07 - S6 Coolant in oil - Complete Engine Teardown

A6 All/ S6 All
#15

The VAG unit is pretty slick with the two separate sliding halves on the top so you can easily separate the engine and tranny.

I had to leave the tranny supported on the lift and then sling the engine from the crane while I took the bolts out. It was a bit of a struggle as when you are lifting the engine, you have no idea how evenly you are supporting it until it lets go from the transmission.

It should go back together easier as I can use the two straps to get the engine at the correct angle and then use the bolts to pull it and the tranny back together after the shaft and the pins are aligned.

#16

Thanks for the lead. What is the mileage? Are they out of an engine that suffered external damage so it could not be sold as a running unit?

#17

There was not much progress this week.

The rotating postal strikes up here have delayed the arrival of some of the things I need to move forward by a few days.

Here are pretty well all of the parts I have received so far.

http://audirevolution.net/addons/albums/images/331765063.jpg

There are a few items there that do not have to be replaced when overhauling the engine.
I am just replacing them because it is so much easier to do with the engine out.

The small flex sections in both of my y-pipes had rotted out so I decided to replace those. The right side can be done with the engine in the car. The left side cannot.

I am also replacing all eight O2 sensors because they are not that expensive and I believe 6 of the 8 require an engine drop to replace anyways.

Here is a list of everything with p/ns and descriptions. There are 85 different parts which, with the multiple quantities required for some parts, combine for a total of 400 parts.

I apologize for the size of the text. From what I can tell, this forum does not allow either the height or width of an image to be greater than 2000 pixels. I will reformat it into two columns in a later post.

http://audirevolution.net/addons/albums/images/838335127.jpg

#18

Extremely impressed man.

#19

Those flex sections can be done in car, did them a few weeks ago on a guys. It was very difficult to do the driver side.
And only if you are ok with MIG weld, and not stainless TIG.
It also helps if you have a 120 or 90 degree mig gun, the regular 45 is very difficult to get up at the top. My weld was probably the ugliest thing I have ever laid on top of the driver side…not happy with it…
What helped was dropping that steel cross member out of the way and pulling the O2 sensor.
Veracious Motorsports were the only ones I found that carry 1.5"x4" full stainless joints.
But its nice you just got brand new pipes. Get another 10 years or so out of them.

#20

Great thread, and good to see another fellow Canadian (I’m in Manitoba)

I’ll be pulling the engine at some point this winter and doing much the same, even if it hasn’t failed on my car yet.

I’ll make sure to take pics as I’ll be doing this without a lift. We did an engine removal at a friend’s garage on a 2013 M5 and we just took the front end off (which I’ll do) and swung the A/C condenser out of the way and jacked the car up and away from the engine sitting on a furniture dolly. Worked pretty good.

#21

eng92, where are you in Canada?

#22

About an hour east of the GTA

#23

looking at the picture of all the gaskets and parts is almost exhausting cause you know just how much work it is to put all of that where it goes.

Great job keep up the good work and the fun updates.

#24

There has not been much progress in the last couple of weeks as I have been waiting on a few items to arrive. Our postal strike has certainly impacted my project timeline somewhat. I have come to the realization that this is probably going to stretch out over a few months so I broke down and bought a car cover to keep the elements (and bird crap) off the car over the winter.

I was able to get one of the heads somewhat clean using brake cleaner and a nylon brush. A dremel was used with a few different shaped brass wire brushes to clean inside the intake and exhaust ports.

The carbon is gone at least until I start the engine.

http://audirevolution.net/addons/albums/images/649327274.jpg

Before installing the new valve stem seals, I checked the guides for excessive wear by measuring the valve tilt using a dial gauge.

http://audirevolution.net/addons/albums/images/473390642.jpg

They were all in the 0.010” to 0.020” range (0.25 to 0.5mm)

The specified limit is 0.8mm.

In the Bentley manual, if the valve guides are worn beyond the limit, they tell you to replace the head. The valve guides are not even identified in ETKA as a separately available part. It is a good thing there are several aftermarket companies that have them available.

Each valve and seat were also checked for proper sealing using a layout marking method I found in a machinists forum. I originally started with a Prussian blue layout fluid but that was too messy and took too long to dry. A thick Sharpie marker will do the same job and is much easier to control where it goes. All the valve seats were covered with black marker and then hit for a few seconds with a heat gun to make sure it was completely dry so it would not smear.

http://audirevolution.net/addons/albums/images/67827310.jpg

The corresponding valve is then installed and rotated a few turns using a lapping tool. Ideally, there should be a uniform width area around the circumference of the seat where the marker has been removed through rotating contact with the valve. If there are areas where it remains, these are points of non-contact (“low spots”) and further lapping or grinding operations would need to be carried out.
I found minor pitting on pretty well all of the valve seats. The intake port on the right in the picture below was one that had the most significant pitting.

http://audirevolution.net/addons/albums/images/965431121.jpg

I just placed an order for a variety of different “grit” diamond pastes to do some lapping operations with. I ordered them from a Canadian vendor (who ships by Purolator) so I am hopeful they will arrive by the weekend.

#25

Awesome work.

This postal strike has me super annoyed, but I think the feds are going to legislate them back to work

#26

Nice work. My engine was done awhile ago. Link to my thread.
http://audirevolution.net/forum/index.php?topic=4228.0

Living in the Nashville TN area now. Anyone else?

#27

The diamond pastes arrived this past Friday so I was actually able to make a little progress this past weekend.

The factory valves and seats have almost a mirror finish on them. My initial goal was to get something close to that as the smoother the finish, the more points of contact you have between the valve and the seat and the better the heat transfer. A true mirror finish would require polishing down to the sub-micron level. In my opinion, I do not think that is achievable in a home garage using the equipment that I have available in a realistic amount of time. I therefore decided that 7 micron (~2800 grit) was the finest paste that I was going to use.

Traditionally, I have always lapped valves by hand using a lapping tool which is essentially a plastic or wooden rod with a suction cup on the end of it. With 40 valves to do and multiple paste changes for each one, I figured I would look for a more efficient (ie. less manual) method of doing it. I saw there was a number of You Tube videos of various individuals using pieces of vacuum tubing stuck on the end of the valve stem with the other end in the chuck of a cordless drill.

I gave it a shot on the first valve and soon decided that it was not the method I wanted to use in my particular application. It would be ideal if you are just using a single valve grinding compound and had no need to clean the valve and seat periodically to check the progress. Two of the more subtle things I did not like about it were that the sound of the drill masked the sound of the grinding action and you have minimal feedback through the drill regarding the grinding as compared to when you do it by hand.

I also quickly found that the suction cup alone on the lapping tool was not going to be sufficient to adequately stick it to valve. Our intake valves have a concave center section and I found that no matter how well I cleaned and dried both the valve and suction cup, it would not stay stuck while lapping for more than about 30 seconds before it would begin to slide around. I tried spraying belt dressing fluid on the cup to soften the rubber a little but that only marginally improved things. I ended up sticking Velcro discs to the valves and screwing the mating Velcro section to the end of the lapping tool. That combination worked quite well.

Here is a picture of head with the “Velcroed” valves and the assortment of lapping pastes I used.

http://audirevolution.net/addons/albums/images/443629343.jpg

I initially started with a 40 micron paste and found it was taking longer than I wanted to get rid of all the pits on the valve itself. I switched to a valve grinding compound (using just light tool pressure) and that took care of all of the pitting in under a minute for just about all of the valves. I then progressively worked though the various “grit” pastes from 40 down to 7 micron.

As a check, after all the lapping was complete, I once again marked the seats with a Sharpie and checked for low spots. All of the valves (in this head) were found to have full seat engagement.

Next up was to install new stem seals. These just push on fairly easily with the use of an insertion tool. A little lubrication and a small plastic sleeve over the end of the valve were used to make sure the lip on the seal did not get damaged during installation.

http://audirevolution.net/addons/albums/images/547207287.jpg

Installation of the valve springs, discs and keepers is about the same as you would find on most DOHC engines.

Here are a couple of pictures of the completed, clean cylinder head compared with the one I still have left to do.

http://audirevolution.net/addons/albums/images/627456288.jpg

http://audirevolution.net/addons/albums/images/519815824.jpg

I am going to wait until I get the heads bolted to the block before I install the cams. This way I can do a leakdown test without concerning myself if any of the valves are open. It is also a lot easier to torque all the cam guide frame bolts down when the head is bolted down to a block on an engine stand.

I am going to proceed with the other head next as there are some items I am still waiting on before I can move forward with the block.

#28

Nice progress! Very much appreciate you taking us along your journey.

#29

This thread is amazing. It’s almost like a Bentley Manual or ELSAWIN if you ask me :). I’m a man who has never repaired a car and this V10 is my first that I’m putting my hands on. Starting from the harder ones… :frowning:

Your motor seems clean when you took it out of the car, even the oil pressure switch you pointed out to me is cleaner than mine. I’ve got a rusted one.

To be honest, will you consider doing that on my car, just for fun? :slight_smile:

#30

[quote=“Ats,post:29,topic:10248”]
It should look fairly new. I replaced it a year and a half ago when my low oil pressure warning light was coming on intermittently.

#31

eng92,

By far one of the best write up’s I have ever stumbled across. Really appreciate all the Knowledge you are sharing with this great community of S6 owner/enthusiasts.

Thanks again

#32

Wow, amazing work!

#33

I love your attention to detail and thoroughness.

#34

Thank you for the kind words folks. I hope some find this thread useful if for nothing else than the pictures showing what the engine internals look like.

If by chance, you are looking for valve spring compressors, you will see a couple of different basic types at the local auto supply store

http://audirevolution.net/addons/albums/images/733333332.jpg

The cheap one on the right is meant for pushrod engines with overhead valves (OHV). These will not work on our cars (or probably most other OHC engines) as there is no room to hook onto the spring coils. The one on the left (that I use) is the type required for OHC engines. You should be able to get one for $50 or less.

Of course it only works if the head has been separated from the block as you need access to both ends of the valve.

http://audirevolution.net/addons/albums/images/682011110.jpg

The VAS 5161 tool presented in the Bentley manual is pretty slick as it works from one side of the head so you can replace any leaking valve seals with the head still installed.

http://audirevolution.net/addons/albums/images/240890295.jpg

I believe they go for about $800 although I imagine there would be cheaper knock-offs available.

The second head went much quicker than the first as I already had all my parts and shop supplies.

Here is a shot of the cleaned head with all 120 parts ready to be installed.

http://audirevolution.net/addons/albums/images/138971493.jpg

Here are both heads now complete and ready to bolt onto the block.

http://audirevolution.net/addons/albums/images/407267976.jpg

Too bad the block is not ready for them.

http://audirevolution.net/addons/albums/images/31694397.jpg

Now I have to take a break from this for a week or so to finish off some home reno projects before family starts visiting for the holidays.