350 Mercruiser TBI replacement options

[Casingbill]

Hello all.
I traded for an old boat. Cleaned up well thought it was running ok but had massive temperature fluctuations. Upon further inspection, I found a horizontal crack in the block below the head.
I'm looking for economical replacement options. I can pull the motor and replace external parts myself. Internals are a different story.
I feel like a short block will be my best bet right now. Plus, it's something I can put together over the winter.
Or even a junkyard engine?
It's a 1995 290hp 350 Mercruiser

Any help and advice would be appreciated.

 

[GA_Boater]

Howdy, Bill.

Are you getting water in the oil? If no, the crack is external and JB Weld might seal it with good preparation. As long as the motor isn't closed cooling, there isn't much pressure in the block.

 

[Scott Danforth]

1990-1995 gm 350 block and heads from a truck. $250 from many pick-a-part salvage yards

 

[Casingbill]

Howdy, Bill.

Are you getting water in the oil? If no, the crack is external and JB Weld might seal it with good preparation. As long as the motor isn't closed cooling, there isn't much pressure in the block.

No water in the oil. It's just leaking down the side. It is not a closed system. I wasn't sure but I thought it may be related to the temperature fluctuations.

 

[Casingbill]

1990-1995 gm 350 block and heads from a truck. $250 from many pick-a-part salvage yards

I'm considering this option as well. Except a stock engine will be a little underpowered .

 

[achris]

...It's a 1995 290hp 350 Mercruiser

Any help and advice would be appreciated.

That would make it a 350Magnum EFI 'Gen+' Tournament Ski, inboard...
To replace that engine, make sure you find a vortec headed engine

This is why we ask for serial numbers and full descriptions.

Chris......

 

[Scott Danforth]

Chris, OPs boat is a 95, Vortec heads came out in 96

 

[Casingbill]

That would make it a 350Magnum EFI 'Gen+' Tournament Ski, inboard...
To replace that engine, make sure you find a vortec headed engine

This is why we ask for serial numbers and full descriptions.

Chris......

Thanks, Chris. But like Scott said, it is not a vortec. I double checked and it has 12 bolts on the intake and not 8 like a vortec.

 

[achris]

Then it's not 290hp... The only 290hp engine in that era was as I stated. Please provide an engine serial number and we can see what this engine is...

Chris.........

 

[Casingbill]

Then it's not 290hp... The only 290hp engine in that era was as I stated. Please provide an engine serial number and we can see what this engine is...

Chris.........

The serial number is F745515

Through my research on this forum, it's my understanding that there were three engine options for that boat. A 265hp TournamentSki, a 290hp Magnum Tournament Ski, and a 315hp Black Scorpion. On my title it lists 290hp as well as having Magnum Tournament Ski on the spark arrestor?

 

[Scott Danforth]

Both the tournament ski and the black scorpion are custom built Motors. The black scorpion is a 377 Stroker. Both have different pistons and different cams than a standard 350

 

[achris]

The serial number is F745515

Through my research on this forum, it's my understanding that there were three engine options for that boat. A 265hp TournamentSki, a 290hp Magnum Tournament Ski, and a 315hp Black Scorpion. On my title it lists 290hp as well as having Magnum Tournament Ski on the spark arrestor?

The only 290hp engine listed by Merc is a vortec. The non-vortec (which is your serial number), is a 280hp engine...

These are the 'snips' from the Merc service manual.

Non-vortec engines...



Vortec engine...



Chris......

 

[Casingbill]

The only 290hp engine listed by Merc is a vortec. The non-vortec (which is your serial number), is a 280hp engine...

Thank you for that info, Chris. That sheds new light on things.

At this point, I may just try the JB weld, provided I can figure out the temperature fluctuation issue.

 

[achris]

What sort of temp variations are you seeing?

 

[Casingbill]

What sort of temp variations are you seeing?

They were pretty extreme. 200 degrees then immediately drop down to 120.... but I think I found the problem tonight. I had changed the impeller because the old one was disintegrated. I just realized that all those pieces were backed up in the oil cooler. Cleaned out and flushed it tonight. I had removed the water pump to check it so I'll have those gaskets tomorrow and get it checked out tomorrow night.

 

[96lt4c4]

You can do what I did. Had a bad cylinder on #3. Busted rings....time for a 383...
https://www.offshoreonly.com/forums/...une-383-a.html

https://www.youtube.com/watch?v=6_sIvJVzrTA

 

[NHGuy]

To really be effective with the JB Weld get the area around the crack clean and dry. Then just before mixing up your epoxy treat the crack with painter's prep. I think of it as wax remover. But get it good and clean and dry.
Then warm up the block with a heat gun, and then mix up your JB Weld. Apply it and run the heat gun over the material to get it to migrate down into the crack. It will liquify if it gets too hot. So just warm it til it gets melty. Like cheese!