07 - S6 Coolant in oil - Complete Engine Teardown

A6 All/ S6 All
#41

I managed to get a few hours to work on this today.

First up was to install the five piston oil spray nozzles in the block. Here they are with the fifteen bolts.

http://audirevolution.net/addons/albums/images/436838974.jpg

The bolts are installed using a high temperature, medium strength threadlocker (loctite 246). The 7649 primer is just used to speed up the cure time.

I re-used the original bolts. If I had to do it again I would buy new ones as it would be much cheaper given the amount of effort required to remove the old thread locker residue from the bolt threads.

I ran an M6x1 tap through all of the threaded holes in the block to remove as much of the original thread locker residue as possible.

Here is a shot of the nozzles installed.

http://audirevolution.net/addons/albums/images/121400996.jpg

Next up was to assemble the block, crankshaft and bed plate together.

Here is a shot of the bolts, seals and bearing shells (upper and lower) that were replaced along with the Loctite 5970 silicone flange sealant that was used to seal between the block and bed plate.

http://audirevolution.net/addons/albums/images/828791489.jpg

In addition to the 24 bolts shown above, there were 28 other 6mm bolts of varying lengths that are used to attach the bed plate to the block.

Here is a shot of the block with the bearings and seals installed. The bearings have been coated with oil to minimize friction during the first initial crank of the engine.

http://audirevolution.net/addons/albums/images/110763349.jpg

Here is the crankshaft, with the journals oiled, installed in the block. A bead of sealant has also been applied. It is certainly not the neatest application job but at least there are no gaps and it is where it is supposed to be.

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Here is the lower bed plate with lower bearing shells installed and oiled

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The block, crank & bedplate assembled

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The tightening sequence for the 24 torque to yield bolts is done in a very specific order in several stages. I will refer you to the manual for the specifics

The last job for the afternoon was bolting the baffle plate to the bottom of the bed plate. It is attached using 21 bolts (which were re-used) that also have a very specific tightening sequence.

http://audirevolution.net/addons/albums/images/99329485.jpg

That is it for today.

#42

I had hopes of getting the PTO unit and the drive chain installed on the back of the engine today so I can install the lower timing cover. This is necessary so I can get the engine back on the stand and start working on the top end stuff.

Those hopes were dashed when I discovered I was missing a small o-ring that goes between the PTO and the end of the block. I do not recall seeing it when I removed the unit. It is quite small and it may have just fallen on the floor when I separated the unit from the block. The problem is I do not see it in the online ETKA diagrams so I am going to have to make a trip to the dealer to look at their parts database. With New Years on Tuesday, this will likely delay the continuation of the assembly process until the end of the week.

Last week while I was waiting for the crank bearing shells to come in, I carried out the following series of measurements on the piston and ring assemblies.

  1. piston diameter
  2. piston ring end gap spacing
  3. piston ring side clearance

Since my initial compression and leakdown numbers were all pretty good, this was more of an academic exercise.

Measuring Piston Diameter

The nominal piston diameter is specified in the Bentley manual as 84.490mm. This includes a 0.01mm thick anti-wear coating on both sides. The minimum measurement is given as 84.460mm

I measured each piston 15mm up from the bottom of skirt perpendicular to the pin. My range of measurements was 84.463 to 84.475mm

http://audirevolution.net/addons/albums/images/567645701.jpg

While doing the measurements, I noticed that some anti-wear coating on one side of some of the pistons was completely worn off. The picture below shows the piston on the left with the wear coating substantially intact while the one on the right is completely gone.

http://audirevolution.net/addons/albums/images/351206908.jpg

Measuring Ring End Gaps

The ring end gap is a very important measurement when engine building. Too much gap and you will have excessive blowby; too little end gap and the ends will touch as the engine heats up. This can lead to catastrophic engine damage.

To measure the end gap, the ring is pushed down squarely in the cylinder bore (till it is about 15 mm from the bottom of the bore) and the gap between the ends of the ring is measured using feeler gauges.

http://audirevolution.net/addons/albums/images/19114294.jpg

The specified ring gaps (new rings) and the range of those measured are:

1st compression - 0.20 - 0.35 mm (new) limit 0.80mm measured 0.35 min to 0.55 max
2nd compression - 0.20 - 0.35 mm (new) limit 0.80mm measured 0.60 min to 0.65 max
Oil scraper - 0.20 - 0.40 mm measured 0.38 min to 0.45 max


Measuring Ring Side Clearance

To measure the ring side clearance, feeler gauges are inserted between the top of the ring and the groove.

http://audirevolution.net/addons/albums/images/140214078.jpg

The specified sides clearances (new rings), limit and the range of those measured are:

1st compression - 0.035 - 0.085 mm (new) limit 0.20mm measured 0.06 min to 0.07 max
2nd compression - 0.005 - 0.045 mm (new) limit 0.20mm measured < 0.04mm
Oil scraper - 0.01 - 0.05mm (new) limit 0.15mm measured < 0.04mm

This is just a note for installing piston rings. The profile of our rings is non-symmetrical so it is important to get the correct “side” facing up. The word “TOP” is etched into the side of the ring that is supposed to be oriented towards the top of the piston

http://audirevolution.net/addons/albums/images/640592314.jpg

I still intend on measuring the cylinder bore diameters but that is going to have to wait till I get the engine mounted on a stand.

#43

While waiting on the o-ring for the PTO unit to come in, I figured I would install whatever other components in the back of the engine that I could.

The balance shaft was first on the list.

Below is a picture of the balance shaft with the end bearing housings and the six seals/o-rings that are being replaced.

http://audirevolution.net/addons/albums/images/866983873.jpg

When installing the balance shaft in the block, care must be taken not to damage the piston oil spray nozzles. They are in quite close proximity to where the balance shaft rotates. You can see them in the picture below just above the balance shaft.

http://audirevolution.net/addons/albums/images/858812690.jpg

In order to minimize engine vibration, the angular orientation of the balance shaft must be set in relation to the crankshaft. To do this, a special setting tool (VAG T40128) is used.

In the picture below, you can see there is an offset slot in the the front end of the balance shaft. This tool is bolted in through the front end bearing holes to hold the shaft in a specific orientation.

http://audirevolution.net/addons/albums/images/555921119.jpg

Once the drive chain is installed and tensioned on the rear of the engine, the crankshaft is set to TDC and the sprocket on the rear end of the balance shaft is torqued down.

I will post up a picture of the rear of the engine once I get the PTO, tensioners and chain installed.

#44

Where did you get the tool? Are there a lot of specialty tools required?

#45

I purchased the two VAG tools below on Ebay from a seller in Germany.

http://audirevolution.net/addons/albums/images/948528423.jpg

The T40116 pins are for aligning the cam guide frames with the cylinder head.
The T40128 is for aligning the balance shaft.

The only other two specialty tools I purchased were offshore knock-offs of the crankshaft locking pin 3242 and two of the camshaft clamps T40070. These are necessary for setting the valve timing correctly

#46

In a previous post, I showed a picture with the baffle plate installed under the crank. Clearly that cannot be installed prior to installing the pistons so I had to spend a couple of minutes removing it. I am a newbie here so I cannot edit my posts to remove the picture. I hope it does not confuse anyone.

I have been waiting on some bolts and more seals to come in so I can finish off the rear timing gear but a mix up in the picking at the local Audi parts warehouse delayed that for another couple of days.

With another weekend here and the desire to keep this project rolling, I decided to temporarily mount the engine on an engine stand so I could at least do some work requiring deck side access.

First up was to measure the cylinder bores to make sure they were within tolerance. As with the ring gap measurements, this was also an academic exercise given the respectable compression and leakdown test results that I had prior to the teardown.

Since I do not have an inside micrometer for measuring cylinder bores, I used a telescoping gauge combined with an external micrometer for measurements.

Here is a shot of the telescoping gauge inserted in the cylinder bore. A square was used to make sure the gauge was positioned normal to the wall of the cylinder.

http://audirevolution.net/addons/albums/images/744288524.jpg

For each cylinder, bore measurements were taken at 25, 50 and 75mm down from the deck surface both parallel and perpendicular to the axis of the crankshaft.

http://audirevolution.net/addons/albums/images/477641648.jpg

The Bentley manual gives a nominal bore diameter of 84.510+/- 0.005mm and a maximum deviation from the nominal of 0.08mm

The majority of my measurements were within the nominal tolerance range which would indicate negligible wear. The largest bore measurements I obtained were the ones closest to the deck surface measured perpendicular to the crank. The largest of these was found to be 84.533mm which was well within the maximum allowable deviation.

With the bore measurements complete, the next step was to install the pistons back into their respective bores.

Below is a picture of the piston and connecting rod assembly along with the new bearing shells and rod bolts. The original shells have also been included to show the typical wear pattern.

http://audirevolution.net/addons/albums/images/20789444.jpg

Although the piston rings rotate during engine operation, it is standard assembly practice to stagger the end gaps by approximately 120 degrees prior to installing the them back in the block

http://audirevolution.net/addons/albums/images/775879234.jpg

Note the arrow on the top of the piston which is to point towards the front of the engine when installed.

A standard band clamp type ring compressor was used to compress the rings to allow the pistons to be slid into their bores. A wooden block was used to gently tap the pistons in.

http://audirevolution.net/addons/albums/images/243660749.jpg

When the connecting rod caps are installed, the molded-in tabs on the pairs of rods sharing the same split crank pin must point towards one another as shown in the picture below.

http://audirevolution.net/addons/albums/images/199670393.jpg

With the new rod bearing shells installed, the last step was to check the radial clearances. Using Plastigage, I estimated the clearance for the set shown below to be approximately 0.044mm. This is midway in the range for new bearing/rod combos (0.020 to 0.069mm) that is presented in the Bentley manual.

http://audirevolution.net/addons/albums/images/872577574.jpg

I was only able to get two pistons (cyls 1 & 6) installed before my budgeted time ran out so I will continue with the rest this later in the week.

#47

Excellent thorough write up and fantastic detailed pictures as always.

#48

Hi eng. amazing work! if you dont mind me askin, where are you located?

#49

Thank you sir

Thanks; Ontario, Canada

#50

The other eight pistons are now installed and the rod bolts torqued. The radial clearances were checked for all and found to be within the range for new bearing/rod combos.

http://audirevolution.net/addons/albums/images/672521232.jpg

Next up was the installation of the upper oil pan.

Here is a shot with the three o-rings, bolts (originals) and a bead of flange sealant applied

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Upper oil pan installed and all bolts torqued diagonally in two stages (5Nm & 14Nm).

http://audirevolution.net/addons/albums/images/339105934.jpg

Here is the oil pump, pipe, all new seals and bolts. The bolts are torqued to yield so they must be replaced.

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Oil pump and pipe installed

http://audirevolution.net/addons/albums/images/950043717.jpg

The engine was taken off the stand at this point so I could continue working on the rear end pto unit and drive sprockets

Here is the PTO unit with replacement seals and bolts (original). The seals for the a/c compressor and the power steering drives look nearly identical but they are actually directional as the two shafts turn in opposite directions.

http://audirevolution.net/addons/albums/images/235485192.jpg

The seals have been installed by pressing in using a socket with an appropriate diameter. Flange sealant is applied around the two drive shaft towers where they pass through openings in the block/guide frame assembly.

http://audirevolution.net/addons/albums/images/538268076.jpg

Here are the drive chain sprockets and the new tensioner and guide tracks. All of the original plastic guides were either severely worn or broke when I removed them because they had become quite brittle.

http://audirevolution.net/addons/albums/images/675565494.jpg

Here is the current state of assembly. I was able to install the sprockets but all of the chain guide and tensioner bolts are torque to yield which are currently on backorder at my local dealer.

http://audirevolution.net/addons/albums/images/473821426.jpg

#51

What’s your best guess of how many hours you have into this?

#52

I honestly do not have a clue.

My garage is like the twilight zone. Time and money spent have no meaning.

#53

Just a quick update today.

The tensioner and guide bolts finally came in so I could finish off the rear drive and timing chain components

Here is a pair of before and after shots. What a difference three months makes.

http://audirevolution.net/addons/albums/images/599861144.jpg

http://audirevolution.net/addons/albums/images/963265264.jpg

#54

;D ;D ;D

#55

Next on the to-do list was to install the lower rear timing cover. This will allow me to get the engine properly mounted on a stand so I can start working on the top end.

Here is a shot of the rear cover parts. The twenty 6mm bolts are torque to yield so they had to be replaced. I just cleaned the 8mm ones and re-used them.

http://audirevolution.net/addons/albums/images/793573648.jpg

I was thinking of pre-installing the rear main seal with the cover off as it would be very easy to press it in without the crankshaft in the way. I decided against this plan when I noticed that the seal lip is at a backwards angle. This requires that the seal be expanded to the shaft diameter using a tapered tool and then slid off onto the crankshaft. I did not have anything lying around with a suitable profile to do that with so I decided to leave the seal install till later.

Here is a shot with the cover installed. I intentionally installed it with the engine upside down. You want to make sure the chains for the cam gears are hanging free when you seal the cover up. It would really suck if the chain(s) got wedged inside the casing and you did not discover it until you already had the heads on and went to install the cams.

http://audirevolution.net/addons/albums/images/100517186.jpg

I decided to let the sealant cure for a day before placing the engine on the stand and rotating it 180 degrees. I used quite a bit of engine oil when I installed the timing components and did not want that running down the inside of the casing and contacting any uncured sealant.

This gave me some time to load up my injectors with new seals and get them installed in the heads.

This may be common knowledge but I only realized about a month ago that the injectors have date codes printed on them.

Here is my collection of 19 injectors ranging in age from 2006 to 2017.

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I would have 20 but I broke one about three years ago when I was pulling them out to get them cleaned. If you look closely, there is a six digit (DDMMYY) date code on each one. My vehicle is a 2007MY so I know that at least one was replaced probably sometime in 2009. I bought three new ones to replace the three originals that I was still running when I started this project.

I purchased this injector service kit about three years ago and I have found it very useful for removing and installing injectors as well as installing the Teflon combustion chamber seals.

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Here is a shot of the ten injectors ready to be installed.

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They just push straight into the head using the tool in the service kit.

I find if you just rotate them ever so slightly back and forth as you are pushing, they go in with a lot less effort.

After giving the sealant time to cure, the engine was mounted on a stand. It was finally time to get the heads installed.

Here is a shot of one of the heads with the new head gasket and bolts.

http://audirevolution.net/addons/albums/images/158309792.jpg

The bolts are tightened in four stages (30, 60Nm, +90deg,+90deg) working from the middle of the head diagonally outwards to the ends. The bolts started yielding part way through the second 90 degree stage of the tightening sequence.

It is finally starting to look like an engine again.

http://audirevolution.net/addons/albums/images/815414419.jpg

Now that the cylinders were sealed, I decided to re-run the leakdown test. The engine is cold so I expect to see quite a bit of leakage past the rings but hopefully nothing past the valves. The cams are not in yet so I do not have to be concerned with making sure I am on the compression stroke for any given cylinder. However, you still want the piston to be at TDC or BDC as you do not want any unexpected rotation of the crank when you pressurize the cylinder. This could wreak havoc with the cam chains loose in the timing cover. I chose to go with TDC as my cylinder bore measurements were marginally larger towards the top of the bore. Also, my previous testing was all done at TDC so it would make for a more logical comparison.

I installed the fuel rails on the off chance that the 100psi test pressure would be enough to push an injector out of the head. It is acting on a very small area but I rather be safe than sorry.

When I first started increasing the test pressure on cylinder 1, I was a little concerned as I could hear a lot of air coming out of the crankcase (no lower oil pan installed) and the cylinder holding pressure was lagging behind the test pressure by about 20 psi. Then all of a sudden once it hit about 70 psi, the sound level of the leaking air dropped dramatically and the holding pressure jumped about 15 psi. This sudden drop in air leakage was a result of the top compression ring being pushed out by the air pressure to seal against the cylinder wall. I had never seen such a sudden change in leakage pressure before. All of the cylinders exhibited a similar behavior at some point as the test pressure was increasing between 50 and 80psi.

Once the rings had “seated”, all of the cylinders showed a consistent leakage of just 5%.

http://audirevolution.net/addons/albums/images/660573394.jpg

Next up will be installing the cams and checking the axial and radial clearances.

#56

Damn 5% on a cold unbroken in engine is fantastic. Best I have seen is 2-3% on a fresh tight prototype build with proper engine dyno break in procedure. Your engine will be right there in spec of a brand new unit.

#57

I am certainly happy with the numbers but these are the original rings so the term “unbroken in” would not apply.

I looked at new rings but the dealer wanted like 130 $CDN per piston. My original compression numbers were pretty good and all my end gaps were within spec so I saw no need to drop that amount of coin on a marginal improvement.

#58

ah true. Yep totally good to use them if they look and spec good. I don’t like replacing parts just “cause your in there” If the part is good, its good. Unless its very cheap lol

#59

The main goal this past weekend was to get all of the cams installed

The first thing you want to do before even thinking about installing the cams is to set the engine to the “TDC” position and install the crankshaft locking pin (3242) . Black pin in the picture below.

http://audirevolution.net/addons/albums/images/873967525.jpg

I am not sure why they refer to it as the “TDC” position because piston#1 is down at least 85mm from TDC when the locking pin is installed.

Doing this is absolutely key as you do not want to try and install the cams with the crank in any other position as you may end up ramming a valve into the top of a piston as you are tightening the cam guide frames down.

What would a progress update be without more measurements???

The only measurements I was interested in checking were the radial clearances in the cam journals. There was visible scoring in the aluminum bearing surfaces and I wanted to see if the clearances were still within acceptable limits.

To measure the radial clearances in the cam journals, the cams were placed on the heads without any rockers or lifters installed. Green Plastigauge strips were placed on the cam bearing points and the guide frame was installed. The bolts were torqued in sequence to 8Nm and then removed again. This procedure was carried out on both heads. Below is a shot of the squashed Plastigauge showing a bearing clearance in the range of .051mm.

http://audirevolution.net/addons/albums/images/170345884.jpg

This was consistent across all ten bearing journals. The Bentley manual specifies a clearance range of 0.024 to 0.066mm. I am towards the upper end of this range. There are no replaceable bearing shells at this location, so the only options are to either leave it be or replace the heads. Needless to say, I went with the former.

Here are all the components laid out for installing the cams on one side. The bolts are all torque to yield so they had to be replaced.

http://audirevolution.net/addons/albums/images/828886860.jpg

The cams are first placed in the guide frame and the camshaft locking clamp (T40070) installed to hold both cams in a specific orientation.

The notorious “oil in the spark plug tube” seal installed and sealant applied.

http://audirevolution.net/addons/albums/images/220347548.jpg

There are no fixed alignment pins to set the cam guide frame in place on the top of the head like you have with the cylinder heads and upper oil pan connections to the block. Short pins such as these would not be much use as there is a fairly substantial gap between the two when you first position the guide frame in place as all the valves are closed.

Audi provides a pair of matching close tolerance holes in both the head and the guide frame for precisely aligning the two parts together. I purchased the VAG alignment tool (T04116) to do this with. It is such a close fit that I had to run a brass pencil brush on my dremel through all four holes individually in order to strip off the thin layer of oxide that was preventing the tools from being inserted. Even then, it was a very close fit just to get it through the hole in each separate part. It needs to be very precise as each part forms half of the bearing journal that the cams ride in. The aligning tools are left in until all the bolts are torqued down and then you use the mini slide hammer out of the injector service kit to get them out

Here is a shot of the alignment pins in place after all of the bolts had been torqued down.

http://audirevolution.net/addons/albums/images/171103051.jpg

I went to start on the other head when I discovered that the guide frame seal was broken where it goes around the end spark plug tube. I probably could have sealed the break with some polyurethane but I decided to wait another few days to get a new seal from Audi.

The next update will likely be the cam gears, chains and tensioners.

#60

You’re freaking awesome. I appreciate and respect everything you are sharing on here. Hopefully one day I’ll be on your level. Lol
-JoN-