Mercedes-benz 190e power steering fluid flush w201 1987-1993 pelican parts diy maintenance article gas pain relief

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There are several thoughts and methods on changing the power steering fluid in a W201. Some people claim that it is a lifetime filter and fluid, to which other people ask, "Then why do they make replacement filters and fluid?" I am not a big believer in lifetime fluids and if there is a changeable filter, I am going to change the fluid as well.

If you are going to change the fluid there are two schools of thought on doing it. The first school of thought is to completely flush out the system while simultaneously adding new fluid. This involves opening the return line to the reservoir and placing a large bucket for the fluid to empty into under it while being prepared to add several liters of clean fluid into the reservoir. Have someone start the car and turn the wheel while you are pouring new fluid into the reservoir so it doesn’t run dry. I do not recommend this method for a lot of reasons. First: You will use a lot of fluid. You will be shocked at how much of a volume your pump can move, and the fluid is not cheap. Second: It can get extremely messy, as everything is slippery and moving under pressure. Third: If you let your pump run dry, even for a few seconds, you can severally damage it.

I prefer the "old school" method of sucking as much fluid as you can out of the reservoir, replacing the filter and adding new fluid. The fluid will not stay perfectly clean as there is still a fair amount of fluid in the lines and pump, but if you do repeat sucking out the fluid and replacing every couple of weeks eventually you will end up with very clean fluid at a much cheaper cost. Also, the fluid has been in there for years, it can wait a few more weeks until it is all changed out.

Use a turkey baster or suction pump to remove as much fluid as you can. Push the plastic stalk in the middle of the filter down and undo the 10mm nut. Remove the plastic stalk, spring and the metal filter underneath. Suck as much fluid as you can out of the reservoir, getting it as clean as possible. Install the new filter and replace the spring, plastic stalk and the 10mm nut. Fill the reservoir to the appropriate level. Change the seal on the cap and replace the cap. You can now start the car and turn the wheel side to side to get the new fluid circulating, then suck out more and refill. You can repeat this process until the fluid remains clear.

Followup from the Pelican Staff: Probably not, this can be a few things but a flush is probably not the answer. First check the belt make sure it’s tight, then check to make sure that there are not ball joints that are preventing the steering assembly from moving smoothly. Then check the power steering fluid for metal debris. If it has metal in it, the pump is bad, replace the pump. Unfortunately if that doesn’t fix it the steering rack or gearbox could be bad. – Casey at Pelican Parts

Why not put a pan under your return hose extend the hose if you want. Then fill the reservoir with power steering fluid and turn the pulley by hand until you get the new fluid, filling the reservoir as necessary. Then you have flushed the power steering system.

Comments: Another good guide. Thanks guys. I bought 2 litres of fluid and extracted 300mls at each partial flush so by my calculations 6 consecutive flushes with some driving in between to remix the old and new fluid means almost 90% of the steering fluid has been renewed and I have 200mls left over for future tops ups if needed.