revitalization checklist for newly purchased 85TD
 

Hi!, First post-

Always wanted a wagon, and just found my first relatively non rusted example in the back of a barn.
It has sat for about 3 years without being fired up, and im working on getting her running again.

Ive had 6 or 7 sedans, so as far as the standard stuff, Ill be doing a valve adjustment, oil change, filter change, belts, coolant, fluids, whatnot.

I do have some wagon specific questions though, what needs to be done to get into this SLS system that I already hate? It was sitting at the correct ride height when I bought it, but as soon as I had it towed, she settled right down like a petulant toddler. Im sure everything is broken, but in the hopes of quick and easy, are there filters/fluids/procedures/links to follow to get an idea of its condition?

Other wagon specific questions are related to the fuel system. Ive got a host of fuel system problems, and im pretty sure the tank is a complete ecosystem by this point. I need a new lift pump, and all rubber hoses and filters. How is the screen setup on the wagons? is it a similar access from the bottom? I feel like the whole tank may need to be removed and hot tanked, is it dropped from the bottom, or lifted out of the top?

Thanks! Some of these questions are pretty foolish Im sure, but right now its sitting so low I cant get under it and completely immobile until it warms up a bit outside. Figured Id fish for information from a position of warmth and comfort first.

From what I've read the SLS system is pretty strait forward, if your Wagon is suffering from Droopy butt Syndrome, the Accumulators(? please tell me if I'm wrong) may need to be rebuilt which once you get them off I think is a few Gaskets and time. my Wagon is an 87, it's tank screen is located at the bottom as well. if you feel your tank is a micro-chasm of life, then I would drain it and have it cleaned or Clean it yourself, no question is foolish, the only thing foolish is the Question not asked.

You will learn to love the SLS over time. :P It could have just lowered due to the angle you used when towing. It will not pressurize again until you start the car again. There may be nothing wrong with it.
It is a very straight forward system. Once you get the car running so that the hydraulic system can pressurize it can be diagnosed. Likely it will lift right up when it starts.

My wagon (81 TD) settles when it sits for a while. The SLS valve near the differential is leaking internally. There are O rings inside that fail. I'm still trying to find the specifications for the O rings so I can rebuild it this Spring.

Your accumulators are probably shot as well (mine are). They cost about $110 a piece to replace. If you have a harsh, bouncy ride that is your problem.

You can rebuild the SLS valve, if need be. There is a kit (can find the number at the moment). Check your accumulators first, though (123 320 02 15). Take one off and insert the eraser end of a pencil in the end hole. If it stops after a little bit, it's good. If the pencil goes way down, time to replace (replace both). There is a filter in the reservoir (002 184 55 01) that you should replace if you don't know the age. I would replace all hydraulic fluid as well if you don't know the history. The system is self-bleeding. Also, check the lines to/from the reservoir for leaks.

Found this on another site for rebuilding the valve: Parts Required: metric o-rings (buna-nitrile or viton) dimensions are listed in mm as cross section (CS) x internal diameter (ID) (1) 2 x 58, (2) 2 x 7, (1) 1.6 x 10.1 , (1) 1.6 x 7.1 (** see below for availability), 1 liter of MB hydraulic oil (to replace lost fluid, available through Fastlane) the total capacity of the SLS system is 3.5 liters.

Yes, if the car hasn't run then you may be getting excited over nothing. That fact that it was at the right height after 3 years is good thing.

Thanks, Dadette123 for the info. I see that MercedeSource now has a rebuild kit for the valve. Kinda pricey, but it also has some sort of a shaft, metal washers, and a spring. No instructions, though.

I'll keep checking around to see if I can find the parts separately or more cheaply.

Since this is a topic about 300TDs and the SLS. does anybody know what size the metal lines are that goto the rear hydraulic pistons?

So far Ive gotten her started twice and have driven a total of .7 miles. The first time was when I went to look at it, and it maintained the correct height during that viewing.

The second time was when I came to pick it up, where it had an overheating problems as well, so I shut it off and called a tow truck.

The Tow was about 30 miles and bouncy, and the wagon got lower and lower on the flatbed over the drive, so I figure that something let go as soon as the suspension was exercised.

You may be right, it may heal itself as soon as I actually drive this thing.

Every bump that the tow truck went over made the wagon go up and down, and every movement upward opens the SLS valve and releases pressure that can't be recovered with the engine off.

You don't need to drive the car to determine if the SLS is working. Take a height measurement at the rear bumper before you start the engine and, then, after its been running for a few minutes. Make sure there is hydraulic fluid (most use only the recommended fluid type) in the reservoir. If the rear doesn't adjust up, try standing and bouncing on the rear bumper a few times (you're trying to clear any possible air out of the valve so it can self-bleed). Hopefully, she kicks up her rear in the air for you.

Can I swap supply and return lines on a wagon like you can on sedans to bypass the intank screen?

Ok, jacked up the back end, crawled around for a while looking at SLS stuff. There appears to be wetness and leaks on both sides from something. Don't really care for all this malarky covered with rust and corrosion down here.

Considering dispensing with the entire system and going with propigskins suspension alternative. opinions?

The SLS is kind of a cantankerous system. It is comprised of the pump, which is on the head, the reservoir, the height adjusting valve, the struts, and the accumulators. Any movement in the lever arm on the valve is what causes the system to go up or down.
The first thing I would check the the fluid level in the reservoir.
The most common issue is a saggy rear that is caused by a leak in the system. It will typically sag over night while sitting and then rise up when you start the car. The SLS valve is the most common leak spot. It can leak internally or you may see it leaking. It sounds like you might have leaks elsewhere as well. The struts could be leaking, or the connections at the accumulators and/or struts could be leaking. I'd check all the connections and wipe everything down to help locate the leak. I have O-ring kits for re-sealing the SLS valve let me know if you are interested. More info here SLS Valve O-ring Replacement DIY
The next most common issue is a bouncy and/or hard ride in the rear. This is the accumulators. They have a rubber diaphragm inside the gives out over time. One side of the accumulator is gas and the other side(the side with the hydraulic line) has SLS fluid. When the diaphragm tears the whole accumulator fills with fluid and the ride goes to pot.
Another less common problem is the rear not lifting when it's loaded, this is an issue with the pump. The pumps can be rebuilt. Prepare to give and one arm, one leg, one testicle, and bend over to get a new one, they are around $1500 new. You do get to chose which arm, leg, and testicle though so thats good:P Fortunately it's fairly uncommon for them to completely break, they tend to start leaking instead. Which is a much cheaper fix.