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D2 - Engine Bay Everything under the bonnet

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Old 15th December 2015, 09:34 PM
Nick Jones Nick Jones is offline
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Question Oil usage

1996 4.2QS ABZ

Uses lots of oil. Like a litre every 500 miles or so, possibly a bit more. It may leak a bit (there is a leak from somewhere around the oil filter housing) but not that much. There is no oil in the water.

I have seen the odd puff of smoke on start-up (more often when warm) but not that often. No visible smoke when driving. Exhaust does not smell like it's burning oil when cold and the cats are still working so no smell at all once warm. Seems to go ok. I've not yet inspected the plugs to see if they show signs of oil burning. I've not compression tested it either, but aim to do both soon.

Oil was changed just before I got the car (about 2,500 miles ago), PO said he used 5 -30 synthetic. I've been topping up with 10-40.

Indicated mileage is 139k. However, though there is quite a bit of history, there is not enough to verify this. My guess from the general condition of the car is that it's done more, possibly alot more (my 284k '96 C4 A6 seems less knackered in all respects!).

I did replace the (completely disintegrated) breather pipes when I first got the car.

Are there any known failure points - valve stem seals, bore coatings etc that are known to cause excessive oil use?

Thanks

Nick
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Old 19th December 2015, 11:47 AM
mannyo mannyo is offline
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The leak down by the oil filter is going to be the oil cooler, a very common failure as you may find by reading the forum. The usual failure is a plastic pipe between the cooler and the engine, but that usually results in loss of coolant. Oil down there would suggest one of the seals has failed between the cooler and block, its major surgery to repair based on the invoice I had with the old D2.
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Old 20th December 2015, 07:33 PM
Nick Jones Nick Jones is offline
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Thanks.

I'm aware that the oil cooler can be an issue. At this point I have no coolant loss and no oil/water mixing. Also not a massive oil leak so I'm pretty confident this is not the prime cause the of the oil "going missing". I'm not about to get involved in that world of pain without good reason, especially with a wide range of other faults to deal with.

What is the normal range of oil consumption for the ABZ engine?
Are there any breather issues or tweaks that can help?
Are there known bore/ring issues as with some of the other Nikasil technology engines of this era?

It does go ok but the irritations are beginning to outweigh the pleasures.

Nick
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Old 20th December 2015, 08:21 PM
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Goran Goran is offline
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Audi coating is Alusil and as far as I know has not had any problems like Nikasil did.
Check also the joint between transmission and engine. There is a big round seal at the back of the engine hidden by the transmission, this almost always seems to leak as it rarely gets an opportunity to be changed.
Oil can possibly collect in the bell of the transmission? and not be easily seen?
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Old 28th January 2016, 06:10 PM
Nick Jones Nick Jones is offline
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So I've pulled the plugs and done a compression test today.

Compression test was done warm with all plugs out and throttle closed (my initial test showed no difference between open and closed).
All were 15 Bar +/- 0.5 Bar.

All of the plugs on the right hand bank were loose, especially #4 (rear) which also had quite a bit of oil around it. Couple of the others on that side had a bit of oil on them. Clearly the cam cover gasket is past its best.....

Plugs laid out by car position. #1 is top right. Car had partially warmed up from cold, mainly at idle, so colour may not be fully representative.


Couple of slightly crusty ones on the RH bank. #2 and #4


Close up of #2


Close up of #4


Was expecting worse to be honest......

What's it doing with the oil?! Doesn't seem like there is enough on the underside of the car or on my drive to account for the amount going missing.

Nick
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Old 28th January 2016, 07:17 PM
MikkiJayne MikkiJayne is offline
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Have you had someone drive behind you to look for smoke? It can be very hard to see while you're driving.

I've seen a 3.7 32V burn a lot of oil because of dried-out valve stem seals, but that did make visible blue smoke.
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Old 28th January 2016, 08:32 PM
Nick Jones Nick Jones is offline
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I did have someone I know behind me a while back. I didn't ask him to look for smoke, but he's a car person and I think he would have commented had there been anything noticeable. He wasn't there all that long though as he couldn't keep up......

I had a Triumph 2.5 PI a couple of years back that also used lots of oil. That also had really good compressions (presumably because the compression rings were awash with oil as it turned out the bores were rust pitted) but smoked very noticeably both on the over-run and when booted hard. It also suffered from epic blow-by. Of course that is an ancient 2v/cyl engine with no cat, so much less likely to able to burn much oil without making smoke.


Nick

Last edited by Nick Jones; 28th January 2016 at 08:58 PM.
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Old 29th January 2016, 12:29 PM
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Goran Goran is offline
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Silly question, is the sump plastic undertray dry? that thing can soak up a fair bit of oil without letting it drip.

A slightly expensive experiment may be to switch to a heavier ester based synthetic like Titan Race 5W40 for the next oil change. Ester based oil is supposed to swell seals and may slow down or stop small leaks?
My car did't use much to start with but now with the ester oil it practically needs no topping up for 6 months/4000k miles between changes.
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Old 29th January 2016, 07:22 PM
Nick Jones Nick Jones is offline
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No undertray present (yes, it's a bit of a shed!).

You can get "stop leak" additives that I think contain some of the same things. I'm wary.....

Wynns "supercharge" had quite good effects on the Triumphs - stone age engineering though.

Nick
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Old 29th January 2016, 08:02 PM
ainarssems ainarssems is offline
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Valve guides do wear out on 4V per cylinder heads on VW/ Audi and do lead to oil leaking down valve stems but usually it's not much of a problem. When I had my AHC engine apart at 124k miles they were a bit worn but not too bad. Replacing valve guides with bronze ones would have cost me over £1k so I was just going to put heads back as they were because there was not much oil usage, then I found pair of heads that have done only 2k miles since supplied by Audi for £400 so I put them on my engine. I was a bit confused about my oil usage because sometimes it seemed like it lost a lot of oil with very little miles, then again like it gained oil after some more use. What I discovered was that many modern oils (I use Quantum Longlife III) expand a lot when warm so the reading between warm and cold engine varies a lot. The correct way to check oil level is to get engine to 80-90C, switch off and check level after 5-10m to let the oil run down. I found that on warm engine it would show max level, but if I left it overnight it would be just over min level.

Quote:
PO said he used 5 -30 synthetic. I've been topping up with 10-40
I never recommend mixing oils, it's not that bad if it is the same brand but otherwise there are so many oils that there is no way they have all been tested for cross compatibility to make sure additives does not react and cause any undesirable effects when mixed.

I am not a fan of stop leak additives, some may work, some work for a short term or does not work at all. Basically they contain solvents that soak into rubber and make it swell up but can make rubber too soft and brake apart if there is too much of them or if it is exposed for too long. It all depends on materials used in car, condition, additive, concentration and the time used. Think about dried, hard bread, you could use some water steam to get it soft again but if you dunk it in the water it will fall apart.

My suggestion would be- check for leaks and eliminate where possible ( and cost effective), head cover gaskets and camshaft seals are known to leak as ids the oil cooler. Short trips can use more oil than long ones and if you do a lot of short trips it could look like there is no drop in oil level because engine uses oil but replaces lost oil with unburned fuel, then you do a long trip and suddenly oil level drops because that unburned fuel evaporates from oil when engine gets to temp and stays there for a long time.

ABZ engine is fairly old and I don't think it will fully benefit from 5W30 oil, you could use thicker and cheaper Quantum Synta 10W40 to reduce oil usage and save money.
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Last edited by ainarssems; 29th January 2016 at 08:05 PM.
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