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Cracked Block Help

M

merkaba

New member
Hey, I recently got a boat for free from a family member. When i got the boat it was left over the winter without being winterized and the block got cracked. My wife's father used to weld for a living, and knows what he's doing, but he's not too sure if welding it would hold up or is the right thing to do. We don't really want to weld it and put the boat back together and have it not work shortly after. Has anyone had success welding something similar to this? I've gotten recommendations from people to use JB Weld, and Marine Tex. What is the consensus? The motor starts and runs perfectly fine. We've let it sit and run for 30+ minutes hooked up to a hose. There is no water getting into the oil from what we can see, so I think that is a good sign. Any suggestions/input would be greatly appreciated. There are a total of 3 spots that would need welding, and you should be able to see them all in the pictures. The specs of the motor are below, and also a picture of the Checkmate that it is out of. I think it's a 1988 but I'm not 100% sure of the year. If you think i should replace the block, what do you think i should pay? Does anyone have any recommendations as to where i could get one? I live in central NH, and got a quote from a place in MA. They wanted $1800 for the long block. I am not very knowledgeable with boats or motors, so all the input you have would be greatly appreciated.

Small Block
Serial: B625122
Model: MCM 260
Displacement: 350-CID
Horsepower: 260
Rotation: CCW
Max RPM: 4200-4600

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There is no repairing this!!! No if ands or buts!!! End of story,

You need a new long block and exhaust manifolds.

Manifolds can be purchased thru this site or any marina, Long blocks can be had thru a google search or craigslist as there are many sources for this, do your research.

MUST BE MARINE!!!!! not automotive or truck.
 
I don't see how it can run without water virtually gushing from those cracks. They are not repairable.
Now you are learning that getting something for free is never "free", or cheap. If you spend a few moments scanning the recent threads, you'll get a pretty good picture of what kind of dough you need. 1800 is about right for the long block. you'll need new exhaust as well so add another $700 or so on top of the engine cost. Random (but critical) hoses and gaskets and you are in the 3-3500 dollar range to get this engine back in order so it will run. You can reuse the intake and carb, disributor, and the electrical and power steering parts from the old engine.
That, unfortunately, is just the beginning. If it were me, I'd have the drive checked out and pressure tested, put in new water pump impellers, check the bilge pumps and thru hull fittings. Replace the batteries, have the tank(s) steamed out and new gas put in...it goes on and on....
A good ballpark figure for a general refurbishing of a boat in this condition will be somewhere around $5-6000 all together. That assumes no other major system needs replacement.

It's a matter of safety not only for you and your guests but everyone else out there on the water that the boat is in good condition. If something breaks down and you are stranded you put others in a dangerous spot if they have to tow you in.
 
Hey, I recently got a boat for free
I am not very knowledgeable with boats or motors, so
Click to expand...

Ayuh,... You need a new motor, plain, 'n simple...
That 1 is an Anchor at Best...
Welding is Outa the Question...Won't/ Can't happen...

You got want ya Paid for,...
Now throw another couple Grand into the hole, If ya wanta go Boatin'....
 
How would i go about finding the proper automotive motor to replace it with? I thought it was a chevy 350, but i'm not 100% sure. I also don't know what year motor i should be looking for. The specs for the motor that is currently in it are below. I found a chevy 350 out of a 93 conversion van with 69k miles on it for $450. Supposedly it runs perfectly and it's from a used car parts shop.

Small Block
Serial: B625122
Model: MCM-260
Displacement: 350-CID
Horsepower: 260
Rotation: CCW
MaxRPM: 4200-4600
Drive Unit Serial: OB752301
 
merkaba said:
I think it's a 1988 but I'm not 100% sure of the year.
Click to expand...

first thing you need to do is verify the year so you know which block you have - 1 pc rear main seal, or 2 pc.

where the heck do you guys live that you can own a boat without a valid registration??? the outback?

I can't even park one in my driveway if I don't have paperwork in triplicate....
 
Your motor id's at a 1987 to 1995 350 mag, alpha 1 Gen 1

So yes the motor you found will work

BUT!!!

you will need to change:

1 the head gaskets, to marine!!!
2 the water pump (use the one on your current boat motor),
3. the oil pump and windage try and oil pan, all gaskets and you may need to switch some of the main studs to accomidate the windage tray. (if there is one in the current baot motor.)
4. fuel pump
5. intake and carb ( make sure the bolt pattern and number of bolts are the same!!!)
6. Starter (marine, use the current boat one)
7 flywheel from boat motor
8 all other parts that you remove from boat motor when doing the change.

Also there is a good chance the cam may be different so while doing the head gasket you may want to install a better cam, one that will increase your power a bit. WHich one I can not reccomend but maybe someone else here can or someone you may know. You want max power from 2000 rpms to 5000 rpms. Your motor should never run higher than 4800rpm when propped correctly.
 
Brass frost plugs in the auto app? Also, I could never get a straight answer from anyone; valve overlap any different from auto to marine for minimizing water ingestion?
 
Good call on the frost/core/freeze plugs,

valve overlap Not applicable for most typical small blocks cams. big issue with HO big blocks.......
If he were to choose a cam that radical.........that would be his problem not ours.........lol

The stock cam is very very mild. I think it may be only like 440" lift may be lower, they are mild cams, as long as he stays with a good torque type cam no issues. Remember max rpm is 4800 so the cam needs only be effective to ~ 5000 or so. Besides if he goes to radical the carb will not be working too well.............it is only good to about 290ish HP, It would need recalibration to handle too much more cam......dose not sound like he is in for that... One of the first couple of service manuals and maybe even the one for his motor MAY contain the cam spec.......then that would be the giude to go by.

Any cam with high lift or severe overlap I would think would be usefull in the 5000 + rpm range......just my opinion and I am no cam/motor expert at all.........I usuall just go OEM.....

I did install a 570 lift cams in my motorcycle..........much more fun to drive but its only two cyclinders.......
 
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When/if you replace this engine, get rid of the petcocks and install regular brass tapered pipe plugs.
This forces us to remove the plugs and probe the drain ports as to remove any rust scale debris that may prevent all water from draining.
This is very likey why the block cracked.

Those petcocks should not be used on raw water cooled engines. :mad:
 
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