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DIY crack testing cast iron block and heads


Unclejake

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I see a few three part aerosol spray can kits on the market for weld crack identification. Does anyone here have any experience with them?

The application will be an old V8 diesel motor that I'm yet to dismantle. The bad news is that I'll need to get the kit(s) sent to me by sea so they could take more than 6 weeks to get here. There's no other local alternative that I'm aware of.

Ta

https://nzsafetyblackwoods.co.nz/en/rocol-flaw-finder-kit-3-part-packet--00977405

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7 minutes ago, RUNAMUCK said:

Before you strip it, Could you pressurise the water jacket with Air?
I realise that where you are the resourses we take for granted here dont exist. (Took us half a day to find a nut once.)

You could have just looked in the mirror...?

/spam sorry.

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I could probably rig something up to pressurise the water jacket, but tbh I'm not entirely sure what that would tell me? There's no obvious water in the oil and the collant in the radiator looked perfectly clean and green (but there was an unknown oily scum in the expansion tank) so any advice is welcome.

Evidently these 6.5 litre GM blocks are known to crack, and something has almost seized the rotating assembly, but until I can pull the motor apart I have little clue as to what it going on.

I don't want to pay >$500 to send a cracked block back to the mainland if it's just going to be thrown away, but I hadn't thought about the logistics of bringing in aerosol gear in until just now. Gah! It's ll so hard.

NickJ, I live on Chatham Island and the supply ship is now going via Norfolk Island and won't be here until late March

 

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Going by the above are you off shore? one trick I read about but never have never tried is to mix kerosene and food colouring (pretty much all the dye penetrant is anyway) and substitute talc or climbing chalk for the developer, the trick will be getting it lightly and evenly dusted

 

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One kit should coat the engine a few times over but remember it needs to be clean, fully degreased (serve a meal on it to the inlaws spec) for that kind of stuff i'd use water based degreaser for the bulk, dry fully (even bake off) then rinse off with brake cleaner before going through the steps.

it really works best on machined surfaces, if there is a crack it will find it, however crack testing on a cast surface can be near impossible, hard to clean up the dye after application then the developer sucks it out of the surface porosity hiding any cracks, if the crack is in a corner of a journal between casting and machining you may need to do a few applications to convince yourself what is going on, take heaps of photos if you do multiple tests!

Its been a while since I was using the stuff regularly, but from memory I left the penetrant on much longer than advised to be sure it got everywhere (searching fatigue initiation on stainless parts) we could find pretty small defects that otherwise were invisible to the eye. 

When cleaning off the excess penetrant, take you time and have heaps of clean rags on hand.

Hopefully that makes sense? been a long day and i'm a few beers down

 

 

 

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the three pack of aerosol crack test kits are 1 - a cleaning agent which can be substituted by buying a can of brake clean or acetone. 2nd can is the dye penetrant - it can be substituted by mixing food colouring with acetone to make a very light penetrant to get inside the cracks. The third can is an aerosol white powder that dries to the component it is sprayed on. I wonder if you ground up the centre sandwich section of gib board if that would work to create the powder.

If you have any cracks the food colouring will show up through the white powder as it is absorbed. So first clean, then food colour (wipe excess off), then powder and you'll know......pretty sure you could get all those ingredients over in the Chathams

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5 hours ago, johnny.race said:

Its that for real?

It wouldn't be ideal because of the shape of the core but if you made a bigger horseshoe shaped core you could slip the primary wingdings onto that .

you could probable use floor sweepings for locating the crack by throwing them on the block with the electromagnet on.

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20 hours ago, ajg193 said:

What a barry thread...

 

Then again I guess chatham island is pretty much the outback

Nah the Chathams is more.remote than that. 750kms of water between there and timaru. You can't even drive to another town to buy anything. Two planes a week (cost me $750 return in 1999) and I don't know how infrequent the boat is.  (IM long overdue to go back actually )

Ling/

 

I was thinking though @Unclejake before you even order that stuff sit the motor on the ground, fill the cooling system with water, apply compressed air to the cooling system, and remove the glow plugs, and the rocker covers. Then have a listen. The fact it's seized might mean a few things. Fact is my mate told me most fol down there are incapable of maintaining anything. Add the harsh environment, and it's a perfect storm.  Did it run when parked? If you do a bit of due diligence pre tear down you might get an idea where to focus your inspections. 

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All points noted mate, but I have pulled the motor down already.

When it was parked ~ 3 years ago it was running, but badly. I'll upload some photos and update the project thread late tonight if possible. The news is all rather good :-)

 

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