Pinhole/crack in Block repair?

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efar

efar

Coastal Cuda
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I just discovered what appears to be a small pinhole in my 340 small block. I discovered it while trying to locate an oil leak. It is in the block on the drivers side behind the motor mount about a 1/2 inch above the oil pan. You can see the oil seep out whenever the engine is revved. Does anyone have any knowledge concerning repairs? Is this a weak point in the casting?
 
Motor mount looks broken on that side and the metal part of mount is touching the block near the hole?
 
I've never had that issue, but once the mount is replaced, i would brakekleen the crap out of that area and apply/spread a high temp epoxy over the leak area and if it seals you can touch up paint it and no harm no foul.... At least it's worth a try.
 
this can also happen to a block if the engine mounts are mis-aligned and the bolts are used to pull the mount into place. this happened to my dads big block. his engine mounts were about 1/8" away from the rearmost mount on the block. he just used the bolts to pull it into place. after time it broke the mounting ear off the block.
 
I'd be concerned that this might spread, or worse, crack into the water jacket.

"Usual" fix with a crack is to drill and tap at each end of the crack for some sort of plug, which helps relieve stress. If it's just a hole, you might be able to do it with one plug. Could be a small bolt, either "underthread" the hole and use sealer, or use JB, etc

'xample:

http://image.moparmusclemagazine.co...der-head-crack-repair+thread-head-removed.jpg
 
I've heard you can even drill a pinhole out and then weld it back up.

anyone know about this method?
 
frosty_the_punk said:
I've heard you can even drill a pinhole out and then weld it back up.

anyone know about this method?
Click to expand...

research metal locking.
if it`s a pin hole,why not drill and tap it then loctite a 1/4 - 20 soft bolt in it.
metal locking is drilling and tapping a 1/4" hole, then locktiteing a 1/4" bolt in, titening it till the head breaks off,then drill the next hole 1/2 in the bolt and half out(following a crack(dead center the crack w/ the drill bit)
make sure you go to the end of the crack , all the bolts will be now broken off, then take a ball peen hammer and peen the end of all the bolts real good. this works perfectly if done right, just be sure to get each end of the crack drilled out in the process! of course this would be next to impossible w/ the engine in the car, but a single pin hole might be gotten to w/ a right angle drill. I did this on the sides of a 426 hemi that froze and burst in three places the repair still holds to this day, it was a 10/40- 10/60 GTX back in the 70`s---------------bob
 
This hillbilly fix may be more of a crack repair, but I seen my dad do it when i was a kid, and it lasted forever. He drilled and tapped the block and made a plate to cover the affected area.sealed it up with hi temp rtv. 10 years later he sold the car and it was still good to go...crude but effective!
 
they sell a plastic called stic tite for repairing aluminum radiators it is made by northern and sold by speedway motors part number 917 34230 I used it to repair a cracked block that was losing coolant cleaned the area with a wire wheel then heated it and cleaned again with muratic acid and wire wheeled again then heat again and touch the plastic material to the area and it just sucks right into the hole/crack and your good to go
 
I think if it was oil under pressure it would leak at idle. Because it only leak at higher rpm it is return oil at no pressure. In that case most anything would stop the leak if its cleaned good first. Brakclean with the straw against the crack, then JB Weld or just RTV applied with force. Inspect your repair every time you change the oil. If the crack does grow or leak persists, more drastic measures such as drilling will be required.
 
famous bob said:
research metal locking.
if it`s a pin hole,why not drill and tap it then loctite a 1/4 - 20 soft bolt in it.
metal locking is drilling and tapping a 1/4" hole, then locktiteing a 1/4" bolt in, titening it till the head breaks off,then drill the next hole 1/2 in the bolt and half out(following a crack(dead center the crack w/ the drill bit)
make sure you go to the end of the crack , all the bolts will be now broken off, then take a ball peen hammer and peen the end of all the bolts real good. this works perfectly if done right, just be sure to get each end of the crack drilled out in the process! of course this would be next to impossible w/ the engine in the car, but a single pin hole might be gotten to w/ a right angle drill. I did this on the sides of a 426 hemi that froze and burst in three places the repair still holds to this day, it was a 10/40- 10/60 GTX back in the 70`s---------------bob
Click to expand...
i done this to an international tractor engine 2 years ago it is the proper way to fix a crack it is time comsumeing do the 2 ends first then fill the crack in.

waggin said:
they sell a plastic called stic tite for repairing aluminum radiators it is made by northern and sold by speedway motors part number 917 34230 I used it to repair a cracked block that was losing coolant cleaned the area with a wire wheel then heated it and cleaned again with muratic acid and wire wheeled again then heat again and touch the plastic material to the area and it just sucks right into the hole/crack and your good to go
Click to expand...
i have herd of this stuff. like waggs said the seceret to this or epoxy is clean and heat clean and heat and clean.
 
Thanks to all, lots of good ideas...I'll let you know how it goes. Hope to pull the engine this weekend to get a better look.
 
Well, it turned out to be just a tiny pinhole in the block. Weirdest thing, must have been a casting defect. No crack, just the tiniest of holes. I'm gonna clean it up maybe drill it out a bit and JB Weld it. Wish me luck. Oh and since the motor is out I went ahead and pulled the trannie too and now I'll begin the restoration.
 
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