Broke a peice of the cylinder next to water jacket

[fishonboat]

I have a 1970 Johnson 25hp. I was removing the head to fix the spark plug threads in plug whole one. In doing so one of the head bolts broke. I really wasn't too concerned about it because like most people this isn't the first time something like this has happened to one of us. Anyway I fixed the spark plug threads with an insert and then started to tackle that broken bolt that was still in the cylinder. I started by drilling a hole in the end of the bolt and used my screw easy outs to try and get it out. With no luck I tried using WD-40 tapping it with a hammer and punch and still nothing. Got the torch out and heated with MAP gas. With it being hot I used the easy out and turned it and the housing that surrounds the bolt broke out. This is the top bolt closest to the thermostat. The piece that broke off is on the inside around the water jacket. I took it to a local welding shop and the guy seems confident in fixing it but I'm not so sure he can. He is going to fill the area by TIG welding it and I'm going to re-drill it and tap it. Has anyone ever had any thing like this happen to them? If this doesn’t work I may just put it back together and leave this bolt out and see what will happen. I will need to fill the whole on the head were the bolt goes through with something to keep the water from shooting out of it. I'm just worried that I won't get a good seal and water will get into the piston. If this doesn’t work does anyone know were to find a used Power head for cheap. What really sucks is that I had this motor out last Friday and it ran like it was new. My compression was 140 on both cylinders. This is a killer. Sorry for the long message but I just need to vent a little. I also just replaced the water pump, new prop, carb rebuilt, new OEM paint job back to original colors, new head gasket (not yet on) and repaired spark plug threads. I would really like to fix. Any thoughts would be great.

 

[davidkockler]

Re: Broke a peice of the cylinder next to water jacket

When you heat metal, the maximum allowable yield stress goes way down (in other words the metal becomes "weaker.")<br /><br />The quality of the seal is going to depend more on whether you have a bolt applying pressure at the face where broken bolt hole is than whether or not the bolt hole is filled. Anaerobic sealant on the head gasket will be very effective around the bolt hole and around the piston opening as long as the pressure applied to the head gasket is uniform. If you have one corner where the pressure is not uniform with the rest of the head gasket surface, you are opening the door for leakage.

 

[fishonboat]

Re: Broke a peice of the cylinder next to water jacket

Well I took it to a welding shop and they were able to fix the area by filling the area with a weld build up and I smoothed it out with a disk sander. After smoothing it out I marked it and drilled and tapped it for the new bolt. I put a new head gasket on and torque it down to the manual specs. It started and ran but I haven't tested it on the boat yet only on the garden hose.

 

[Blueclaw]

Re: Broke a peice of the cylinder next to water jacket

you should be fine. water jackets have been welded before with good results. The weld is stronger then the cast.

 

[CATransplant]

Re: Broke a peice of the cylinder next to water jacket

Good job. I'll bet things work out just fine. Let us know how it goes.