Recently I purchased a X350 w/100k from another state and brought it home, and like many, had a the issue with the ZF 6HP26 torque converter control issues. Knowing that it had to be addressed before damage occurred, I pulled the pan and found it had never been serviced. Visual inspection of the pan revealed little damage, however the fluid condition was as expected with so many miles.

So I chose to seek another valve body from REXMAX, who advertised that they replace 6 valves with oversized, and completely wash and recondition. However, what I found was an upper valve body that was from a 6HP19 that had not even been washed, 2 of the accumulators more than 0.030 below the surface (which means the rubber material was beyond service life) and no valve work whatsoever. The area which the plastic check ***** resided were scored by a pick to help them locate the location, but damaged the surface on the wall lands where it meets the separator plate. They did change the plate with a Sonnax brand, but in many places the sealant had be damaged or missing. The lower valve body, I could only find 2 valves that had been replaced, however, the body was never bored to fit oversized valves. All of the end caps were originals and showed wear. The solenoids provided were never cleaned, and on 3 of the 7 had flat O-rings, and none of the solenoids had the O-rings replaced. Screens on 2 still contained debris from prior service.

I ended up purchasing a new set of solenoids from ZF, a new separator plate and Sonnax ZIP-Kit to get new accumulators, and replaced the old end plugs. After this, a clearing of adaptions and relearn has now returned the ZF back to a drivable condition. Buyer beware.

 

good to know