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Almost finished 1951 with a 235 in it. Just noticed a hairline crack in the water jacket on the left side at the bottom rear of the jacket. About 2" long. Just crusty around it from weeping but no drips. It seams to have sealed itself? Should I leave it alone or try to fix it? I have a history of making small problems bigger by trying to fix them!
Thanks,Howard

I would just forget you saw it. Keep monitoring water level, and maybe keep in the back of your head the need to start looking for another engine, but I drove my old 54 for 10 years that way. It probably happened due to lack of anti-freeze at some point in its life. Might want to make sure its good too.

Howard
In the tech tip forum there is an article on this subject. They talk about a product called loc-n-stitch. If the engine is out it is a very simple process. I know first hand. My 216 also had a crack and like yours was crusted over and slowly weeping. Since I had my engine out it was a no brainer to do the repair. My crack was roughly 10" long. I first pulled the freeze plugs and water pump removed the head and cleaned all of the crude out of the water jacket. I know now what caused the crack. There was about an 1-1/2 of hard mud which prevented antifreeze from protecting the block from freezing. Then came the repair. I called loc-n-stitch and they assisted me in obtaining the materials that were needed for the repair. The actual repair took less than an hour and after paint you can't even see it! Best of all, no leaks. Check them out on you tube for yourself. Oh and good luck! But you won't need it! It's simple!!!! Take care,
Jim

Jim, how much was the kit?

Try applying a layer of Marine-Tex over the crack after sandblasting the area or roughing it up a little with a flap wheel on an angle grinder. As it's curing, press a piece of 40 grit sandpaper over the patch to simulate the surface roughness of the surrounding cast iron. Lots less expensive and quicker than metal stitching.
Jerry

Carl,
Off the top of my head I'm not sure. I'm on vacation and can look it up next week. I did buy the drill template just for accuracy! That really sped the process up! If you are interested in doing this type of repair, I am more than willing to let you borrow the template. That should save you a hundred bucks or so. Like I said, I'm very pleased with the outcome!!! They will break down the cost for you,give them a shout. Let me know and I'll mail the template to you if you go this route.
-jim

Thanks for all your opinions. I had previously cleaned out all the "mud" from the cooling jackets so that may have allowed the crack to start weeping. At this point it will be difficult for me to drill holes in a block that is currently not leaking. (with my luck I would make it start leaking!) I plan to watch it and if it gets worse I will either use the loc-n-stitch method or the epoxy method. Does anyone know the approximate thickness of flat area under the left rear freeze plug?I may want to partially drill the ends of the crack but not all the way through.
Thanks very much
Howard

Honestly, if I were you, I'd just drain the coolant, clean the affected area of all contaminants and just do the epoxy and the Barr's stop leak treatment. That would be more than good, unless you wanna just get a new engine but i don't think thats necessiary

Honestly, if I were you, I'd just drain the coolant, clean the affected area of all contaminants and just do the epoxy and the Barr's stop leak treatment. That would be more than good, unless you wanna just get a new engine but i don't think thats necessiary

Patch that one up and watch the water level and drive it like you stole it. Just keep searching for a new engine, because the crack will get worse! GOOD LUCK!!!

Even tough your hesitant on drilling I would drill the ends of the crack as that will help stop it from running farther with heat and cooling cycles.

Do you think it is necessary to drill all the way through or maybe 1/8" deep ? It is kind of hard to get to so I don't want to do it twice.Is there something to put on the crack to make the ends show up good for an accurate drilling? What size drill?
Thanks to all of you.
Howard

At the very end of the crack drill and tap for a 1/8th inch short Allen set screw. You have to drill far enough to allow the tap to put threads in for the allen screw to go in. If you use a bottoming tap then you could likely avoid drill through.
The drilled hole will stop the crack from creeping.

Then take a Dremal tool or small die grinder and make a shallow V along the crack. Remove the Allen set screws and coat them with epoxy and replace it. Epoxy the crack or cast weld.

"Identify the crack with your three-part penetrating dye system. First, spray or paint your penetrating dye over the suspected crack and the surrounding area, then wait 5 minutes. Spray the dye-cleaner on a lint-free cloth and clean all of the dye off of the surface of the block. Once you have all visible traces of dye off, spray a light or "dry" coat of developer over the area, then use compressed air to accelerate the drying. Wait at least 1 minute; the crack will be clearly visible in bright purple, red or blue."

Read more : http://www.ehow.com/how_4752906_repair-cracked-engine-block.html

Thanks for all the help. I assume I can get the dye kit at my FLAPS.
Howard

I got the Magnaflux 3 part penetrant system ($65.00) and did just as instructed.No crack showed up at all. I talked to Magnaflux and they said I did everything right.They think the crack may be too small for the penetrant to work. I guess all I can do is put some JB Weld over where I think the crack was and forget it. Without the weepage or paint it is not
now possible to see the crack.Any thoughts or ideas???
Howard

Plug up the water inlet and outlet and adapt a garden hose to the block drain. With pressure applied from the average household water system, the crack will definitely show up. Just be sure the radiator and heater core are disconnected from the engine!
Jerry

One that was done with Marine Tex five years ago and has given zero trouble. Rubber freeze plug used in cracked freeze plug hole after repair. These plugs need changed out once a year or so to keep them in proper shape but will seal an irregular hole.

http://s32.photobucket.com/user/coilover/media/40%20Pontiac%20engineand%20trans%20002.jpg.html

Again, thanks for all the help.
Howard