eng92, where are you in Canada?
About an hour east of the GTA
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.
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.
Awesome work.
This postal strike has me super annoyed, but I think the feds are going to legislate them back to work
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?
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.
Nice progress! Very much appreciate you taking us along your journey.
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… 
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? 
[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.
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
Wow, amazing work!
I love your attention to detail and thoroughness.
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.
Very well documented process.
Have you considered getting the heads decked a little for a bump in compression? How much room do you have for piston to valve clearance?
Just found that cometic will make you custom head gaskets of your choice of materials in whatever thickness you desire if you want to bump compression.
With the heads assembled as far as I can take them, it was now time to turn my efforts towards the block.
First up was to check both decks for flatness. Since neither head was warped as a result of the overheating, I really wasn’t expecting to find any surprises.
Using a precision ground straight edge and a set of feeler gauges, I checked the two decks for flatness in the 28 positions designated in the image below.
http://audirevolution.net/addons/albums/images/908827384.jpg
The thinnest gauge I have is 0.04mm (~0.0015”) which I was not able to drag out from under the straight edge at any of the measurement locations. I know they give a flatness limit of 0.1mm for the heads, I could not find a specification for the block in the Bentley manual.
I am replacing all of the upper and lower crank bearing shells so the next item I checked was the radial bearing clearances. The quickest and easiest way to do this is to use Plastigage.
For those who are not familiar, it is a simply a strip of plastic with a cross section extruded to a very precise tolerance. It is available in different cross sections which each cover a range of radial clearances. For crank bearings, the package is green and it covers a range of 0.025 to 0.076mm
http://audirevolution.net/addons/albums/images/232627967.jpg
You cut it off in sections (the width of the bearing) and lay them on the top of each crank journal. The bed plate is then installed and the bolts tightened to 30 N-m (22 ft-lbs). The bed plate is then removed and you are left with flattened pieces of Plastigage sitting on the top of each crank journal. There is a width gauge printed on the side of the package that you compare the deformed section to. Obviously the wider it is, the less radial clearance you have.
The bearing shells are available in different colors which represent slightly different thicknesses.
According to the Bentley manual, the color code for the each of the six upper bearing shells is supposed to be stamped into the side of the block up at front on the left hand side.
http://audirevolution.net/addons/albums/images/51819807.jpg
I could not find any six letter stampings anywhere on the block. The next place to check was the original bearings themselves as they should have a paint marking on the side of them (either blue, red or yellow). I believe all the cleaning I did with the heavy solvents must have dissolved any paint marking that may have been on them. The ETKA system at the dealer does not have the bearing colors for specific VINs either.
I decided at this point to take a little bit of a leap of faith as the code GGGGGG was stamped into the face of the counterweight on the end of the crankshaft
http://audirevolution.net/addons/albums/images/359247243.jpg
and there were also “G”s stamped next to each journal on the bed plate (circled in yellow below).
http://audirevolution.net/addons/albums/images/84727608.jpg
“G” is the code for yellow.
According to the Bentley manual, both of these locations are for the lower (bed plate) bearing halves. Without any better information available at the time, I decided to order yellow for both upper and lower and see what the results of the radial measurements showed. The bearing shells are relatively inexpensive so if I had to get six new upper ones, it would not be a big deal.
The radial clearance measured using the Plastigage on the crank bearing journals was in the 0.076” mm range for all six journals (picture below).
http://audirevolution.net/addons/albums/images/385864725.jpg
The Bentley manual specifies a radial clearance of 0.017 to 0.044 for new and a wear limit of 0.08 mm. Mine were all too close to the wear limit for my liking so it was time to get a precise measurement of the actual journal diameters and select bearing shells accordingly.
I measured each journal at two different locations around the diameter and found all twelve measurements to be in the range of 64.960 to 64.964mm.
http://audirevolution.net/addons/albums/images/846792365.jpg
Using the chart in the Bentley manual, this corresponds to the “blue” bearing shells.
http://audirevolution.net/addons/albums/images/651491580.jpg
I had new “yellow” ones installed for my initial radial clearance measurements.
Of course when I called up the Audi dealer, the “blue” ones have to come from Germany. The “yellow” ones I purchased initially were in stock at the local warehouse.
With the holidays upon us, this adds another two to three week delay to the project.
nice thorough process. This is the proper way of rebuilding an engine and adds significant cost over just teardown and reseal for someone having it done for them.
From the audi engines I have been in, seems yellow code is nominal. Good you ordered the blues, keep everything in exact tolerance.,
Wowwwwww Eng92. Didnt know you were rollin like that.
This is a well narrated post. I really appreciate it. Now I need to clean out my garage and drop my engine too but all I have is an engine hoist, jack stands, and a small motorcycle jack. The motorcycle jack you have is huge!
I plan on engine hoisting the the body frame and dropping the engine .
There are a number of different ways to get the engine/tranny out. Whichever way you choose, just be safe as you are dealing with a substantial amount of weight.
Unbeknownst to me, the parts guy at the local dealer rushed the “blue” bearing shells in for me UPS red. I was not expecting to see them till the second week of January but he called yesterday to say they had just come in. With a four day weekend ahead of me, I am hoping to make some good progress.
Last night, I swapped out the yellow shells for the blue ones and re-checked the radial clearances using Plastigage.
Below is a comparison of the difference in the width of the compressed Plastigage pieces between the yellow and blue bearing shells. The Plastigage using the blue shells is noticeably wider. It was consistently in the 0.051mm range across all six journals.
http://audirevolution.net/addons/albums/images/842711398.jpg
The increase in bearing shell thickness resulted in roughly a 30% reduction in the measured radial clearance which puts them much closer to what would be expected in a new engine.
The last clearance to check prior to commencing the assembly of the bottom end is the axial play in the crankshaft. The Bentley manual specifies that the axial clearance should be in the range of 0.090 to 0.158mm.
In the picture below, you can see that the axial clearance is 0.004” (0.102mm). The measured clearance being at the low end of the specified range is a direct result of replacing the thrust bearing set.
http://audirevolution.net/addons/albums/images/915406529.jpg
Now I can finally move along and start putting the bottom end back together.