crack in yanmar block

Tim R. · Nov 8, 2009

Cracked blocks are very difficult to repair. The properties of cast iron are very hard to match with a welded repair. The heat and cooling cycles usually break the weld again. If it were a fresh water cooled system I would suggest trying some Bars Leaks but this will not work in a raw water cooled system. There are techniques for "stitching" the crack but this is expensive and does not always solve the problem.

Start saving for a new block and keep the bilges pumps running in the mean time.

woodster · Nov 8, 2009

if you can find a good welder in your area you may have him look at the crack and see if he can get some certainium 889 aloy rods to do the work with ....but if that doesnt happen the you can take a die grinder with a cone shaped stone and clean the crack some and all around the area and then after that wash it down with some lock tite degreaser and use the dark grey marine tex a two part mix and build it up about 1/4 of an inch thick then let it alone for about a week ....this has worked for me in the past on a old crysler inboard inline 6 flat head ventage 1956 ...there may be other ways to fix it but at this time i have told you everything i can think of to do .....

good luck

woody

Douglast · Nov 8, 2009

woodster said:
if you can find a good welder in your area you may have him look at the crack and see if he can get some certainium 889 aloy rods to do the work with ....but if that doesnt happen the you can take a die grinder with a cone shaped stone and clean the crack some and all around the area and then after that wash it down with some lock tite degreaser and use the dark grey marine tex a two part mix and build it up about 1/4 of an inch thick then let it alone for about a week ....this has worked for me in the past on a old crysler inboard inline 6 flat head ventage 1956 ...there may be other ways to fix it but at this time i have told you everything i can think of to do .....

good luck

woody

x2 for the suggested repair above with die grinder...i have also been successful using jb weld

sand sailor · Nov 8, 2009

i.ve welded cast iron blocks before if you know what your doing its not a big deal just time consuming. so find someone who does cast iron in your area AND GET REFERENCES before you let him do it

Brian M H23 · Nov 9, 2009

I'm kind of confsed. People have been welding cast iron with a torch and bronze brazing rod for..I don't know how long. But a long time.

wonkodsane · Nov 9, 2009

Brian M H23 said:
I'm kind of confsed. People have been welding cast iron with a torch and bronze brazing rod for..I don't know how long. But a long time.

It's easy to weld for applications not requiring a large temperature differential, but it requires more skill and different materials to make a repair that will stand up to repeated heating/cooling cycles.

Hermit Scott · Nov 9, 2009

Since it is salt water cooled with a pin hold leak, it probably won't leak for long.
But I would be worried the crack would creep. You say the crack is between the two freeze plugs, does the crack stop at each freeze plug?
BTW I broke a cast iron exaust manifold on my engine. I grinded out a bevel where the two piece fit together, clamped it to a table and welded it back together with the heat up high. I have about 30 hours on the engine without any signs of a problem yet.
Did you not drain the engine for the winter? I don't know where port arthur is but your story makes me glad I am in south texas. I was scuba diving under my boat last weekend with out a wet suit.

tommays · Nov 9, 2009

I would go with epxoy of your pick as to weld it correctly would require removing it form the boat unless your real comfy with that many sparks

Fairwind · Nov 9, 2009

I repaired a freeze-damaged (cracked) block in a Petter Diesel. Grind out the crack a little with a grinder or Dremel tool. Clean with acetone. Repair with J-B Weld, slow cure, and you are done. There is little stress or pressure here..

Madbanshee · Nov 9, 2009

small hole in block .

galynd said:
I found a very small crack between two freeze plugs in my 1982 yanmar 3gm. It is a saltwater (raw water) cooled engine. It has a slight pinhole, constant leak, when the motor is running and none when off. It is on the port side. There is no water in the oil. The motor runs great but I know that won't last long with this condition. Any suggestions for repair?

U could try bore about a 1/16 hole and fill it with JB Weld it shpould work if u clean it out propperlyand mix the 2 parts real good it will most often last out the motor I no because I have used it on a few truck motors and it never failed me .

zeehag · Nov 10, 2009

i was advised that before buying new engine, try jb weld--goood luck--isnt any pressure there so might just work --doesnt get really hot--mebbe one of the epoxies----

sailaway78 · Nov 10, 2009

One more comment

If you have a crack, drill a small hole at each end of it, which will stop it from expanding. The JB weld should work if you gring out a small valley, and clean it really good. Be sure to let it completely cure before you start the engine. On the raw water cooled engines, hardly any pressure on it, and they run pretty cool.

RichH · Nov 11, 2009

Suggest since you are near Port Arthur that you find a welder experienced with (petro-chem) heat exchange equipment (and its repair) as such a knowledgeable welder 'can' sometimes braze a small crack in cast iron at most times with good results. Cast iron is PITA to 'weld' correctly (requires heating the base metal to the proper correct temp before welding, etc.) and the results are are always 'so-so'.

As other posters have stated, "stop the crack from propagating and apply a bit of JB, etc." is probably the 'easiest' ... and see then if it 'works'.

crack in yanmar block

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