GLENN S.

Replaced Hyd. pump, was leaking, low pressure code. Still has code & fluid is at the same level before starting engine and after a short test drive. Scanner showing 0 bar of pressure. Does the new pump have to primed some how? No fluid coming out of return line. I assume the electrical switch on top of pump is the pressure sensor. Connections are good. Any help would be appreciated!
Been working on Benzs for 44 years.

biker349

from what i've heard if you don't prime the pump and run the engine you will destroy the pump. there are many threads on priming the abc pump.

GLENN S.

Thanks, I filled fluid and spun pump with air ratchet for 2 minutes. I thought that would have primed it. I've replaced pumps on other high line cars and never had one not prime. I guess I'll pressurize the resovoir and see if that works.

biker349

i have heard of both methods. most people pressurize the pump, but i was told filling the reservoir and spinning the pump should work as well. maybe you got a bad pump. was it rebuilt, or new?

GLENN S.

New, hope it's not def., not a pleasant job!

GLENN S.

All fixed. Pressurized bottle and pump sucked in the fluid. Had return line going into a bucket. Lots of crap coming out. Went through 5 containers of 11S. Also changed the filter.

biker349

good to hear. so i guess the pressurizing the container is preferable to spinning the pump for priming purposes.

GLENN S.

I would suppose. Never had this problem. Has 192 bar pressure at idle.
Thanks for the response!