SLS high pressure line plastic things - PeachParts Mercedes-Benz Forum

chrisgt · #1 11-03-2015, 05:14 PM

What do all the little white plastic things and the red plastic thing in the high pressure SLS line do?

My 84 300td blew the high pressure SLS line so I replaced it with a 4000psi hydraulic line from TSC and some plumbing fittings from Lowes... Now I have a weird whining sound that's related to engine RPM, not speed or gear. Neutral, drive, reverse, doesn't matter. I can't hear it outside of the car, just when I'm in the driving. It's a really annoying whine and was wondering if those weird plastic things had anything to do with it.

Before I went and bought the hydraulic lines I was using a piece of auto trans line with hose barbs, and I put all the plastic things in it. This worked, however when I loaded the car it made too much pressure and blew the line.... Now with a hydraulic line that doesn't happen, but I've adopted a whine...

dude99 · #2 11-03-2015, 06:00 PM

I seem to remember digging up a thread about this. The plastic things in the original line are baffles to prevent resonance, aka the whine you're hearing. They are reusable so if you have them, just put them in your new line and you should be good to go...

chrisgt · #3 11-03-2015, 08:13 PM

Hmmmm, well, that makes sense. It sounded exactly like hydraulic resonance to me, I've dealt with the same issue on hydraulic stabilizers on big boats. Exact same noise, usually putting a nitrogen damper in the circuit fixed the issue.

Unfortunately, I can't just put the plastic dealies into the line because it's a pre-crimped line, just grabbed it off the shelf at TSC and figured I'd be good to go

I'll have to figure something out, at least I'm not harming anything (in terms of that...) driving the car. Ride is terrible so I ordered a set of accums today, that should help sort things out back there

I might just have to get a line made for me so I can install the plastic thingies before the ends are crimped on. What a PITA.

chrisgt · #4 11-04-2015, 07:51 AM

Now I've read a guide saying how to PROPERLY re-use the hose ends. You need to save the outer cup thing, which I'm pretty sure got thrown out... I'll be at my shop this weekend to see. but UGH that sucks, I just ran a die over the fittings and put NPT threads on them. Oh well, live and learn. Maybe I'll get really lucky and find an SLS hose in a junkyard I can rob for the ends, but probably not.

martureo · #5 11-04-2015, 02:31 PM

My project wagon didn't have anything in the high pressure line. I replaced the rubber line with the original ends, but nothing was inside of the old line.

I wonder if anyone has a spare one of these "plastic things" they could send me. I'd love to draw one up and send it out to get machined. Might even be a group buy if there were enough interest.

chrisgt · #6 11-04-2015, 03:28 PM

Or you can just unscrew the fittings from the old line, unscrew the caps, put the caps on new hydraulic hose and screw the fittings in... Like an idiot I screwed up the caps thinking it was a normal pressed line which had to be ground apart .... Oh well.

BillGrissom · #7 11-05-2015, 04:18 PM

Several threads showing how to rebuild the SLS hoses. Same deal for the h.p. power steering hose, which is why I read them (don't have SLS). Those "field repairable" fittings are quite expensive (~$80), so great that M-B was nice enough to use them. For sure don't toss them. All you need is a few wrenches to re-use them.

Also much discussion on the SLS plastic "anti-whine" inserts. In a related note, minivan people complain of power steering hose whine (long hoses). Chrysler says to refill all older power steering w/ ATF+4 for less whine, and that comes in the newest cars. I use it in my M-B p.s. I don't know if SLS fluid is special or different. If regular p.s. fluid works, you might try ATF+4, if you can't find the inserts.

dude99 · #8 11-05-2015, 05:31 PM

Quote:

I use it in my M-B p.s. I don't know if SLS fluid is special or different.

It is different, SLS fluid is very specific, I really can't recommend using anything other than the proper fluid.

ATF is a valid substitute for power steering fluid, but not for SLS fluid

chrisgt · #9 11-05-2015, 06:15 PM

I had to put ATF in the system when I was driving the car home and the HP line started to leak really bad, it's all I could get late at night on a weekend. We did a lot of googling and the general consensus was fluid is better than no fluid, it's since been flushed.

I'm bummed I ruined the rebuildable fittings, I got some bad advise, etc. I'm trying to get another used line, or just the fittings from anyone who is parting a car out. For now it works, just whines. My new febi accumulators arrived in the mail today so I'll throw it up on the lift this weekend and replace them. I can't wait!

dude99 · #10 11-05-2015, 08:51 PM

VsTech is usually a good source for parts like that in the states, might be worth sending him a PM

vstech · #11 11-05-2015, 09:22 PM

... I'm going to check and see if I have any more SLS stuff...

shaler · #12 11-06-2015, 08:20 AM

FWIW, saving those plastic inserts doesn't always seem to prevent the noise. I went through this same thing last year when my original hose started to leak. I replaced it with the Gates 6G2 hose that folks on the forum recommended. Saved the little inserts, made sure they all went back in the same way they came out, re-used the fittings etc. and the noise was ever-present. I finally got a good used OE line and that stopped it.

I think a couple factors are the cause. The new hose was much firmer and was steel braided instead of fiber (like the original) and the ID was just a little bit larger than stock. Those plastic pieces were loose in there instead of snug which probably reduced their ability to dampen the resonance.

martureo · #13 11-06-2015, 12:29 PM

Quote:

Originally Posted by shaler

FWIW, saving those plastic inserts doesn't always seem to prevent the noise. I went through this same thing last year when my original hose started to leak. I replaced it with the Gates 6G2 hose that folks on the forum recommended. Saved the little inserts, made sure they all went back in the same way they came out, re-used the fittings etc. and the noise was ever-present. I finally got a good used OE line and that stopped it.

I think a couple factors are the cause. The new hose was much firmer and was steel braided instead of fiber (like the original) and the ID was just a little bit larger than stock. Those plastic pieces were loose in there instead of snug which probably reduced their ability to dampen the resonance.

Do you still have those plastic pieces? Is it possible I can borrow one so I can get some made up?

chrisgt · #14 11-06-2015, 06:05 PM

Quote:

Originally Posted by vstech

... I'm going to check and see if I have any more SLS stuff...

All I really need are the outer screw on shell pieces, if you have a set let me know.

TopKnot · #15 11-06-2015, 07:55 PM

To the OP I've sent a PM about a hose assembly I have.

To anyone else interested I have a second hose assembly, came from a TD with a working SLS, the hose is marked "ARGUS" which I believe is the OE supplier. This assembly could probably be installed and used as is because there is no apparent damage from the looks of it. I don't know if all these hose assemblies came with the plastic inserts, but if they did this probably includes them.

$40 for the assembly, can be shipped complete for $13 USPS Priority, or if someone only wants the ends they can be cut off and shipped for $6. Anyone interested feel free to PM me about these parts.