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.

what year is your 6's engine ?

original-ish 6's should have an obvious drain plug in the middle of the obvious drain plug plate (covers the oil strainer).

you've removed the oil pressure relief valve.

find a way to drain the strainer, and you'll also have to drain the tank at the coupler in the hose...

Originally I focused on the circular plate on the bottom of the engine, thinking the drain plug would be under there. After removing a couple of the nuts oil started leaking and I thought maybe I was at the wrong place. At that point I went Aha, and saw what I thought was the drain plug. The engine is based on a 2.0l block so is this an "originalish" engine? If I remove all the nuts on the circular plate on the bottom center of the engine will I find the right drain plug? If so is it normal for oil to leak out of that plate when removing a couple of nuts? I feel like an idiot now, thinking that I went to way too much trouble and now have to start all over again, plus I have to pay for another 11 quarts of mobil 1. Does anyone have a picture of where exactly I need to go to find the drain plug? This reminds me of the stories I hear of people going to jiffy lube to get their oil changed in their brand new audi and find that the high school kid working there emptied the tranny fluid and added an additional 6 quarts of oil to the engine.

the drain plug is supposed to be a 19mm plug in the middle of the circular plate.

maybe someone has 'updated' your oil pump to one that uses the drain-plug-less cover. or maybe someone just updated the cover. no way to know unless and until you get it off and can see what kind of oil pickup you've got in there.

i would suggest picking up a Haynes manual - 2, actually, one for the year 911 that your engine is, and one for the 914, although the 914 Haynes does cover some /6 stuff...

anyway - if you have no drain plug in the cover plate, yes, the correct technique is to loosen the peripheral nuts and let the oil drain out around the plate. if you loosen one side only a little and the other side more, you can pretty much direct which way the oil will go. then remove the plate, and the strainer or whatever you've got in there. if you have the newer oil pump we'll need someone with more time on those than me for specifics -- i've never had to deal with one of those (yet) ...

you will still have to drain the oil tank at the coupling in the line - only about half the oil lives in the sump...

PIctures I have seen for the oil relief valve include a piston that gets inserted into the spring, but mine did not have this. Is it something that should be there? Apparently my engine has a 3.2 oil pump and that is why there is no drain plug protruding from the sump pan? Anyway, will it be safe to remove the sump pan and drain/change the oil like normal, or is it something that I need to bring to my mechanic?

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 ?

If anyone cars, I figured out the solution to my stupidity. I have an early engine with no drain plug. In order to drain my oil I just loosen the sump plate and the oil drains out. I did in fact erroneously remove the oil pressure relief valve from the plug which I thought was the drain plug. My mechanic says changing the oil the proper way will remedy my problem. Thanks for the help.

Your mechanic seems to be a very wise man. You should continue to use his service more frequently.

Glad to know you got it fixed.

He is a wise man and I use his services often, although after spending thousands of dollars with him I try to save a little here and there. While I didn't this time, I will in the future since I know what I am doing now and will not have to go to where the car is, load it on a trailer and tow it across town to his shop.

did you resolve the issue with the pressure relief valve (plunger) ?

Yes. As far as I know. Some pictures I found show the plug and the spring and some show a piece that goes in on the "plug" side. Only a spring came off with the plug in the drain pan and my mechanic said that is the way it is on this car. The car runs and has proper oil pressure and he says everything will be ok.