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Alright, long story short. The control valve to the steering was leaking at the top where the steering shaft comes in (Video attached). This has been a known issue on the OM642 engines. There has been a thread on other forums regarding this, I will edit to include the link next time.
I do not want to take out the entire steering rack. I just want to take out the control valve. Maj. Dundee has uploaded the procedure to R&I steering rack. But this involves unbolting the diff and taking out the front axles. Autodoc UK has remanufactured racks for Left-Hand Drive versions, but not for RHD, which is what we use in Australia.
A steering specialty shop quoted me AUD$1500 for a rebuilt rack, but I have to take it out. I found a rack rebuild seals for AUD$200 on ebay. So this is what drove me just to replace the seals on the control valve.
Steering Rack Part Number (RHD): A1644600325
Pros: save money if issue is isolated, no special tooling required
Cons: potential waste of time, least beneficial option
LASTLY, if anyone has any procedure on how to rebuild the rack, that would be greatly appreciated
Ebay reseller steering rack seal kit (OEM is Kotek)
Mbworld post for procedures by @Maj. Dundeehere.
2hrs to take out Steering rack clearance port Steering clearance device?? Little wiggle room to work on. Speed solenoid in picture. Plug taken out, 17mm hex socket
Steering rack
Last edited by DLB_Adelaide; Mar 2, 2025 at 07:39 AM.
I chickened out of doing this myself a few years ago and paid $2k for the shop to do it. Glad I did, because it leaked again and they had to take it out again.
Can you take some pictures when you put it back in and of the tear down.
I chickened out of doing this myself a few years ago and paid $2k for the shop to do it. Glad I did, because it leaked again and they had to take it out again.
Can you take some pictures when you put it back in and of the tear down.
hey mate
There are multiple steps to it but it is fairly easy. As always, you need to understand how to put it back before pulling it apart. Plenty of research was done. Youtube helped as well. Videos showed steering rack rebuilds from other brands. They will be of similar technology with some slight differences. Will have a rack, pinion, housing fastener bolts, inlet outlet return pipes, clearance adjustment mechanism, or bolt to hold the valve (not found in w164 x164). Here is a video of a rack-pinion removal for an ML.
I sure will include pictures when I take it apart. I am hopeful nothing else leaks. But once the system operates back at operating pressure, there is a chance that other seals will leak. Lastly, you will notice how I have been using Imperial size sockets like 3/8". This is because I dont have the hexalobular sockets required for some of the bolts. You just have to find the closest fit possible.
Circlip and bearing to remove first. Housing bolt-holes and pipe bracket bolt-hole can be seen here Steering shaft spline. White paint marks before removal
Clean picture from eBay
External hexalobular bolts
Jack stands Work area
Here is a rack rebuild video of a Toyota steering rack. Time skipped to the control valve portion.
Although I think it is leaking from the hose coming from the pump.
I'm after details of part 40 below if you still have it apart. Apparently a non stocked item. Do you have any details on what it is (measure it for me if you have it apart, I'm assuming its a copper washer - its not the oring which is item 50)
Is it the white spacer next to the green oring in the photo below:
I couldn’t find two o-rings on the pipe. The one I am holding below picture is the pipe going to radiator. Which means theother pipe in the picture is the one from the pump.
Originally Posted by alive19
Comically mine is leaking now.
Although I think it is leaking from the hose coming from the pump.
I'm after details of part 40 below if you still have it apart. Apparently a non stocked item. Do you have any details on what it is (measure it for me if you have it apart, I'm assuming its a copper washer - its not the oring which is item 50)
Is it the white spacer next to the green oring in the photo below:
I have an update to this thread. The seal kit has arrived and have replaced the seals/circlips in the control valve. If there is anything I have learned in this, is that the seal kit I ordered is for the steering rack without the Speed-sensitive Power Steering (SPS) or no solenoid. You will see in the below pictures that the kit will only have QTY 4 sets of seals for the spool valve but needs QTY 5 to replace everything. The fifth seal is for the SPS circuit.
All in all, it wasnt that difficult to replace the seals in the control valve if you have decent tools. Also notice that the spool surface condition where the leak is happening is rouher or more worn out. One of the pictures below will be closer where you can see the surface condition of the various hydraulic circuits; supply, left, return, right, SPS. The o-ring and teflon ring on the leaking side wasn’t rubber anymore. Hence, the leak because the rubber was brittle and could not seal properly.
Soft hammer blows from the steer-shaft side Bearing and seal at the other end Took out first rubber o-ring and teflon ring New set which is only for QTY 4 circuits. Black is the rubber o-ring on inside and will be covered by the white teflon ring Seal and shaft-side bearing New seal and shaft-side bearing isntalled Tools used to punch out/in the shaft-side bearing Notice that there are QTY 4 white teflon rings and QTY 1 black teflon ring (unreplaced) Halfway through reinstalling spool into control valve housing
All items replaced within control valve QTY 4 spool seal set QTY 1 circlip QTY 1 shaft-side seal QTY 1 rack-side seal
Last edited by DLB_Adelaide; Mar 28, 2025 at 02:16 AM.
I stand corrected. That white teflon spacer is indeed there. I didnt see it at first because of all the smudge.
Note: that white teflon spacer cannot be found in the kit I am using.
Originally Posted by alive19
Comically mine is leaking now.
Although I think it is leaking from the hose coming from the pump.
I'm after details of part 40 below if you still have it apart. Apparently a non stocked item. Do you have any details on what it is (measure it for me if you have it apart, I'm assuming its a copper washer - its not the oring which is item 50)
Is it the white spacer next to the green oring in the photo below:
I have finally installed the resealed control valve. No leaks so far. There is a leak elsewhere in the Steering system but this is not from my workmanship. The leak is somewhere between the pump, reservoir, or the pipes going down to the valve; since I found this on the Left Hand Side (LHS) of the car. The next step to this would be to realign the steering and the wheels. Currently, it is off by a few splines on the steering shaft.
NEXT PROBLEM: I have disconnected the battery for about a month now. Once I opened the door, I noticed that the side mirrors did not unfold. The control unit for the side mirrors might have run out of juice and lost its memory. This is only my theory and I still need to find out the cause. What makes it worse, is the previous owner installed a "fake" window switch module on the door which does not have the Mirror Unfold feature.
Do you know anything about your door module?
I doubt they would have different hardware. More likely a software change, or just and adaptation required? It may be that the old module didn't have the mirror fold programmed in.
I replaced my orings, so hopefully the teflon washer doesn't need replacing. Too early to see whether it leaks.
Thanks for the write up.
Edit - just reread your mirror. So you don't have the window button. Lol. Maybe get one of aliexpress. You should able to activate it if you have a decent scan tool.
I dont have a bi-directional OBD tool. So that idea is out. Also, I do not want to go to a workshop just for a mirror, so this idea is also out.
So what I did was just jump the Mirror fold motor and supplied voltage. My mirrors are now OPEN again. I will also disable the fold when locked option in the HMI settings, just in case the control unit does something funny again.
12V to pin 6. GND to pin 7. This will open the mirror. pin 6 and pin 7 for the mirror motor
Originally Posted by alive19
Do you know anything about your door module?
I doubt they would have different hardware. More likely a software change, or just and adaptation required? It may be that the old module didn't have the mirror fold programmed in.
I replaced my orings, so hopefully the teflon washer doesn't need replacing. Too early to see whether it leaks.
Thanks for the write up.
Edit - just reread your mirror. So you don't have the window button. Lol. Maybe get one of aliexpress. You should able to activate it if you have a decent scan tool.
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