New Engine, Cracked Block, Fixable?

[Twigger]

So have nearly $3k tied up in this engine and everything is new. When I was installing the oil filter adapter the large banjo bolt that holds the adapter in place cracked the block where it threads into the side. The red line indicates where the crack is on the threaded part. Now my question is, can I fix the block or do I have to scrap it?

 

[mk3supra]

Try posting an actual picture, that would help alot. The threaded part in your drawing, is that the banjo bolt? or a NA filter stud?

 

[Doward]

Scrap it - 7MBoost went through the SAME EXACT thing.

 

[sneakypete]

scrap it if your ever planning on making stock or higher power levels

 

[revmatcher]

Thats pretty lame, sorry to hear. Well one thing that I can say is, you can weld iron and you could weld that and then try to retap the block there for your oil filter banjo. But at the same time are you sure of how far the crack in the block goes? Its probably not worth it to try and use it. Was just trying to offer another opinion.

 

[suprarich]

Yes, it is possible to fix the block, but with the cost and headache of doing so, I would replace the block with a good one everytime. Was the block checked for cracks prior to doing any work on it? That is the first step in any motor build.

 

[Tanya]

Scrap it... weird, this seems to be a fairly common issue in this area, at least on the 7Ms... wonder why...

 

[rtrdpenguin]

I don't know about you, but having that crack in the back of my mind every time I drove the car would make me insane!

 

[paradox616]

whats wrong with getting the crack properly welded up and then retapped... its never going to be good as new but still assembly costs arnt cheap, you may aswell throw your money in the bin otherwise...

did you over tighten the bolt? i dont think its supposed to be done up super tight

 

[Doward]

Cast iron - that means to PROPERLY weld it, the entire block must be 100% disassembled, pre-heated, THEN welded on by a damn competent welder.

In other words, it'd be cheaper to replace the block with another

Rich, are you crazy? Hot tank THEN Magnaflux!

 

[IJ.]

"If" you have access to the root of the crack you could drill a small hole to prevent it continuing then Silver Braze the crack shut after thorough cleaning and that would stop it in it's tracks but that hinges on the "if".

 

[Twigger]

I usually check torque specs on most things before installing but I figure it would be safe to just get it snug. The torque spec I believe is 36ft/lbs and I pretty sure I didnt have much more than that so whether or not is was already damaged Im not sure. This was going to be made for 400+ horsepower so I had the block check carefully and was not going cheap anywhere. That crack goes really deep and wide so Im not sure it can be stopped.

 

[FullNelson]

First thing I was thinking it might have been one of those overlooked details like 36 in lbs and misread as ft. lbs.

Seriously though, 36ft.lbs. isnt a ton of pressure and perhaps all that happened was it exerted pressure on an existing crack.

Did you have the block Magnafluxed when it was built?

 

[Twigger]

Yeah it was magnafluxed, but I really didnt think much of a 1 inch diameter bolt going into a cast iron block. Unfortunantly for me and my lost job, Im probably just going to have to cut my losses and sell out on everything.

 

[dumbo]

Shitty deal dude. This brings...
"If it aint a cylinder head it don't need to be --"
To a whole new level.:nono:

 

[Frank Rizzo]

That 36 ft/lbs torque spec is a MAX spec.

You would apply more clamping force and less stress on the threads using a 30-40% torque reduction with moly or antiseize compound on the threads, than you would with the threads dry @ 36ft/lbs.

If you used ANY lube at all and applied 36ft/lbs well then you reap what you sow.

And there is no way you can judge torque with out a torque wrench. Too many variables, length of wrench used, where it is griped, cleanliness of threads, etc.

I really didnt think much of a 1 inch diameter bolt going into a cast iron block.

It's not about the diameter of the bolt that you should be worried about, it is the threaded hole it goes into and how weak/thin the wall of the threads are.

Every terrestrial metal has a breaking point. Just because it is iron does not mean you can go gorilla on it's ass.

 

[Zumtizzle]

Well i'm surprised no one noticed this. Mistake one was keeping the stock oil filter housing.

 

[suprarich]

Rich, are you crazy? Hot tank THEN Magnaflux!

Hot Tank??? No way. I only do thermal clean on blocks, we save the hot tank for the cranks. And yes, I am crazy, I have a mk3:biglaugh:

 

[Twigger]

It's not about the diameter of the bolt that you should be worried about, it is the threaded hole it goes into and how weak/thin the wall of the threads are.

Every terrestrial metal has a breaking point. Just because it is iron does not mean you can go gorilla on it's ass.

That is true, and no I was not going gorilla although I wanted to after it broke. Not 100% sure on this but I believe most of the bolts on this engine are torque to yield bolts, so tightening them to factor specs well run the risk of them coming loose. However to solve this problem I bought just about all the important bolts from the dealer so I could torque them to the factory specification. This was one of the bolts I did not think to get, so back to where I was, not sure if the block was bad or a combination of the two.

 

[grimreaper]

did it make a noise or did you remove it to find the crack? (could you hear/ feel it when it cracked on you?)