1985 300TD self leveling question - PeachParts Mercedes-Benz Forum

engatwork · #1 08-20-2002, 09:08 PM

I have read some on how to tell if the self leveling system is working or not but now I need to know how to check/set it for the proper "height" and how to tell if it is right. This afternoon I changed the hydraulic fluid and filter and in trying to determine if the car is level or not I measured from the ground to the centerline of the jack point. They were all 10" from the ground to the centerline. Does this sound right? The reason I ask is that whenever I go around a curve fast I get some pretty loud feedback from the tires (squeeling) and the insides of the rear tires are showing the most wear. I do not hear this noise when traveling the same curve at the same speed in the 300D. I plan on moving the front tires to the back and putting new ones on the front but would like some thoughts/opinions on how to tell if it is set at the proper level. The car drives down the road and tracks straight.
thanks

engatwork · #2 08-21-2002, 06:16 AM

ttt

joe p · #3 08-21-2002, 07:10 AM

Get it set and aligned by a experienced alignment guy. When I say experienced I mean with Benz knowledge. Setting the ride height is easy, simply adjust the rod on the r/h rear control valve.

Joe

peterhardie · #4 08-21-2002, 10:46 AM

I just did this on my 85 TD. We measured another wagon height, and got 25.5", asphalt to highpoint on wheel well, if I recall. Detach the linkage rod between the valve lever and the torsion bar back there, and push the lever up or down (car running) to get the height you want, reset length of linkage rod, re-attach. Mine looks high at 25.5", we think because he has 15" rims and I have 14s and more gap. So I may bring mine down a hair, maybe an inch.

I suppose if you had the thing way too high or way too low, it might have some impact on driving, but I don't think the setting is hyper-critical. I drove my wagon for months with the tail down, on one occasion loaded to the gills, and I didn't notice anything other than the weight wagging the car a bit.

Let's see if someone says I am off the mark.

peterhardie · #5 08-21-2002, 10:49 AM

I get no squealing with my wagon. Joe p is right, have an alignment shop do a good alignment, AND have someone check you rear suspension rubber (especially the subframe mounts). If they are worn, you will have funny tire wear.

joe p · #6 08-21-2002, 10:50 AM

One other thing I just thought about, front upper control arms will cause these to wander and..... well, they seem to understeer going in the corner and then "roll" into oversteer.

Joe

engatwork · #7 08-21-2002, 02:35 PM

It does not look like the self leveling is working properly. I raise the back of the car and put it on jackstands and "manipulated" the valve lever arm and did not see any movement of the back tires - elevation wise. This was done with the car running at idle. I'm sure my pump is working because of how fast it pulled the level down when I changed the fluid yesterday. Any thoughts on how to verify that it is the valve versus the hydraulic shocks? Should the movement of the rear tires (up/down) be instantaneous when I manipulate the valve lever? Worst case I will just replace the valves and shocks. Oh yea - at the back upper part of the wheel well the height from the ground is 23.75" running 205 70 14 tires.
thanks

jcyuhn · #8 08-21-2002, 03:02 PM

How did you setup the car to test it? The part about jack stands confuses me - you need to have the cars' weight resting on the suspension to test the valve. I tested mine with the car resting on all four tires.

On my 124 wagon it takes ~2 minutes the fully raise the car when the valve is moved to the "fill" position. The car raises up about 3 inches - it looks *really* funny that way...

Note there is a minimum pressure the valve maintains within the struts & accumulators. (I forget what it is - check your shop manual.) It will never let the pressure fall below this value, no matter how long you leave the valve in the "empty" position. Some pressure is required to insure the damping action of the struts; as well the hydraulic system is partially responsible for supporting the weight of the car. Wagons which are "dragging tail" have lost pressure in the hydraulic system.

peterhardie · #9 08-21-2002, 03:14 PM

The hydraulics control the height of the body in relation to the wheels. The problem with the wheels off the ground is that the system is unloaded, so the height is probably at max. The system only pushes, gravity does the work in the opposite direction.

Use properly rated car ramps to make it easy, unless you can slide under the rear with the car on the ground. Otherwise get a skinny teenager, and be VERY careful. I did it, but it gets a bit hairy with the car lowering down on you. I don't recommend it. Height off ramps may not be height off the ground though, so you may have to fiddle.

peterhardie · #10 08-21-2002, 03:27 PM

I am a bit slow today. It just dawned on me that you haven't described anything symptomatic of the self-levelling. You may not have a problem with the self-levelling. Get another family member and stand on the back of the car, and have a third watch the wheel well rim in relation to the wheel. Or sight something against the roofrack and see whether it moves. Hop off and do the same. If your car moves up and down, move on to suspension stuff.

My tech says the systems are pretty robust. The shocks leak when they go bad. If they ain't leaking, they are probably ok. And they are $$$$, so don't go there if you don't have to.

The accumulators lose gas pressure, and if I recall, the ride is harsh, little to no "spring action". Some say it feels like the back end bangs over bumps.

1. Look for leaks at the shocks.
2. With the car on the ground, test your valve. Something should happen when you move that lever, or you should hear something trying to happen. If you see or hear nothing, rebuild or replace the valve.
3. If you get movement, adjust and test with a couple family members on the back bumper or in the cargo area. The car should go up when you all hop in, and back down when you get out, since you have already heard the valve working.
4. Test drive.
5. If it is harsh driving, replace the accumulators, $75-95, depending on who you talk to when.

6. If your shocks are leaking, replace em.

But if you are only worried about tire wear and noise in corners, you may be looking at the wrong things.

engatwork · #11 08-22-2002, 06:13 AM

Thanks ya'll - I'll nose around some more tonite.
a) I do not see any leakage anywhere.
b) I tried to test the car on jackstands - rear tires pretty much off the gound. I will retest with the car on the ramps tonite.
c) The ride is not harsh.
After the re-test, if everything looks good, I will take it to an alignment shop and get their input.
thanks

engatwork · #12 08-22-2002, 08:18 PM

Didn't have time to get the cars on the ramps and test again today but I did get the tires that were on the front on the back and get new ones on the front. I will take it to about the only alignment people I trust tomorrow and let them hang their equipment on it. Since doing the tire thing I do not have anymore squeeling going around curves. I'm optimistic that it will come right in tomorrow on the machine

.

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