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Guest Message by DevFuse
 

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Checking for cracked heads


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7 replies to this topic

#1 Bratwerst

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Posted 22 February 2004 - 01:05 AM

At the JY tomorrow I dont have a lot of time, nor does my helper - I want to be at least 90% sure the heads on the long-block I'm picking up are good.

SO - any tricks-tips for telling if a head is cracked without pulling it?

fyi - I will pull the heads if need be, so if thats what you're going to recommend, its definately an option.

- Erik Hosa - Tacoma, WA -

#2 Snowman

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Posted 22 February 2004 - 03:35 AM

Aside from pulling heads, I can't think of any other definitive way. I would shy away from engines that show any odvious signs of overheating or lack of cooling or oiling system maintenance.

#3 viceversa

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Posted 22 February 2004 - 03:40 AM

Check compression?

#4 asavage

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Posted 22 February 2004 - 01:07 PM

Originally posted by viceversa
Check compression?


On a motor in a JY? Hard to do.

Also, the cracks that are the ones to worry about are not going to show up on a compression test. They're the ones in the intake ports and exhaust ports. You can (supposedly) see the ones in the exhaust ports on EA82T engines, but to see the intakes, you have to remove the intake valves (according to Aluminum Head Rebuilders ) and look near the casting seam.

The cracks between the valve seats seem to be non-worrisome -- at least, that's the majority concensus here for Subaru heads.

#5 northguy

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Posted 22 February 2004 - 01:33 PM

Check compression using a sall airtank with a spark plug fitting. If the cylinder leaks profusely, pass on it.

#6 asavage

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Posted 22 February 2004 - 03:18 PM

Originally posted by northguy
Check compression using a sall airtank with a spark plug fitting. If the cylinder leaks profusely, pass on it.


The other part of that equation is that you have to have each cylinder on TDC on the firing stroke to test that way, which also implies that you can turn the engine over and that the timing belts are intact and still in-time.

Again, not things you can easily accomplish at a JY with most engines.

And, you have to convince them to let you in the yard with a portable air tank.

#7 ShawnW

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Posted 22 February 2004 - 03:27 PM

Most junkyards give you a warranty on parts so you just pick the one with the lowest mileage that has a clean looking carburator and such. .

When you pull the exhaust off and look up into the head sometimes you can see an extremely clean area like it was steam cleaned.

#8 Bratwerst

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Posted 22 February 2004 - 10:11 PM

Thanks for all the replies guys -

I have my eggs in my $124 basket (longblock) from PAP now - block looks generally clean, oil wasn't milky, (or in a puddle in the air-filter housing) and they have a newer filter on there so they at least cared enough to change it... now we'll see how it adjustst and installs and :gasp: maybe it even runs!:rolleyes:

- Erik Hosa - Tacoma, WA -




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