oil change, spring on oil plug Options

[vintage914racer]

So I decided to change the oil on my racecar myself, after usually having my mechanic do it during check ups, and was surprised with a spring behind the oil plug. At first I thought nothing of it, until I let all the oil out and tried to put the plug back in. To make a long story short it took a lot of time, cursing and effort to get the thing back in. What I am wondering if is this something on all 6 cylinders, or is it something special? I've changed oil in plenty of other cars, but have never seen anything like it. I remember my mechanic talking about some kind of oil pressure thingy down there, but right now my memory fails me.

[ArtechnikA]

there -should- be a valve / plunger up in there. (probably. maybe check with whoever prepped your case. i can't imagine a case where / why there wouldn't be one - or why there'd be a spring if there were no plunger, but i don't claim to know -all- the case prep tricks...)

so - two possibilities -- one is that it came flying out and escaped somewhere. into the oil drain pan, maybe ? the other possibility is that it's stuck up in there. Pelican Wayne's 911 engine book shows pictures of the two (old, pre-scavenge mod, and new, post scavenge mod) pistons. sometimes it's possible to get s flat-bladed screwdriver to engage with the bottom of the plunger, sometimes it takes something like a 10mm tap to screw in just a little and give you something to extract it.

(if you're using the 3,2 pump it is almost certain that your case has had the scavenge mod applied...)

the 964 pump is a very good pump, recommended by many, and the pump i'm probably using on my next engine build, which is one reason i'm trying to learn as much as possible in this thread...

yes, removing the sump plate is the approved and correct means of draining the sump oil. there may be a way to use a plate with a plug in it -- check with Mainely By Design to see if they have a plate with an external plug for this purpose. (i'll be asking them this, sooner or later, if you don't ...)

do you have a way of draining the oil tank ?