Extra Part Appears During Reinstall - PeachParts Mercedes-Benz Forum

BabyBlueBenz · #1 03-09-2009, 12:17 AM

As I was replacing the Mixture Control Unit & Air Guide assembly back on my '86 560SL today, I spot this washer sitting atop my Throttle Valve Switch:

It's a washer. It looks recently used. I never saw this part before. I was replacing my injector insulators & seals and some of the idle air distributor hoses today, repeating the procedure I documented at The 560SL Throttle Valve Switch Replacement Narrative

After getting it all back together, I took the car for a test drive and nothing extraordinary happened. In fact, besides my ongoing high-idle symptoms, she's running very well.

Does anyone have an idea where this may have come from?

450slcguy · #2 03-09-2009, 11:14 AM

Quote:

Originally Posted by BabyBlueBenz

As I was replacing the Mixture Control Unit & Air Guide assembly back on my '86 560SL today, I spot this washer sitting atop my Throttle Valve Switch:

It's a washer. It looks recently used. I never saw this part before. It wasn't there during the earlier tear-down. I was replacing my injector insulators & seals and some of the idle air distributor hoses today, repeating the procedure I documented at The 560SL Throttle Valve Switch Replacement Narrative

After getting it all back together, I took the car for a test drive and nothing extraordinary happened. In fact, besides my ongoing high-idle symptoms, she's running very well.

Does anyone have an idea where this may have come from?

Looks like a crush washer for the fuel supply/return line on the fuel distributor or thereabouts. Check for fuel leaks.

JonL · #3 03-09-2009, 11:20 AM

Yes, looks like a crush washer. Possibly the reason you've never seen it is because they have a tendency to stick to whatever they were attached to during disassembly, and then fall off later on. Perhaps you disconnected a banjo bolt from something, the washer stayed on one of the pieces and wasn't noticed. Try to retrace your disassembly steps.

BabyBlueBenz · #4 03-10-2009, 02:05 AM

As suggested, I retraced my steps during this job, but found nothing I'd touched related to the mysterious washer.

So, I reached back further in time, and remembered that I had recently removed the B11/2 Coolant Temperature Sensor to determine its part number for finding a potential replacement. I haven't confirmed the match physically yet, but the size of the washer and sensor from memory suggest that they belong together. Plus, when I replaced the sensor I remembered thinking that it was odd that the orientation of the two top jacks was slightly different (and even feared that I had overtightened it).

Here's an image showing the sensor, where it lives on the engine and the faintest hint of the loose washer from photo taken the very next day. BTW, the OP photo was staged, as I had extracated the washer to look at it, then thought to take a pic.

Thanks for your help! I'll be getting that washer back on B11/2 ASAP. I consider myself lucky that the washer didn't fall into the Infinite Void.

BabyBlueBenz · #5 03-10-2009, 05:59 PM

For all those folks worrying about my errant washer, it has been returned to its rightful place on my car's engine, keeping my B11/2 from falling off.

donbryce · #6 03-10-2009, 08:59 PM

Is there something special about those 2 odd connectors on the top of B11/2? They are different from all the other connectors on the various temperature sensors. Special insulation maybe? Surely the attaching wires simply conduct electricity, so why are these different....

BabyBlueBenz · #7 03-11-2009, 09:22 AM

Quote:

Originally Posted by donbryce

Is there something special about those 2 odd connectors on the top of B11/2? They are different from all the other connectors on the various temperature sensors. Special insulation maybe? Surely the attaching wires simply conduct electricity, so why are these different....

German engineering overkill against the heat & dirt. Although, I saw the same connector used for the oxygen sensor in the passenger footwell...not much heat & dirt there.