Hey guys I really need help here,

a few months ago my car had a major issue of oil in the coolant resvior and I realized that after starting the car and hearing loud whinning noise coming from under the hood and saw a “Low Coolant” warning on the dash, I immediately switched off the car kept it in place for a few days till my appointment at my local MB dealership came, they told me that there was a leak caused by a faulty line and that they have flushed the system and fixed the issue but on the repair notes they recommended that I get my Power Steering resviour replaced and they told me it was urgent so I had it replaced and on that day they told me that I would also need to have the Steering Rack and Pinion replaced (they quoted me $4,200, which to me seems absurd considering the whole car’s value is probably below that) so I told them I wouldn’t drive the car often and I can’t spend any more money than the already $3000 I spent (regrettably) after driving the car for a bit out of the dealership and on the way home, a loud whinning noise appeared and I immediately turned around and went back and they told me that this will keep happening if I don’t get the steering rack replaced and they told me I’m gonna have to keep filling up the power steering resvior with fuid frequently. I lost all and any sort of trust I have in them after they have told me that the whine in the first place was from the powrr steering and that replacing it will solve the issue temporarily for at least 6 months and after they replaced it, it seems like the issue became worse.

Now when I start the car there is no noise and no noise when I drive it for about a mile, afterwards the noise suddenly appears and is rather very loud and I really don’t know what the issue could be, is it truly the steering rack? Or could it be a torque converter? Or do I have a bad transmission? The car shifts smoothly, never noticed any sort of leaks or puddles under the car, no white smoke when I start up the car, the car runs fine and the steering wheel also feels normal even after the whine appears. I have attached a video of the noise and hopefully someone can help and guide me through a fix for this.

much appreciated everyone thank you for reading this and I would be more than happy to answer any questions if I left something out or forgot to mention something

2008 GL450
around 164K miles
No dashboard lights or check engine light or overheating issue just a “low coolant” sign and my coolant is already full

 

A few points that might help you get a better response:

1. What did they do regarding the coolant? Was it low? Im assuming that they havent suggested that the low coolant level was associated with the steering. Maybe explain in more detail what they did to fix the coolant issue
2. The noise in the video isnt your steering rack as it changes pitch with the engine and tranmission. Does the noise remain if yoy shift to neutral whilst rolling and keeping the rpm constant?
3. How many miles has the car done and what is the frequency of the tranmission services that have been done?
4. Have you ever changed the power steering fluid reservior? Does the noise in the video change if you move the steering wheel.
5. Does the noise go away once its started?

If I had to guess, I'd be focussing on the power steering pump, then tranmission.

 

As BlackML550 just stated, I would completely focus on the Power Steering pump. Mine just went and it made a god awful noise as it was going as it was dumping ps fluid on my driveway. I opted to go to a local Indi guy here in Naples and completely happy at this point. Couple of items:

1. Can't believe that your dealer would replace just the reservoir and not the PS pump as well. 4.5 years ago my PS was leaking and they refused to just replace the resy. Not real happy that 4.5 years later the pump went again. My Indi guy looked at my old invoice and questioned why they replaced it with a remany pump. He replace the entire assembly with new and it cost me $875 plus tax and that's here in Naples where everything is expensive!.

2. My guy also mentioned the rack but said it looked good at this point. After replacing the pump he flushed extra PS fluid thru the system to make sure no debris in there before completing the steering wheel stop to stop bubble purging procedure.

3. Prior to my replacing the pump last week, my 2009 ML 350 was wandering just a bit at high speeds. My recently retired Indi in his last job, recently replaced my front springs/struts and bushings on the rack so had several alignments but still a bit wobbly. The rack was major problem as it was moving up/down because the bushings were worn away. After Indi replaced the bushings on it (a real bear of a job he told me)said t, he said that some leaking from the PS pump probably contributed to the bushings deteriorating. I had noticed some drop in the ps fluid a few months earlier so put some stop leak into the resy and the leak stopped. Guess I didn't get it in time and the leak not only killed the bushings but it was also the beginning of the end for the pump itself.

4. Now that my pump replaced, I can't tell you how happy I am that it also fixed the wandering of my ML at highway speeds. Now at 70-80 mph, the steering tightens up a bit and tracks straight and true.

Hope this is helpful.