Determining if cylinder has cracks...

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  #1  
Old 10-24-03, 07:06 AM
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Determining if cylinder has cracks...

I'm doing some work on a friend's van. 1997 Voyager 2.4L DOHC w/ 73k miles. Van had been using coolant for about a week. Brought it over - found signs of coolant on #4 plug. Pulled it apart to replace head gasket. Head is at machine shop getting checked right now. I found several lines (more jagged than straight) down the #4 cylinder of various lengths 1-3". They are at the back of the cylinder - near the coolant passage I believe had been leaking.

Is there any way (at home) to verify whether these are cracks or not?

I'm attaching a picture of what I found. Any ideas helpful.

Thanks,
Steve H.
 
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  #2  
Old 10-24-03, 07:18 AM
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Well I couldn't shrink the photo enough. So, here's a link:

http://f1.pg.photos.yahoo.com/ph/apr...ks.jpg&.view=t



Check it out and let me know what you think. I can't catch my nail on any of them. Don't know if I'm just being overcautious - but I don't want to reassemble it and find it has a cracked cylinder later.

Thanks again,
Steve H.
 

Last edited by srponies; 10-24-03 at 07:52 AM.
  #3  
Old 10-24-03, 07:43 AM
Joe_F
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Photo page is invalid with cutting and pasting or clicking .

Are there any other cylinders with this problem? I would probably hone the cylinder, lightly so you get that nice cross hatched pattern again.

Chances are if you cooked it, you scored the walls a bit.
 
  #4  
Old 10-24-03, 07:51 AM
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Sorry - since I changed the link you can't cut and paste. Just click on the link. Now it's fixed and set for public viewing.

None of the other cylinders are the same - just number 4. The original cross hatch is still visible on all 4 cylinders. No gouges or deep "scoring" . Do you think that's it - just heat lines / not cracks.

Just spoke to the machine shop where the head is. They said the head is not cracked - but it's warped .006. They're going to mill it. I asked them about the lines - they second the thought that the lines are light scoring.

Steve
 

Last edited by srponies; 10-24-03 at 08:17 AM.
  #5  
Old 10-24-03, 10:07 AM
Joe_F
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From the picture, it looks like discoloration (from muddy coolant or overheating), more than a crack.

Take a little WD40 on a rag and try cleaning that area. Do the marks lighten up? If so, it's rusted coolant.

What makes you think they are "cracks"? Look at them with a magnifying glass under good light closely....
 
  #6  
Old 10-24-03, 09:54 PM
mike from nj
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judging by the dome of that piston, compared to number three---it looks like that head gasket was leaking pretty good, and for a while. i don't think i've ever looked that closely to see anything like that.

keep in mind, aluminum will crack way way more easily than an iron block, i've done probably hundreds of head gaskets in my life, seen a good few cracked heads, never a cracked block. at the absolute worst, i've seen cracked ring lands on pistons from the coolant pouring into the cylinder. it's not much more bolts to drop the pan and pop the piston out, and to look at the thin aluminum piston lands between the compression rings(note: this was on an old dodge v8, and it was a seriously blown gasket)

whatever course you take, make absolute sure the fan cycles on and off as you're warming the engine up, and not from the a/c system cycling, warm it up with the interior fan completely off. i'd have to say the 2.4L has been pretty reliable as far as head gaskets go(coolant-wise, not oil-wise), always use a new thermostat and new head bolts aren't that much money either, and will add that extra sense of reliability.
 
  #7  
Old 10-25-03, 03:44 AM
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Magnaflux

You could buy a dye pen kit I dont know were or how much probbably an aviation supply place.They are made my magnaflux.
What it is is a penetrent.cleaner,developer and a good black light in a kit.
What you do is clean the suspected cracks spray on the pentrent let it sit then hand wipe with cleaner and spray with devloper to suck out the floresent penetrent.to be viewed under black light.
Have used this thousands of times in the millitary on airplanes and is a good way to find surface cracks.
Also look for a brand called zyglo.
There are other ways but would not be cost effective for a one time deal.
Just for your info they used the method in the 1800s on R/R track but they used kerosine and talcum powder to draw out the liquid.
 
  #8  
Old 10-25-03, 03:36 PM
Joe_F
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Thumbs up

Excellent suggestion by Michael. The machine shop likely uses the same method.
 
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