This has been covered ad infinitum, but here I go again. This write-up is for the SLK32 AMG. I believe the other “baby” SLKs are similar.
Installing a new supercharger intercooler pump is not hard at all. It shouldn't take you more than an hour to do, even if you're slightly OCD like me.
First, buy a pump! The Johnson CM30 seems to be the favorite choice and it's what I used here. Make sure you get the pump with 3/4” hose fittings.
You will also need two hose clamps (the OEM clamps will not provide sufficient seal), a self-tapping screw, a couple of male Quick Disconnects and two 3M T-Tap connectors (3MBTT).
You will also need a tire tool or 17mm socket and breaker bar, an 8mm socket, 10mm socket, 13mm socket, appropriate ratchet, pliers or Channel-Locks and a screw driver or two.
Prep the new pump by stripping the insulation from the lead wires. It probably comes from the factory that way. I tinned the leads as I feel that provides a better long-term connection when you crimp the connectors.
After soldering the ends of the leads, I crimped on two male Quick-Disconnects. I purchased an inexpensive ratcheting crimping tool. This tool is worth the money, especially compared to those POS kind you get in the package with the assorted connectors. After crimping those connectors in place, it's time to attack the car.
As always, when jacking a car, make sure the transmission is in park, the parking brake is set and you place an appropriately rated jack stand for safety. Also confirm that you are lifting at the appropriate jack point. Though the job can be done from under the car, I chose to work while seated on my arse! To facilitate this, I removed the right front wheel.
I then removed the front, lower portion of the splash shield. You'll notice in the photo that mine was missing a good portion of the shield. This “little” problem is what caused my tire to disintegrate. Ouch. There is one screw and two plastic flanged nuts that hold the splash shield in place.
After removal of the wheel and shield, the pump is clearly visible and easy to access.
Disconnect the power connector by squeezing the plug to unlock it and then pulling the plug out. Note the orientation of the plug and corresponding wires. My pump had markings for + and – terminals. On my car the Red w/ Blue stripe wire was the positive lead. Cut the plastic cable tie that secures the wiring to the pump bracket. This will make it easier to work with the wires. CAREFUL: Cut only the cable tie and not the “stand off” used to secure the tie to the bracket.
To leave the harness as original as possible, I chose to use 3M T-Tap connectors. These connectors allow you to tap into the existing wires without removing the original plug. Additionally, as opposed to the “self stripping tap” connectors, the T-Taps allow you to plug a male Quick-Disconnect into the Tap. If you ever need to remove the pump, simply unplug it! NOTE: the T-Taps pictured are yellow and are designed for 12-14 gauge wires. Use blue taps intended for 16-18 gauge wires.
It's time to remove the pump. I decided to unbolt the pump first and the hoses second. The hose clamps were hard to get to with the pump still bolted in, so removing the pump from the bracket made sense. If you do it this way, make sure you don't damage the hoses after the pump is detached from the bracket.
Remove the single bolt at the bottom of the bracket. You may need a screwdriver to gently pry the bracket apart. With the pump free, use a pair of pliers or Channel-Locks to compress the OEM spring-style hose clamps and move them further up the hose. With the clamps loose, pull the hoses off the pump. Again, a screwdriver may be needed to GENTLY loosened the hoses from the pump. You will lose some coolant here, but if you work efficiently, you can minimize this loss.
With the pump free of its bracket, wires and hoses, its time to install the new one. Slide the OEM hose clamps off the hoses and slide the new ones on. Put the hoses onto the new pump. Slide the new hose clamps into place and tighten. You may have to reposition these later, but for now, they are in place and the new pump is keeping the coolant where its supposed to be.
Using the bracket supplied with the new pump, attach the bolt removed from the old bracket through the new bracket and onto the backing plate. Make sure the bracket is vertical.
Using the other hole in the bracket as a guide, drive in the self-tapping screw through the bracket backing plate. I chose a self-tapping screw for several reasons. First, it's just plain easy! Second, you can buy and use a self-tapping screw that is short enough that it doesn't over-penetrate the rubber mount on the backing plate. I used a stainless steel screw and drove it with an electric impact driver. Don't completely tighten the bracket at this time.
Now slide the pump into the bracket making sure that the wires are not bound or pinched in the bracket. Position the pump so the orientation matches the OEM pump and that the hoses are not bent or kinked. Now tighten down the OEM bolt and the self-tapping screw. If you've done this right, the pump will be secured firmly in the bracket. If it is loose, use the nut and bolt included with the pump to “pinch” the bracket together, securing the pump. Loosen the hose clamps and reposition the hoses if necessary.
Attach the lead wires from the pump to the T-Taps on the chassis wiring. Create a strain relief for the wires by doubling the wires over and securing with a cable tie in the existing cable stand off. Reinstall the splash shield and wheel.
After everything is back where its suppose to be, you'll need to bleed air out of the cooling system. I'm not sure if there is a MB sanctioned method, but here's how I did it. Start your car. Open the coolant reservoir and monitor the level. Add additional coolant as needed. Continue this until the engine is warm and the coolant level has stabilized.
That's it. Hope this helps someone out there. Either way, I enjoyed doing it and documenting my technique.