cracked block, hardblok or epoxy?

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turtlevette

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The numbers matching engine in my bandit has cracks at the floor of the block. It has a slow drip when cold. Various stop leaks work for a while then it starts up again.

My plan is to punch out the freeze plugs wait for the block to get dry then pump in something to fill the bottom 1 inch of the water jacket. To the bottom of the freeze plug hole. This is done all the time on street/strip engines with no overheating consequences. It strengthens the block keeping the cylinders from moving around.

Anyone done this? There are a few different products out there some being concrete based and others epoxy based. Then I've seen big tubes of jb weld at az for under 20 bucks being the cheapest option.
 
Is welding it not an option, or are you looking for the least expensive patch?
 
Originally Posted By: DemoFly
If it's this important to keep the matching engine, take it to a professional to be welded.


I'll research that some more, but so far what I've found is cast iron is very hard to weld. It cracks around the weld area as it cools.
 
There is a product called hard blok that some race engine builders use. Its designed to be used in water jackets , but i don't know that it will seal up leaking cracks. I don't think its designed to be used without the engine being torn down and probably hot tanked first.

here is a link, perhaps you could call them.

http://www.hardblok.com/index.html
 
Is this a 403 Oldsmobile engine? I ask because it is very rare to hear of just the bottom of the water jackets to form cracks. Sounds more like the Main webs are cracking & the cracks have extended into the water jacket/bottom of the bores.
 
Originally Posted By: clinebarger
Is this a 403 Oldsmobile engine? I ask because it is very rare to hear of just the bottom of the water jackets to form cracks. Sounds more like the Main webs are cracking & the cracks have extended into the water jacket/bottom of the bores.


No its the Pontiac 301. The short deck lightened version of the Pontiac 400.
 
Originally Posted By: turtlevette
The numbers matching engine in my bandit has cracks at the floor of the block. It has a slow drip when cold. Various stop leaks work for a while then it starts up again.

My plan is to punch out the freeze plugs wait for the block to get dry then pump in something to fill the bottom 1 inch of the water jacket. To the bottom of the freeze plug hole. This is done all the time on street/strip engines with no overheating consequences. It strengthens the block keeping the cylinders from moving around.

Anyone done this? There are a few different products out there some being concrete based and others epoxy based. Then I've seen big tubes of jb weld at az for under 20 bucks being the cheapest option.



I had a crack in the block of a 94 Honda Accord. The crack was near he exhaust manifold and affected a oil return galley. My car was out of warranty at the time, and Honda wouldn't do anything. I cleaned it up, used a wire brush and then tried JB weld. It didn't seal it up that well. You should try to call some engine shops to get some professional advice.
 
Originally Posted By: turtlevette
Originally Posted By: DemoFly
If it's this important to keep the matching engine, take it to a professional to be welded.


I'll research that some more, but so far what I've found is cast iron is very hard to weld. It cracks around the weld area as it cools.



Welding would be one option if it's done correctly. You can also see whether it's a candidate for stitching. Here is a shop in MA that offers the service: http://www.jandm-machine.com
 
Originally Posted By: turtlevette
Originally Posted By: DemoFly
If it's this important to keep the matching engine, take it to a professional to be welded.


I'll research that some more, but so far what I've found is cast iron is very hard to weld. It cracks around the weld area as it cools.



Research how,they are repairing the cast iron Capitol dome I'm Washington DC.
 
Originally Posted By: Padawan
Originally Posted By: turtlevette
Originally Posted By: DemoFly
If it's this important to keep the matching engine, take it to a professional to be welded.


I'll research that some more, but so far what I've found is cast iron is very hard to weld. It cracks around the weld area as it cools.



Welding would be one option if it's done correctly. You can also see whether it's a candidate for stitching. Here is a shop in MA that offers the service: http://www.jandm-machine.com


I've researched stitching too. I could do it myself. Just takes a lot of patience to drill and tap hundreds of tiny holes.

I see no downside trying the short block fill first. If that doesn't work I could still stitch it. Yank it out rebuild it with a stroker crank.
 
Take to a pro. They will most likely furnace braze it. They'll stick in a huge furnace and heat it, then braze it with iron rod. When they're done, you'll never know it was repaired.
 
Originally Posted By: turtlevette
Originally Posted By: clinebarger
Is this a 403 Oldsmobile engine? I ask because it is very rare to hear of just the bottom of the water jackets to form cracks. Sounds more like the Main webs are cracking & the cracks have extended into the water jacket/bottom of the bores.


No its the Pontiac 301. The short deck lightened version of the Pontiac 400.



The 301 Poncho is probably worse than a 403 Olds about the main webs cracking, If your [censored] bent on keeping the #'s matching engine, You need to have the block MagnaFluxed too know where you stand.
 
Originally Posted By: clinebarger
Originally Posted By: turtlevette
Originally Posted By: clinebarger
Is this a 403 Oldsmobile engine? I ask because it is very rare to hear of just the bottom of the water jackets to form cracks. Sounds more like the Main webs are cracking & the cracks have extended into the water jacket/bottom of the bores.


No its the Pontiac 301. The short deck lightened version of the Pontiac 400.



The 301 Poncho is probably worse than a 403 Olds about the main webs cracking, If your [censored] bent on keeping the #'s matching engine, You need to have the block MagnaFluxed too know where you stand.



Yep, I had the oil pan off to change the bearings and the webbing is very thin. It looked like freeze cracking to me but it was hard to see the main webbing.

The thing could blow its bottom end out. Or it could be fine for a long time. Well see.

The other thing about changing to a 400 or Chevy small block is the air cleaner and shaker are completely different. Another 600 bucks in parts.
 
What is so special about a cobbled up repair on a Pontiac 301? That would add negative value to any car with that motor. If is was a 455 SD or something, then a professional repair might be worth the money, and effort. What you are asking to do, the motor would need to torn down anyway and cleaned. If you have the turbo motor, get a new block.
Trying to glue a dirty engine together, would be like trying to stick a Band-Aid on a wet finger.
 
Last edited:
Originally Posted By: Traction
What is so special about a cobbled up repair on a Pontiac 301? That would add negative value to any car with that motor. If is was a 455 SD or something, then a professional repair might be worth the money, and effort. What you are asking to do, the motor would need to torn down anyway and cleaned. If you have the turbo motor, get a new block.
Trying to glue a dirty engine together, would be like trying to stick a Band-Aid on a wet finger.


Exactly. We're not talking about high value car here. "Numbers match" isn't going to make or break the value. Replace the block with a good one if you want it fixed. If not, just stick with your original plan of putting block fill in it.
 
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