Cracked Block Help

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

 

A good certified welder gets $60.00 to $ 70.00 an hour so I consider their quote out of line. You will have to pull the engine out of the boat and tear it down so it can be seen if there is any damage to the interior not visable on the exterior. You will get a lot of answers from others more knowegable then I--it sometimes just takes awhile. Many, many cracked blocks have been fixed and last as long as ones not cracked.

 

Thanks a lot for the quick reply. The $1800 dollar quote i was referring to was for a new long block to replace the whole thing. My wife's father used to weld for a living and he is comfortable doing it, just doesn't have a lot of experience with blocks and wasn't sure how it would hold as a long term solution. I look forward to hearing more

 

To weld it, you have to completely disassemble the motor. There is a large amount of heat distortion. The manifolds will probably not be saved. If you want a quick and dirty fix, use an epoxy with metal filler to plug the cracks. The worst that can happen is that the crack will get bigger. Drill holes at the end of the cracks to help prevent them from getting bigger.

 

Don't bother welding it, it's not worth the bother. Go down to the local automotive bone yard and buy a 350 block. You can get them for dirt cheap and a lot less then welding what you have. Have it machined as necessary to accept new rings, bearings, etc. and throw a rebuild on the thing. Assuming good cylinders and bores, you should be able to get all the parts for less then 500 bucks. Transfer all the extraneous stuff from the old engine to the new. Blown out water jackets can be welded, but is usually reserved for a block that would be difficult to replace or has some sort of special value, such as an original Keith Black 426 casting or something. I welded a guy's 327 a few years ago, but it came out of an original fuely Vette, si keeping the block was the only option. With the millions of 350 blocks laying around, you can get one for under a 100 bucks, if you any kind of friends in the business.

 

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

 

You need to save certain parts from the old (MARINE) engine such as the cam, starter, carb, alternator, pumps, etc as these are different then the ones used on auto engines. Any GM or chevy dealer can tell you about the engine with the info you posted. They have books to look up any engine made by them.

 

That's a Mercruiser Marine engine, probably a 350 built in Baltimore. There are several numbers on the block to help identify it, the casting number is helpful. Did you get the engine ID number from a stamping just in front of the right side head? It's on a machined boss, that sticks out and often hidden by an alternator or bracket.

In any case, just pull the head and measure the diameter of the cylinder. If it's a 350, it'll have a 4" bore, if it's a 305 it's a 3 3/4" (short) bore. The casting number will be the definitive answer. A casting date is located on the left hand side of the engine just forward of the flywheel.

Mercruiser also puts a metal tag on the valve cover (usually) which has this information on it. If it's a 260 HP Mercruiser it's a 350.

 

i cannot believe what I am seeing here, what are frost plugs for, I can only assume the jacket void is very narrow and the iron is very thin

 

you need to check that the block you replace it with is also a roller cam version as yours will be I would think.
The only item to chase is the block to oil pan layout as there is a kick to allow for the oil didpstick tube and that is different on auto block to what is are used as marine blocks/industrial, usually
PS the bores generally are thinner than the case that just split as well!

 

Dean, even with freeze plugs, you can have such a volume of ice in the water jackets that it'll crack the block, even if the plugs have popped out.

You may be right Powerabout, but I'm fairly sure these are old school tappet engines.

 

1988 engines have regular lifters. You should not install roller lifters with a regular camshaft, it will get pitted very fast.

 

Not only is that engine a done deal but It would take more time and labor prepping it for repair than replacing it.

 

Just had to replace my block due to cracking. To weld you need to strip the block. When welding the bolck needs to be heated so that it does not crack in th heat affected zone at the edge of weld. heat needs to be broght down slowly. It's so much cheeper to replace the bloke then it is to weld. Just remember after you strip the block down, you will need to replace all gaskets at minimum. And after all that work and money spent you still have a used engine....... Welding cast iron is a pain in the butt.

 

By the way ..... If you get the casting numbers off the block you can call a chevy dealer and they can tell you the replacement..... It has to be the casting numbers. Usually those are on top of the block where the heads attach. Back of the block right hand side. These numbers are stamped into the block.....