Is this the dreaded "C"

[Dieselguy123]

Hey all, This is a little off topic but this is where all the brains are. I am working on a 77 cj5 258 I-6 and I tore the motor down cause it was knocking a little and loosing a little coolant. Upon further inspection I found a spun rod bearing on #1 Cyl and when looking at the cyl's I also found this in the #1 cly wall. Is this what cavitation looks like, When I Run my finger over it is is rough. IS there any way I can test a bare block for this? I know its not diesel related but any input is appreciated. Thanks

 

[sassyrel]

if you take the block to a machine shop--they can pressure test it--they have a plate they bolt on and air pressure it----

 

[icanfixall]

That looks like the block was bored really poorly when it was made and thats a low spot in the bore job. A good machine shop can test the block for you but finding a trustworthy shop will take some time.

 

[towcat]

Where the imprefection is located, I'd say you may have a bad casting. Getting it pressure checked is one thing, a sonic check is in order for the block if it passes the pressure test. I've been messing around with Buicks for years and they have the same issues with thin castings too like the IH, a sonic check is the best way to tell for future problems. Keep in mind, block casting is more an "art" than a science. There's many opportunities for things to go wrong and it won't show up immediately.

 

[BigRigTech]

I've seen the same thing....Nothing to worry about in my opinion...Looks like a low spot that didn't get machined....That far down the bore it shouldn't be an issue. Have it bored out and see what they find. Tell them to do that hole FIRST.

 

[Dieselguy123]

Thanks for the help guys, I am going to have it checked out here in the next couple days and go from there. Much appreciated.