Unknown leak

I've noticed my 996 has developed a bit of a leak, but I've no idea how serious this is, if it's an easy fix or what part of the car this even is (so feel a bit stupid for asking). Is this a common issue?

Clean it up and tweek the clamps see if it stops it would be my first thought. You can get some oil misting in the inlet from re circulation of crankcase gases if I'm seeing the image correctly.

Thanks. Annoyingly the part I've highlighted is obscured by the water mark. It's easier to see if you click on the image.

That looks like the little breather pipe is weeping and allowing oil vapour to condense around the plenum. Either that or the rubber plenum pipes are leaking. Would run like poo if it was that though.

When you say run like poo, I assume you mean runs rough? I'm not sure if it was just my mind playing tricks but it didn't seem to be a little down on power but certainly not slow and not rough. It looks like it's starting half way up near the small pipe that joins there but it's really hard to tell as it's not the cleanest part of the car I guess it's best to take it into the garage at some point (if they're even open). I assume there's no major harm driving it as long as I'm sensible?

Clean it off with some spirits and see where its coming from.

These engines do get oil in the inlet manifold as normal ... it's only a problem when its excessive which is usually the AOS or on 997 bore score can cause similar. In these instances you will get heavy smoking which you haven't mentioned . lets just say i've seen this many times .. oil sits inside the inlet tract and on the rubber pipes each side of the throttle tube ... it will over time cause a misting or a dampness in this area. These cars are pretty good at adapting to engine problems such as air leaks .. You could easily pull off a small vacuum pipe and the car over time will adapt to this and be able to give the correct air/fuel ratio to each cylinder . It's not hard to remove the throttle housing and the first tube to clean it up if you wish but i feel as stated above .. a small tightening of the jubilee clips will suffice .

Thanks everyone. I think I'll take it off, clean it and tighten it all up. If I give it a good clean it will help to check if there's still a leak.

I've spent a while taking the air intake box, throttle body and plenum out. Oil seemed to be coming out of both sides of the plenum with a fair oil coating on both the rubber joints attached to the plenum. I've cleaned up the plenum but wondering if I should buy replacement rubbers? There didn't seem to be any leaking on the rear intake plenum behind it. Also, to the point about heavy smoke coming from the exhaust, it's not something I've noticed apart from once every few months on start up but not every time but then it's fine again. I've had the car since July/August last year and only put around 1.5k mile on it.

That's up to you .. i can only say i've never replaced them in 16 years . From your description then you don't have any AOS issues but if it is original its something to put on the list of items that are worth changing . AOS air and some oil enters into the front section hence thats the one that will be damp . You also need to drive it more Just my 2 pennys anyways .

Thanks deMort. The rubber doesn't look in bad condition I have to say, I'll remove them and give them a clean too. I've left them on attached on the car at the mo, it will also give me a good chance to give the condition a good check over. A job for tomorrow now, I'm enjoying a cider in the sun

Took all the parts off last Sunday and cleaned them to help spot any further leaks but only managed to put it all back together today. Started it up and it was running really rough so thought I'd take it out for a spin to see if it cleared up. The bloody thing cut out at the end of my street and did street and did so every time I came to a stop (luckily on 2 or 3 more times). Went for around 25 miles and it was fine under normal driving but when I got home I had the dreaded check engine light and still rough at low revs Obviously the first thing I'll try (tomorrow) will be taking it off again and try refitting it, as somethings probably not hooked up quite right. Don't have a code reader to check what the problem was. Also noticed a funny noise when the car was idling, a rattling sound of some sort which went away when I pressed the clutch in. So, I'm guessing the clutch is on it's way out? Not a good day.

logically and something has not gone together quite right .. Start with making sure the air mass sensor is plugged in .. Then check the air box to throttle housing pipe is correct .. finally moving on to the rubber pipes each side of the housing tube are seated correctly . If it helps then i can still have problems doing this job .. and i've done hundreds of these over the years . worth checking the oil filler cap as well .. needs to be tight . Fault codes for this would be lambda sensors and adjustment out of limits . Clutches can make a noise , usually the release bearing but as this wasn't an issue before the bad running then fix that first . If a clutch isn't slipping .. if its doing its job then a noise from a bearing is often just that .. an annoyance .. Sound clip would help though

Thanks again deMort Having had a think about this overnight I remember one of he jubilee clips holding on the rubber sleeves felt a little odd when tightening up so I was going to look at this first. However before I got too far I noticed that rubber/metal stand off which connects the throttle body to the engine had snapped in half. This clearly didn't help things so I need to replace this. It looks like the part number for this is 99970326500 from what I can see but costs around £30 for the damn thing! Does anyone know where I can get one of these at a better price or do I just have to suck it up?

Regarding the broken Anti Vibration mount, have you tried to:- Superglue it back together as in https://www.renntech.org/topic/46612-help-with-bonded-rubber-buffer/ or search Ebay for "anti vibration rubber mounts m6" assuming M6 threads.