Piston Ring Test

[gregmercer]

I have the head off of my volvo 230, at the machine shop getting a valve job. I want to test for bad piston rings.<br /><br />Would it be possible to fill up the cylinders with some kind of oil, leave it overnight then check in the morning to see if any leaked out a lot of the oil?<br /><br />Anyone ever done this before?<br /><br />What kind of oil should I use? I was thinking motor oil might be too thick...<br /><br />Thanks!<br /><br />Greg

 

[Don S]

Re: Piston Ring Test

Not really. How they act under pressure is the test. Leakdown and compression tests are how they can be tested.

 

[Reel Poor]

Re: Piston Ring Test

You would need one of these to check sealing ability. This tool pulls a vaccum on the cylinder and lets you measure the amount of leakage past the rings. Oil or whatever will eventually seap past the rings. If you can move the piston around in the bore and there is not enough of a ridge at the top of the bore to "hang" your fingernail on, it is probably ok.<br /><br />

 

[rodbolt]

Re: Piston Ring Test

ya really cannot test it with a vacum as the rings are not really desined to seal both ways. once you get the heads on do a leak down test.<br /> thats why the rings are marked for top up and bottom up on most applications.

 

[paulie0735]

Re: Piston Ring Test

Piston compression rings are designed to seal under pressure, the pressure created by the compression of air and fuel will work its way past the crown of the piston and into the ring groove. The rings are than designed to trap this pressure and use it to expand the ring and seal it against the bore. You cannot do an effective piston ring check unless you can pressurize the cylinder. Check the bore for size, taper and roundness, which will give you a strong indication of the condition. If it’s out of spec than as a minimum you will need to hone the bores and replace the rings. That or just bolt it back together and hope ……..

 

[michael-lagrange]

Re: Piston Ring Test

the head/heads must be on to do this test.<br />pull the coil or all plug wires so the engine won't crank up.<br />do a compression test on all cylinders and write down the results.<br />one cylinder at a time, add a tablespoon of motor oil to the cylinder thru the plug hole, crank over the motor a few turns to spread the oil around the cylinder, do another compression test write down the results, if compression stays the same=good seal, if compression goes up=blowby.

 

[gregmercer]

Re: Piston Ring Test

Thanks for everyones insight.<br /><br />There are no marks in the cylinder, I can still perfectly see the honing marks so I am hopeing the rings are all good.<br /><br />Greg