What exactly happens when a motor is pressure checked and magnafluxed when being rebuilt, bored/stroked, etc? What do these two procedures do and test?

 

they check to make sure there are no crakes in the casting. i dont know what they do but im pretty sure thats what they are checking for.

 

cracks throughout? like the heads, shortblock, and intake?

 

Pressure checking would be like block and heads. Magnafluxing would apply to the crank and rods most likely. If cracks are suspected in the heads or block, dye penetrant testing may also be used.

 

So, if both measures were performed on the motor after it being newly rebuilt, what are the possibilities of it having a leak from a crack in the shortblock area causing a leak from a coolant passage?

 

One of the most likely crack areas of the block would be in the lifter valley. Many times you can see it in plain sight on a clean block. The side load the cam puts on the lifters really stresses the block.

Not sure I exactly understand your situtation, but could it be something simple like not using sealant on the head bolts and coolant getting up into the valve spring area?

 

Well, this crack is on a newly built, lt1 bored/stroked to a 383. The crack is on the outside of the block. Pass. side on the #2 cylinder. It is horizontal, about a half-inch to 1 inch in length. Motor has not been started up by me yet. Coolant was just put in by me prior to the discovery of the leak and what was supposed to be the first time I fired up my new setup.

 

Here's an overview:

Magnaflux is the brand name associated with the MPI(Magnetic Particle Inspection) process. Being magnetic it only works on ferrous materials such as cast or steel blocks, cranks, heads, etc...You induce a magnetic field through the part to be checked and dust a colored iron powder on the parts, the field will pull the powder into the crack and make it visible. We also have a wet mag machine that we use for cranks and rods - same process but the iron is suspended in a liquid and poured over the part which will then show cracks under the black light.

Pressure testing involves pressurizing the water jacket of the block or heads with air at about 40lbs, then you spray all over the casting with soapy water and check for bubbles. We use this to check anything aluminum and to double check my crack repair work.

That crack on the outside of the block is not too common - is there witness marks like something was dropped on the block while at the machine shop? It can be repaired like new if your machine shop does crack repair - not many do anymore, but I have to do it for restoration projects where the old blocks and heads are irreplaceable - did a 235 straight 6 last month were the crack was 8 inches long on the side of the block, took 36 pins and hours later no leaks and you could not see the difference on the side of the block.

 

Just through brief searches, it seems very uncommon and I feel alone on this situation. As far as witness marks, nothing that appears accidental, HOWEVER, and I'll have to double check, but the area that the crack is in appears to be dimpled. Almost like a natural dimple. Could this have been a source for a weak spot in the core? It does not seem like something that could have resulted from being dropped, nor does the location and direction of the crack appear to be from mishandling.

 

hey does anybody no if the stock ls1 motor will handle up to 650 hp to the crank and be able to handle it.

 

Can you upload a picture of it?

Also, you will want to get some 2nd and 3rd opinions, but if it is a decent distance away from a motor mount and the head bolts - I would consider drilling a hole at the end of each crack (this reduces the stress concentration and keeps the crank from growing). Then use the best epoxy you can find and repair it.

When I used to work at a engine shop, they used epoxy to fix a crack on the shop car 800hp iron big block - and amazingly it worked and held for years.

 

Thanks rhamm,
That's the first time someone has mentioned epoxy. I almost can't imagine the epoxy curing well enough to seal and hold, but it's an idea.

 

 

Used block that's been frozen, due to lack of antifreeze???

 

Yeah, that was random

As far as the freezing, I'm in SoCal and we just don't get freezing weather in this particular area. So, I feel safe to rule that out.

 

As far as the previously mentioned epoxy comments, block repair is actually one of the recommended uses for JBweld epoxy. Also, the guy who posted random **** in this thread did it in others as well.

 

yea, i got the chance to magna flux a bunch of stuff in school. Got to see some cracked heads wit hit on, some on good heads. Makes little cracks really stands out for sure.

 

Nice post.
It's Great to see there are still some "Craftsmen" in the world! Big thumbs up!!

 

Somebody missed something. Magnafluxing of all iron blocks is the first thing a good machine shop will do before performing hours of labor to bore, square, line hone, and deck plate hone a block.

Not to worry, your block is repairable. You need to find a shop you does crack repair. Somebody with a Lock & Stitch set-up. Works wonders, but takes time to do. Done right, the average person can't even tell. Do a google search and read about it. We have a set-up at work, pretty cool stuff, works too!

 

Helicoil,
Thank you soooo damn much! I searched under lock & stitch and found promising news. Here are some good links for anyone interested:

Very good article:http://www.automotiverebuilder.com/ar/ar80050.htm

and, http://www.locknstitch.com/Metal_Stitching.htm

Local automotive welding shop (SoCal/ San Diego area)---> http://www.kenyonmachine.com/contact.html

Turlock, where that locknstitch shop is located, is in Cali too but several hundred miles away. I don't know if I'll end up having to use the Welding shop in San Diego bcuz it's closer though. What do you think? After reading the article about lock&stitch compared to welding, I'm almost hesitant to have someone weld my block.