Cracked block issue??

[jeepin]

Now here is my disclaimer - I don't know anything about boats, and do not plan on running the boat more than maybe 8-10 times for the summer.<br /><br />I have a 1988 Rinker 4.3L Mercruiser Inboard and have a question about running with a cracked block. Eventually I am going to replace the engine, this engine is practically new, but cracked block. Doesn't seem like a large crack, on the right side close to the freeze plug. How long will a motor run with a cracked block (Enternal VS. Internal crack.) It would seem not as big of a deal as a car engine, because its not pressurized likie cars. Water comes in, circulates, and then is discharged right? I just want to run the engine until its dead, and then replace it. Will it run for awhile?

 

[flashback]

Re: Cracked block issue??

what your asking is hard to say. I have had a car engine datsun 240z that was like that and it ran for several years and may still be running. all i did was to drill a small hole at each end of the crack and then grind a V down the length of the crack. then I filled it with JB weld, which is a two part epoxy filler. worked good for me. but with a boat I think where I was boating would be the determining factor as to weather I would do this or not. on a small lake OK, but on the ocean,or a large lake, absolutly not.......

 

[johnkc]

Re: Cracked block issue??

if you have ran it long enough to be sure it doesn't leak water to the inside ,into the engine oil, then jb it and go boating{after the jb cures}many engines are out there running with jb on an external crack

 

[Rich-ard]

Re: Cracked block issue??

I had the same engine with a crack in the water jacket. I wired brush the crack and put enough JB weld on the crack to stop the leak. Only a few drops of water would appear. It I used the boat that summer but then I had problems with the lower unit so I sold it cheap. We also fixed a cracked block on a 58 Ford truck with a six cyl. engine. I've heard you can have them welded but I don't know if that is true.

 

[SS MAYFLOAT]

Re: Cracked block issue??

For a more permanent repair, try laceing the crack with pipe plugs, drill bit, and pipe tap. Its cheap, simple to do, and it won't heat stress the cast from welding or brazing. The constant expansion and contraction process will eventually cause the JB to fail. Been There and Done That!<br /><br />Center punch 1/4 inch from the ends of the crack. Drill a hole at the punch marks, tap threads in the hole, use pipe dope on the plugs and intall in your threaded holes. Now grind off the top of the plugs. Now drill a hole on the crack overlapping into the plugs that you just put in. Tap those holes, install the plugs, and grind. Continue doing this until you have closed the crack. Grind everthing smooth, prime, and paint. Even the best mechanic will never know it was cracked and repaired.<br /><br />I have saved 3 engines this way. Black iron pipe plugs are about 10 to 25 cents. The most it every took me to do a crack was 12 plugs. Drill bit and tap under $10. None of these repairs leaked. <br /><br />This procedure dates way back into the 20's. I was glad that I learned this trick from my father. It has made a cheap deal on a boat to profit within days. It took about 4 to 6 hours to do with the engine still in the boat. A right handed drill works well in tight spaces. Just a thought......going the extra mile usually makes me smile