F-20 Cracked block problem

Anonymous-0 · Jan 19, 2009

I noticed my F-20 block is cracked. Same place on others I have seen about 2 inches long. Can I have it welded without tearing it down?

Thanks in advance,

Mark

Old-F20 · Jan 19, 2009

(quoted from post at 16:54:23 01/19/09) I noticed my F-20 block is cracked. Same place on others I have seen about 2 inches long. Can I have it welded without tearing it down?

Thanks in advance,

Mark

im guessing along the side behind the carb???

yes it can be fixed, but first pull the head and check for cracks in the deck also. if its cracked there, dont waste your time fixing it, get a new block. water is a very strong force when it freezes. I should take a pic of what it did to a customers engine i have in the shopr right now. broke the block AND the head :roll:

Anonymous-0 · Jan 19, 2009

I have an F-30 that had a crack in the block in the usual place behind the carburator. I cleaned it all up with a grinder and then used fiberglass and put 4 or 5 layers of mat using plenty of resin on it. After it dried smothed it all out and painted it. If you look for it you can see it but it holdes good and has been on there for 2 years now with no problems. It has no stress or pressure on it so it is just a matter of sealing the crack. You can weld it but this works also. Better than JB weld.
Fred.

SproutW · Jan 19, 2009

I've had a few cracked F-20 blocks along with many on this forum. A crack behind the carb is pretty common on these old engines. I've also had cracks on the deck between the cylinders. My shop simply drilled a hole at the end of the crack in the divider and the head gasket sealed it up since it's a wet sleeve engine. I've had a couple blocks which were cracked in the water jacket all the way up through the deck (not between the cylinders). Those two blocks got scrapped. Pop the head like mentioned here and take a good look. You never know if the head has a few internal cracks as well. I personally have my machine shop check a cracked block/head and I let them weld. I hate tearing an engine apart twice. I'm sure others have done their own block repairs with good results and will share.

Anonymous-0 · Jan 19, 2009

Hello All, I have welded this very problem, clean, pre-heat, then use a large C-clamp and bring it into place. Take a thin grinding disc and cut a grove along the crack. Pre-heat about 100 degrees, and weld slowly with nickle...Although there are better rods now for these old blocks. I have repaired cracks, that have gone through the block along the water gacket. It is time consuming, but can be done...lots of luck, jdriver

Andy Motteberg · Jan 19, 2009

You are lucky if it is only 2 inches, the block on my F-20 had a very long crack. I patched it up with JB Weld. You don't need to take it all apart, but it is easier with the carb off.

SproutW · Jan 20, 2009

Dang Jim. Sure wish I would have known you then. The shop took one look at that block and said, "no way". Not much of a welder myself so I didn't even try to fix it myself for the heck of it.

F-20 Cracked block problem

Anonymous-0

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Old-F20

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Anonymous-0

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SproutW

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Anonymous-0

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Andy Motteberg

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SproutW

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