07 - S6 Coolant in oil - Complete Engine Teardown

A6 All/ S6 All
#91

It has been a few weeks since my last update. The arrival of spring and the additional home and yard maintenance items that come with it have limited the available time I have to work on this project.

The engine went back in without any noteworthy issues. I left the front drive axles out and the suspension disconnected initially. This way I could start the engine up and confirm that there were no fluid leaks that may require the engine to come back out.

I came across my first issue when I first keyed it up after finishing the electrical and reconnected the battery. I just turned the key to the ON position and after a couple of seconds, the word “SAFE” was displayed on the cluster where the trip meter normally appears. I thought that was strange as I have never had the immobilizer lock me out after having the battery disconnected for an extended period. I left the key in the ON position and went and grabbed my VCDS tool. I then keyed it off, plugged the HEX-NET tool in and keyed it back on. The instrument cluster remained dark and the scan tool would not connect. Battery voltage was good and all the relevant fuses metered out ok. After a bit of searching online, I found that if you turn on your hazards and high beams and press the brake pedal, VCDS can connect and you will have access to a limited number of modules. I did this and then ran an autoscan, cleared all the codes and the next time I keyed it up, the cluster came back to life. This time, “SAFE” was not displayed in the cluster. I thought this was promising, so I turned the key to start and there was nothing.

I redid the autoscan and found it was still not connecting to some of the modules, most notably the engine, transmission and immobilizer. I had a fault code in the start access authorization module for an “open or short to ground on terminal 15” A quick review of the wiring diagrams pointed to the J329 power supply relay being the likely culprit as I knew the fuses were good and I had not disconnected anything inside the car when I dropped the drivetrain. This is the “370” relay under the dash on the LHS.

I removed it and connected the relay coil terminals directly to a 12V power source and nothing.

After ordering a replacement and installing it, I turned the key again to the ON position and “SAFE” was once again displayed in the cluster. The engine will start and run for about a second before the immobilizer shuts it down. I did this about ten times so the ATF pump could draw up some of the fluid out of the pan. I started with about 3.5 L of ATF in the transmission as that is the point where it started to drip out of the filler hole. After bumping the starter about 10 times, I am only down 1.5L from what the ZF states as the capacity. I want as much ATF in the tranny that I can get in case someone inadvertently decides to take it for a “spin”.

There is a VW dealership about 5 minutes from my house. After talking with a VW tech, I found out that although they use the same software as Audi, they have to access different systems as far as the immobilzers are concerned so they cannot do anything for me. I will have to get the vehicle towed to the closest Audi dealer which is about 30 miles away.

The car is at the dealer right now and is ready to be picked up but I cannot get a flat bed in there till tomorrow night.

#92

That’s a major bummer. Please let us know why the immobilizer kicked in when you find out. I had always thought as long as you disconnect the battery there would be no issues.

#93

A few things to try that might help.

With the key can you unlock the doors.
Can you turn on the radio with key on ignition.
Try swapping the ECU location of each ECU to the other side. Its happened that the slave goes into the master harnus it will give you a safe lock.

I have had this happen in the past and I just left the key in the key on position for about 45 min. But also know that if there isn’t com between the dash the key and the ECU you will get an immob issue. The car starting shows the ecus are working but something isn’t communicating at some point.

The fact you can’t com with the ECU with vag com to me says that’s what you have to really look into.

#94

All of the other electrical (radio,doors, seats, windows etc.) worked fine

I labeled the ECUs master and slave before I removed them from the vehicle

This was not effective

That was before I changed out the failed “370” J329 power supply relay. Once I installed a new one, I was able to connect.

#95

I do not think you will find a definitive answer on this.

Before arranging to get my vehicle towed, I talked to two Audi, one VW and a local indy tech who specializes in Audi/VW. The general consensus with the immobilizer 4 system is that it is kind of hit or miss when you disconnect the battery for an extended period whether the system will go into “safe” mode or not when the power is restored.

#96

Will the key work to unlock the doors.

You dais the techs said system 4. I never heard of system 4.

I know its the
dash
key
ECU

But that being said. Try connecting the power and then disconnecting the power. maybe that will kick on the immobilizer.

Can you connect to the ECU in vag com now.

#97

Yes, the key will unlock the doors (both mechanically and electrically)

There are plenty of online resources for the different generations of VAG immobilizer systems

Here is one: http://wiki.ross-tech.com/wiki/index.php/Immobilizer

That was not effective

Yes, once I replaced the failed J329 relay, I can connect to all of the modules (including the engine).

The immobilizer has been reset at the Audi dealer. The engine runs and the vehicle is back on the lift in my home garage to complete the re-assembly process.

#98

Things are looking good so far.

I had it up on the lift idling for about 20 minutes last night while I topped up the ATF level. Nothing was dripping (other than the water out of the exhaust). There were also no drips on the floor under it this morning.

If I have time tonight, I will put the headlights and bumper cover back on so I can take it for a spin.

Here is a current shot of the engine bay

http://audirevolution.net/addons/albums/images/38724649.jpg

#99

amazing work eng92! now for some full car shots!

#100

Did you also replace the oil cooler? If not, how did you Determine it wasn’t a contributing factor for oil leak?

#101

No, I am still using the original oil cooler.

I thought I made a post regarding this but could not find one when I went back through this thread.

I did a low pressure test on the coolant side. I plugged the coolant pipe on one side of the cooler and then filled the oil side of the heat exchanger with solvent. I then connected a regulator and an air line to the open coolant pipe. I set the regulator at about 15 psi and then watched for signs of bubbles to surface in the solvent. None had appeared after about 20 minutes so I considered it a pass.

#102

I have put about 1600 km (~1000 miles) on it in the last few weeks and everything is good so far. It is running better now than it has in the last three and a half years that I have owned it.

My coolant level in the reservoir has been rock steady. Prior to the engine rebuild, I would have added at least a litre by now given the distance driven.

I had it on the lift last night and did not come across any signs of early oil leaks.

Also, I think it is the first time ever that my misfire counts have all been zero for any length of time.

http://audirevolution.net/addons/albums/images/576199894.jpg

Only time will tell how long that will remain the case.

#103

Whoa, hold on! How do you get the scan tool to come up the the MMI screen?

#104

So glad all this hard work has ended up in such great results.

What would be the top 5 things that you found in the rebuild that everyone should know.

Also that is neat on the vag com. Is that via aux port? Do you have full control?

#105

assuming that’s some sort of Android box replacement for the MMI

#106

This thread is legendary and in my opinion should be permanently posted to the top of the S6 page.

Also now that the rebuild was deemed a success, what’s your verdict as to the cause of the disappearing coolant?

I imagine it could be a combination of things but i’m curious what you think having gone through the motor with a fine tooth comb.

#107

I don’t recall there being anything totally unexpected or especially noteworthy during the project.

If you have patience, perseverance, the tools and the FSM, you just take your time and work through it methodically.

Unless you have severely overheated your engine to the extent that I did, there should be no need to tear things down to the bare block. If you do need to do this, then:

  • Organization is key – group, bag and label all your smaller parts during disassembly

  • Take lots of pictures during disassembly – especially the electrical and plumbing

  • Use an online Audi parts database to identify all the seals and bolts, etc. that you need as you work through the disassembly process – This should save you some time and frustration at the dealership. I would just email my parts lists to the local dealer and then pick them up the next morning.

It is an Android touchscreen communicating wirelessly with the HEX NET interface in AP mode.

I originally installed the touchscreen last year so I could run a more modern navigation app. It was only after I installed it that I realized I could just install VCDS mobile and not have to use my phone or laptop.

The MMI interface is still there. An FM transmitter broadcasts it to the touchscreen. It automatically switches to the back-up camera image when you shift into reverse.

#108

I never did really find any obvious signs that any of the coolant pipe/passage seals were leaking when I did the teardown.

I know in Greg50H’s case, the leak was at the o-ring seals where the internal coolant pipes run through the cam covers at the back of the engine. I inspected all four of my seals and there was no erosion of the o-rings or the seats.

After changing every seal and gasket in the engine, I have not seen any coolant loss in the thousand miles I have racked up so far. It may still be leaking internally, but it would be at a greatly reduced rate compared to what it was.

I will be looking forward to seeing the Blackstone results after my first oil change.

1 Like
#109

Excellent documentation of this build process. Thank you for doing it. The time and cost seems daunting to rebuild the motor, but I thank you for doing it.

#110

@eng92 what an awesome thread (need more words to describe how cool this is) it is a dream of mine to do this some day.

by any chance do you have the original photographs from the build? none of the links in the thread seem to be working, this might be a factor of the forums moving to the new format.

Even more ideal would be if a moderator could somehow get these links to work once again.