thefisch

The steering on my 2011 has been relatively effortless and noise free thus far. But recently I have noticed a low groan when turning on rare occasions. By rare, I mean it tends to happen within a mile or two of the house in the morning when turning sharp right at speed (90 degree right at 20mph or so). Turning in the neighborhood at slower speeds, at traffic stops, or in parking lots on the same drive results in no sound. And it doesn't seem to happen when turning left at all, only right, perhaps because those are sharper turns. After the car is properly warmed up, I don't recall hearing any groaning at all. In fact, it happens so infrequently that often I've forgotten about looking into it.

But today I remembered and thought I would check the fluid level just to do sure. The dipstick has two measurements - one at 80 degrees Celsius and another just below at 20 degrees Celsius - so I suppose either would work but I'd rather do what is most accurate.

Also, does the engine need to be running to get a proper reading? Is it better when the engine is properly warmed up after making a few lock to lock turns or can I do this cold in the morning before the car has been started?

For background, I haven't checked the fluid before on this car. My other cars have a nice clear reservoir with clearly marked max and min lines which makes it easy. My car has been dealer serviced thus far and I know it is listed as part of the procedures to check it with each service, but I always doubt they check all those things. I haven't noticed any signs of leaking on the ground or around the reservoir. PS fluid changes are not in the maintenance manual AFAIK

belarus27

Had similar situation , when making uturns or or going around in curcles(was testing) , or sometimes even when just making a turn on low speed... and usually when its cold or havent been driven for too long.
added some ch 11 (cant remember since it was couple months ago) and noise went away.

i also read some articles though as i wasnt sure... and at this point i cant remember , but i did add a small amount.

thefisch

Thanks, I found some online tutorials about checking the fluid like these - http://www.mercedesmedic.com/check-a...teering-fluid/ and https://www.carcarekiosk.com/video/2...ck_fluid_level
Just didn't know if it made a difference if you checked cold or warm. The MB workshop manual (link is for coupe but should be the same) says the ignition should be off and doesn't say whether hot or cold is better, just says use the reading for the current temperature. I may try it both ways. There are threads about changing or flushing the fluid - don't want to bother with that now - just trying to make sure it is topped off.

Seems like the most prevalent fluid mentioned for adding is the Pentosin CHF 11S which runs about $20 online and in some stores. My local NAPA has another option which they tell me they ordered specific for someone's MB. Going to see if it meets spec. https://www.napaonline.com/en/p/AOF0009898803 Anyone try this other one?

Mud

I think that the dipstick marks are for cold and operating temp levels, as with most of the PS caps/dipsticks. I have found that if the fluid is level is correct, either reading works.

I've never checked the fluid when the engine is running, as the reservoir (at least on other vehicles) can get slightly pressurized from the fluid circulation at the pump. MB reservoir is above the pump, so less chance of splash, but on our Silverado, taking the cap off when the engine is running invites a nice coating of fluid everywhere lol.

I bought the recommended Pentosin fluid online as my thinking was not to mix fluids when topping off. I also pull some PS fluid out of the reservoir every oil change or so using the good old turkey baster method and replace with new fluid. Over the long run it may not be all new but better than all old fluid.

thefisch

Well it seems I am low on power steering fluid after all. To warm up the car, I did a test drive and listened during some lock to lock turns and heard nothing unusual. I even made a couple turns that had produced a groaning sound on prior trips and heard nothing. So I was thinking that it should be fine. Well after returning to the level garage floor and turning off the warm engine, I checked and the dipstick was dry. I can see some fluid lower in the reservoir, but it is not high enough to reach the dipstick.

thefisch

Well I think that NAPA has the wrong compatibility information on their Febi Bilstein Nr. 08972. Their website and the store I called said it was compatible with my W212, but when I look at the product information at the manufacturer website it only shows older MB's. This appears to be the non-synthetic fluid. I also found this thread on benzworld comparing the different fluids - http://www.benzworld.org/forums/w202...-11s-febi.html

During my searching, I also came across a Prestone European Power Steering fluid that is commonly available at most auto parts places, even Walmart has it. It goes for around $7-8 and says it is compatible with CHF 11S. Anyone try it?

belarus27

Yes pentosin chf 11s , in a green little canister...

thefisch

Well the plot thickens a little bit. I called the parts department of my local dealer and the guy tells me NOT to put Pentosin in the power steering system - they have a quart bottle of regular PS fluid I can use for $9. I asked him what's the difference and he said Pentosin is designed for the hydraulic systems like suspension and not for PS alone. He said added the wrong fluid could lead to problems. My current fluid is golden yellow and he said the regular fluid is too - whereas the Pentosin is green.

So I decided to call some other dealers just to see what they said. The next two parts departments I called said to use Pentosin - one didn't know much about it but another said that's the fluid they use in all their cars now. When I asked about the different colors and mixing fluids, they didn't say offer anything other than that is what their system told them.

I called a fourth dealer just outside my area. He said the system said to use Pentosin. When I asked about the different colors of fluid, he cautioned me against mixing different types of fluids and it can harm the seals. He offered that I should bring it over for one of their mechanics to ID the fluid that is in there now.

C Smith

It may thicken a little more. Hydraulic fluid doesn't evaporate. You're losing it somewhere. Whether that's a hose fitting or the rack leaking internally, you have a problem. Diagnose that first.

KEY08

Well, you are definitely low and it should be topped off. I am sure this is the cause of your groaning.I cannot understand how there is so much disagreement and difference among the various dealers you have contacted. Perhaps your car had a power steering issue before you got it and it doesn't contain the normal recommended fluid, which I always thought was Pentosin CHF 11S.

thefisch

I haven't found any signs of leaking in any of the seals or hoses. My plan is to top it off and record the amount used and dipstick measurement and then monitor the level from there. Unfortunately, I don't have a baseline to go by since it is the first time I've checked the level.


The VMI didn't show any power steering work that I recall. At this point, I plan to have a tech look at it (or at least the photo) so I can add the same fluid for now. The color of the existing fluid makes me think it is not a synthetic like the Pentosin CHF11s.

thefisch

So I called a few more dealer parts department. A couple of them didn't even ask for model of car - once I said 2011 they said pentosin. One explained that pentosin is kind of their go-to PS fluid now and most of the cars come with it. If the car came with regular PS fluid, he said you can add pentosin and it won't hurt it (guess mixing fluids is debatable), but if the car came with pentosin you don't want to add regular fluid.

The gold star goes to the one guy who asked for my VIN (only one who did) and he said that my car came with the regular PS fluid, not pentosin and that I should use the same kind. $9 a bottle.

KEY08

Bingo, you are the super sleuth!

cetialpha5

This was covered in some older threads. Basically the yellow fluid is the regular stuff that came with the car and you can't go wrong using that. However the green stuff is the synthetic stuff that everyone seems to recommend, some threads said it was fine others said not, but I'm inclined to believe it's fine, you're just mixing synthetic with regular. If you have the option, the regular is just cheaper. I seem to recall that the danger was using the regular fluid in a system that called for the synthetic so to play it safe, they always use the synthetic.

belarus27

I didnt check the color , i just added it , cuz i think it says on the cap chf 11s so i was pretty sure about topping it off... i also added pentosin on my 2004 bmw 545 years back..
so far no issues after mixing (or possibly adding the SAME) fluid , and its been a long time , and also fixed the noise...
pheww lol

thefisch

Thanks for confirming that. Most of the threads I found only mentioned pentosin. There were many more discussions about other models, not many on W212.

I didn't even think to ask if there was anything written on your cap because mine is just plain black with no lettering whatsoever. It would have a lot easier if my cap said the fluid to use. Perhaps they started using labor's on the cars that came with CHF 11S.

thefisch

So I went by the closest dealer and met the parts guy who was the first to tell me not to use Pentosin. Not because I wanted to meet him but they were the closest location. He explained the PS sometimes shares it's pump with other hydraulic systems like body control. He is not a fan of mixing pentosin with the regular oil based fluid, especially when the original part is cheaper.

$8.70 plus tax out the door. And they even put it in a fancy tote bag like I was buying one of their fancy accessories.
Of course I snagged a bottle water and cookie while there. The car wash would have taken 30 minutes and I had somewhere to be (and maybe started to feel a little guilty).

I do owe an apology to NAPA because the fluid they showed as compatible is the same one as the one I just picked up. Every other website I checked only showed the CHF 11S. I did take a second cookie to bring to them as an apology but I ate it before I got there.

Timeplson

Hmmm, the car can tell you when u r low on coolant, but not telling that when u r low on power steering fluid. That sucks.

cetialpha5

You don't really need a warning sensor know when you're low on power steering fluid. The car will be harder to turn or it will make noise. And nothing really bad will happen if it's low. On the other hand being low on coolant or oil will toast the engine pretty quickly. Haven't really heard of any car that tells you when you're low on power steering fluid.

KEY08

I like your persistence, Fisch. You always find the right answer to issues and never jump on the first thing. You avoid all kinds of problems this way by being cautious like that.

thefisch

Thanks, but sometimes all the research still gets me to a wrong answer. Thankfully we have forums like these to help each other out so we're not at the mercy of the dealer service centers.

thefisch

Finally had a chance to add some PS oil this weekend. Funnel is a must obviously. I was trying to add it in small increments when the engine was cold in order to not overfill - well that didn't work. I added about 75ml (hard to tell since the first mark on the container is 800 ml) and the dipstick showed it was already over the max line for 20^C reading. It is a small reservoir and the lines on the dipstick are pretty close together. Drove it around and then checked it warm and it was just over the 80^C max line. So I removed some oil with a straw to get it right to the max line. Probably only needed 50-60ml.

Will have to try some of the same turns this week to see if the groans are gone. And now that I have a good level, I can check for any loss in a month or so.

jvakos

have a 2015 e63 and a similar steering groaning noise from the front end that occurs when turning the steering wheel left or right at very slow speeds...the steering wheel feels slightly harder to turn when it happens and you feel a slight vibration..

its loudest when temperatures are very hot and has continued to get louder for 2 years despite dealer visits telling me they cant replicate the sound/issue.

Here is a video of the noise - turn your volume all the way up and you can definitely hear it. When you guys had low power steering fluid did you experience noise like this? will check the fluid but am concerned its something with the steering column or steering rack????? any feedback would be hugely appreciated as i have 3 months of factory warranty left and need to get this figured out asap

thefisch

It's been a while but the sound seems similar - unfortunately I didn't take any video of it. But mine occurred at a higher speed. It was at slow speeds. I would check the fluid first just in case.

MBNUT1

Heard a slight groaning sound today when I turned the wheel. The fluid looks low. :How low depends on whether I screw the cap in all the way or not. What is the correct way to check it? Also is the conclusion not to use Petosin 11s? I ask because I have some in my garage.

Thanks