treimche

I'm considering taking the valve cover off to do another leak down test. I started by lining up the timing marks on the crank pulley and using a long extension down the #1 spark plug hole, watching for the very top of the stroke while turning the engine over by hand, the pressurize the cylinder. Then turned the crank 180 degrees with the extension sticking out of cylinder 3, watching for the top of the stroke, then did the same with cylinders 4 and 2 in that order.

If. you've ever done a valve adjustment, you can see that there is some duration that the valves in a cylinder stay closed, even when turning the crank by hand. That being said, even if a cylinder isn't 100% completely at TDC, the valves will still be closed as long as you're very close to TDC. I even purposely tried doing the leak down test on a cylinder when it was 180 degrees off, which showed almost a complete loss of pressure in the cylinder.

Ordered a bore scope that will be here tomorrow, so I'll look around and see what the cylinder walls look like. If everything looks alright, I'm probably just going to install the turbo kit and send it.

rpg51

I must say that it does not make a lot of sense to me that this engine has clean and dry plugs and runs perfectly fine with these compression numbers and leak down results. It seems your testing methods are sound.

Tell me folks, when there is liner damage, does oil typically get into the combustion chamber through the rings? If so, shouldn't OP be seeing oily plugs and misfires?

I think your plan to have a look see with the scope is the best next step. The bore scope is an incredible tool.

VashTheStampede

Woah woah woah.... This couldn't be a head gasket failure between 1 and 2 and 2 and 3 would it? Was this car ever FI'd before, or had its HG replaced? If so, was the head torqued correctly or the old gasket reused? You don't have to have a coolant leak to have a blown gasket. These numbers are weird, so I'm throwing out a weird response.

treimche

When I have the plugs out later to look around in the cylinders, I'll post a pic of the plugs. They don't look bad.

As far as I know the car has never been boosted or had a head gasket changed. Everything engine/transmission has been very virgin (besides a cold air intake). Trust me, the thought of the head gasket leaking between cylinders 1-2-3 has also crossed my mind. Is it likely? No. Is is possible? Sure, anything is possible so I'm not ruling it out.

This is a really odd situation as everyone in this thread can see.

starchland

I would try it cold just to see what happens to the numbers. Adjust valves and recheck, my guess is tight valves.

rpg51

Was the valve adjustment referenced in #6 post above done on a cold engine?

treimche

Yes the valve adjustment was performed after the car had sat overnight and most of the next day. The engine was cold.

rpg51

I don't think it is tight valves. It will be interesting to see the bore scope images.

But - any one know whether oil would ordinarily be passing the rings into the combustion chamber if it has liner damage? See question above.

I remain baffled about how it is that this engine runs fine.

s2000Junky

Yes

s2000Junky

Bent valves. They don't seat, causing high leak down. This would otherwise show no oil residue on spark plugs. I would expect to see some irregularity on plugs though, showing signs of higher combustion temps, blistering or white crust on plugs to some amount.