that little cap Wont dance.

[Aquaticedge]

I am assuming That this may be a good thing, though my assumptions could be very wrong. on my 87 TD, the oil cap does not dance, Quite the opposite, It gets lightly sucked onto the hole, The engine runs mostly smooth (I need Motor Mounts bad...fixed coming monday) I just find it quirky... Is this good..bad...Normal?

[C Sean Watts]

Originally Posted by Aquaticedge

I am assuming That this may be a good thing, though my assumptions could be very wrong. on my 87 TD, the oil cap does not dance, Quite the opposite, It gets lightly sucked onto the hole, The engine runs mostly smooth (I need Motor Mounts bad...fixed coming monday) I just find it quirky... Is this good..bad...Normal?

That is a good sign but it's mostly from your intake/PCV system sucking the air inside the valve cover. You really don't want to see any blow by but there will be some positive pressure.

For "TEST PURPOSES" try this. Pull out the pcv hose from the intake elbow on the turbo. Cap the elbow off with a plugged hose or anything that will not get sucked into the compressor - very important. Run a hose from the PCV fitting on the valve cover to a vented catch can or bottle of some sort then repeat the test. You'll get a true indication of blow by with the teapot oil cap test. There are many aftermarket "PCV air/oil separators" out that attempt to 'clean' the blow by before feeding it back to the intake. With ours, the soot comes mainly from the EGR valve and very little from blow by.