forum.audiv8.com Foren English Audi V8 Forum oil consumption and pressure

As some may be aware, my car is currently running a 4.2 ABH engine in my 1990 (PT) car. I have been keeping an eye on oil consumption for a while, as the engine is a bit of an unknown quantity, and has a tendency to blow some oil smoke on hard acceleration, especially when doing a lot of acceleration/deceleration.

The engine is running the original electronics and injectors for the PT engine, with an 'ABT' derived eprom in the ECU. De-cat'ed. The exhaust is a hybrid of PT manifolds, x-pipe, cat pipes (minus Cat honeycombs), and the rear exhaust from the ABH setup.
the odometer on the donor car indicates 145k miles, but I suspect it is more likely 200k mile plus.
Emissions at the last MOT were well within parameters. There being negligible difference between values with Cats and 3.6L engine, and without Cats on 4.2L engine.
Oil pressure is consistent at about about 1.8Bar idle in park or neutral, and 4.5Bar on load.

In general, oil consumption has been in the region of that quoted by many sources, 1-2 litres per 1000miles. I've mostly been doing motorway miles, at about 70mph. Fuel consumption has remained fairly consistent at about 25-26mpg, 17-18L/100miles. It increases markedly when doing lots of town driving. I have also noticed there is a greater tendency to smoke after an abrupt right hand bend, followed by acceleration. ie. UK roundabouts.

When I installed the engine, a compression check showed comparable values across the 8 cylinders. I shall of course do another, and record the values this time.

My initial thoughts were that the valve guides and stem seals are in need of replacement. (I once before had issues on a WR engined quattro, where the seals were breaking up, resulting in part of a seal remaining on the guide, and part of it travelling with the valve- that then encourages oil to be squeezed down the guide.) they probably are in need of attention.
I removed the throttle assembly recently, to clean and inspect. I found that there was a small amount of oil pooled in both the upper and lower chambers of the intake assembly.

In the last week, I have watched oil consumption apparently increase, but not consistently. In some cases, it appears to be not using any oil at all, other times it appears to be using more.
I top up the oil whenever it approaches the minimum mark. I also top up to just below max if I am going to be driving in excess of 200miles. I routinely check oil at rest stops.
On todays drive, after about 2 hours continuous driving at about 70mph, I noticed that oil pressure had increased, and was remaining high. Off scale, even.

So. my points to raise discussion and gain some feedback.

I have a suspicion that oil is being pushed through the breather system.
I know there is a small weep of oil from the rear of the left head gasket. Evidenced by oil tracking down the crank position sensor and lambda cables.
Sometimes, I get a smell of burning oil when driving, with no evidence of oil being blown through the exhaust. I expect this is due to accumulated oil dripping on the lower end of the manifolds/cross pipe.
There is plenty of evidence of oil being retained in the left hand cylinder head.
Sometimes, the oil level appears completely unchanged after several hours of driving, even though there is plenty of evidence that it should have burned some oil.

questions and hypotheses. Is it possible that oil is being trapped in the cylinder head? The cause of this might well be down to one or more blockage in the drainage/passages back to the sump. What about the oil retention valves? Can these/have these any history of problems causing oil to accumulate in the cylinder head, or in the breather system?

Smoking, on throttle. Various amounts, but particularly noticeable on large throttle changes.

Oil and filter were changed yesterday. There was a trace of debris in the oil. Fine metal non-magnetic 'dust'. A large item that came out was what looked like a calcium fragment about 1mmx1mmx0.5mm in size.

Compression check shows,
#1-7 = 13bar to 14.5bar.
#8 = 9bar

Plugs, all tend to be darker
#1,2 dry, a little dark
#3,4 wet, oiled
#5,7 dry, a little dark
#6,8 wet, oiled

Only #8 correlates lower compression with an oiled plug.

choices-
rag it until it dies spectacularly
mothball until time and (another) replacement engine is sourced. (planning on this option)

Is there anything I should be aware of?

And if anyone has a good 3.6 or 4.2, long or short engine, I'm interested. Again

ABH and ABZ engines.

Faced with being engineless again, I'd like to investigate whether the top end of these 2 engine variants are interchangeable. One reason for this being the relative lack of Audi V8s originally in the UK, compared to A8. So good engines are hard to source.

ABZ engine has been fitted to a 'V8' chassis, but how do you accommodate the coil pack/distributor-less ignition?
There's a number of components common between the 2 engines. I wonder if this goes far enough to make it possible to swap major parts about.

options-
Option 1. A full rebuild of the current engine. My concern with this is that I do not know at this stage where the problem lies.

Option 2. Will the heads from ABH fit ABZ? Then, a good bottom end from ABH could be mated toABH heads, and retain original ignition/ECU/EFi

Option 3. ABZ complete swap, including electronics. Having just stripped a V8, including removing wiring harnesses, this is something I would rather not contemplate just yet.

Option 4. Install ABZ, and convert/modify current electronics.

any advice, knowledge gratefully received. If anyone knows of information in the german language section, this could be translated to assist.

Ask Martin A. he is building a AEC bloc with ABZ heads.

Yes. All fits but you have to change/modify the camshafts.
You can install ABH/PT camshafts or you modify the ABZ camshafts (shorten and add the nut for the distributor).
Valve guides from Audi 1.8T, valve stem gasket from Mercedes (Viton material!!).

I'm on the way to built a AEC block with ABZ heads :)
AEC has a different waterpump than ABH (dia of the pulley).

That's excellent news.
I shall look at building a ABZ/ABH/PT hybrid over next winter, or sooner if time allows.

I have all the components that were left over from the PT engine. So, spare cams there.
The current ABH may or may not survive. The jury is still out on that one.

I'm thinking about installing a free ECU like Mega Squirt and install Coils on Plugs like ABZ has. Extra trigger wheel (on pulley or S6+ or S8 flywheel (60-2 trigger) and using the standard ABZ hall sensor to have real COP.
With that I could adjust a fuel trim and also a spark "trim" for each cylinder because the manifold and my hand work on the heads isn't perfect (perfect only CNC can do).

But I also think about using a ABH ECU with stock hardware (distributor etc.) but with extra mapping. Then you have to install ABH camshafts (because of the distributor) or to modify the camshaft. One camshaft end is longer than ABH camshaft and without nut for the distributor. Shorten and make a nut.

Here you find pictures of both parts:
Head: http://www.v8schmiede.com/include.php?path=forum/showthread.php&threadid=43
Block: http://www.v8schmiede.com/include.php?path=forum/showthread.php&threadid=63

I only would use ABH/AEC engine parts, because there are some differences between 3.6 and 4.2 (extra pins for the cambelt and some other details).

I will need some time to fine this project because I only can work one weekend in a month, when I visit my parents (500km away from my work where I life).

you mean notch not nut?

Jipp...