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1999 SLK 230
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937 Posts
Discussion Starter #1
I had discovered that the alarm was not working on my car a while after I purchased it used under the Starmark program. The dealership replaced the PSE under warranty. Now, that was almost 5 years ago, but I had a failure again last year. That time, it was the connectors that had corroded, so badly that one of the pins stuck and pulled out of the circuit board. But, I was able to repair it.

Sunday I went to the car to retrieve an item from the trunk, and the alarm sounded as soon as I opened it. Turned out that the car was locked (and the alarm armed), but the trunk lock had not engaged. Well, at least the alarm was working. A little diagnosis revealed that the air/vacuum pump itself in the PSE was not working properly.

I disassembled the PSE and removed the pump and motor assembly. Testing on the bench revealed that the pump would sometimes run and sometimes not. The pump itself is a rotary vane type (What’s that? Here’s an animation I found: http://www.pumpschool.com/principles/vane_ani.htm ). I took it apart and noticed that the rotor holding the vanes would stick to the pump wall. I lubricated this with graphite power and reassembled it. I also cleaned the motor armature and brushes. After this, the pump started and ran reliably for several tries. I put the whole mess back together, and the system is working again. Not sure how long it will last. I would sure hate to have to pay for a complete PSE if only the electric motor proves to be bad.

This system seems way more complicated than it needs to be.
 

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2002 SLK 32 AMG, bone stock. 1987 190E 2.3-16 valve (destroyed). 2005 E320 new toy.
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14,926 Posts
That type of vacuum pump is common in aircraft, and is usually VERY reliable. The graphite should do the trick for as long as you own the car.
 
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