Oil leak and power loss - connected?

Hi,

Okay, please bear with me. This is my first turbo car so I'm still getting to grips with the mechanics and I'm hoping some knowledgeable people can chip in to remove some of my stress.

Right, I've got a 2007 2.0 TDI (140) Sportback that I bought 3 weeks ago. It has been driving fine and all good except for a couple of electrics niggles that I've mentioned in another post or two. However...

On the way home tonight I was on the motorway and realised that I was basically putting my foot flat to the floor in 6th only doing about 70-75ish (maybe a little more). Dropped a gear and the revs rose the car responded better but just didn't feel like it was pulling properly. Checked the MPGs and they were still up at the 45-50 mark which is what I've experienced in those conditions before.

Once off the motorway I experimented a little and the car definitely felt a bit sluggish. The second/third gear kick from the turbo wasn't really there and it just felt a bit slow, however it didn't feel totally limited (e.g. limp home mode - as far as I know).

Got home and had a look around the engine and noticed a bit of an oily smell (something I'd half noticed previously but not really clocked it now I think about it) and found some wet oil on the fuel filter and all down that side and onto the under trays, some of it wet/new, some of it built up grime. Looking under the car I then noticed some distinct patches on the road that show it has dripped a bit over the last few nights when it's been parked there in different positions (but I haven't seen it as it's been dark).

Checked the oil and the level is still 'max' so it can't actually be losing gallons. Decided to take it for another drive once the roads were clear and it definitely seems to not be pulling as hard as it used to, also I can't heard the turbo spooling (I never have come to think of it) however my assumption is that it must be at least partially hitting some boost otherwise surely I wouldn't be getting 47MPG@70mph out of the basic lump without any turbo help?

There are no engine warning lights and I had a VCDS scan coincidentally last Friday which showed no faults for anything that would effect these things.

Photos of oil and patches below...






So the things I want to know...

- Any likely candidates for where that oil leak is from in that area?
I've dug around with a torch as much as I can but can't see any likely culprits with all the plastics in place.

- Any ideas on where this power loss may stem from?
My initial thought was something like the EGR, Air Mass Sensor or something choking the flow a bit, however then after reading about turbo failures and not hearing the spooling I've not myself worried it's something to do with that. Possibly vacuum hoses? I'll be honest I don't really get the detail of the turbo setup yet.

- Could the two be connected or likely to be different issues to resolve?
My gut says this oil leak may be something that has been around a while where as the power loss is something that I think has only crept up (that I've noticed) in the last 24 hours. However I don't know if the increased about of oil loss could be something that could be linked to issues with the power.

- Do you think I can drive the car (carefully) in it's current state?
I need to drive it to my mechanic contact anyway (which is near my work) but I wasn't sure if I should be parking this up until I can diagnose more. I can't afford to kill the engine or anything!

My plan is to try and get it to a friendly mechanic I know tomorrow but I think he'll be busy/tied up for Easter so will be unlikely to fit me in till sometime next week to look at it properly/do anything. Plus, I'd like to have some idea what we are dealing with/try to fix it myself if I can. I am ordering my own VCDS cable to scan for any new faults that might have popped up but will be waiting delivery on that for a few days (given the Bank Holiday).

Any advice/input gratefully received as I'm pretty stressed about this as cash flow is very tight with my wife's maternity (I have a 12 week old) and I was kinda hoping this car would see me through the year without too much expense.

Cheers,
Andy

Okay, update on this based on my drive into work...

Firstly, the power is most definitely down. It gets up there eventually but the torque is down and the throttle response feels off, it has to be driven more like a petrol engine (higher up the rev range) otherwise it just bogs down. Fuel efficiency is there or thereabouts the same over my commute as it has been for the last 3 weeks (not sure if that tells me anything or not). I don't know if it's an airflow thing or not?

Second, the leak. I actually think it might be a leak from the fuel filter and diesel coming out. The patches on the ground yesterday were dark but I think it's actually just collected from grime from inside the engine bay when it's leaked out. I'm hoping that may be as simple as a gasket failure?


Going to go see my mechanic at lunch but I'm considering plugging in my OBD2 reader in and using Torque to see if I can get any boost readings from the car. I presume this is detectable via generic OBD2 and not just VAG-COM?

Thanks.

Thanks SAILO.

Yeah, sorry I know that is the fuel filter, it was more that I originally thought there was an oil leak around that end of the engine. However it certainly now seems like a fuel leak. I've had a closer look and to me it looks like the top isn't properly flush to the casing so I wonder if it's just been screwed down without being properly seated? I know the car had a service just before I bought it so it could be a bit of sloppy spannering.

Can I remove, reseat and replace the fuel filter and seals do you think? Or are they one use (i.e. I need a new set?).

Interesting that you mention fuel pressure and limp mode. If that is the problem and it's just a seal I'd be made up. I'm awaiting a VCDS cable delivery so I'll definitely check any faults and see what comes up. I'm surprised limp mode doesn't trigger a main day engine warning light?

Hmmm... okay so I decided to go out in the rain to investigate this a bit further quickly. Looks like we might certainly have a candidate for cack-handed mechanic of the day after finding this...




As they have tightened down the screws so much it seemingly has bent the casing lid I'm assuming I'm probably going to need a replacement unit. I'll try removing and refitting it in case it straightens up but I'll start sourcing a part.

Unfortunately I don't have any spline sockets in the car so I can't try it here at work.

I'll drop him a line and see what sort of price it's going to be. Cheers.

@mjr901 I've just opened up a parts request a second ago. That okay or shall I PM you the details as well? Cheers.

Soot1 said:

Had this problem of leaking diesel a couple of years ago. All that seals the top of the fuel filter is an O ring around the top edge of the paper filter inside, no other rubber gasket on the lid itself. Your fuel filter top is obviously bent so that needs a replacement. When you do get around to installing the paper element itself make sure it's Audi oe version, mine was a cheapo and the O ring would not seal properly.
The hesitant engine would be due to lack of fuel pressure as air was leaking into the fuel filter.

Click to expand...

Cheers. It certainly seems connected as I've just counted the number of patches on the floor of my regular parking space and it roughly matches up with the number of days I've had the power issue. Going to get it resolved (first port of call is going to be a bit of lid 'persuasion' with a hammer and then replacement if I'm not satisfied its sealing), run a VCDS scan and see where we are then. If it is a fuel pressure issue and this sorts it I'll be very happy. The thought of things like new turbos doesn't particularly excite me!

SAiLO said:

I'd take the car to the garage which serviced it and make them replace the unit free of charge. That is if you have all the paperwork confirming they changed the fuel filter in the first place.

Click to expand...

You do have a point but it wasn't me that got it serviced (previous owner) and I'm not sure the paperwork is that specific but I'll check.

Right... I have a bit more info on this now, not really any the wiser...

Firstly, I wanted to establish if I was seeing a turbo failure as I still wasn't sure what was going on with the blower. I tried the car with an WiFi OBD2 dongle in and setup some gauges on DashCommand and it would seem that the turbo is actually spinning up and creating some boost. Now I'm getting to know the car better I think I have been able to hear it as well (but it is very quiet). It's starting and running smoothly but the car still lacks the 'kick' I'd felt from 2nd upwards and just simply won't go much higher than 70mph (with nothing left on the pedal).

Second, I've run a full VCDS fault scan on the car and found... nothing. Well there are some codes that I'd previously read (and not reset) but nothing new that would be connected to this issue. No low fuel pressure faults, no indication of limp mode, nothing. This seems surprising.

My course of action is still the same. I'm getting a replacement filter and seal kit from Mike, going hammer my fuel casing lid back into true and then refit it all to try and rule out this diesel leak, but I was sort of hoping to see a distinctive clue in the fault log that would connect the fuel pressure to the reduced performance.

Do you think it's feasible that it could simply be that a potentially reduced fuel pressure is restricting the power (i.e. at higher revs the car is asking for more fuel than it can physically get and ends up running too lean)? But not enough to trigger a fault.

Just to close the loop on this...

On Sunday I took the fuel filter apart and got slightly concerned as I couldn't see any evidence that it was the source of the leak. As I had it apart anyway (and a new filter/o-ring from Mike) I thought I'd carry on and see.

I managed to use 2 pairs of pliers to man-handle the casing lid back into some sort of true (my original plan of hammering it against a brick failed as the fuel pipes were very tightly attached and I was concerned I'd rupture them getting them off so couldn't remove the lid itself). Popped it all back together (image below) and wiped everything down to be able to more clearly see any leaks, went for a drive and it seems to have sorted it!

Did about 15-20 miles of testing on various roads. The torque seems to be mostly back (although I'm now guilty of over analysing it so I'm not 100% sure, and think I need a map for some more!!) and best of all after the run the engine bay was as dry as I left it! I can only assume either leak residue had dried since the last run, or the seal was only partially failing under high pressure so wasn't an obvious 'leak' under lower loads.

Hooked up to DashCommand again and it seems to be boosting fine and the wastegate is operating so think the turbo is thankfully okay. Still wonder if the EGR needs some attention so I'm going to do a blank on it and see how it feels.

Thanks for the help/suggestions!