Cracked Block

[sailstoo]

Friend has a Yanmar 3GM with a small crack above the starter. It goes drip...drip...drip when running. Someone, not him, "patched" it with some sort of poly years ago. Boat is in freshwater. Engine is raw water cooled and runs and starts good. Suggestions?

[Astrid]

One could take it to a welding shop and see if they can weld the crack up with a certainium 889 aloy rod.

[capttman]

Many people have used J B WELD works great even on blocks

[galynd]

I had the same problem, same spot, with a 1982 3gmd. I would clean it up, lightly grind then fill in with J B weld. It would hold great for about 6 months, then start leaking again. The problem was, as a raw water cooled engine, especially in salt water, it rusted from the inside. Over about 2 years the crack got worse with more leaks.

The J B weld gave me plenty of time to shop for a deal on another engine. I eventually replaced it with a 3gm30f. Any 3gm has the same foot print and will drop right into place if you have room. If you look hard you can find reasonably priced 3gm's. I found mine used for $2300. There are rebuilds available for about $4500 and even less.

I feel his pain. Good luck.

[zeehag]

as you advised us you sail in fresh water, you should not have much problem with jb weld----- should be fine for mebbe 8 months or longer--keep us posted....

[foggysail]

I have seen engines repaired with a plates welded over cracks. But the real concern is whether there are internal cracks. If it was my engine, I would do whatever to keep it alive and functioning for as long as possible.

[hugosalt]

Use Marine Tex ...shape with a wet finger...let dry ...usually can use motor with no worry for many years.

[Bill Burgette]

I worked in a steel mill and we repaired hydraulic tanks filled with hot fluids and heat exchangers under pressure with a product called Belzona 1121. I don't recall ever having to redo a repair. The stuff makes JB weld look like Silly Putty. If you can find it, it could be a permanent repair.

[Pblais]

Bill,

I did a quick check and these folks make a few other products that seem almost too good to be true but the specs seem to indicate they really are what they say. I just could find no link to actually get some. It appears to be a product you need an account with the supplier to get. I could find no prices and it sounds like you need to order it in 3 kg containers.

As you say JB Weld is like silly putty compared to this stuff.

[scallywag]

J B Weld has a few different mixes. One mix has a max temp of 200 degrees. The other mix has a max temp of 1000 degrees. I was not aware of the different mixtures. It is a two part product. I would have liked to purchased a premixed product. So far it(1000 degree) has held on the chain cover. I tried to weld a cast piece holding the water pump. It did not hold and I have now added another piece of metal to be J B Welded to the assembly.

John

[Steve W]

FWIW, filled a crack in the head of a 1978 Fiat Spyder convertible with JB Wleld as a temporary fix and it was still holding about 3 years later when I sold it. The crack was right next to the exhaust manifold, about 1.5" long. Just cleaned it with a wire brush and degreaser. That double overhead cam engine would really rev and I never believed the JB Weld would hold, but it did. Put maybe 20k miles on the JB Weld.

[Bill Burgette]

Steve, a little off topic but how in the world did you keep an 1800 cc Fiat running for 20,000 miles. I had a bunch of friends back in the day with 1800's, and some of the 850 Spyders also. That's how I learned to work on mechanicals. I also owned a 1967 Alfa SpIder for 20 years and love the Pinninfarina styling........Fiat's too. You do know that "FIAT" is an acronym for "Fix It Again, Tony". Sorry, just couldn't pass that up. My British sports car days taught me how to work on electrics. We learn by our experiences.

[Steve W]

Bill, the car was bought new by a Navy F-18 fighter pilot who was a close friend and neighbor. He drove it from Annapolis to San Diego, all thru Mexico and back to Jacksonville, FL over the years. When the first Gulf War was beginning, he was a squadron commander and did the intial raids on Bagdad in the early '90s. While he was deployed, the Admiral and I helped his wife and two babies maintain their house, cars, etc. When it got back, he gave it to me as a thank you. It had around 55k miles when I got it, all I did was clean it up and put big wheels and tires on it and with the top down, I could pretend it was a Cobra. It was reliable, never failed to start, and I can remember putting a battery, JB Weld, belts and hoses on it, but that is about all. It was kept in a garage and it had about 75k when I sold it for $1500 and still looked good. The Fiat reputation killed its value, but it was a hell of a lot of fun.

[sailstoo]

Originally Posted by Bill Burgette

I worked in a steel mill and we repaired hydraulic tanks filled with hot fluids and heat exchangers under pressure with a product called Belzona 1121. I don't recall ever having to redo a repair. The stuff makes JB weld look like Silly Putty. If you can find it, it could be a permanent repair.

A knowledgeable yard guy said it appeared that JB Weld had been used on the crack a long tiime ago. Thanks for the tip on Belzona 1121. Their website is certainly industrial strength. I have contacted them through their site and we'll see what happens. If not, we'll look at Marine-Tex. Thanks to you all once again.

[perchance]

I am surprised no one has mentioned brazing which used to be the standard fix for cast iron. Cast comes in several varieties and some are more weldable than others, the main problem is controlling the heat that can cause the crack to run upon cooling.