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Thread: Q7 3.0 TDI Engine re engineering

  1. #1

    Default Q7 3.0 TDI Engine re engineering

    Hello all , recently I posted about the oil leak I have in my 2011 Q7 . I have read many forums, discussions etc about these 3 TDI engines that spring a leak at the rear and I see suggestions range from rear main seal to turbo pipe. What I've seen if your 3.0 TDI is leaking oil in the rear and it's dripping off the engine/transmission Junction it's almost 100% its that upper sump. Mine was just diagnosed with this problem and a 7.5k bill to fix. Now I get told by many that " Yeah, they are a great engine mate,worth fixing" Well I call bull**** on that. These cars are around the 110-120k AUD brand new, but then your time is relatively short. Once it's upwards of 100k kms it's not if but when is this upper sump going to fail. So,unless you have a fat wallet and can buy brand new I would suggest don't buy one that's over 100k kms. I am one of those blokes who has a wallet but not fat enough to throw money at something that needs re engineering. Don't get me wrong I love the car,I put it through **** off road and it handled it just as good as a 4wd but with comfort. When I took mine to a great mechanic, that handles these motors and went through and looked at exactly what has to happen and seeing it dismantled WOW, literally because a tube of sealant failed it's a 7.5k fix. And it 100% WILL do it again down the track, and because the kms are rising so will many other problems. Now in my world,having an engine that will nearly cost as much as a wife to maintain is NOT the great engine I hear of,sure it goes well,runs smoothly but it's just a throw away after 100kms. I had 3 options, 1- Lose out and flog it off as part 2- Spend the 7.5k and keep it for a year or 2 then sell it which by them it's worth nothing anyway or 3- Drive it into a big tree and claim the insurance. In a perfect world number 3 would give me the best return, but unethical (so they say). I have chosen number 2 but won't keep it over a year. MY QUESTION FOR YOU.
    Q 1: Having 2 flat surfaces to seal and prevent leaks when there's temperature, pressure etc to deal with and any gasket sealant will deteriorate over time,would having a small groove,like a rope seal groove in 1 mating surface give you a better seal and give it a longer life?
    Q 2: If the above answer is yes, if I took the upper sump and had this groove put in the surface would it affect the whole integrity of the sump?
    Sorry for raving on, just in that situation where I have to make the tough call,like sometimes when you love something you have to set it free, and It's the Q7 that's gotta go , the wife has to many overheads. 😁 Cheers to anyone bothered to read this!

  2. #2
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    Thats a pretty racked off owner venting! Perhaps before you slit your wrists and jump off the harbour bridge, you should positively confirm where the leak is. I have a 3.0 tdi that has just turned over 302000 Km and in its life it has had a turbo replacement and the dreaded rear seal replacement. It has a very minor leak at present that I am slowly trying to identify. Some of these issues are very expensive and I don't for a moment think that most people will find the outlay palatable or affordable.

    Yes, it is hard to stomach the issue but at least confirm the real problem before diving in. Among all the housewife tales, there seem to be a literal swag of sources that don't get much mention.

    The oil pan plug copper sealing washer? The sump oil level sender gasket?

    Have a look at TSB 10 16 13 2044546/1 June 14, 2016. Thats Audi's official take as of that time re some oil leaks.

    This comment came up:
    I then found there is a cap about 80mm Dia on the RHS of the engine. It is at the back of the tappet cover. You can access it from the top of the engine. It's a bit of a reach but not impossible.
    My car had a pinched o ring seal that was causing the small oil leak. It's a very unusual size seal so I ordered it from VW for about US$5.

    ...and this one
    copper injector seal leaking. There is a port per injector above the exhaust manifold where excess unburnt diesel/soot drains

    I am a relatively new convert to this model so I have everything to learn and I'm sure that there is much to trip over in the process. VW is a renowned manufacturer of diesel engines and while their software woes may be a bit farcical their mechanical work generally stand the test.

    No one can answer your question as the testing to see if heat, vibration, strength etc etc is beyond the resources of anyone here. In theory a seal is possible but the assembly to ensure it remains in the groove during assembly is fraught with problems. Would it seal any better for longer. Who knows?

    The only solutions are get a new car or a really old one. One is covered by warranty and the other is fixable by you at minimal cost. My own experience is there is a sweet spot with cars and that is around the year 2000. The machining and assembly is light years ahead of the earlier cars which were an almost daily job to keep on the road. Back in the 60's and 70's blokes spent a part of most weekends just keeping their chariot on the road. None of this really helps with your dilemma so over to you to work out whether to fix or torch it. GL.
    C5 RS6: Sportec, Milltek & Wagner -- B5 RS4 : modified -- B5 Audi 1.8 quattro 132 Kw -- 2007 VW Touareg TDI 3.0 with air suspension and lockers-- UNIMOG 404 TLF8

  3. #3

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    Firstly, I'm certainly not gonna slit my wrists, and as in all the other obvious oil leak spots you mentioned,yes,for 2 weeks I've been cleaning the oil off,then back under chasing the oil. I've replaced the sump plug,there is no leaks from the top or the rear timing cases. I have taken it to a mechanic, put it up on the hoist and yes,it IS the upper sump leaking. When you say it would be hard to keep it in the groove,what in the groove? There is no gasket here,a sealant is used so the groove theoretical should be a better seal than 2 flat surfaces. So you've replaced a turbo,rear main and other leaks,then the upper sump is inevitable at some point. And I didn't come on here without research,weeks of chasing oil and if you read my post again you might see I mentioned that yes,I have had it diagnosed so maybe you should read a post properly before diving in. And oh,the wife thing, it's called a little light humour, which most blokes can relate to,obviously not you. And yes there are people our there that can answer my questions,and the machining and assembly light years ahead, ummm yeah I don't think so,machining 2 flat surfaces have been around for a millennium with precision and assembly is the easy bit. I'm happy you have had a good experience with your car and hope it continues, but the bleeding obvious wasn't the answer I was after, and my belief won't change. These motors are excellent for a relatively short time,then they are pretty much disposable. Certainly no bang for buck. Thanks for your reply mate,have a good day 😀

  4. #4
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    There are many instances of mis-diagnosis by factory and other mechanics, so if you are confident the assessment is right for $7.5k outlay, no problems.

    You asked "would having a small groove,like a rope seal groove in 1 mating surface give you a better seal and give it a longer life?" Your reply to my comment "ummm yeah I don't think so,machining 2 flat surfaces have been around for a millennium with precision and assembly is the easy bit" seems to indicate you may have forgotten you asked two specific questions in your initial post. In my younger days I was a fitter and turner so you got an answer from someone who has at least done that and had to assemble the finished product too.

    I think I can do light humour and it's good to see someone newly participate in a forum who is having a bad car experience and yet it is everyone elses fault. "Cheers to anyone bothered to read this! " yes I did, all the way through. Maybe you should too.
    C5 RS6: Sportec, Milltek & Wagner -- B5 RS4 : modified -- B5 Audi 1.8 quattro 132 Kw -- 2007 VW Touareg TDI 3.0 with air suspension and lockers-- UNIMOG 404 TLF8

  5. #5
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    keep it civil..

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