Defect in block casting - looks like a crack.

[Mart]

Have a look at these images.

This is the motor that came with my 41 pickup. I was disappointed when it arrived because, although not stuck, it did not want to turn over all the way. Furthermore it appeared to have a big crack around the pan rail area.

Here's a pic of what I could see.



I cussed my luck but what puzzled me was why there were no rusty stains below the line. I did not use the motor because I had already fitted one I wanted to run.

I looked at it more closely yesterday and I cleaned the area with a wire brush on an angle grinder. Here's what I could see.



Now, for the life of me, I cannot actually see a crack. I am crossing my fingers and am hoping the block is all right. The lack of a visible crack backed up by there being no evidence of any leak staining is pushing me towards the conclusion that the block is ok, and this is just a casting flaw from the sand cast moulds. (If that is the right term).

So, my question is, has anyone seen anything like this before?

Oh, I also investigated why it did not want to turn. I looked at all the valves and none were stuck. I pulled the heads and found why it wouldn't turn.

There was quite a lot of carbon build up in the combustion chambers. The motor looks like it had stood for a while, and some of this carbon had flaked off and had collected at the outside edge of the pistons. This carbon was getting squashed between the piston and the head and stopping it from turning.

Here's a pic:



A good result, I think.

Bores are stock size but showing some wear. I have 8 of the valves out, have to do the exhausts next. I used the tyre iron down the inlet method on 7 of the inlets, one was too tight so I had to use a more long winded method. needless to say trying to use the fork tool was futile.

What I thought was good, is that the "part number" cracks on the deck face are either not there or hardly visible. Also the head nuts did not seem to be "murdered" up tight, which has helped save it from the cracks.

I'm not sure quite where I am going with this, I might just lap the valves and put it back together to see how it runs. I'll have to clean it out first, the valve chamber is very crudded up. It's full of dead dinosoar remains I think.

[Bulligen]

I have a block that has a similar looking flaw and I think it is just the way the block was cast?

[Karl Wescott]

It looks like the sand mold fractured and shifted. The resulting casting should not be called "flawed" as it surely met spec's, just has a "cosmetic anomaly".

[rotorwrench]

It could have been a core fracture due to heat or it could have been some sign of shrinkage during the cast but I don't know. All I can say is that I've seen similar flaws before. There is a relatively inexpensive dye penetrant inspection method a person can do to see if it's a crack. Magnetic particle can be done but it may show up as a crack due to the nature of the blemish.

I use Magnaflux or Spot Check brand dye and developer that come in spray cans and use electric contact cleaner for cleaning. A person has to get the visual stuff though. Zyglo stuff is out there too but a person needs an ultraviolet light for that. The kits are available but all you get is a set of sets of cans and a small instruction manual with a plastic case for your 100 bucks investment. A lot of folks don't like it because it's messy but it works better than most methods of NDT and it doesn't care what the material being tested is. It just finds the crack by capillary action of the penetrant

[Russ/40]

I would take a die grinder, and cut the shoulder of the blemish down to level and re-examin the area. Then you can use the die or magnetic techniques to test with confidence. You could try some penetrant to see if it wicks into a crack.

[flatford8]

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Have you had the pan off to see the inside?..... What about pressure testing?...... Mark

[Bored&Stroked]

Doesn't look like a crack to me . . . and I've never seen one like that in that area. Since the block is STD, pays to take it apart, mag it, sonic test it and rebuild it.

Hopefully you have a very good block to work from.

B&S