1980 450SEL with 158k miles. Doing the 75k majors and more.

Using a stethoscope with a probe I'm 90% certain I've isolated a moderately loud squeal to the power steering pump (manufactured 12/79 by ZF). Since I've not changed on the V-belts yet, I plan to remove the pump's belts to see if the noise goes away. I also have a leak somewhere in the pump area. Not a lot...yet, but it's getting messy.

I've done a search for this and found the instructions for changing out the fluid and to not use ATF but use power steering fluid (Thanks Larry Bible and MB Doc). I did probe gently looking for sign of a filter, but found none (manual is not clear if one exists for this pump or not, or how to change it). Did find about 1/32 to 1/16" of crud on the bottom. Left well enough alone.

Need thoughts on options:
- Swap out the fluid AND try and locate the filter.
- Pull the pump and replace the seals and clean it up
- Buy a pump from a dismantler (Potomac German is just down the road)
- Knuckle under and buy a rebuilt ZF

What else is there worth trying?
Can anyone tell me if there is a filter?

I'll probably be driving this car for at least 5-10 more years.

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S, J.R. Brown
2000 G500 LWB Obsedian Black
2005 Toyota Tacoma Access Cab Off Road Sport
1993 Volvo 240 Sedan Anthracite
1980 450SEL Champange (owned it for 15 years. Great car)
1986 280GE LWB Anthracite (Sold it and kinda wish I hadn't)