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Converting V12 ABC pump to a V8 power steering only pump.

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S-Class (W220) 1999-2006: S 320 CDI, S 320, S430, S 500, S 600

Converting V12 ABC pump to a V8 power steering only pump.

 
Old 06-09-2017, 12:17 AM
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2004 S600
Converting V12 ABC pump to a V8 power steering only pump.

Backstory: I bought my 2004 S600 with 78k miles and failed ABC. Had it towed to my house, (had to use a special race car trailer because it sat too low for the flatbed wrecker. I paid $2700 for the car, which was a "can't lose" price; the seller was just done spending money on it, and the $3k estimate for fixing the ABC again just pushed him over the edge. Anyway, I got a nice low mileage car (not a creampuff) for silly money. My intention was to delete ABC and go to coilovers from the get go. After a less than pleasant experience with Strutmasters, I ended up with a set of Yellowspeeds in the car, which I'm very happy with. Since my ABC system was ruptured, I have simply been running the ABC side of the pump dry, which I've heard may or may not work.

I've been enjoying the car for the last 6k miles, until recently, when the power steering began complaining. It became hard to turn at low speeds, and making uncomfortable groaning noises. Info on this forum indicated that the ABC pumps do not last long running dry, but a popular conversion for V8 cars was to swap power steering pumps from an air ride car. Unfortunately for me, it seems no one has done this on a V12 yet. User Cowboyt is running coilovers on his V12 with a fluid recirc to a regular ABC pump.

I like the idea of running the V8 PS only pump on my V12 car, but there are some obstacles, which as far as I know, nobody has solved yet. So I got busy trying. First, I bought a used PS only pump off of an S500, with the idea getting both pumps in my hands to compare them and see if it is worth doing. Comparing pictures was very promising! Then, I removed the tandem pump from my V12, (and you know what a pain that is) and got them on the bench together. Well, there are some obstacles!

1) The pulleys don't match. V12s have a 7 rib belt, V8s have a 6 rib belt.
1.5) Pulleys are not interchangeable
2) The mounting holes are the same pattern, but there is a lot of space to make up just to get the V8 pump to match the V12 belt line.
3) The rear mount is different.
4) The power steering line output is in a different position. Big problem!
5) The V8 pump mounted fluid reservoir interferes with the V12 coilpack.

Photo shows my V12 tandem pump (top) and a V8 PS pump (bottom) with the mounting tabs roughly aligned. Offset is significant.



So, my ideas were that I would need to custom fab something(s) to make this work. But What?
1) Spacers/mounts/bracket to match M275 beltline (not too bad, if you get the measurements right the first time)
2) Custom 7 rib pulley to match beltline (LOTS of machine time =$$)
3) Custom PS output line (Again, not too bad)
4) Rerout reservoir supply to OEM remote tank. (Easy)
5) Custom PS fluid reservoir
6) Convert V12 to 6 rib belt to match PS pump with off the shelf Ford part (Easy!)

If none of this works, I will buy a reman ABC pump, and fab a fluid recirc system like Cowboys

Project in progress, updates as they occur!
Attached Thumbnails Converting V12 ABC pump to a V8 power steering only pump.-ps-pump-comparison.jpg  
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Old 06-09-2017, 10:50 AM
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Update! Measurements taken, everything checked twice, and latheing up some spacers for the correct standoff. This should get the V8 pump pulley into the correct beltline on the V12. There is 1.375" (35mm) standoff difference between the pumps, measuring from the inside edge of the pulley on both. I've made 4 spacers total. From the front of the motor, the lower left mount needs a 1.375"x .750" spacer. The upper right mount has a separate hanger bracket, so needs a spacer on each side of the hanger with a total stack height of 1.375". The stock rear mount does not align with the V8 pump, but there is an unused hole on the V12 that does line up with a mounting hole on the V8 pump, so that is what I used, also with a 1.375"x .750" spacer. I have also measured and sourced for new mounting bolts. I need 2 X M8x70mm in front, and 1 M8x60mm for the rear. Thanks to my pal Joe for the custom lathe work!




Last edited by TenZero; 07-19-2017 at 01:53 AM.
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Old 06-09-2017, 02:59 PM
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Will a 6-rib belt run well on a 7-rib pulley?
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Old 06-09-2017, 09:40 PM
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You don't need the spacer. The mounting points are the same between the tandem pump and the PS pump. Both are about 4in
Converting V12 ABC pump to a V8 power steering only pump.-photo644.jpgConverting V12 ABC pump to a V8 power steering only pump.-photo206.jpg
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Old 06-10-2017, 12:01 AM
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Looking forward to good results. This is really helpful to V12 owners who wish to convert their ABC system whenever it fails. Good luck.
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Old 06-10-2017, 12:05 PM
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Originally Posted by DrDoe View Post
You don't need the spacer. The mounting points are the same between the tandem pump and the PS pump. Both are about 4in
Attachment 356584Attachment 356583
Actually, you absolutely need spacers to make it work, but you really need both pumps out of the car and in your hands to see why. In your pictures, you are actually comparing the the location of the front mounts on the tandem pump to the rear mounts on the V8 pump, which are definitely NOT interchangeable. Check the photos in my OP. I'll post up photos of the spacers in my next update for you, and you'll see what I mean.

Last edited by TenZero; 07-19-2017 at 01:56 AM.
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Old 06-10-2017, 12:10 PM
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Update:
After getting all the measurements sorted, and making the spacers, it's time to test fit everything. The spacers are made from steel bar stock, so I coated them in orange primer to prevent corrosion. This also makes the spacers easy to identify and visualize in the pictures, in case I didn't describe them well enough. Now that they are fitted up, everything is spaced and aligned perfectly to the belt drive line of all the other accessory pulleys on the V12. I'm really happy with how this is turning out so far. From the front, you can see the 1.375"x.750" spacer on the left, and the two spacers and the stock hanger bracket on the upper right. In the second pic, you can see the rear mount with the other 1.375"x.750" spacer in the unused mount position. The rear mounting bolt threads straight into an available 2nd mount on the back of the V8 pump. Below that, you can see the stock rear mount position on the bracket, which does NOT align with the other rear mount on the pump (just to the left). They are off by about 3/4", and it would have been a much more complex spacer to make.





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Old 06-11-2017, 12:53 AM
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Update:6 rib pulley solution

After getting all the spacers sorted out and ensuring the 6 rib V8 pulley is correctly aligned with the inside 6 ribs on all the 7 rib pulleys on the V12, here is my solution to the 6 rib/7 rib problem that everyone seems to be getting hung up on.

Firstly, machining a custom 7 rib pulley is a LOT of work (Time=$$) for a qualified machinist, especially if it is a one off project that he can't continue to make money on to spread his costs. There are probably 3-4 hours total in just getting my spacers right. Unless you have the tooling to do it yourself, you would be looking at paying for at least a dozen hours of time to get it right. This would eat all the cost incentive to use a V8 pump in the first place. As far as I could tell, no one has done the work and sells a part like this.

What someone DOES sell, and it is in stock at Autozone, is a 6 rib belt in the correct length. Dayco part #5060923, for $35.99. By aligning my V8 pump with the inside 6 ribs on all the other pulleys, I can just run the car on a 6 rib serpentine belt, and call it done. The 7th rib, (closest to the radiator) will remain unused. There is no reason why this shouldn't work, as long as a premium quality belt is used. I would expect slightly shorter life expectancy, since the 6 rib is about 0.1" narrower than the 7 rib. Rib spacing, depth, and cut are all the same standard. I got it all installed, and the belt length is the same (the pulleys are the same diameter, just different ribs). Just crank on the tensioner, and slip it on, just like a standard belt.
Attached Thumbnails Converting V12 ABC pump to a V8 power steering only pump.-6-rib-belt-installed.jpg  
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Old 06-11-2017, 02:16 AM
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Awesome ! Is it cheap /easy for you to make more spacers for others who need them ?
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Old 06-11-2017, 02:58 PM
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nice write up thanks and keep it going.
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Old 06-14-2017, 02:04 PM
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Update: PS hard line

I've had to take a few days off from this project, because life happened. Everything has gone really well so far, but now I've gotten to the stickiest part of the conversion. Now that the V8 pump is successfully mounted, and the belt installed, the last real obstacle is that the power steering supply line to the rack is too short to make it to the pump output. As you can see in the pics, the output port on the pump (large gold hex on the left) is about 4" farther forward from the port on the old tandem pump. The hard steel line is about 4" short of being able to connect, and there is nowhere near enough flex in the line to make up the distance. Looking from the front, there is also about a 30 degree difference in clock position, or about 1.5" of vertical I need to make up as well.

Since the fittings on each end are Mercedes specific, I want to keep them original for simplicity. My plan is to remove the line from the car, and then have my local hydraulic shop add 4" of flexible extension near the top, right before the 90 degree bend that goes into the pump. that should give me the necessary length, and the flex line will allow for a little fine tuning of the fit in case the measurements aren't exact. The other simpler option would be to just braze in a section of hard tubing in the correct length. I will defer to their expertise on the best way to solve this of course. Removal of the line looks to be the hardest part; and once this is done, The rest is easy, just plumbing a reservoir and return lines, filling ,bleeding, checking for leaks, etc.
Attached Thumbnails Converting V12 ABC pump to a V8 power steering only pump.-ps-line-side.jpg   Converting V12 ABC pump to a V8 power steering only pump.-ps-line-front.jpg  
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Old 06-24-2017, 11:56 AM
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Update: Plugs and gaskets

I've done some of the "while you're in there" jobs. To get to the Tandem pump and get enough access to everything to do this conversion, the driver's side coilpack, intercooler and intercooler hardline needed to come out. I noticed the valve cover gasket shows weeping, and I was not certain of the age or condition of the plugs. The car had 78k on it when I got it (about 85k now), and the previous owner claimed he had all the plugs changed when on of the coilpacks was replaced at the dealer. With all the other klugey bull****e mistakes the dealer 'mechanics' have done on this car, I just decided to change all the plugs anyway. That way, I KNOW they've been done. So, off with the coilpack and intercooler hardware on the passenger side as well. Really only about 10-15 minutes extra work.

On my car, (13 years old, 85k miles), the valve cover gaskets were toast. They were so crispy, they crumbled into little pieces when I pulled the covers. The spark plug valleys had quite a bit of oil in some of them, so I hosed them all out with carb cleaner and compressed air *before* removing the plugs, to keep oil and dirt from draining into the cylinders. On removing all the plugs, I found 3 different brands and ages/condition in my car, so my decision to change them all was a good one. 24 new Denso Iridium Power IK20's went in, along with the 2 new gaskets. Also good to have the chance to clean all the oil and gunk from the coils, to keep them functioning properly and hopefully extend their lifespan.
Attached Thumbnails Converting V12 ABC pump to a V8 power steering only pump.-valvetrain.jpg   Converting V12 ABC pump to a V8 power steering only pump.-plugs.jpg  
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Old 06-26-2017, 11:47 AM
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Update: PS hard line

So here is my solution to the power steering hard line mismatch. You can see in the photo that I needed to make up about 4 inches between the end of the hard line and the pump output. The hard line has numerous bends and angles in it that carefully route around the turbo and exhaust plumbing, so you can't just pull it up to close the distance. Luckily, I found that there is a joint in the line where the hard line can be separated. This means that I didn't have to remove the whole supply line to the rack (a huge job). The fitting is on the drivers side, just at the end of the heat shield jacket. Using a a nice 3/4" piece of plywood under the oilpan, I jacked the engine up about 2" or so, and removed the hardline. It has to be finagled out, and there is a bracket holding it to the motor that has be removed (1 bolt) but it comes out the top. By the way, there is no room at all to be able to use a flex line to replace this. Hydraulic hose with the correct ID for the fluid flow is just too fat to fit and make the intricate bends the hard line does.

The end closest to the pump has a 90 deg bend where it enters the pump. Basically, I cut the 90 corner out, and was left with about a 1" piece with the Mercedes fitting that screws into the pump, and about 2" of straight line on the end before the next bend. The hydraulic shop brazed a 90 deg fitting to the 1" piece, and a straight fitting on the end of the hard line. In between, they made a 3" piece of hose with corresponding fittings on each end. Since we were operating off of cell phone pics, and weren't exactly sure about the length, they also added extension fittings so I could make it a little longer. (These weren't needed, it fit perfectly) The fittings are loose, so everything can be rotated and clocked just right during install. I finagled the hardline back in, then I plugged the new line into the pump, bent the flex into position on the hardline, and then tightened everything up.

My power steering pump is off an air ride S500, and it came with a pump mounted reservoir. (Bought on Ebay for 90 bucks) On the V12, the S500 reservoir can't be used because the left coilpack is in the way. I had hoped to be able to ditch the giant ABC tank, but I reinstalled it to use the original PS reservoir. I will probably go back and get rid of the ABC tank later. I then found that the supply hose from the V12 reservoir is bent the wrong way to match up to the pump and not interfere with the pulley. After I stared at it for a while, I took the hose off the tank, reversed it, installed it backwards, and it fits perfectly with plenty of clearance for the pulley. Now, all the custom stuff is done, and it's ready for reassembly and shakedown testing. I really think this is going to work!
Attached Thumbnails Converting V12 ABC pump to a V8 power steering only pump.-ps-line-side.jpg   Converting V12 ABC pump to a V8 power steering only pump.-new-line.jpg   Converting V12 ABC pump to a V8 power steering only pump.-supply-line.jpg  
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Old 06-28-2017, 11:09 AM
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Update: Done!

Once the power steering hardline and fluid supply hose were attached, reassembly was otherwise normal. Since I aligned my pump spacers to the inside edge of the pulley on both pumps, I made sure to align the 6 rib belt leaving the rib closest to the radiator unused on all the other accessory pulleys.

After reassembly, I filled the PS reservoir to the top with Pentosin CHF11S, and jacked the front wheels off the ground before starting the engine. Immediately after engine start, I turned the wheel full left and full right and then shut the engine off. After this job, there will be a substantial amount of air in the PS system that must be bled. This needs to be done with no load on the wheels to avoid pump cavitation. After shutoff, I found the reservoir to be nearly empty again, so I refilled it once more. After this first time, it should monitored, but you won't likely suck any air. If you do suck air, you need to do it all over again.

After waiting awhile for air bubbles to settle out of the system, (A couple of hours, and this won't happen while the pump is running) I lowered the car and started her up. Everything works perfectly, just as it should. I've driven it about 200 miles before writing this up, just in case I screwed something up, or the idea didn't work out. From the driver's seat, you would never be able to tell any difference. The power steering functions exactly like it did when running the old tandem pump, the ratios and variable assist seem spot on. There are no odd noises, and the 6 rib belt drives the AC and charging system (the two highest load accessories) with no complaints. In short, it's a custom install that does not have any idiosyncracies or minor niggles to explain away. It works just as intended, and you'd never know unless you needed to replace a belt or something down the road. Result!

Since I've already done all the engineering work, this is actually not too difficult a mod to accomplish on your own V12 if you want to.

What you need:
1) Power steering pump off an air ride V8 car S430/500 (I got a pump off a 2001 S500, I don't know for sure if there are any variations in model years)
I recommend getting a used pump from Ebay or something. You will need the mounting bracket and pulley. New pumps I looked at didn't come with these pieces. My Ebay pump came with everything. Cost: $90 shipped

2) Custom fabricated hydraulic hose modification to original hardline. Cost: $65 + a 12 pack of beer for the shop. Use my pics so they know what you're talking about.

3) 4 spacers, machined from bar stock. I used steel, aluminum would work too, I guess. They are all .750" diameter, and two of them are 1.375" long. The two smaller ones are different thicknesses from each other. I'll edit this later when I find where I wrote the dimensions. All these are gun drilled with a .325" hole down the center to fit an 8mm bolt. You'll also need your version of my good friend Joe with a lathe to make these for you.

4) 3 new mounting bolts, 2x M8x70mm, and 1 M8x60mm, and a couple a washers. About $5 at Lowe's
(The metric hardware selection at Lowe's is way better than Home Depot)

5) Dayco belt part #5060923, about $35, in stock at Autozone.

With the spacers already made and in your hands, you can swap the pumps out fairly quickly. Getting the tandem pump out is the worst part of that job. The most time consuming part is extracting the hardline and having the custom line fabricated. Once you get that back in, easy.

Total cost: About $200, all in.
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Old 06-28-2017, 04:55 PM
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Nice! Great to see someone successfully do the first V12 with a standard p/s pump! Update us on anything that happens relating to the mod.

There seems to be a lot of labor, custom fabrication, and time involved with the mod, however. Do you think it would be easier to get a reman tandem pump for $250 and recirc the abc portion back to the reservoir so the pump will last long only serving as a p/s pump?
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Old 06-28-2017, 10:32 PM
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There seems to be a lot of labor, custom fabrication, and time involved with the mod, however. Do you think it would be easier to get a reman tandem pump for $250 and recirc the abc portion back to the reservoir so the pump will last long only serving as a p/s pump?[/QUOTE]

See my summary above. If you go with a reman pump, the pump costs $250 (at the minimum) and you still need to engineer and fabricate a recirc line, so you need to add that cost as well. One member here (Cowboy, I think) did it that way, and seems happy with it, so I'm not gonna knock it.

Some reasons I chose to tackle the problem the way I did:

1) Ease of maintenance. Now that the conversion is done, the V8 pump is a piece of cake to change out if necessary at some point in the future. 3 accessible bolts, no jacking the motor, no weird tools or contortions, tons of room to work. I can probably have the pump out of the car in less than 10 minutes. The V8 pump also makes the AC compressor and hoses more accessible if needed. These cars aren't getting younger, and that ABC pump just sucks to work on, always.

2) Cost: I'm in this for around $200 turn key. If I have to fix the power steering again in the future, a brand new V8 pump with a lifetime warranty is much cheaper and easier to find than even the cheapest reman ABC pump. (less than $150 for a life time warranty PS only pump from a V8). I chose to start this project with a used pump, because I wanted all the brackets, reservoir and hoses that came with it to see what I needed to make it all work. Also, I didn't want to spend a lot in case it didn't work.

3) Reliability: Even if you run an ABC pump on recirc, you are still running 2 pumps instead of 1, so you have twice the failure potential, plus the added risk with reman pump quality. The ABC pumps are a known weak point, whereas the regular pumps don't really seem to ever be problematic.
*This could be offset by the possible reduction in service life of the 6 rib belt setup, but that's unknown at this point. It runs all the accessories without complaint so far; I highly doubt it will be an issue.

4) Performance: By going to the V8 pump, you are reducing the accessory drive parasitic load on the engine by a total of one pump. How much is that worth? I have no idea, as I never dyno'd my car before and after. But? Getting rid of a whole pumps worth of drag has to be a good thing.

5) Easy: I already did all the measuring and figuring to engineer this, which took most of the time. To duplicate it, all you have to do is follow my instructions in this thread, and I think it would be cheaper and easier than the recirc option. The only custom stuff is the line mod (which you'd have to do with a recirc anyway), and the spacers.

Last edited by TenZero; 07-04-2017 at 02:10 AM.
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Old 06-29-2017, 04:21 AM
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It is great work, very nice

I suggest that if your tandem pump is ok and you want to convert from abc to coilsprings
keep your tandem pump and reservoir:
connect ABC part of the pump like this: PUMP OUT > RESERVOIR > PUMP IN
you can remove the ABC radiator too, you will gain engine cooling
this I have tested for over a year, and is perfect.

https://mbworld.org/forums/cl-class-...-partlist.html

https://mbworld.org/forums/cl-class-...ping-pump.html

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Old 07-18-2017, 10:46 PM
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Any updates? How is everything holding up so far?
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Old 07-19-2017, 01:39 AM
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Originally Posted by AlexMercedes View Post
Any updates? How is everything holding up so far?
The conversion now has over 1000 miles on it, and is continuing to work perfectly. The steering feel and effort is the same as OEM, and there are no odd noises. If you didn't know it was converted, you couldn't tell. Once I bled the system first after install (see my instructions) and made sure the fluid level was correct, it hasn't leaked anywhere or consumed any fluid. The 6 rib belt is working great, just like the stock 7 rib; even running AC in the Texas summer.

Since I used a pump I got from Ebay off of a junkyard 2001 S500 car, (90 bucks) I wouldn't necessarily be shocked if the pump itself gave up, since it was of unknown mileage and condition. But that wouldn't have anything to do with the actual conversion process. Now that the conversion is complete, it would be easy to just throw in a brand new pump from any air ride car if it was ever needed. I'm not doing that, because mine works just fine. Without ABC, changing the converted PS only pump is pretty easy, should it be necessary. * If you decide to do this conversion, I recommend utilizing a used V8 pump, since they come with all the brackets and most importantly, the pulley. Many of the new or reman pumps at parts shops I found didn't have this stuff, and you'll need it.

Last edited by TenZero; 07-19-2017 at 02:02 AM.
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Old 07-19-2017, 06:24 AM
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Thanks, this is really starting to look convincing for me. My tandem pump pulley is getting really noisy, and my abc is acting up very strangely. I could tell its on the verge of ending its life...

My only concern though is getting the spacers and new ps hard line fabricated properly. If anything, do you mind getting them fabricated for whoever requests it since you have experience with it? Especially since you have someone that already made the parts and has experience with it. All shipping costs and an extra courtesy costs paid by the buyer, of course
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Old 07-20-2017, 11:23 AM
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Originally Posted by AlexMercedes View Post
Thanks, this is really starting to look convincing for me. My tandem pump pulley is getting really noisy, and my abc is acting up very strangely. I could tell its on the verge of ending its life...

My only concern though is getting the spacers and new ps hard line fabricated properly. If anything, do you mind getting them fabricated for whoever requests it since you have experience with it? Especially since you have someone that already made the parts and has experience with it. All shipping costs and an extra courtesy costs paid by the buyer, of course
Alex, I asked my machinist pal that made my spacers if would be willing to knock out a few sets for other people, and he said he would do them for $100 a set. Since I already did all the work to get the measurements correct, it's still about an hour or so of machine time.

Here's the risk to doing 'custom by remote': I would have no way to guarantee fit without having whatever V8 pump you sourced in my hands. My spacers were measured and made for the pump I had. I have no idea if there are any differences in year/models etc. Same thing for the PS hard line conversion and the location of the PS output. Everything *should* fit the same as my car, but you need to understand the risk if you aren't doing the setup work yourself.

As far as converting the line, I looked hard for a hydraulic shop that was even willing to do the work, and they are 100 miles from my house. I'm not ready to drive your parts up there and back for you, but we could probably make an arrangement for you to ship your parts to them for conversion based on the one in my pics. I think they charged me 75 bucks or so.

None of this super difficult, especially if you read my instructions thoroughly, but there is definitely value in being able to source the machining and hydraulic work locally to you if possible. The hardest part other than removing the tandem pump, is getting the measurements right for the spacers, and I did that already. I'm happy to help as much as I can.
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Old 07-20-2017, 06:54 PM
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Thank you TenZero, I have read this thread thouroughly and understood as much as I can. I am going to be doing all the work myself. As far as I have researched, there is no real difference between ps pumps in the model years. They have had a few changes in part numbers, but I'm sure none of them had to do with mounting positions since they are all made interchangeable. Here is the part number of the newest version and all the part numbers it replaces:
http://www.genuinemercedesparts.com/...p-002466860187

The only issue is that I had a hard time understanding the hard line conversion. Instead of going through the trouble of removing it from the car and modifying it, can't I just fabricate a fitting that screws onto the oem tandem pump fitting, then have a hose extension like you have done that goes into another fitting that screws into the standard ps pump? That would be WAY easier than going through the hassle of removing the hardline, bringing it to a shop, modifying it, bringing it back, and reinstalling the line. It would also be a plug and play solution that anyone can do if they wish to do the conversion.

Also, I have no good hydraulic shops anywhere around me either. I don't want you to drive 100 miles to your shop and back, so I think the better option would be to call the shop myself and see what he can do. Do you think having a plug and play fitting extension is possible?
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Old 07-21-2017, 12:13 AM
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2004 S600
Originally Posted by AlexMercedes View Post
The only issue is that I had a hard time understanding the hard line conversion. Instead of going through the trouble of removing it from the car and modifying it, can't I just fabricate a fitting that screws onto the oem tandem pump fitting, then have a hose extension like you have done that goes into another fitting that screws into the standard ps pump? That would be WAY easier than going through the hassle of removing the hardline, bringing it to a shop, modifying it, bringing it back, and reinstalling the line. It would also be a plug and play solution that anyone can do if they wish to do the conversion.

Also, I have no good hydraulic shops anywhere around me either. I don't want you to drive 100 miles to your shop and back, so I think the better option would be to call the shop myself and see what he can do. Do you think having a plug and play fitting extension is possible?
Alex, great question. I'll do my best to answer. First, I should state that I am by no means a hydraulics expert; I know just enough to be dangerous.

Next, a bit about hydraulics in general, and power steering in particular, and Germany. The hard line in question is known as '10mm' hardline, which refers to its ID, or inside diameter. Due to its metric sizing, and the metric fittings on each end, it is not directly compatible with any standard hyraulic fittings that are commonly available in the US. Most US hydraulic shops make their bread and butter from the trucking and heavy equipment industries, which is standardized around SAE sized fittings, hoses, and hardware. There may be a specialized custom metric shop that deals in this stuff for race cars or something, but I didn't find anything. So almost anywhere you go, they will only have industry standard SAE stuff to work with.

This means they can't make you a custom hardline, because they don't have the metric size tubing, or any of the correct metric fittings you need to plug it into your Mercedes. What they DO have is the ability to modify your hardline by taking a small piece from the middle and brazing their SAE pieces in to extend it and get the end to reach where you need it to. Since the very specific fittings are already present on your hardline, it's not too hard to cut and weld it up once the line is out of the car. The hardline is actually not that tough to get out, once you find the inline joint near the driver's side exhaust downpipe. DO NOT attempt to drop the steering rack! It's not needed, and is a huge PITA to put back together. The hardline is mounted in 3 places: to the pump, a small bolt/bracket in the bottom of the block, and the inline coupling before it goes under the engine. If you jack the engine up an inch or two, it makes wiggling the hardline out from the top much easier.

Now. The reason you can't just make a flex line from the existing hardline end to the pump inlet, is because you can't find the correct fittings to attach to the ends of the flex line. As far as I know, the parts don't exist in the US to do that, except the ones already on your hardline. If you can get your hands on another hardline or two to chop up, be my guest. It's a $500 part from Mercedes.

The other thing is flex line. 3/4" and 5/8" hydraulic flex line is manly stuff. It is also not all that flexible. Not like a 6mm braided stainless brake line. So it can't be used as a replacement for the hardline, because it simply won't fit in the tight spaces the hardline navigates (5/8" is 15mm OD). Brake line sized flex tubing can't be used, because while it's flexible enough, the ID is only 3mm, and won't support the flow needed for the power steering system. The flex line and the fittings you use need to be close to the original 10mm size ID to ensure fluid flow to the rack is sufficient.

I thought about and engineered all these possible solutions before I came to the conclusion that the way I did it is the most cost effective and best engineering solution I could get made in a hydraulic shop. The way my guys put the line together, with compression fittings, and extension if necessary, made it easy to assemble and tighten everything in the correct positions during assembly. Pie in the sky, a whole new hard line with all the correct bends, correct fittings, and correct length would be perfect, but I don't know where to get that fabricated. I'm sure it would be expensive.
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Old 07-21-2017, 06:39 AM
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G500, S600, 745Li
I understand that the US shops don't carry the metric equipment, but after some online searching I found a bunch of 10mm metric fittings that look like they can work.

If this could work out, the best case scenario would be to get a 10mm flow ID flex line, cut it to appropriate length, and attach 10mm fittings on each end. One that would screw into the stock mercedes fitting and the other one screwing into the pump. The fittings may need to be L-shaped, I've also seen those in metric 10mm and they exist. With the pictures I'm looking at now, it looks like that may just work. Of course, I don't have the parts in my hands to even know for sure, but if I can order the correct fittings and the correct flex line I may just be able to do it. No real modifications done this way, just fully plug and play and even reversible for whatever insane reason I may want to throw a tandem pump back in there. Of course if all else fails I'll have no other choice but to go through the main method. What do you think?
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Old 07-21-2017, 09:12 AM
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If you can find the metric end fittings and metric sized lines to go with them, I don't see why you couldn't make it work. I don't know enough about hydraulic line building to know if metric lines and fittings can be built using more common SAE crimping tools, so you may have a hard time locating a shop to build it for you. You only need to make up about 4", so it's also possible that you could make it yourself with 90 degree and U bend hardware and a bit of 10mm hardline, with no flex line at all. If you go this direction, you will be exceeding my limited knowledge of hydraulic line fabrication, so I'm very interested in the result.

If you can figure this out, that would be awesome. I certainly wouldn't be the one to tell you it can't be done. It's kinda fun figuring things out. I just wouldn't let the task of removing the hardline be the issue you're trying to work around; it's really not that difficult to get out. Permanently modding the hardline is a risk if it gets butchered, but it worked out in my case. My guys did a good job for 75 bucks.

You will never go back to ABC. It is liberating to not ever have to worry about ABC again, and it transforms the experience of driving the car. Such a nice car when you can just drive it!
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