What's the design idea behind the inspection plate drain/vent tube on the 1098?
Mine has been dumping oil. Why would it do this?
Venting:
Currently I have a line from valve cover to the air filter housing on a Weber and I just this morning drilled a small hole through my oil filler cap as it was originally supposed to be vented (I think) and the one on my PO-added polished rocker cover isn't (wasn't, it is now).
So, why the tube and what does loosing oil through there tell me?

PS
sorry if any of you, like me, hang out at different forums where I've asked this same thing.

The tube is a "draft" tube and was designed to have fumes sucked out of the engine while the car was moving by creating a draft.
Of course this worked on paper but in the real world, it's an oil leak.
You may need a positive crankcase vent to ease the crank pressure and *slow* the tube leak.

I've got a hose from Weber's air filter to rocker cover. Is that positive enough? I swear it didn't use to leak from here (lots of other places yes). But now there's a 3 inch spot and I don't idle it over that spot either. Tube should turn up, then head down, and should have baffles to catch some oil. IMHO.

Think it just may be time to check compression and leak test.

Did compression test. Remember, I'm very amatuer at all this.
off it's own battery, warm engine, throttle held open, all plugs removed
Dry Wet
#1 180 235
#2 180 210
#3 160 175
#4 180 210

I don't think I have the stuff for a leak test (pressurizing the the engine, right?).
I must report this though:
There is a rather disturbing trail coming down the rear of the block from the head gasket. It was there when I pulled the motor, I cleaned the block and repainted and it slowly came back,I thought the paint just hadn't stuck well there but maybe the head gasket is bad. It's always dry to the touch though, I'd think if it were the source of oil it'd be oily since there's a fairly decent puddle down there. Hmmm
I did run her a tad harder tonight then I normally would, I think she liked it.

Compression is not great but just fine really.

I agree, I think I would order a new head gasket just in case.

Have you checked the torque on the head nuts, adjust the valves after of course.

I did not retorque the head nuts or check valve lash yet. I confess I'm putting it off a bit because the pretty polished valve cover leaked when I got the car and I struggled to seal it so I hesitate to disturb it but I know I got to get in there.
So those numbers aren't too bad? #3 disturbs me a bit being that much lower than the rest.
She's a sweet little car. Hoping to crash an MG club rally tomorrow, maybe pick some brains.
Tinkering around tonight, trying to kill an exhaust leak I'm pretty sure is at the header center pipe to manifold. Might need a shim or something. Rare evening of just me and the car, kids and wife are off camping, leaving me home with MG, dog and a few too many beers already!

Hehe, drive it. You arn't going to hurt anything.

Oh how I would love to see those kind of numbers.Take 75 lbs off of my 1098 in Bugsy and 50-60 off of the spare 1275 in the garage. But Bugsy is running and really feels pretty strong even with not stellar numbers. Go and drive.

Put a hose on it and ran it back up. Drove about 10 miles. Oil had been sprayed around the engine and when I pulled the hose back off a good amount of oil ran out. hmmmmmmm

You need a PCV 'Flying Saucer/GULP Valve" in there. Without that you'll have oil everywhere. On my 1098 without that in place I had the Exxon Valdez parked in my garage. The valve provide just the right amount of negative pressure in the crankcase. Not so much the engine is pulling oil out of the crankcase but justenough that there isn't poisitive pressure pushing in out the rear seal.

Oh and did I mention the DPO had vent cover blocked with a 3" 3/8 drive extenser crammed in there and a spark plug stuffed into the manifold intake. Oil and I mean oil everywhere. Adding the valve did the trick. Gotta have them plumbed correctly.

Added a bit of oil and put on 100 miles today. Other than the sudden return (about 2 miles from home) of the fuel starvation (I think) under high load issue, she ran great. I parked it and looked for oil droppings, none? Impossible, checked oil level, it was down a bit but still had oil. Very strange. Oh well, I'll just keep my eye on everything and see what transpires. I'm really perplexed, I've had oil from that tube consistently for quite a while and A LOT right before I left for the day and just now, nothing after 100 miles. Self healing? Sure, that's it.

I fixed it. Long distance. I knew you wanted to ride. LOL

Could you tell me what you did? This isn't working out as is, something weird is going on. Got the car back on the road today (brake work). And the "normal" oil leak was there. I drained and refilled the engine just so I knew exactly how much oil I had. Was very disturbed that I only drained out less then 2 quarts. Dipstick read on the low end of the scale, is that a normal "low" 2ish quarts?. Refilled with 3.5 qts and "calibrated dipstick" (moved the PO installed hose clamp on the diptstick tube until the stick read full).
So, I decided to retry my plug in the dipstick hole trick, expansion nut it was pretty snug, cruised around, took quite a long ride, check under and there's a ton of oil. The plug fell (or got blown?) out and oil is EVERYWHERE in the bay, all over the bottom of the hood too. I don't know if that's to be expected (if you removed the dipstick and tube) or if there is way too much pressure in the crankcase. Compression test as reported in earlier post.

Could you elaborate on what you did?

I run this by you, and I have no idea of the condition of your engne, but extreme crankcase pressure can be caused by rings that are not sealing. With the 1098 engine you should ave the can on the front lifter cvoer, they are form the factory packed with a brillo pad, stell wool type material, is it still in the can, evne so it sould pour out of there. Is your valve cover vented? What is the condition fo your motor?

My early 1098cg has no can. I think I decided it originally would have had; the vent tube from the inspection cover, open to the air down low, rocker cover hose to carbs (in my case the air filter on a Weber). And I believe a vented oil filler cap on the rocker cover. My aftermarket rocker cover had a non vented filler cap, I drilled a tiny hole in it. I don't know much about the motor. Compression seems okay as stated above. It could have a head gasket issue, there is a bit of a trail from right the right rear corner of head to block. Not sure if that could be a factor.
I know my (here) dipstick set up is goofy and some oil seems to sneak out there.
I haven't adjusted valves yet either...

Here's a photo of my 1098 with its original setup.....no can ever!

Yep, that's picture I used to check against mine. Little puddle under the tube every time I shut it down (and presumably as I drive down the road to, as per my earlier post where I put a hose on it and tied it up. Oil was sprayed around the engine bay and when I pulled the hose quite a bit of oil came out onto the ground.
So, yeah too much blow by for the "stock" vent system or something amiss with the "system" (if one hose from rocker cover to air cleaner and one open pipe can be called a "system").

Do you have a PCV valve on your intake manifold?
Might help if we could see a photo of your engine

No valve anywhere that I know of. Open hose from rocker into air cleaner.
http://gallery.me.com/jvandyke#100169