I checked the compression on my ZC,

180 in 1-3
190 in 4
the manual says 192 is nominal with 28psi variation... so I'm happy with those.

I'm still burning about 1/2 quart of 30 weight oil per 1000 miles. Should I be concerned about valve seals or just not worry about it?

 

that loss isnt that bad, mine was burning about 1 quart every 300 miles, do you rev the car alot, if so thats probally it, hondas normally use a bit of oil at high rpm

 

a leakdown test is more suited to find where you have potential oil leaks.

greg

 

I would replace your valve seals. a leak down won't show you if there bad.

 

Valve seals. Get someone to help you and watch the exhaust when the car is first started after it has sat out overnight. You should see some smoke from where a bit of oil settled in the cylinder overnight.

 

You can still have good compresion in the top rings and have your oil rings be worn and burning oil because of this....Mike

 

...a leak down test WILL tell you if the valve seals are bad, but if you're sure the rings are not bad, then the valve seals would certainly be the next culprit.

 

Can I ask, but have any of you actually performed a leakdown test?

When the cylinder being tested is at TDC compression, both the intake and exhaust valves are closed. At this point, valves that aren't fully seated would still 'leak' yet any lost cylinder pressure would escape through the port. What would you even look for when trying to spot a leaking valve seal through a leakdown?

Both compression rings on all modern day IC engines are chamfered at the top to allow compression gas to force the rings out of the grooves and press against the cylinder walls. Oil rings do not benefit from this feature and ring tension is the only force that keeps them against the cylinder wall. So what does all this mean and what is my point? When you set your cylinder at TDC compression and introduce pressure into the cylinder, the compression rings expand from cylinder pressure yet the oil rings remain the same. To associate 'bad oil rings' from blowby does not make any sense.

This in fact seems to hold true to any honda engine that i have diagnosed with oil burning problems. I've seen motors with great compression and leakdown numbers, yet burn 1 quart a week. Upon disassembly, both compression rings are free moving yet the oil rings are seized in the grooves. I've also seen the opposite occur where compression numbers were low yet the motor did not burn a drop of oil.

I hope this clears up any confusion.