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jlawley97

z24 Knocking after replacing rod bearings. What to do?

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Hi,
So, I bought this z24 engine block to use put it together it started knocking after a little bit
timing got messed up valves touched pistons
pistons and valves were fine and still hold compression
took it apart
replaced rod bearing and pistons rings
checked oil path ways reassembled.
knocking much quieter and only really hear when warm and at idle.
check the main bearings now. They arent great great copper is showing.

I have another z24i block with crank shaft installed that is known to be good(has no pistons but oil and water were mixing and it was not determined if the block was cracked or the headgasket was bad)

 

SOO
should I replaced the main bearings with the engine in the truck, measure clearances and not get crank shaft machined
OR
put the pistons from z24 block into the z24i block, because if I take out the z24 block to get the crank shaft machined.

 

I know what the right thing to do is but i don't want to keep dumping money and time into this truck and removing engines is difficult because I have to work in the dirt
 

Basically I dont have time to check the roundness of the crank shaft  at this moment in time and dont want to worry about it constantly
I want to know the likely hood that the crankshaft needs to be machined if there was no visible scoring on it. If i could remove the crankshaft without removing the engine this would all be a non issue. Thank you for following me through this thought process.
 

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ALSO
could the piston wrist pins be the cause of the knocking? There didnt seems to be any visible damage to them.
the knocking sound is loudest in the center of the block and  can mostly be heard in the exhaust pipe.

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You can't remove the crankshaft without removing the clutch and flywheel and the transmission so easier to pull the engine and easier to work on once out.

 

 If it held compression why put new rings in it.???

Why replace the main and rod bearings????

 

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the compression was 90psi across the board which is below the recommended threshold.
and was knocking ill take a picture of the bearings but as i mentioned they were showing copper and definately needed to be changed
Here is a video of it before I changed the bearings

 

 

 

 

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Did you measure the cylinder wear or just hone and re-ring. Maybe one cylinder is loose and the piston slapping around? It may have needed to be over bored and larger pistons. I've never had good luck with honing. Maybe a year's use and they begin to smoke again. Plasti-gauge the the crank and see if it's got good clearances. You said it was smooth so probably ok. Maybe a rod bolt is coming loose? 

 

Try a quick short rev of the engine. Rods get very loud under load, quieter when you let off.

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i did measure but with a plastic mirco meter . So I am going to get a proper high percision one and try again
heres a video of the knock now
as you can tell it doesnt get loud when revved.

 

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Check the valve lash. Sounds too high a pitch for rod. Intake and exhaust 0.012"

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i agree with mike its to tingy to be a rod and it runs too good. 

 

these things and L series are rattle traps to begin with. its in the top end.

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7 hours ago, scooter said:

 

  L series are rattle traps to begin with

 

yes....

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