How to tell if SLS is working - PeachParts Mercedes-Benz Forum

bigblockchev · #1 10-13-2011, 12:29 PM

In my sons 85 TDT it is obvious when you start the car the back end rises up an inch and a half or so. With my 87 TDT not so much. Is there a definitive test or spec for this. Cheers Dan

kerry · #2 10-13-2011, 12:31 PM

put a few hundred pounds in the back of the wagon with the engine off. A hefty wench will do. Make sure it visibly weighs down the back. Then start the engine. The back of the car should raise up to level

sixto · #3 10-13-2011, 12:47 PM

Al Bundy would say there can be too hefty a wench for even the mighty SLS

Maybe your son's SLS bleeds down more than yours does with the engine off. Or he empties the trunk of the day's haul after shutting off the engine.

Sixto
87 300D

StaggerLee · #4 10-13-2011, 02:34 PM

Most likely your SLS valve is leaking but I would do a search for more info (There's a lot on SLS). How low does it sit before you start it up? The fact that it rises up when you start it leads me to believe the pump is working but if the valve leaks it will lower itself until all of the weight is supported by the springs. I think you measure from the center of the wheel hub up to the fender lip in order to set the correct height. Like I said, do a search and you'll find your answer.

bigblockchev · #5 10-13-2011, 03:03 PM

I will borrow my son's haul of hefty wenches to test this theory. I can just picture this in my mind.

Cheers Dan

Biodiesel300TD · #6 10-13-2011, 04:44 PM

Here is a thread on how the SLS works and troubleshooting the system -
Self-Leveling-System - How it works, and troubleshooting the system

Sounds like you leveling valve is leaking. They can leak internally, so you won't see any drips, but it bleeds pressure off over time and allows the rear to sag. The rear shouldn't lift at all when you start the car. The fact that it's lifting says your pump is working, but system has lost pressure over time.

kerry · #7 10-13-2011, 09:46 PM

It's his son's car that is drooping, not his.

ds190 · #8 10-14-2011, 09:58 AM

Quote:

Originally Posted by kerry

It's his son's car that is drooping, not his.

+1. Right up there in the beginning of the thread.

My 91 300TE does not sink down at rest- ever. Load it down with mulch from Home Cheapo, and the rear rises up to level. Unload, and back down to normal.

Biodiesel300TD · #9 10-14-2011, 11:03 AM

Quote:

Originally Posted by kerry

It's his son's car that is drooping, not his.

I don't understand why you made this statement. Every post is about why the SLS is sagging. It actually doesn't matter if it's his son's 85 TD or his 87 TD. The troubleshooting is the same.

Orv · #10 10-14-2011, 02:01 PM

Does it harm it at all to sag when the engine is off? Mine sometimes bleeds down while parked but pumps up and works fine with the engine running. The cosmetics of the car having a saggy butt while parked don't bother me, but am I doing any long-term damage by letting this persist?

Biodiesel300TD · #11 10-14-2011, 03:27 PM

Quote:

Originally Posted by Orv

Does it harm it at all to sag when the engine is off? Mine sometimes bleeds down while parked but pumps up and works fine with the engine running. The cosmetics of the car having a saggy butt while parked don't bother me, but am I doing any long-term damage by letting this persist?

I wouldn't think letting it sag would cause issues. But the sag will get worse and worse, that is it will sag more quickly when sitting as time goes on. You may also not be getting as much out of your SLS as you could be if your valve wasn't leaking. In the long term you are putting more stress on the springs and they may wear out quicker. A saggy rear is an easy fix. A few bucks worth of o-rings and a bottle or two of fresh fluid.

Orv · #12 10-14-2011, 06:13 PM

Quote:

Originally Posted by Biodiesel300TD

I wouldn't think letting it sag would cause issues. But the sag will get worse and worse, that is it will sag more quickly when sitting as time goes on. You may also not be getting as much out of your SLS as you could be if your valve wasn't leaking. In the long term you are putting more stress on the springs and they may wear out quicker. A saggy rear is an easy fix. A few bucks worth of o-rings and a bottle or two of fresh fluid.

Yeah, to be honest I've mostly been putting it off because I don't want to risk breaking something trying to take apart a 30-year-old valve.

Merc 1979 · #13 10-14-2011, 09:58 PM

Valve O ring kit fixed my sagging rear end. Wish I could say the same about the missus.

kerry · #14 10-14-2011, 10:17 PM

Quote:

Originally Posted by Biodiesel300TD

I don't understand why you made this statement. Every post is about why the SLS is sagging. It actually doesn't matter if it's his son's 85 TD or his 87 TD. The troubleshooting is the same.

Where does the original poster say his 87TD is sagging? He just says he doesn't notice any change with it and wants to figure out if its working or not.