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I have my "50 1/2 ton up on blocks and I've noticed a small puddle of radiator fluid. It looks like the water's coming from the middle of the block. There are some kind of water plugs there. Is this going to be a big problem or is it a common ailment.

Those plugs are called freeze plugs. In the event that the coolent freezes in the engine, the plugs are popped out as the ice expands in the block. It keeps the block from cracking. If that is where the water is coming from, you will have to change the plug. But, I recommend that you change all of them. If that one is popped, there could possibly be others that have also done so. The other possiblility is that the block is cracked and is leaking fluid. But, I would bet on the freeze plugs.

That's not really their original purpose, they were there for casting. Something has to index the cylinder bores to the water jacket.

Stove bolt motors are also famous for rusting out between the bottom of the water jacket and the crankcase or outside of the block when the coolant isn't flushed often enough. Pull the water pump and check for lots of scale in the block.

Those steel soft plugs are prone to rusting. They aren't too hard to remove if you can access them. If they're rusty enough you can drive a screwdriver throught them and pry them out. If they're solid, get a big sheet metal screw and run it in, then pry on the head. The hard one is between the bell housing and the block. I have started replacing them with brass, your parts store should be able to sell you the right ones if you know the diameter and style. They're either a cup or dish style.

Also, coat the inside face and edge of the plugs with a thin film of aviation form-a-gasket. It will help to seal and prevent internal corrosion of the plug.

Thanks for all the advice. After closer inspection the coolant is leaking from three of the plugs. I talked to my NAPA dealer and he's pretty confident he can match up the plugs.

I had quite a time trying to get my side ones out. All I was doing was creating more holes. Then my machinist told me to take about a 1/2" dull chisel, and hit it on the side to tip it in so that the other side tips outwards. The next step is to grab it and yank it out. Those ones on the side of the block can easily be knocked right inside the water jacket, and then the fun begins!

Well...loks like I have a 3" hairline crack below the 5th freeze plug on the side. Don't what I'll do now.

tater,

Your reasonable options just went down to one - time to find a new block.

Your only other option is to try to repair the hairline crack. I would always be afraid of the crack extending beyond the already split area. So I wouldn't be able to use the block with any certain peace of mind. Who knows. There may be other cracks/problems you have yet to discover.

-ftyler

I did a search on the forum and saw a post where a guy used a Hi temp epoxy product to fix the problem. Sounds like a band-aid, but I have to save up a little cash to get a new block, maybe a temp fix will last until I do that.

tater... you can also try J B Weld

Jb! JB! JB! WO WO WO!!!!
Man, I love that stuff. Fixed a crack in my head...well the head on my 305e. Have had no problems since.
I would find another block though. No tellin where else she split. Good luck.

Would it help if I drilled each end of the crack to keep it from splitting further?

tater,

JB Weld is worth a try (trust Paul Harvey and stevesr and Kenner).

Several years ago I had a leaking "freeze" plug and I most likely cracked the block of 261 above the rear/side plug when trying to remove it. After fixing the leak and finding the crack, and after crying to myself, I figured "what the hey"; might as well try that JB Weld stuff.

No leaks in 5 years. It IS worth a try. I drilled an indentation at each end of the crack in my block before I carefully cleand-up the area and applied JB Weld.

Good luck,
Tim

Maybe you are lucky and it's not really a crack. My old 216 had a funny ripple in the casting that looked like a crack but was just a crinkle in the surface. Hit it with a wire brush or grinder and see what happens. Cracks can also be stiched- they drill and tap the crack for special plugs and then keep doing that in a line and it fixes it right up.

Tater , these old stovebolts are often seen cracked along the water jacket at the base of the cylinders ,, they will continue to run for years with a little sealer applied ,, say ,, some JB weld applied to the outside , or some Chemi Weld in the radiator .
I welded the block in my '39 truck once ,, drained the water out , drove it over to the workshop , had the block stinkin' hot , got the arc welder out and stitched it up , made a heck of a mess tossed a can of ChemiWeld in and continued to use the truck for another 60,000 miles .
If all your frost plugs are rotten , then the block is maybe heavily corroded and sludged up inside too , I believe this is when that crack eventuates ,, Pull a frost plug and see what it is like inside , maybe flush it out with the hose , but most of all "Don't Panic"