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Discussion Starter #1
i have a 94 dohc mark viii engine i'm trying to swap into a 96 cougar. did the compression check today and all showed a consistent 180-195, except for cylinder 4... which showed 30. we added a few drops of oil to the cylinder and retested and the pressure leak was sealed and the compression went back up. this leads me to believe that it's a ring problem and not a hole in the piston or valve problem.


here are my questions:
-does it sound reasonable to just replace the rings on piston #4?
-i guess it depends on the sidewall surface condition when we open it up, but i'd like to stay away from honing the bore since i don't want to contamitate the rest of the engine with remaining debris/grit. has anyone also ignored this step with success? if not, any tips on keeping debris out of the rest of the engine while honing?
-if the main bearings don't show any detrimental wear, can i just reuse them without a problem?
-can i even get the #4 pison and rod out as an assembly without removing other stuff?


i've looked through some of the manuals, but everything is written as if i'm rebuilding all 8 cylinders. i'd like to stay away from that if possible.

let me know. thanks.


bob
 

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If you try to take the piston out the top, you get to pull a head, and reset the valve timing, etc.... :D If you pull them from the bottom, you may need to remove the crank, (I am not too sure on clearances) and at that point, you may just as well re do all the rings , etc. :rolleyes: Should it become necessary to do any bore work, you have then hit the jackpot , as you will then need to pull both heads, and its close to a complete rebuild job :( .... So you might just as well, either look for a better engine, or figure on a good rebuild, and maybe even upgrade to forged parts...It makes no sense to swap a POS engine into a car no matter how cheap it was... Whatever you decide , good luck!
 

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Discussion Starter #3
yeah it sucks.

i was just wondering if it's possible to get the piston and rod out the bottom without removing the crank.

if i'm lucky and the sidewalls of the bore still look alright, then i might be able to get away with just doing the rings and no honing....

?
 

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The Parts Guy
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You might be able to pull the piston/rod assembly out the bottom of the block, but how do you plan on compressing the rings to get it back in? I don't think a regular old ring compressor is going to work from the bottom of the block.

Do it right, do it once.

-Rod
 

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Ill go with both of emm on this. If you are going to do it, do it right. These cars can be a pain to repair once they are in the car. First off though, I would pull the piston out and be sure the ring gaps are not juts really close to being in line. Depending on how much oil you used, this could have solved your problem. Probably not though so dont get your hopes up.

Chris
 

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Discussion Starter #6
i will rebuild this entire engine and keep the forum posted. thanks.



(i will also be sending in my membership check since i just noticed the giant 'membership expired' under my name.)


bob
 

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Good for you!....... Twice over for two great decisions... Good luck on the rebuild. Now, lets see , those ultra lite forged pistons and rods should be good for how many RPM?? ;)
 

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The Parts Guy
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boba said:
i will rebuild this entire engine and keep the forum posted. thanks.



(i will also be sending in my membership check since i just noticed the giant 'membership expired' under my name.)


bob
Good idea x 2. :D

-Rod
 
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