Hello, 2008 ML63 with 113k miles here. I've had an interesting power steering issue develop on my ML. When I first start up in the mornings the power steering just isn't there. There isn't any groaning, the fluid level is normal, there's just no power. Once things warm up a bit, usually within 5 minutes, the power back in and then everything is fine and it works just like normal. I've searched through the forums but I can't find anything that matches these symptoms. It almost seems like it could be an internal seal in the pump that's letting fluid slip past until it's warmed up and expanded enough to stop leaking and then starts working. But I'd hate to remove it, rebuild it, put it back on and not fix the issue. Has anyone else seen or heard of this type of behavior before?

Thanks,
Rich

 

I would start with replacing the steering oil reservoir, it has a small screen (filter) that gets clogged with time. Maybe the screen restricts viscous fluid when cold, but as it gets hotter the viscosity becomes lower and fluid is able to pass through the screen.
Even if the issue is caused by the pump or rack, I would strongly suggest also replacing the reservoir as its cheap and has an updated part # from AMG.

Good luck.

 

Thank you, that's exactly what I ended up trying first. Finally remembered that I did that once before. Unfortunately it didn't take care of the issue but man was I hopeful.

However I did the power steering rack bushings yesterday. I will say if your bushings are sufficiently damaged like mine were you can replace them by only removing the three bolts from the differential. That gives you just enough leeway to back out the drivers side (in the US) bolt. Don't go into it thinking it's going to fall out, I still had to tap it out with a hammer and a ratchet extension and left a very small scratch on the differential. However, I considered it worth it since I didn't have to remove the axles and such. Then when you reinstall just put the nut on the backside rather than the front. I have no idea why they didn't do that to begin with... Another option that may seem ghetto but would probably save a ton of time? Go ahead and buy a new steering rack mounting bolt, very carefully cut the damn bolt head off, then tap it out. I'm sure some people will be aghast at the idea of doing that on an AMG but in my opinion it's just a bolt, it can be replaced, and it can save a few hours of time. If I'd had the spare bolt that's what I would've done.

Anyways while I was under the car I noticed a the power steering pump was incredibly oily so I think I found my slow leak - the pump. I'd forgot to mention that in my first post. Looks like FCP Euro sells a rebuilt pump for $267 so I'll just go ahead and order that. From what I've read before you have to remove the A/C compressor to get to it which is annoying but not too bad. Basically just like working on my C32.

It will be a couple weeks before I can tackle this but I'll post again afterwards once done with an update. Maybe it will help someone else down the road.

Thanks,
Rich