No matter what, all of us who own a C32 AMG will eventually have to replace the water to air intercooler pump. The OE pump is know to fail often on our AMG's, but even without component failure the pump will inevitably give up due to the electrical brushes wearing out. A failed pump will become obvious when the supercharger is disengaged due to internal air temperatures rising too high. You will experience a complete loss of power. Some people say it's like having a naturally aspirated M112 engine, but in reality it's far worse. Engine timing is cut back dramatically, and your left with an engine that can barely accelerate.
At this point you have several options. In most, if not all cases, there will be no check engine light due to a failed pump. If you take the car to Mercedes they will be able to diagnose IAT too high with on-board diagnostics. You basically pay them $100 dollars to determine what is already known. The signs are very obvious. They will give you a quote of nearly $650 dollars to replace the pump. That includes the $350 dollars for OE intercooler pump, and three hours of labor at a $100 dollar rate. Now you can just buy the OE pump, and take it to another shop that will probably charge around $100 dollars to change the pump out. So you're still stuck with a big chuck of change lost.
Luckily there are other options for this pump. You can replace it with the Ford Cobra/SVT Lightning pump, or the Johnson CM30/CM90 pump. In my case I went with the Lightning pump as it seemed to be the most available, and also the cheapest. Purchased it on ebay for right below $100 dollars. I did quite a bit of DIY work on my old Mercedes 02' C230 Sportcoupe, and am comfortable working on these cars. They are actually designed to be worked on easily for the most part. Plan to devote at least three hours to changing the pump. I spent around six hours, but that includes a complete radiator flush with flushing agent.
So, let's start with a list of supplies, and tools. I'm included what's needed for a complete radiator flush. If you don't plan to do that you will still need some antifreeze, and distilled water to replace what is drained while removing the pumps tubing. I also soldered new wiring onto the replacement pump. By the way, I recommend two people for removal of the old pump.
One bottle of OE Antifreeze
Six gallons of distilled water
Prestone flushing agent
Two large oil storage tanks
Lightning pump - 0 392 022 002
Two small screw clamps
Electrical contact cleaner
Hot glue gun (Use fast cure epoxy putty instead!)
Lug nut wrench
Small C clamp
Small flat head
Once you have all the supplies neatly organized as my obsessive compulsive self you're ready to start. Jack the car up on the front passenger side, and place a jack stand just in case. I've always found it easiest to use the OE jack supplied with the vehicle. However, my jack pad was missing, and the OE wasn't working, so I used a scissor jack. Just my luck for the pad to be missing only where I needed it... Remove the passenger side front wheel. OE lug nut tool works great. I didn't loosen the lugs before jacking up the vehicle completely, but that will help get them off easily. Doesn't help fighting a free spinning wheel.
See the square panel on the wheel well? The pump is located directly behind this panel. It is held in place by four bolts with 10mm head, and a few pressure clips. The bolts come out easily without any problems. However, the clips can be a problem. I found it easiest to move the center pressure rod down some with a small flat head screw driver, and then pull it out completely with needle nose pliers. Again, set the panel aside, and keep the bolts along with the clips together.
Now would be a good time to remove the bottom front skid plate. It has six screws with 8mm bolt head. Remove all screws, and set the plate aside. It was removed to access the radiator drain plug, but will need to be removed anyways to aid in removal of the pump. You need to get at it from the bottom of the vehicle also.
You should now have a direct view of the intercooler pump from the wheel well area, and the bottom of the vehicle. First unplug the electrical harness from the pump. The pump itself is held in place by a bracket. The bracket has a 10mm bolt on the bottom. Remove this bolt, and remove the bracket.
Before removing the fluid tubes on the pump it would be wise to drain all coolant from the system. There is a red cap located on the bottom driver side of vehicle. This is the radiator drain valve. Place your oil collection container directly under this valve, and use pliers to budge the valve loose. After the valve is loose you can turn it by hand. Unscrew the coolant reservoir cap in the engine bay completely, and open the drainage valve all the way. Drain all coolant from the system, and close the valve.
Here comes the hardest, and most time consuming part. Mercedes uses proprietary pressure clamps. They are incredibly hard to remove, and are very annoying. I have experience with this type of clamp as it was on the MAF sensor for my Sportcoupe. Easiest way I have found to remove them is with an adjustable turn based C clamp. You will need a small C clamp to release pressure on these clamps which hold the tubing in place. This is also where you will replace these clamps with screw based ones. The pump itself will need to be rotated slightly for access to the clamps. This is why I recommend two people. My girlfriend was a great help with her small hands... Just take your time, and try not to get too frustrated. Even with the system drained some coolant will still come out when disconnecting the inlet tube. The one on the front of the pump. I recommend removing this tube first, as it makes it a lot easier to remove the outlet tube which is angled sideways. Once the clamp is loosened pull the tube while the other person pulls the pump in the opposite direction. Do the same for the outlet tube.
When the old pump is removed there are several things you must first do to get the Lightning pump prepared for installation on the vehicle. The two pumps look nearly identical except for several differences. Most obvious is the electrical connection is complete different. The inlet, and outlet tubes are also slightly smaller than the OE Mercedes-benz pump. The two pumps only differ in part number with the ending digits "003".
Remove the large metal clip on the rubber molding around the pump. Then remove the rubber piece. Use a screw driver to bend the rubber away from the pump as it is slightly adhered. It will take awhile to get it off. Use the posted photograph to place the two pieces back onto the new pump in the correct orientation. Look at the part number tag...
There is a harness available for the new pump. Easiest way to obtain this part is through a Ford/GM dealership. You will just use the OE lightning harness to add wiring onto the pump. The wiring harness that leads to the pump on the vehicle will need to be cut off, and the remaining wiring spliced onto the new harness. Being that I have experience working on electrical circuits I decided to just skip the harness, and solder in place wires directly onto the new pumps electrical contacts. I wouldn't recommend the soldering method if you do not have experience as you could easily bridge the negative, and positive on the new pump. I used hot glue to fill the remaining space after soldering, and create a water tight seal.
**Edit: Do not use hot glue as the engine heats up the surrounding area too much. This will cause the hot glue to liquify, and drip off the wiring. Instead, use fast cure epoxy putty. Seems to be the only epoxy with a higher temperature rating. Will hold up to 250F temperatures. Most of the others only hold up to 125F.**