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W221 wheel shaking when turning (power steering going bad?)
You know the feeling when you turn your steering wheel at the underground parking lot where the road surface is very "grippy", and the steering wheel feels like it was trying to shake when you turn it? It still works, does not make any noises, but gives you this unpleasant experience... yeah... so now I have it on any type of surface in my W221.
More than this - I can visually see my wheels area actually shaking/vibrating when turning when the car is stopped.
No funny noises from the pump area so far... Should I start looking for a new pump? Car is 13yr old... less than 60k miles on it though...
if you have ABC you need to find a specialist URGENTLY - if you have the normal stuff (the version that comes with air tragic), it should be basic servicing and diagnosis
Mine sometimes feels like this when I am turning and the engine is at idle (or more specifically when I let off the gas and turning, and perhaps the engine dips just slightly below idle for a moment). Someday I'll replace the reservoir/filter and see if that helps. Otherwise it is probably just the pump getting tired.
Dragging up this thread again. I also have steering shudders in the steering during low speed parking maneuvers.
Fluid is fine, no ABC system, belt is fine, suspension joints are fine (50K miles). Rear drive only, not 4matic.
Motor mounts and trans mount are new within 10K miles.
Feels like the steering wheel has PS, then no PS, then PS, etc. Frequency about 2 or 3 cycles per second. Shudders.
Question- is this the sign of a bad PS pump, plugged filter (need location), or a bad rack and pinion?
What are the diagnostics possible for this condition?
This is a standalone pump, so cost is cheap compared to tandem. I do all my own work and have SDS.
my airtragic car has issues - low RPM and a lots of work to do, and the PAS pump is running too slow and lags behind driver input with inconsistent feel - nothing to be done - just bad design / poor engineering
but with ABC you get a whole lot of extra fun in the mix, as PAS and Suspension share fluid and components - they were a lot of issues with hoses and dampers that got tweaked on early cars, likely need an expert to check / service stuff - these need fluid change OFTEN
on many other normal cars, if you drive badly enough to hold on full lock the effort the PAS pump has to do goes off the scale (other than over heating and ruining the oil it will take seals out and eventually give up), the massively increased load can make a dry worn belt slip and thus the PAS pump gets intermittent drive leading to noises and strange sensations...
expect the system to struggle the wider the tyres and low sidewall heights, or the drive belt slipping
lastly NON standard wheels with the wrong offset will create hell - turn axis on std cars and wheels, is mid point of the tyre contact patch - wrong set up isn't.... there is a huge issue with RHD Merc monster trucks where they forgot to consider at design, where the 4x4 running gear and steering rake fit between LHD and RHD build - something all BMW's had right for years on all their 4x4s (X Drive models) - Some late model Merc monster trucks with RHD in markets such as Japan, India, Australia, New Zealand, Botswana, South Africa, Malta, Ireland, Scotland, Wales, England etc. all have massive judder on full lock where the wrong geometry from the factory means the tyres literally judder jumping off the road as they try to self destruct going around tight corners
ABC cars up to 2014 are equipped with a “Duo pump” which is a pair of pumps on one shaft that do not share fluid to make one expensive pump. Cars with Magic Body Control use electric power steering assist.
There are separate reservoirs for power steering fluid and ABC fluid. Fluids that need to be changed annually to keep the pump and expensive components alive.
Dragging up this thread again. I also have steering shudders in the steering during low speed parking maneuvers.
Fluid is fine, no ABC system, belt is fine, suspension joints are fine (50K miles). Rear drive only, not 4matic.
Motor mounts and trans mount are new within 10K miles.
Feels like the steering wheel has PS, then no PS, then PS, etc. Frequency about 2 or 3 cycles per second. Shudders.
Question- is this the sign of a bad PS pump, plugged filter (need location), or a bad rack and pinion?
What are the diagnostics possible for this condition?
This is a standalone pump, so cost is cheap compared to tandem. I do all my own work and have SDS.
Thanks a bunch in advance.
My 2013 S550 with the hydroelectric power steering demonstrated the same issue whenever purchased. A simple fluid flush fixed the issue, but has returned (very intermittent) after 3 years. I will be changing my fluid reservoir and filter soon. Start by changing the fluid reservoir, filter is built in, and flush the system several times with fresh Pentosin CHF 11S. Flush procedure: fill the reservoir, start engine, turn steering wheel lock to lock at idle 5-10 cycles, suck fluid out, replace fluid and repeat until desired (won't ever be perfectly clear, unless you do a two bucket system (two people) to pull completely fresh fluid in while the engine is running and the outflow is discarded until clear).
I do think my best bet is a new fluid flush, possibly a filter and tank change (or reverse flush of tank filter).
Will do his after the holidays, and let the group know what the results are.
If the pump is failing, it looks like a used one can be swapped in for under $100.
Nice to have the old school non-ABC, non-electric pump!
my airtragic car has issues - low RPM and a lots of work to do, and the PAS pump is running too slow and lags behind driver input with inconsistent feel - nothing to be done - just bad design / poor engineering
Thoughts…if a smaller diameter pulley could be adapted to the pump, then it would spin faster, providing enough volume and pressure to operate smoothly at low rpm. Might be an answer to this problem.
if there room for the belt to tension and nothing rubs, and you can get the pulley you need, and it doesn't cause issues at high revs, and you like to play..... shame they didn't design the car correctly in the first pace
I was able to suck out the power steering reservoir, then refill with CHF11S, and turn the wheel back and forth with car running. Did this 3 times, and fluid is now clear.
Shuddering while turning the wheel is no longer happening. However, the weather is cooler right now, and I need to remove that variable from the potential cause of shaking.
I will post again if the issue returns.
BTW - getting the pump out looks like it would require pulling the radiator hose, and I was not able to determine if a different pump pulley is available. Hopefully I won't need to go there.
(in his video) that fluid looks very thin.... yep most systems get as much out of the reservoir as poss - fill - wind steering lock to lock and keep going 3 times and it does quite a good job
her focus they filled with old school red when its meant to have the later green stuff - still have forums arguing the owners manual was printed wrong - nope ! lazy factories using old stock of the wrong stuff..... soon goes grey and leaves half the steering pump going round in circles - until the poor design HP pipe fractures and pukes its guts on the road to kill motorcyclists...
the ford green of the correct spec gives lighter steering than a common aftermarket fluid out there.... Suitable for use where the following applications are called for: CHF 11S and CHF 202 - Comma MVCHF
here we go - a random post I found about the two fluids.... I wonder what the manual says for the merc !
So I was missing a bit of power steering fluid. Notice that CHfF11S is now replaced by CHF202 which is supposed to be thicker in cold weather.
Initial impression after adding about 250ml. Had some strange fluctuations in power required to turn wheels, but only when cold. Like there were hard points/spikes.
So I went ahead and replaced progressively the whole remaining CHF11S that was in there from factory with a full can (1L) of the newer 202... "Hardsl spikes" are gone, but wow does the steering feel heavy when cold. Much better when warmed up, but still stiffer than previously.
Anyone had similar experience with the new fluid?
Driving in Canadian winter conditions (-10C this morning). Car is a 2.5T 2006.
Reply
Description - CHF11S:
Pentosin CHF 11S is a synthetic high-performance hydraulic fluid for lifetime application in modern vehicle aggregates. Pentosin CHF 11S is specially designed for hydraulics in the automotive industry with the highest technical requirements such as in: power steering, level control, shock absorber, hydro-pneumatic suspension, stability and traction control, hydraulics for convertible tops, central lock systems, etc. It is suitable for all extreme conditions and guarantees full performance from -40°C to over 130°C system temperature.
CHF 11S PRODUCT ATTRIBUTES:
Appearance Dark Green
Density at 20°C 825 kg/m
Kinematic Viscosity at 100ºC 6.0 mm/s
Kinematic Viscosity at 40ºC 18.7 mm/s
Kinematic Viscosity at -40ºC 1100 mm/s
Viscosity Index 313
Pour Point -57°C/-70.6°F
Flash Point 160°C/320°F
Ignition Temperature 235°C/455°F
Description - CHF 202
Pentosin CHF 202 is a synthetic high-performance hydraulic fluid for lifetime application in modern vehicle aggregates. Pentosin CHF 202 is specially designed for hydraulics in the automotive industry with the highest technical requirements such as: power steering, clutch hydraulic, electro-hydraulic mechanisms of convertible tops, etc. It is suitable for all extreme ambient temperatures and guarantees full performance from -40°C to 130°C system temperature.
CHF 202 PRODUCT ATTRIBUTES
Appearance Dark Green
Density at 15°C 840 kg/m³
Kinematic Viscosity at 100ºC 6.1 mm²/s
Kinematic Viscosity at 40ºC 19.3 mm²/s
Kinematic Viscosity at -40ºC 1400 mm²/s
Viscosity Index 302
Pour Point -54°C/-65.2°F
Flash Point 154°C/309.2°F
Ignition Temperature 245°C/473°F
We kindly inform you that Pentosin CHF 11S is not available for EU, that is the reason why it did not show up on the UK web site.
We have different regulations and products to the USA so products may not be the same - as we must comply with local rules.
Mercedes S500 2006 requires MB 345.0 quality for Power steering. In the UK we do not have product with required specification.
Genuine Mercedes-Benz ML Power Steering Fluid - 1 Litre Bottle A001989240309 MB345.0
A000989880310 is an older number - just went to get some more and he struggled with the new part number above I had
and its as thin as hell and is now GREEN 'multigrade oil for power steering" according to Mercedes - I just swapped out 1ltr of the older straw coloured Merc fluid stuff that in my car was 8 years old. I was reading somewhere they have a shelf life of 5 years, so overdue... The stuff coming out is a bit dirty - and seems thicker.... but now my steering is heavier !!!!
You need 1.5 ltrs to fully swap it... I could only pipette out 250ml at a time - then top it up wriggle the steering (with it running), and do that 4 times... another 2 times would see it all thoroughly fresh green
not in europe - castrol say they aren't allowed to sell oil of that spec ??? - and if you buy from your stealership you have some come back - they told me its the MB345.0 - the indy garage that just re did my trans fluid with RED gave me a bottle of MB345.0 when I asked for some power steering fluid....
not driving like aloon, but the steering feels more consistent, maybe 5% heavier but more fluid throughout its range - what was in it was the recco MB fluid of its day put in some years ago that was a light brown colour....
strange world.... love the description...... Model 221, Power steering at outside temperatures below –25 °C
yep I knew USA bods use the CH11S in post #15 I copied this response why castrol don't have a product....
We kindly inform you that Pentosin CHF 11S is not available for EU, that is the reason why it did not show up on the UK web site.
We have different regulations and products to the USA so products may not be the same - as we must comply with local rules.
11-02-2020, 01:21 PM
Car is 13yr old... less than 60k miles on it though...
