Hey Guys, Had my 430 for nearly 10 years now, done 38k miles and I'm about to replace my e-diff solenoid for the 2nd time. I still had my old solenoid that I replaced a few years ago so I thought I'd see if I could take it apart to see what's in there hoping there might be some repair possibility. So here is it, looks pretty simple, an electro magnet, a piston, a filter screen and a spring at the top and that's about it. The only thing I can really think of that must wear on these is the little piston rings which must then lead to not being able to maintain pressure. It looks to be pretty much impossible to disassemble this without completely destroying it, but this one was broken anyway so interesting to open it up. The solenoid mostly intact although it has had some Dremel action in this pic Image Unavailable, Please Login Separated top/middle/bottom Image Unavailable, Please Login Pulled the little filer off the top for this one Image Unavailable, Please Login And finally, all the component parts. Image Unavailable, Please Login So looks like these can't be repaired, if anyone has any insight as to what fails on these and why they're sensitive to tightening torque then it would be interesting to know John.
Looking at the internals, over-tightening would cause the body to distort slightly around the piston barrel and cause the piston to seize.
Does the piston have loose piston rings or are those machined from solid, it looks like a hydraulic shuttle valve piston to me, if so then those control the supply and return.
When I put a voltage through the old solenoid it actuated, the procedure with torque was adjusted from 15NM to 9NM, I can't get my head around 6NM being the difference between these working and failing. To answer all the questions, the rings are machined, not removable and I was getting a couple of codes, plausibility of the control valve and pressure outside limits or something, I'll need to dig out the exact codes, but I got e-diff warning on the dash and manetino stuck in wet mode. The solenoid that's currently in my car was put in in 2015 at 15nm per the old procedure, worked for a bit then stopped working then started working again until it seemed to fail properly a couple of months back. Still can't really get my head around how these fail John.
The errors i'm getting are below, exactly the same errors I got last time. 6016 - Plausibility of Magnetic valve current and lock pressure More detail on the error is "General plausibility - An error was detected on the magnetic valve current and on the differential locking pressure 6017 - Check: Pressure deviation too high More detail on the error is "Over maximum threshold - An error was detected due to a high pressure difference. The error is set when the difference between the pressure requested by the control and the pressure measured in the system exceeds 1 bar. Check the pressure sensor and sensor ECU wiring for proper working condition" John.
These sort of shuttle valves can wear and signs of this are small scratches on the side of the shuttle valve piston, ( also a loss of the square edge where the rings are machined on the piston )they then start to lose pressure between the pressure and the return side as the pressure leaks over. A lot of industrial hydraulic control valves are similar. Some of the expensive ones, i think they overhaul them by honing out the cylinder and fitting an oversize piston to suit.
