So I have been to the main dealer today for the brake hose recall and they did the health check and there was so much on that list it was comical, I am not too worried as each tyre had a point despite over 3mm and the oil had a point as it’s 1mm over max on the dipstick as did pas fluid and coolant.

However the one that got me was oil leak... there was no oil leak 10 days ago when I bought it - having one leak like a sieve before this was one of my key criteria

So I put my head under and sure enough... oil. I have had the top off looked all around the rocker covers and they are bone dry. So I go back underneath and wonder if it’s actually front diff oil? Any ideas? Also a side note I didn’t see anything obvious causing my vacuum leak can you from the pics? The long term trims on each banks are 20% so running lean any ideas? This is only at idle or if you take your foot off the gas completely when driving at all loads it’s between -3 to +7 max - so it’s a lot worse when idle?

4.2 sc btw 2007

Thanks

Does look likely to be the diff weeping oil to me.
Vacuum leak maybe where the hose clips onto the pcv , poor design...

Great thanks - is there a common place they go so I know what to fix?

Re vacuum is it the corrugated tube going to the pcv with the pcv having an arrow pointing at it? If so what’s the fix? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Morning - so I got up early armed with a can of easy start to try and find the leak. Attached is a pick and in yellow is where I sprayed and the pitch of the engine didn’t change one bit - is there anywhere I missed? On a side note the cat effienciency bank 1 fault came up. Is there any chance that if the cats playing up the o2 tells the engine to run lean as it’s detecting rich and so the cycle begins? Only issue with that theory is I get lean on both banks but cat fault only on bank 1...

Cheers

The corrugated pipe to the pcv will be pulling in air IME needs either new o ring doesnt last long IME.
I wrapped the joint with self amalgumating tape , its better to remove the pcv to do it.
Vacuum leaks no more👍

Progress

A quick hunt around in my lunch hour and listening with a tube had yielded a result. There is a hiss where the super charger joins the left bank of the plenum? Sorry if my terminology is out this is my first supercharged car anyway it’s only present on the left banks and is coming from where pictured. I’m guessing it’s a new seal I need - what the best way to attack this? Also the is a few drips of oil under it so maybe it does have a leak from there

Click image to enlarge

Are you sure it isnt from the end of the pcv hose which connects right behind the area you've highlighted?

I lay my finger across that and the sound stopped - it looks a common problem on the jag forums. Also there is oil at the bottom of the seal which indicates a leak as well wouldn’t you think? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Hi all

Rather than start a new post will continue this as it’s relevant...

Changed the above ducts and for the price of the pcv changed that too. Also smoke tested and found the passenger brake booster hose was loose engine side so reseated it.

Now the long term trims at idle fluctuate between -5 which seems to be on start up to about +8 and anything within that?

When driving they tend to stay in low single figure minuses however they do both blip up as much as -12?

Is this normal? Should it fluctuate between a little rich and a little lean? The maf was also replaced last month with a denso one.

On a maybe side note since fixing the vacuum leaks I seem to get a howling or resonating above 50mph? Nothing below could that be related? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Here is the noise it’s existing in drive an neutral above 60 but not below it resonated through the upper center vent too

 Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Just had a look on my misfire counter most cylinders are occasionally misfiring at idle too along with and I hadn’t noticed but my short term fuel trims are 15-20% lean? Any advice as stuck Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Bump - really stuck what to do now  Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF