Believe it or not, I'm a bit ahead of you on the shorter belt suggestion. My initial attempt to get by was to remove the compressor and just bypass it with a shorter belt.

I measured out the belt size with and without the compressor on by routing some string around it and guaging the measurement against the spec. length. As luck would have it, the spare belt that I had on hand for my 92 300D 2.5L was the size I needed. I assume that those clever folks over in Germany want to keep their part number count down, so maybe the 2.5L engine with air conditioning uses the same size belt as the 3.0L without air conditioning.

Anyway, I had it all put back together an had it fired up and idling. Boy did I think that I had really been clever. Unfortunately, after idling for quite a while, I shifted the car into reverse to back it out of the barn, heard a clunk up front and shut it off. The clunk I heard was the belt slipping off just as some load was put onto the motor.

Honestly, I cannot explain it for sure. It shouldn't have happened.

It's possible that the belt simply didn't have enough tension on it to keep it on, but I can't tell for sure. It seemed to be as taut as the normal belt with the compressor on.

The only other item that I could possibly attribute it to is the crumbling power steering pump brackets. There are 2 long bolts that hold it in place on one side and the front sleeves of the bracket is where it is coming apart. The pump works fine otherwise. It's hard to describe. Anyway, the result is that the pump does not appear to have any real good structure to its mounting and I was watching it experience quite a good for-aft oscillation at idle. Perhaps the extra load shifting into reverse was enough to throw the pulley far enough out of plane with the rest of the pulleys to allow the belt to slip off.

Obviously, this is why I am either fixing or replacing the PS pump.

Any thoughts on this would be very much appreciated.

__________________
*******************
I miss by Benz
92 300D 2.5L 403,000+ *SOLD*
87 300SDL 3.0L 252,000+ *SOLD*

Since a rebuilt ac compressor is $800 for the SDL! I was wondering if thier was a shorter belt that could work. Now I know thanks.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Sixto,

One thing I forgot to add. My plan is to not connect the control wires to the AC compressor so that the clutch will not be able to engage. That way, I figure that just the pulley will turn and the compressor will never cycle. From a compressor standpoint, the unit won't even know that it's on the car, except for the free-spinning pulley.

Does that seem reasonable?

__________________
*******************
I miss by Benz
92 300D 2.5L 403,000+ *SOLD*
87 300SDL 3.0L 252,000+ *SOLD*

The CD manual says that a 603 without AC uses a 2080 mm belt and a 602 with AC uses a 2100 mm belt. That could be the difference. And I guess the bean counters lost the argument

I'm not concerned about the wires because you can pull the Klima relay to prevent engaging the compressor. The tach will work without a Klima relay. It's the refrigerant passages and chambers within the compressor that hate moisture that you should protect.

Sixto
95 S420
87 300SDL

What's a klima relay, and where can I find it.

Thanks for your help.

__________________
*******************
I miss by Benz
92 300D 2.5L 403,000+ *SOLD*
87 300SDL 3.0L 252,000+ *SOLD*

Six, Are you sure on those specs? The parts site I always use (alloemautoparts.com) lists 2145 for the 3.0 and 2100 for the 2.5.

Do you think the PS pump wobble could have been responsible?

__________________
*******************
I miss by Benz
92 300D 2.5L 403,000+ *SOLD*
87 300SDL 3.0L 252,000+ *SOLD*

The Klima relay is along the firewall inboard of the brake booster. You'll see the overvoltage protection relay with it's plastic top revealing a blade fuse and the Klima relay beside it. The Klima relay pulls right out.

The CD manual says 2080mm for a 603 without AC.

I don't see how shifting to reverse can be more traumatic than shifting to drive.

Sixto
95 S420
87 300SDL

Folks,

At risk of jinxing my luck.... I installed a rebuild Nippondenso... whatever model fits the SDL and it has lasted 2 seasons so far ( about 40,000 miles overall ). The rebuilt from a company in California was about $375 with a new dryer, no core requested. I am still considering myself lucky that it has lasted this long. Hope it goes another year or so. I believe the new compressors were in the $700-800 range. If needed I might be able to find the company name. Let me know.

Chuck.

What's the risk? The original is a Nippondenso.

Sixto
95 S420
87 300SDL

Fyi the 420SEL and 300SDL used the same ac compressor. The 560/300SEL's used a much cheaper Delco one. (I think it is Delco)

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Really? My 91 300SE had a ND compressor. EPC shows the same p/n as the SDL.

Sixto
95 S420
87 300SDL

hmm I'll have to check again.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200