degimus

Recently purchased 04' A8, it has extremely loud engine knocking sound and excessive oil sludge.
The noise was pretty loud at first but then after 5 min of engine running the noise would go away. Then about week later the noise would not go away and became louder. So we opened the Head Case and discovered that there is excessive oil sludge and build up. We believe that the oil is not circulating properly.
Also we need torque specs in order to repair the cams from the oil sludge build up.
WE NEED ANSWERS TO THIS POST AS SOON AS POSSIBLE FOR WE ARE NOW WITHOUT A CAR. THANK YOU FOR ALL YOUR HELP

snapdragon

I would search ebay for ELSAWIN and buy the official manuals due to all the peculiarities, torque settings, procedures and precautions that can't be guessed at this level of engineering.

degimus

Do you think that "ALLDATA.com" would be sufficient with detail on an automobile with this level of engineering?
I'm not familiar with the ELSAWIN. Is some sorta of comprehensive manual for high end automobiles? What is the cost?

On the other hand, i have used diesel in crank case to help breakdown oil sludge, I just wasnt sure if there was a common issue with the engines.

I was hoping that i could meet someone who has went through something similar

bmwm750

Wow. Someone didn't change the oil in that car nearly often enough. I'd pull the oil pan and have a look down there as well.

You might be able to save this motor, but it's not a fun adventure.

You can use diesel and ATF to break down the sludge and deposits, but the problem is that you can't always be sure where they go once loosened up. On a modern motor like this, the oil is used for more than just a lubricant, but also as a hydraulic fluid, and there are many oil pathways which are very small, and can easily become blocked.

If you want to try cleaning this up without tearing the motor down, I would put the valve covers back on, drain the oil, fill the motor completely up with diesel fuel. Let it soak for a few days, then drain it from the drain plug. Do this again at least once. Then repeat using ATF. Then fill the motor to the proper level with cheap engine oil. Start the motor and let it idle for a few min. Drain this and change the filter. Fill again with engine oil and start the car again. Drain the oil again.

If all this goes well, you will have removed a substantial amount of the sludge and deposits, but there are no guarantees that you haven't inadvertently blocked some oil passages.

If you get lucky and all is well, you can then pull the valve covers again, and manually go in there and clean up the head area. You could pull the cams, and if you do, I would replace the lifters any any oil solenoids. Then pull the oil pan and clean the bottom end of the motor and oil pump/ screen.

As far as torque specs and procedures, alldata can be hit or miss on the German cars. If you pull the cams, you will need the cam timing tools to re-time the motor, and while you're there, I would also do the timing belt/ water pump/ t-stat/ service.

Good luck.

mishar

+1

In my opinion the best way is to replace this engine. Junk yards already have them.

dvs_dave

Wow. The engine has clearly been very neglected. How many miles does it have? What condition is the rest of the car in?

With that much gunk and the engine already making a loud knocking I fear it may be too late and it's already developed the death rattle. Consider looking at junk yards for replacements as this motor will likely only give you more problems.

Mister Bally

There is prrof why you must use oil with the VW 502/505 designator. Although the '04's did not specify this in the owner's manual. VW/Audi changed this andf sent out pamphlets and decals to be placed in the engine compartment. A fossil based oil will look like that in a super hot engine (the Audi 4.2's run really hot) soon after the recommended interval is exceeded while a full synthetic like those with the VW 502/505 designator will just get thinner as they are used past their recommended interval.

A Bently or Elsa manual will be of little help for troubleshooting. They merely give disassembly and assembly procedures. You will need one of these manuals for torque specs so best to buy one. You really will just use basic mechanical engine troubleshooting skills to determine the knocking cause as you disassemble the engine.

My guess, and this is only a guess as I did not hear the noise nor how it changes with varying speeds loaded vs. unloaded; Connecting rod bearings have play caused by wear from poor lubrication. Both around the crankshaft as well as the ones around the wrist pins. Basically you replace them all and all wrist pins. You may find that the crankshaft has worn surfaces as well. Heck, since the pistons have to come out, all piston rings should be replaced.

I'd buy a cheap car for current transportation needs. You are looking at a few week job if doing a few hours at a time here and there. I assume this is the case as full time shops would not likely post questions about a job requiring this much effort.

bmwm750

My guess would be worn rod bearings, and maybe main bearings. This motor is likely not worth even tearing down. 4.2's are a dime a dozen at salvage yards, and unless you've got the mechanical know how, and want a serious project (like maybe building this into a strengthened, lowered compression motor to run major boost on or something of the sort), it's just a viable option.

mishar

There is a guy turning an apparently better engine into a coffee table.

NeonAudi

How did it all turn out?

Could an engine flush dissolve that sludge?