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Gas Compression Check
Topic Started: Jun 15 2010, 08:46 AM (543 Views)
rudie20
Fresh Fish
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I am looking for a little expert help. I just installed new piston rings and reinstalled the pistons into the block as per the service manual on a 1.3L. Before I put the pistons in I honed the cylinders to get the cross hatched pattern as well (and was careful to only remove the glaze). After I put the pistons in I did the gas check to make sure that they will hold compression. All 4 pistons have a slow leak were gas drips through the cylinders into where the oil pan would be. Is a slow leak like this normal or should the cylinders completely hold all of the gas that was poured onto the top of the piston?

Thanks!
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Rooy


New rings need and honed cylinders need to wear in before they make a good seal. Assuming the cylinders were in good enough shape to get away with just honing (not too worn), you should be fine.
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mwebb
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FOG

did you use soapy water and a hose to remove all of the honing residue ?
if no
remove the pistons , and
use soapy water and a hose to remove all the honing residue , then oil the piston rings by dipping the piton and rings upside down in a coffee can of oil.
make sure the ring gaps are in the correct position
reassemble

do NOT put gas in the cylinders after that as putting gas in the cylinders washes off all the oil and when the engine starts
there is no lubrication between piston and rings and cylinder walls

no matter what
gas is going to leak through the gap in the rings , the gap must not be zero when the engine is at room temperature if it is it will be less than zero at operating temperature .

it can not be less than zero for long .... before all the magic smoke is released from the engine
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slander
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Tech Certified

mwebb is right. Gas will always leak between the ring end gaps. So yes, a slow leak is going to be normal.

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