Boat Trouble, Please Help...

depends on where, temp, press, etc. what caused the 'crack?

J-B Weld is The Gold Standard IMHO.

"I'm pretty sure I have a crack on the water jacket side of my boat motor, can I repair it without having to take the motor out or replacing the block?"

Paul Harvey recommends J-B Weld epoxy, grind, drill, file, etc. when hardened.

It's worth a try.

My dad (the mechanic) has had Marine-Tek sitting around for years. If the crack is in the water jacket, I say go for it. If the crack is in the combustion chamber... Well, it's worth a try.

In each of these situations, you have to concern yourself with "micro cracks" at each end of the crack. Certain metals (alloys) have a tendency to have micro cracks that will continue widening as time goes on. But it beats buying a new engine if you don't need to. Please let us know what happens.

Vermin wrote: "you have to concern yourself with "micro cracks" at each end of the crack. Certain metals (alloys) have a tendency to have micro cracks that will continue widening as time goes on"

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Elnav writes: to stop cracks from propagating drill a small hole at the end of the crack. Both ends in your case. Its important to get at the very end so use a magnifying loop or better yet the crack detecting fluid that fourescees under UV light.

Drilling a fine hole, 1/16 - 1/8 depending on crack size will create a destressed area that relieves the forces causing the crack. Did you by chance forget to drain block and let it freeze?

If MarineTex doesn't adhere to the wet water jacket crack sides another epoxy product called "Splash Zone" is designed for underwater epoxy repair.

The short answer is yes, you can probably repair the crack without removal of engine block.

Pretty informative and cool, elnav!!!

What kind of stuff do you use to make the cracks fluoresce?

What kind of stuff do you use to make the cracks fluoresce?

We used a similar product to detect cracks is ground bar stock. First you spray the bar with can 1 which was a very thin pink paint (I use the word paint loosely!) give it a wipe and then spray on can 2 which was an activator. wait a couple of seconds and then wipe that as-well! when you put on the UV light, the crack would show up very easily even though it is now essential

Check this out!

do you know what caused the crack? If it was caused by water freeze, then you likely have several cracks, internal and external. Any water in the oil? Marine-tek will work but only on very minor cracks.

He is up in your face with the truth, dude.

I wouldn't go king crabbing with that motor, dude.

You can repair an external crack in the water jacket the way I fixed a crack in my old plymouth (1948).

Drill a hole about 1/4" beyond the end of the crack in line with the direction of the cracks run. This relieves the stress formed by the crack. Tap this hole and screw a low grade bolt into the hole after coating it with permatex avaition sealer. Grind this flat and center punch the bolt 3/4 of the way toward the crack. Drill another hole and again tap and screw in a bolt. Grind flat and again drill and tap another hole. Do this for the length of the crack and when done you will have overlapping tapped bolts that will not back out. Also this will seal the block and you can get on with your boating.

Good luck.

Ric

Alliance Engineering LLC

Assuming the size of this engine is <70HP, aluminum water jacket, the risk is low to use Marine Tek. Searching for micro cracks can become a non value added process. If however you're involved with ferrous based materials and an engine that is >70HP and used beyond 25 miles offshore, my opinion is pull the engine and do it right before you risk your investment to more loss.

Remember, an outboard will get you out but it won't get you in, if you keep thinking like this. Usually when this scenario happens, there's a storm approaching over in the northeast, I don't suggest to play with anything cracked on an outboard. I'm from Smith Island and during my 7 teenage years there, I've seen two drownings in frigid water. One had two outboards and two skiffs, the storm was so treacherous, they didn't find him until the Spring; he swelled up to the size of a volkswagon. Elison was a Veitnam vet trying to get his new fishnets in from Kedges Straites in November, he was finally washed-up on the Bayside in April.

Most of the posts concerning external water jacket repairs are excellent. I have used Marine Tex, JB Weld, and various "Plumber's Epoxies". I have found, purely experimentally, that the clay like plumbers epoxy compounds are superior, especially the "ATLAS" brand, which is very hard to find, and is apparently only sold in commercial plumbing supply shops. In Home Depot et al, you can find "Hercules" brand, which is almost equivalent. The Atlas comes in two frankfurter sized tubes, Resin & Hardener. The Hercules comes in a single smaller diameter tube about 5/8 inch in diameter, and the same frankfurter length. Hercules uses a coaxial put up of the resin and hardener. I used Atlas to repair a 1 inch long through crack in the lower crankcase of my BMW motorcycle well over ten years ago, and it is still holding fine. I have also used it to repair automotive brass radiator tops, and 4 inch cast iron cracked drain pipes, as well as automotive gas tanks. I also used Hercules to repair cracked cast 4 inch DWV (Drain, Waste, & Vent) pipes, as well as missing chunks in my 22 foot boat's fiberglass transom, courtesy of steel piling bands. All these applications were successful because pressures were low, almost zero, and temperatures did not exceed 250 degrees F. The one failure I experienced occurred when I attempted to seal a crack in the top of the head of a straight 6 engine, close to an exhaust valve guide penetration. Probably too hot, or too much vibration, or both. The useful shelf life of these epoxies is only a few years. The putties should be like modeling clay, not hard or even semi-hard. After 3 or 4 or 5 years they turn to rock, so squeeze the banana before buying any. They can be smoothed after application by wetting your fingers and rubbing.

Try JB Weld. I've used it to repair some components under very extreme conditions. I've even used it to repair the exhautst port on an old 1947 Harley cylinder head with success. It is still holding after 22 years.

Ed

I'll add my 2 cents. JB Weld is my recommendation and I agree with the posts about stress relief holes. There are two forms of it, a quick set (about 4 minutes) and the original which I forget how long it takes to set. You will need to rough up the surface a bit around the crack to give it something to adhere to.

Since you say you're "pretty sure" you have a crack means to me you haven't found it and may have another problem.

I see JB Weld or similar as a tempory fix. Sure with proper surface prep is holds like hell, but over time with heating and cooling cycles plus vibration, it will fail.

Can it be properly welded without pulling the engine? Otherwise what type of engine is this? My 7.4MPI can be pulled in 30 min and reinstalled in the same amount of time. I guess it depends what type of engine we are talking about.

It depends on the crack. Ussually they will advise the engine block to be replaced. However, I have seen a number of engines with exterior water jeckets fixed with JB Weld. You can find it at any auto parts place. It is a two part epoxy, just mix it cafefully or just mix all of it at once. If the crack is not big it can work.

I agree with the JB weld or the Atlas plumber's epoxy. I second the need to find the ends of the cracks with a flourescent crack finding kit and drilling holes to stop the cracks from progressing beyond the fix.

You also need to be sure the iron is very well degreased and dry before applying the epoxy. A good engine degreaser followed by methanol poured on the side and then acetone poured over the side of the block should do the trick. You might want to warm the area with a blow dryer or heat gun and then let it cool just before you put the epoxy on.

Sounds like a lot of bother but if you want the repair to have any chance of lasting then you're going to have to do all the grunt work. I guess it will be cheaper than a new engine in the long run but I would have a good set of paddles and a good VHF radio on board just in case. And don't run this boat out of the King's Park in Niagara Falls without a really heavy anchor and a chain rode!

If you decide to go the epoxy or JB weld method, make sure that the area to be glued is roughed up and then clean it with methylated spirits. Nothing else works as well and most other liquids like gasolene for example, leave a residue that precludes good bonding....

Clean it with the meths and either a fresh piece of kitchen roll or a clean piece of rag. Once clean, do not touch with your fingers.

Give the repair stuff/glue plenty of time to reach maximum strength, if epoxy based, run engine till hand warm, switch off, wait till cold, do it again but a little warmer. Do that three or 4 times till the epoxy is fully temperature cured.

I do believe that JB Weld does not need that.

Also epoxy likes some glass matting over the whole area as well as in the crack for strength....use the fine stuff that looks like material for garments, several layers....each layer to be added before the layer underneath is fully hardened.

If you're patching aluminum, check this out... If you expose the aluminum to 25,000 RPM vibrations (say, from a Dremmel tool), oil will come oozing out of everywhere! Aluminum can absorb that much oil!!!

If you "buzz" the case over-and over until no oil comes out, you'll probably have a better chance of getting a good seal with any kind of resin.