300 SDL Loosing Power

[rmckee242]

My 86 300 SDL has never been a powerhouse but when I started using the AC this year it has no power from a dead stop. I was burning WMO/diesel mix and thought it may be the fuel. Ran it down and same thing on pure diesel. No problem in my other vehicles with the WMO mix or the Benz in the past for that matter. Any ideas on where or what to look for. Is there something on this model that advances injector timing or increases fuel when the AC is on? When the turbo has time to spool up it does fine.

 

[The Warden]

Your A/C compressor may be dying. I had something similar happen on my old '85 300D. My power level started declining and my fuel economy got REALLY bad (less than 20 mpg) over the course of about a month. Then the compressor failed altogether and my power came back up and I got 30 mpg on my next highway trip.

I would spin the center of the a/c clutch by hand and see how difficult it is to turn. You should feel SOME resistance, but if it doesn't turn fairly easily, I would say that the compressor's dying. Here's to hoping that you have the inexpensive R4 compressor and not the ridiculously expensive Nippondenso compressor.

Hope it helps some. Sorry for the delayed response. Good luck!!

 

[rmckee242]

Tried turning the compressor. It doesn't have anymore resistance than the compressor on my 97 powerstroke. There hasn't been a noticeable drop in fuel economy since I started having this problem. Anymore ideas? Oh yea I have the high dollar compressor so good thing it seems to be OK.

 

[72f2504x4390]

My 81 SD is a total dog with the A/C on also. Turn it off and it runs great. I always figured it was just because they are so low powered before the turbo spools.