in the impeller-wear ring.

Did that happen to you? A close inspection from the nozzle and up into the intake tunnel. It will cost less than $4800.

That could be a possibility, I do not think the water was shallow when it happened but who knows, its worth a look, I will check it out in the Spring once Michigan is out of the freeze.

 

[Dr Honda]

On your comment about the Opti engine.... you would need the ENTIRE and not just the power head. The 250 HP is a 3L engine, and uses a different jet drive. The 240 was the largest engine for the pump in the boat.

I rebuilt my engine for around $1700. Mine threw a rod, and blew a hole in the side of the block. But with that said... I owned a Machine shop at the time, and I built engines. SO... my labor would have been expensive. I had the equipment to weld aluminum, and machine a new sleeve. But if you are the type who isn't afraid to tackle a big job... and there isn't any physical damage tot he block... you could rebuild it yourself for $1500 or so.

As said above... the pumps fail way less often that people would want you to believe. Actually... the pump itself it rock solid. It's the drive gear that gets trashed (From overheating the engine) and it fails. AND... that's actually caused by the lack of maintenance of the owners, and not really because of a bad design. In my experience... boat owners are more worried about a clean and pretty boat over the mechanical being good.

And finally... these engines don't have a pressure sensor. SO, your mechanic doesn't know what he's talking about. The only oil alarm is if the small tank on the engine gets low.

Anyway... take the boat home, and pull out the engine yourself. That's the only way to actually know what went wrong.

 

[Dr Honda]

Here's my thread

https://www.seadooforum.com/threads/dr-hondas-islandia-project-engine-rebuild-and-other-stuff.46114/

 

[Jeep_Creep_]

On your comment about the Opti engine.... you would need the ENTIRE and not just the power head. The 250 HP is a 3L engine, and uses a different jet drive. The 240 was the largest engine for the pump in the boat.

I rebuilt my engine for around $1700. Mine threw a rod, and blew a hole in the side of the block. But with that said... I owned a Machine shop at the time, and I built engines. SO... my labor would have been expensive. I had the equipment to weld aluminum, and machine a new sleeve. But if you are the type who isn't afraid to tackle a big job... and there isn't any physical damage tot he block... you could rebuild it yourself for $1500 or so.

As said above... the pumps fail way less often that people would want you to believe. Actually... the pump itself it rock solid. It's the drive gear that gets trashed (From overheating the engine) and it fails. AND... that's actually caused by the lack of maintenance of the owners, and not really because of a bad design. In my experience... boat owners are more worried about a clean and pretty boat over the mechanical being good.

And finally... these engines don't have a pressure sensor. SO, your mechanic doesn't know what he's talking about. The only oil alarm is if the small tank on the engine gets low.

Anyway... take the boat home, and pull out the engine yourself. That's the only way to actually know what went wrong.

Thank you for all the feedback! Come spring you have given me the confidence to try to rebuild this myself. I can deal with a $1500 + any additional machining I might need to hire out. It's a ton better than dropping $4800 on a whole new motor like the mechanic suggested, I just don't have that kind of money. I much rather spend my time learning to do it myself. I am very mechanical, I just don't own a machine shop. If I need to purchase a cheap press I can, any milling that might need to be done, I might be able to have someone help with that. I think the biggest worry I have is my buddy who does this kind of work more frequently than I do said that if the motor ran dry, then the pistons have practically welded themselves to the block. That statement has put the fear of impossibility for me. I really want to try it, at this point there isn't much to loose me trying it myself. My plans to pull the motor out, I want to build a 6x6 frame in front of my shed (on concrete) and make a Gantry Crane / Car Port, for doing such jobs as this. From there I will invest in an engine stand, and see what I can do this spring. Maybe if I find the room I will attempt this in the garage. Hopefully I can throw questions your way as I go along with this build. One question I do have, I read your thread and you said you were pulling I think close to 50mph you said, because of tuning, any suggestions there, I think you said a milled piston and higher compression, is this something a machine shop could do for me?

 

[Dr Honda]

I didn't mill the pistons... I milled the top of the engine block so the combustion chambers get effectively smaller. A good performance shop can do that kind of work... but I would recommend finding one that works with 2-stroke engines.

You really don't need an engine stand. Just put it together on a work bench. It's a small aluminum block, and it's not really too heavy.

If there wasn't any oil being put into the engine... yes... the pistons will "Weld" themselves to the cyl. BUT... that's not a fear point... that's a good thing. Once you get them cracked loose... you just need to clean the aluminum off the cyl walls, and then give them a hone. At that point... measure them and see if they are in spec for the stock size pistons. If not... have it machined to the next size.

 

[Jeep_Creep_]

I didn't mill the pistons... I milled the top of the engine block so the combustion chambers get effectively smaller. A good performance shop can do that kind of work... but I would recommend finding one that works with 2-stroke engines.

You really don't need an engine stand. Just put it together on a work bench. It's a small aluminum block, and it's not really too heavy.

If there wasn't any oil being put into the engine... yes... the pistons will "Weld" themselves to the cyl. BUT... that's not a fear point... that's a good thing. Once you get them cracked loose... you just need to clean the aluminum off the cyl walls, and then give them a hone. At that point... measure them and see if they are in spec for the stock size pistons. If not... have it machined to the next size.

Awesome! Well saves me from buying a stand. I have watched videos of people honing using a drill attachment with a hand drill. I assume that will work ok. If the cylinder walls are more than just scorched like gauged (more than light abrasion) then at that point I am guessing is where it needs to be bored to the next size up. As far as measuring the cylinder walls I do have a set of digital calipers would that work? I’ve been told it’s good to let the machine shop order the pistons as they can purchase the correct size to the amount of bore they need to go to in order to not rely on the rings entirely to hold compression if my cylinder walls have become to large that is.

 

[Tim75]

Awesome! Well saves me from buying a stand. I have watched videos of people honing using a drill attachment with a hand drill. I assume that will work ok. If the cylinder walls are more than just scorched like gauged (more than light abrasion) then at that point I am guessing is where it needs to be bored to the next size up. As far as measuring the cylinder walls I do have a set of digital calipers would that work? I’ve been told it’s good to let the machine shop order the pistons as they can purchase the correct size to the amount of bore they need to go to in order to not rely on the rings entirely to hold compression if my cylinder walls have become to large that is.

Those spring-loaded things that people call "hone" is properly called a "glazebreaker". A proper hone machine is a dedicated 8 ft. tall machine. It can remove metal at fantastic rates or very slowly. Your calipers won't work. You would be interested in the diameter from top to bottom. You need a dial bore gauge. When I had an old Suzuki bored out (honed), I found an aircraft engine rebuilder. They were used to honing blind holes as in your Merc block. They checked the block for size. We ordered the next oversize and they honed to size and clearance. Perfection!

 

[Dr Honda]

Yep... what Tim said.

In my own shop... I used a boring head to cut the cyl to size with a CNC mill. (undersize by 0.002") then I used a machinist hone to finish sizing it. While you can use that style in a hand drill... you need to "Machine" the cyl first to a controlled size using proper tools. AND... a cheap machinist hone will cost you $150 or more. It has ridged stones on a frame, and you adjust the tension, and total size. And... as Tim said... you need a bore gauge to check. Using a mic or calipers, and a "T" gauge isn't very accurate.

BUT.... if they cyl walls aren't ripped up, and are still in spec.... you can use a ball hone to just give the rings a new surface to cut on.

 

[Dr Honda]

Oh... one last thought. When you get inside... yes... you may see dry, burnt pistons. But look in the crank section. If you find signs of oil... and the bearings aren't blue from overheating... then it wasn't an oil issue. This is also why these pumps get a bad rep. Guys will automatically say "That (2-stroke) engine died because there wasn't any oil being injected." But the reality is... the rings start going bad, and people still keep running it. Unlike a 4-stroke, where the performance will drop, and it it will burn oil from the crankcase... in a 2-stroke, when the rings start to leak, you will get blow-by. That will be hot gas from the combustion. That hot gas will overheat the piston skirts, and displace the VERY SMALL amount of oil that is in the fuel. In turn... you melt pistons. I tell people all the time... with a 2-stroke... check the compression as normal maintenance. If you start to see it drop... even if the engine is running OK... it's time to re-ring, or do a top-end. Replacing a few parts before a meltdown is WAY cheaper that replacing an engine.

 

[Duke796]

Hi everyone, New to the forum. Bought a 2001 Seadoo Challenger 1800 with the Mercury V6 240 EFI two weeks ago, put it on the water for real for the first time this Saturday and blew the engine. The seller guarantees it was working fine when he had but I beg to differ. My fault in the end since I bought this thing, however am stuck between a rock and a hard place.

I found a 250 Optimax for sale in my neck of the woods, however reading the threads and comments from Dr.Honda it seems as though it is not a straight swap. however the mechanic confirms that it would be a straight swap. he said the motor is fully loaded and that I would only need to change the transmission shaft since it is longer for the Optimax. Can anyone confirm or deny? Not sure if I should embark on this mission or sell the boat as is with a busted engine and cut my losses?

All and any suggestions are welcome,
Thank you!