Category: E55

All posts pertaining to my daily driver E55

Simple Plug for Supercharger Vacuum Port

~ Joe Ernst ~ 8 Comments

A very common place for a vacuum leak on the E55’s is that port on the rear of the supercharger with a strange multi-piece plug in it.   I assume that port is used for the brake booster on cars that don’t have the SBC system, but it is beyond me why the engineers at Mercedes-Benz decided to make a three-part plug to fill it instead of using a simple rubber plug.  This is especially strange since there is an existing Mercedes part that seems to work perfectly.

I was at Mercedes Benz of Portland today, trying to get a new plug for my car since the old one is leaking.  For some reason the parts diagram on the computer only shows two of the pieces required.  It was clear that it would not work without that third piece, so after some head-scratching the parts guy said “Hey, I’ve got an idea!”  He ran into the back and two minutes later came out with a plug for the windshield washer on a CLK320 (part number 210-987-00-45) that is the perfect size for the port in the supercharger!

Killer Chiller and Front Mount Tank

Killer Chiller Tank Test Fit
~ Joe Ernst ~ Leave a comment

If you own an M113k-powered Mercedes-Benz you know that keeping the intake air charge cool is one of the biggest headaches of the platform.  Any supercharged engine will have increased IATs due to the compression of the charge, but the M113K engine suffers more than others because of the size and placement of the intercooler.   The intercooler is relatively small, and it sits under the supercharger, in the “V” of the engine.  Heat soak is all but guaranteed after each high speed run.

Things get especially bad at the dragstrip because the car spends a lot of time in the staging lanes with no airflow over the heat exchanger, effectively rendering it useless until you start a pass.  By then it’s too late and your IAT’s have likely climbed above 90 degrees, which is where the computer starts to pull timing.

There are various ways of dealing with this issue, such as a larger heat exchanger, larger circulation pumps, or methanol injection.  I decided to go a different route and use my A/C to cool the intercooler water, courtesy of Kincaid Performance’s Killer Chiller.

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E55 Subframe Bolt Replacement

Replacement bolt for the rear subframe.
~ Joe Ernst ~ 6 Comments

The W211-based E55s have a serious design flaw in the rear subframes.  There have been many reports of the rear subframe bolts snapping in two or ripping their mounting bosses right out of the body.

This typically happens under hard acceleration and can cause a lot of expensive damage to the car.  The rear subframe is held in by four bolts, and it always seems to be the rear two that have the problem, never the front two.  This makes sense, since under acceleration the rear end is trying to squat while the front end rises due to the torque imparted on the chassis by the drive axles.  The front half of the subframe, ahead of the axles, is pushing up into the body, while the rear part, behind the drive axles, is pulling down on the body.  With 516 ft-lb of torque available from even the stock engine, those two rear mounting points tend to fatigue and fail when you least expect it.

Adding the large-diameter washers is the key to this fix.

The fix is pretty straight forward, especially if you do it before it becomes a problem.  It’s a simple matter of replacing the factory rear subframe bolts with a pair of new bolts with nuts and large washers on them, creating a “sandwich” that is much stronger than the original setup.  Adding the large-diameter washers is the key to this fix.  They spread the load out over a much larger surface area than the original mounting bosses, thereby making it nearly impossible to tear them out of the body.  My car has over 180 dragstrip passes on it, all on sticky Hoosier drag radials, and the bolts have held strong.
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