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Re: Replacing/Topping off of Convertible Hydraulic Fluid
Way to go - a little preventative maintenance on the hydraulic system will go a long way, especially down South!
Here are the fluids again that I had recommended in the thread quoted above:
Pentosin CHF-11S. This is a good hydraulic fluid that is used also in some power steering and self-leveling systems. It can be purchased online in many places, or in some good auto parts stores.
Another fluid that is approved by Mercedes-Benz for systems with all the same materials in it as your Crossfires, is FeBi 02615, along with Mercedes' own fluid p/n A0009899103. It, too, is also used in power steering and self leveling systems. I would recommend this fluid for Crossfires without reservations. In fact, I recommend it to all of our customers. FeBi02615 is generally a bit cheaper than CHF11S, and the characteristics are practically identical. In Europe, the same fluid is also sold as Aral Vitamol. I suspect that Aral is actually the manufacturer of the three fluids above. It is also sold under the brand name Weyle down under, with p/n 0009899103. These are all called "ZH-M" fluids.
You need only a quart to flush your system, unless the old fluid is really bad. FeBi 02615 sells online for some $10 per quart, but shipping is almost as much. I can post a link to an online seller (not related), if that's not against forum rules - the link is also on the bottom of our website's FAQ section.
I would recommend to use whichever of the above fluids is easiest for you to get. The important part is to get it done... :-)
Re: Replacing/Topping off of Convertible Hydraulic Fluid
DJohn14296,
in short, flushing really dark looking fluid is a good idea, there is no official procedure for it, the Crossfire system is more sensitive to contamination than the SLK system, and the Crossfire pump is quite different from the SLK pump.
Why does the fluid need to be flushed? The main culprits are suspended particles in the fluid (turning into sludge) and water on the bottom of the reservoir (from condensation if you are in a warm, humid climate). Suspended particles are created by friction on the cylinder walls, inside the pump, and largely from fragments of decaying seals. Their biggest impact is wearing out the pump, but they also change the chemistry of the fluid, and they can make it corrosive in the long run. Water is supposed to sink to the bottom of the reservoir. If the level of accumulated water gets too high, then it will be sucked into the pump and wreak all kinds of havoc. This is rare, but needs to be mentioned for completeness.
What is so special about the recommended hydraulic fluids? They lubricate the system without damaging it, they have low viscosity (thickness) even at low temperatures, and they do not have emulsifiers in them, or other additives that would damage the seals in the OEM cylinders. If you had all seven cylinders rebuilt by Top Hydraulics, then you could actually use transmission fluid, because our seals are chemically much more stable (they hold up fine even to water, "stop-leak", or acetone...).
How do you flush the system?
A perfectionist would take out the pump, dump its fluid, and then cycle the top manually to get all original fluid out of the system. That's what you would have to do if you had accidentally put the wrong fluid in, and hope that it didn't do any harm yet.
A more practical way for preventative maintenance would be to suck the fluid out of the reservoir with a syringe that has a hose on it (so that you can stick the hose through the fill plug until it reaches the bottom of the reservoir), suck out the fluid, move the top manually to get the fluid from the cylinders pushed into the reservoir, suck out the fluid again, move the top some more, then suck out old fluid again, then add new fluid to the reservoir and use the pump. Keep filling the reservoir until the fluid level is constant and within min/max range. The system is self venting. Almost all air will be out of the cylinders after some three cycles. I am not a fan of folks taking off the reservoir, because some of them get damaged upon re-installation and the owner will end up sending us their pump for rebuild just because there is now a leak from the reservoir...
The easiest way if you don't want to go through the trouble of moving the top manually after evacuating the reservoir, is to empty the reservoir with a syringe with a hose on it, refill it, cycle the top once with the pump, and repeat the procedure several times. You still get the majority of the fluid flushed this way - somewhere between 50-90% depending on how many times you do it.
Now that Top Hydraulics is a forum sponsor, I can talk about what we are doing: we rebuild the hydraulic cylinders and make them better than brand new ones for a fraction of new price (if you could still get new cylinders), we rebuild the pumps, and we manufacture new hydraulic hoses. The quality of our work is unmatched, as is the quantity. There will always some guys out there trying to offer a "cheap" rebuild service and not doing the job right, until they disappear because their customers will be back when the incorrect rebuild has failed. Conversely, we do it right, we replace and upgrade ALL seven seals in each cylinder, and we have tens of thousands of happy customers (no kidding). Sorry to be so direct; it gets me very upset when I see how some outfits will try to get away with replacing just one single seal and usually butchering the cylinder while they are at it...
Replacing/Topping off of Convertible Hydraulic Fluid
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