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Tuesday, September 27, 2011

Mercedes Engineering

Mercedes engineering at its best in this 1992 Mercedes Benz 300E 4-Matic. I know it isn't an Audi but when testing both the 4-Matic and Quattro systems, neither showed a significant increase in acceleration on both straight and flat, upward grade, or cornering. Smooth shifting, sleek lines and an inline 6 cyl brings the classic 300E to the top of my list for quality classic luxury.

Saturday, September 17, 2011


I will start out by stating that you DO NOT HAVE TO REMOVE THE TIMING BELT TO REPLACE THE TIMING CHAIN TENSIONER. As so many guides including the Audi manual itself states that you have to essentially remove everything, timing belt, bumper, radiator, etc.. just to replace the timing chain tensioner. This is not the case at all and I have performed the repair multiple times in under an hour. The symptoms of a worn out timing chain tensioner are caused by one of two things: The first is the wearing out of the pads or deterioration of the high strength plastic they use. This will cause a consistent grinding, rough idle, low power, and the valves will not be correctly timed at all rpm's. The second type of failure is the hyd piston itself. If this fails it the timing chain will be fluctuating from completely compressed to complete extension. This will typically cause the timing chain to scrape against the valve cover. If you put your hand on the top of the valve cover you will easily be able to feel the metal on metal scraping.  I will give a general walk through below:

  1. Remove plastic Audi cover
  2. Remove all wiring and coil packs from top of valve cover
  3. Remove bolts that connect the metal pipe to the left side of the valve cover
  4. Disconnect any air or vacuum lines making it very easy to remove the valve cover. When removing valve cover it must be lifted straight up off the studs and can not be angled.
  5. After the valve cover is removed loosen all of the caps for both camshafts.
  6. Remove the first 3 camshaft caps that are nearest to the timing chain tensioner
  7. Be sure to keep tension on the timing belt to avoid any slipping
  8. Remove the bolts that are holding the timing chain tensioner in place
  9. Carefully angle both cams upward lifting the timing chain tensioner with them. This will take a little bit of time to finagle it out but it will come out without damaging any of the cam bearings as long as you take your time. You have to trust me though because the first one I removed this way seemed almost impossible until I stepped back and took a look, it reminds me of a the brain teasers you used to play with when you were young. 
  10. Once the old tensioner is removed slip the new one in and make sure it slides in level with the base it is bolted too because a high pressure oil line runs from the head into the tensioner itself. 
  11. When laying the cams back into place do not use force (pressure will be holding them up a small amount) 
  12. Once you have the bolts started for the cam caps SLOWLY start to tighten each cap a very small amount moving from one end to the other. It will damage the cams if you do not tighten each cap bit by bit to bring the camshaft to its normal position. 
  13. Now that the cam is lying in place and the tensioner bolts are tight you can proceed to torque the camshaft bolts to the proper torque depending on what DOHC engine you have. 
  14. Install the valve cover 
  15. Connect all vacuum lines and bolt the metal antifreeze line back to the valve cover
  16. Install each coil pack and connect the corresponding harness (the coil packs are not cylinder specific so you can mix them up)
  17. I would recommend an oil change before initial start up
  18. Start it up and after about 10 seconds the tensioner will build pressure and be back to new!
Let me know if you have any questions and feel free to comment!

AUDI ENGINES Running Regular 87 Octane Fuel

With gas prices so high these days one of the biggest questions I am asked is if an Audi engine is capable of running a lower grade fuel. It is very difficult to see the result of not running the recommended 91 octane fuel over a long period of time because no one typically runs regular fuel through the entire life of their new Audi, especially the first 100k. After many engine tear-downs I have managed to gather a collection of data showing what parts will break down first if a lower grade fuel us used while proving the fact that lower grade fuel will exponentially lower the performance of the engine leading to Lifter/Follower failure, Camshaft lobe wear, Valve seat carbon build up leading to compression loss, Cylinder ring failure and eventually total loss of compression on all cylinders. Typically the cylinders located towards the firewall tend to see the results of low grade fuel first. This is due to the increase of heat both being further away from the cooler antifreeze after leaving the radiator and the heat that is held by the metal of the transmission during longer trips. This heat builds as the engine slowly transfers its energy into the transmission and everything else that it can. The heat of the engine will keep decreasing the time it takes for the engine to prematurely ignite the fuel. You may have noticed if you have ever used regular fuel on a long trip in a car that is built to have a higher octane, after four hours of driving or so it will become sluggish and less responsive than at lower temperatures. 

Destruction is what WILL happen if you run regular fuel often. The reason for this premature wear simply for the fact of using a lower grade fuel is extra resistance on the camshaft(s), pistons, valves and essentially everything that is involved with the ignition process. The difference between PREMIUM fuel and Regular is the rate at which you can compress the petrol before it ignites. Typically well built engines such as the ones Audi produces are a very high compression ratio compared to most coincidentally requiring a more expensive fuel in order to avoid premature detonation during the compression stroke. This is often referred to as knock or ping and will take thousands of miles off the life of your engine. When the fuel prematurely ignites before it is intended too, all of that momentum the engine is carrying is now meeting an intense resistance going in the opposite direction or applying most of the pressure directly on the crankshaft, rod, piston and corresponding bearings. This is the most damaging to the engine because the blunt of the resistance is being forced down at the exact time the rod and crankshaft is at TDC, "when the piston is at the very top of the compression or exhaust stroke." Now all of the pressure is being applied over and over wearing down your engine with every stroke...thousands of times per minute. 

After personally looking at many engines, documenting the results of consistent regular fuel usage and seeing consistently what parts wear first I have came to the conclusion that the cam lobes immediately begin to see the effects of regular fuel within the first 50 gallons. As the cam lobes begin to wear down the intake and exhaust stroke begin to decrease lowering performance. The camshaft lobes then begin to cut through the valve lifter slowly wearing down until the camshaft lobe makes contact with the snap ring in the lifter resulting in a terribly loud TICK. This is usually where most of the vehicles are taken in but in some cases the heat effects the cylinders, rings and valves more than the camshaft and lifters. Either way it is my recommendation that you run at least at 91 or greater octane rating to eliminate any chances of premature detonation and giving your Audi engine the long life it deserves. If you have any questions or comments please feel free to let me know! 

Thursday, September 15, 2011


An extremely common problem on Audi engines and more specifically the 1.8 turbo is the coil packs going bad or becoming intermittent. This will cause a major misfire and depending on how many coil packs have gone bad, in some cases the car may not even maintain an idle. Aftermarket coil packs from Autozone or Advance Auto will work but many times over I have seen them fail months after installation. One of the reasons for this is an incorrect gap for the spark plug. This will cause a short in the coil pack overtime leading to premature failure. 
The steps to fixing this problem for good is to first: 

  1. Scan the Audi for codes to determine what coil pack or coil packs are bad. 
  2. Purchase new (NOT USED) coil packs, aprox cost is $29.00.
  3. Replace or check the gap on all spark plugs. When replacing the spark plugs with new ones still go through the process of checking the gap, in many cases I have found new spark plugs that have had a spark gap that was not even close to stock specifications.  

How to replace the coil packs:

  • Remove plastic black Audi cover on top of engine by using a Philips head screwdriver to turn the screw 180 degrees to the right while applying downward pressure.
  • Each coil pack has its own small wire harness that you will need to remove. Apply pressure to the tab that is right where the harness plugs into the coil pack. While applying pressure slowly pull back and it will pop off. Sometimes this takes patients and the clips break very easily so take your time.
  • You will now see four coil packs if you are working on the 1.8L turbo model. Each coil pack has two bolts that will need a hex head tip to remove. 
  • After the bolts are removed slowly pull out the coil pack.
  • You are now ready to install the new coil pack! Slide it in and follow the directions backward. 
The coil packs are not cylinder specific so do not worry about interfering with timing or anything else for that matter. Good Luck!


AUDI A6 ENGINE REVIEW for the 2.7T and 4.2L 

I will start out by saying what a great car in general the A6 is from 1997 to 2004. The C5 body style has been completely refined from the older 1994-1997 C4 style that was so popular. Audi was able to bring a somewhat lightweight body for the size, keeping curves and giving a very futuristic feel to the car both inside and out. I am writing this review based on my personal experience from owning, driving, and tearing into these well built machines. 

Starting backward with the 4.2L V8 DOHC engine that they somehow managed to stuff under the hood of this A6. Out of all the options for engines I am most fond of their 4.2L for the simple fact of immediate torque and the distinctive growl that is just unattainable with the smaller liter engines. The 4.2 has consistent power through all stages of acceleration and the small cylinder v8 does well under load yet will still purr on the freeway with a great cruising speed around 80  mph. This is my first choice as an option for the A6 although the 2.7T has more potential for increasing power giving you more bang for your buck if that is the route you are looking at.

The 2.7T is a work of art and similarly to the 4.2L it is crammed under the hood of the short nosed A6. Both the 2.7T and 4.2L are comparable in width except for the extra room the K03 turbos take up. If work is ever needed on these cars expect to be pulling off piping in order to get at anything other than the nice shiny emblem on the top of the engine. The way both post and pre boost piping is routed makes it one of the most difficult engines to work on and also makes it prone to leaks typically from the turbo to the intake. All of this looks great though when you open the hood but it was not built with the everyday mechanic in mind.  Besides the mechanics of everything, the 2.7T is an extremely well balanced engine. The more lightweight V6 gives the car a lighter feel and during acceleration it is the opposite of under powered. During the first initial moments of acceleration you do feel a slight lag until the K03 turbos build enough to satisfy the 2.7L thirst for air. After boost is built be ready for a consistent pull through all gears with the torque feeling steady up until about 500 rpm before red line and if you choose to upgrade to the K04 turbo and upgrade/re-program the ecu with something from APR, you will feel that power to the limit of the engine. As a stock 2.7T it is a well built power plant by itself but with a simple upgrade such as Ko4 turbos you will create a whole new car. In my opinion it is well worth the investment. The cost to horsepower is by far the best deal not to mention tying it all together in a sleek, option packed German piece of engineering! 

My conclusion is that if you want a an A6 ready to go that gives you consistent power with a nice roar the 4.2L is for you. On the other hand if you would like a well powered car with the potential of being an extraordinarily powerful car with minimal investment then the 2.7T is the right choice.