964Andrew

I've done the conversion to MB electric frunk mounted PS pump a year ago and until recently it's been working well. A week or so ago I noticed that the steering rack or pump got very loud on full lock. With that any repeat quick movement to left and right causes the steering feel gummy for couple of seconds until the pump builds up pressure.

Inspected the system and found no leaks, changed the fluid (initially thought it has helped) but the problems persists.

I am trying to isolate the issue to either the steering rack or pump. Has anyone experienced this and can help me figure out what's going on?









Thanks!
Andrew

HiWind

maybe check the Mercedes Benz A1 forum somewhere? Mine solid after 2 years

964Andrew

Sooo, I'm back at it again. Long story short: I have rebuild steering gear and bought new (used but in great condition) MB A-Class electric power steering pump. All was well for 7-8 months but today the pump gave up! Shuts down under seemingly small force of steering not even going full lock. This is a second pump in 2-3 years

So far I checked: electrical connections, power draw, alternator charging, voltage under load, added secondary battery for testing, checked pump mechanical pressure release (activated on full lock)... no change in behavior. Frequently fails under moderate load, and always on full lock.

I don't know anyone close by who has this conversion and before I will give up on this I wanted to compare line connections, electrical wiring, sound under load and steering support behavior.
If anyone can help me by recording several video clips and answer some questions or is willing to jump in on a video call that would be AMAZING!

Otherwise, I'm close to reversing back to belt driven pump, which is going to suuuuuuuck! because I cut all the lines out

Thanks!
Andrew

Peteinjp

Gus

964Andrew

Thanks for the tip on MR2 pump. Preferably, I would like to find out why they crapped out and try to fix the issue. If that fails - look for replacement or back to belt.

Thanks!
Andrew

robt964

Hi Andrew, my MB pump is still going strong several years on now. Are you using 2nd hand units? Perhaps you've just been unlucky with getting a few duds.
I'm happy to assist you where I can. My car is not runnable at present due to mods-in-progress but the car is still on its wheels and able to run-up the pump.

964Andrew

Thank you Rob, PM sent.

Thanks!
Andrew

-nick

Maybe just bad luck with your pumps? Mine is working fine despite a lot of autocross abuse. I haven't looked at the amp draw, but that could be a place to start. With the wheel stationary, I imagine it's around 10-15amps. Turning the wheel against the lock is likely >35amps.

What fluid are you using? Rumor is that the stock Pentosin maintains its low viscosity at colder temperatures compared to other ps fluids, which is what we want with the system far from anything that would warm it up.

Very nice installation though!

964Andrew

I've been using pentosin too. What color and consistency is yours? How often have you been changing yours?

Thanks!
Andrew

-nick

I haven't! Looks the same as in the bottle. Edit: I do fill it higher than the max line. I figure that it can't hurt anything and a little more volume might help keep it cooler when the steering is getting worked hard.

964Andrew

The consistency of my fluid has changed. Not very drastically thou. I might send it for analysis to see what if any metals are in it.
Maybe I have it all connected backwards?

Thanks!
Andrew

robt964

I opted to use the fluid that was listed for the MB pump which if I recall correctly was regular MTL fluid. No leaks.

Gus

Here are some pictures of my MR2 install. Basically I ran a power line from a fuse box I installed at the battery to a relay which was operated by a switch I mounted in the cockpit. This way I could turn the PS pump on without running the engine to make pushing the car around easier to do with the PS on.
Mounted the MR2 pump using the stock MR2 mount and some aluminum angle iron. Ran Aeroquip lines to the PS unit using bulkhead fittings. Ran direct line to PS unit from pump and return route was through a small cooler I got off ebay (AN6 fittings).

Gus

Forgot to add that I opened an area below the cooler and added a small scoop to direct air flow through the cooler - Also raised the hood a small amount in rear to allow for air flow. Pictures of relay and a circuit breaker ( white ) follow - Additional pictures as well.