Johnson CM30 install tips - Mercedes Benz SLK Forum

Performance MODS for the R170 Tuning and Performance modifications for your SLK

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#1 Old 06-08-2014
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Johnson CM30 install tips

So this weekend I installed a Johnson CM30 intercooler pump to replace my stock Bosch unit. The stock one wasn't failing, but since 1) I have the IC/HE isolated 2) it will eventually I figured I may as well do the replacement now. (I also had the wheel and brakes off to do a complete brake upgrade, so I had plenty of room to work... )

A couple tips for anyone looking to do the install themselves:

1) Use the stock mounting bracket. The CM30 has a lot smaller diameter than the Bosch unit, but the solution there is to wrap it in some (closed cell!) foam. I got some foam that was thick enough that the stock bracket could juuuuust barely fit when unscrewed, ensuring it was nice and secure when it was screwed down. This ensures that you don't have to worry about placement of the inlet/output hoses -- they just bolt up exactly like they would on the stock unit.

2) Unwrap a bit more of the stock wiring, and put the tap connectors higher up than you might initially want to. There's plenty of slack in the wiring, and this way you'll have a good bit of spare on the stock plug to use in case you decide to cut it and re-solder to return to a stock setup.

3) Electrical tape and/or grease the hell out of your tap connectors and the stock plug. On my car, the splash guards had warped over the years -- it *is* a 12-year old car, after all -- and water can definitely get in there. Experience elsewhere has taught me to over-engineer any wiring that's exposed to the elements, so I wrapped anything I did in plenty of good-quality electrical tape. Same for the (now exposed) stock plug end.

4) Test the pump before you do #3, and definitely before you put everything back together.

5) If you have the Needswings IC isolation kit, this is approximately a thousand times easier, since you don't have to worry about all of your coolant draining out of the bottom of the car. Keep the system isolated when you swap the pumps, let the IC/HE empty when you take off the stock one, do the swap, then open the valves between the IC and the main system to re-fill everything. Couldn't be simpler. If you started with a full coolant tank, you won't even need to add anything.

6) There's a series of holes in the metal above where the IC pump is. You can use the left-most one as a location for a zip tie to keep all your wires up above the pump (as it's not used for anything, or at least it wasn't on mine.) This keeps them further out of the way of an errant puddle, plus it looks nice and tidy.

All in all, I'd highly recommend this. It's a simple fun project for a boring weekend afternoon, and it's definitely better than waiting for your stock Bosch unit to commit suicide.
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