Powersteering Check Valve removal

[tdott]

Timestamp 23:45 is where FCP talks about this. (granted on a non m)
But I confirmed that M3s do use a bolt with the check valve also.

Found this part that replaces the bolt with the check valve.
https://www.moreheadspeedworks.com/p...o-check-valve/

I think the theory from FCP is that removing the check valve prevents leaking seals when hitting curb at the track happen. The check valves causes pressure to build and leak past the seals, or something like that.

I often ride curbs at that track, but haven't had any issues with leaks.

Anyone heard of this?
Thoughts?

[Redd]

What's the danger of running without a check valve?

[bigjae1976]

I wouldn't remove it - I'd guess that its a safety device for the PS pump.

The PS pump is a positive displacement PD pump and is designed to spin 1 way or it will destroy the vanes inside of the pump. My theory is the check valve prevents a backward pressure surge (like shutting the car off) spinning the pump backwards. It also ensures any excess pressure is vented through the reservoir, not back through the pump.

Most of the times in the industry a pump will have a check valve downstream as a protection device for the pump.

[bmweye]

Originally Posted by bigjae1976

I wouldn't remove it - I'd guess that its a safety device for the PS pump.

The PS pump is a positive displacement PD pump and is designed to spin 1 way or it will destroy the vanes inside of the pump. My theory is the check valve prevents a backward pressure surge (like shutting the car off) spinning the pump backwards. It also ensures any excess pressure is vented through the reservoir, not back through the pump.

Most of the times in the industry a pump will have a check valve downstream as a protection device for the pump.

Thanks for your clarification bigjae1976
I have been thinking about this topic for a while. Found a 1999 scientific paper by Honda R&D which explains the reason behind the check valve on the banjo bolt, which is on the discharge hose from the pump, going to the steering rack. The purpose of the check valve is to close the channel for the potential reversal of the fluid when the vehicle is hitting bumps (i.e. steering kickback) which may destroy the pump. But I can't understand the other scenario, which you mentioned, where the fluid reversal would happen after the engine has been shut off. Is it the case when you shut the car, the fluid travel stops, hits a dead end, and wants to reverse the opposite direction? Can you shine some light on that?

http://eb-cat.ds-navi.co.jp/enu/tech...7E/157E_10.pdf