Replace Hydromatic worn shocks with regular shocks

How have you determined the shocks are bad?

Install 420SEL shocks in lieu of the nitrogen spheres?

How much $$ difference will be realized and what will become of the hydraulic system?

I wonder if the 420SEL and the 560SEL use the same steel springs or whether the 560SEL rear depends on the hydraulic system for basic support rather than just leveling when rear passengers weigh down the back.

The whole rear of the 560 is an homogenous piece. The springs and shocks are organic to the 560 and rely on the accumulators for additional springing. I asked how the PO determined the shocks were bad because they probably are not. The accumulators go first and are much, much cheaper to change.

The hydraulic load levelers do much more that what shock absorbers do. They actually change dependent upon the amout of weight (load) that is in your car, keeping your car at optimum balance regardless of the amount of weight you have in the vehicle. If you have ever seen a Mercedes that is "sagging" in the back, that is, the rear bumper is obviously too close to the road and the front of the car is too high, it is most likely because the load leveler system is defective. There are safety implications related to this. Your car is designed to steer and brake properly when the weight distribution is correct. Less well designed vehicles which have only shock absorbers in the rear are not as safe as vehicles with load levelers which keep your vehicle at optimum balance regardless of load. Changing to shocks would make your car unsafe to drive.

Are your spring struts leaking? (They are not shock absorbers, and do not absorb shock, that function is performed by a part called the "accumulator") The only reason to replace the spring struts is if they are leaking. My 1982 TDT has 394,000 miles on it and I have replaced both rear struts twice, the first time with used and the second time with new parts.

I have done the same with the accumulators. These parts are readily available online. If you are experiencing rough ride but your struts are not leaking your accumulators have probably failed. They are a metal sphere with a rubber diaphram in the middle inside separating an air chamber from a chamber that is part of the hydraulic fluid path of the leveling system. When you hit a bump and pressure increases in the system, the rubber diaphram stretches and compresses the air in the air chamber, absorbing the energy of the deflection of the axle because of the bump. When the diaphrams fail the air space fills with hydraulic fluid. A property of fluids is that they do not compress, so there is no more cushioning effect in the system and your rear end starts to bounce. That might be good in bed but it is terrible for driving a car.

There is also a very expensive valve on the system that is what controls the flow of fluid based upon the deflection of a torsion bar that is part of the rear suspension. You hope that has not failed because they cost about $500. You should change the fluid and filter in the system annually to prevent damage to the parts and make sure that the fluid level is maintained or you will have to replace the entire system, which is how I learned about it the hard way shortly after buying my car in 1993. Cost in 1995 was $1200 U.S.

I forgot to mention that you don't need to use the expensive hydraulic fluid that Mercedes sells for about $20 a liter. You can use anything that lubricates and flows through a tube. I have tried motor oil and transmission fluid. If you have slow leaks with the hydraulic fluid in your struts, try motor oil, it likely will work for about 200,000 miles before the leaks get bad.

If your struts don't leak, use automatic transmission fluid. I use the Chevron stuff they sell at Costco. It's cheap, it doesn't foam badly or leak, and I have about 280,000 miles on my valve and struts with no problems.

I decided to try it after a crazy friend of mine was caught up at his summer home in the mountains of eastern Washington with no brake fluid for his Cadillac after he forgot to tighten a bleeder and the best thing he could find (or at least that'w what he thought) was paint and he made it back to Seattle with paint for brake fluid.

I just posted a long message about the levelers (rear shocks) on the message board but I forgot to send it to you directly, so check the board again.

I figured if he could run paint I ought to be able to get away with transmission fluid and it has worked for hundreds of thousands of miles in my car with no ill effects noticeable.

Thank you for your reply. The ride for the back seat has become very harsh and hitting any kind of bump on the freeway is very uncomfortable for back seat riders. This may indicate the accumulators are broken rather than the "shocks" from what you are saying. Also, as a generic statement: replacing the shock/stuts needs to support the hydrolic system, you have to replace with the proper equipment.

I also have a E320 with hydrolic rear struts. One shows signs of leaking. Can I wait on replacing it or best to replace the slowly leaking rear hydrolic strut??

Thanks

Chas Hurst wrote:

Hi heav,

You really know the Mercedes 560SEL! It has 189,000 miles. The struts are not leaking, no signs. It is just a very harsh ride with bumps almost throwing the back sear passengers. It is no longer a comfortable ride. From what you stated, I need to have the accumulators checked.

I have an 2001 E320 with 102,000 on it and the rear hydrolic strut on the left side shows signs of leakage. That would indicate need to replace the struts in the rear?? Also, you mentioned the need to change the oil in this system once per year?

Thanks for your knowledgable tips. Please c> 560sel wrote:

You have the classic symptom of failed accumulators. I just ordered a set for my E320 wagon. Some leakage in the spring strut (as Benz calls it) is normal. I wouldn't replace it untill it becomes messy.

Thanks Chas I will keep the E320 spring struts and have the accumulators checked for replacement.

Do you have a good MB parts supplier? I have purchased from

Chas Hurst wrote:

I have been using the same source with good results.

I would try replacing the very thin Mercedes hydraulic fluid with motor oil. That virtually stopped the leakage in my system. If you live in a cold place (I live in the Mojave desert) you might want to try automatic transmission fluid first.

As long as you keep the fluid level up in the reservoir you won't hurt too much be having the oil leaking out of one of the struts. But the oil will eventually damage other rubber parts.

Mercedes recommends changing the fluid and filter in the load leveller system annually.

Like I said before, I use automatic transmission fluid in mine and it hasn't damaged anything.

Paul