Repairing hydraulic hose for SLS hydropneumatic suspension on TD - Page 7 - PeachParts Mercedes-Benz Forum

macdoe · #91 09-22-2010, 12:39 AM

more pics....
In one of these pics I am squeezing a piece of the oem old hose almost closed.....there is also another pic of me trying to squeeze the new steel re-enforced hose....that new hose does not budge. I cannot compress it at all!

I am now curious as to what exactly these plastic pieces are for? I briefly thought like you did in that they may be some sort of restriction or dampener, especially when examining the orange closed off bit at the end closest to the pump. I think because of the design of the orange piece alone that you are correct.
If it was just the white plastic hollowed through pieces.... I might have thought that they were put in to keep the hose from collapsing?
The way each of these plastic bits are ribbed will allow fluid to always be able to flow through around the outside....and with the orange "cap" at the end they may even increase pressure???
I wonder who would be an authority on why exactly these plastic things were put in the lines....any vascular surgeons on here?

hey_allen · #92 09-22-2010, 02:56 AM

I seem to remember these being mentioned in an older thread on the topic, and if I remember correctly, the consensus was that they were noise dampers in the fluid flow.

This is definitely not authoritative on my part, as it's just a vague memory of seeing them mentioned before, and I suspect that it was partially a guess on the part of others in that thread, though there may have been someone complaining of the system being noisy after replacing the hose and leaving the pieces out.

upliftmovement · #93 06-16-2011, 11:41 AM

@macdoe - did you get that steel reinforced hose to work with the old fittings?

i realized that the peice my hydraulic shop just sold me is that type as well. looks great, but i am worried that the original screw in fittings won't work.

anyone?

thanks..

and will i need to bleed the system once reassembled?

kerry · #94 06-16-2011, 11:54 AM

Usually the system is self-bleeding. A few members have reported failure to self-bleed.

macdoe · #95 06-19-2011, 11:37 AM

Yes, the steel reinforced hose worked with the old fittings....or at least I can tell you so far, so good.

I should also mention that I put all those little plastic pieces back into the replacement hose. I figured that they should be there for whatever reason they were put there in the first place.

Before replacing with the new steel reinforced line, I did patch together the old hose with a couple of hose clamps and a double ended barbed fitting until I had time to properly replace the old hose. I removed all the plastic bits when I did the temporary fix. I did drive the car like this for awhile and I think the rear suspension was actually better without those plastic bits in the line. (could be that my nitrogen sphere's are getting worn out?)

In hindsight, if I were to do it again I am not sure that I would put those plastic bits back in the line. I never did get a straight answer as to why those plastic pieces are in the line. If they are there for backflow prevention, fine ...but if they are meant to prevent the line from collapsing.... then with this newer steel reinforced line they are not necessary as you cannot compress the newer steel line.

As far as bleeding the system....what Kerry said. I did not bleed my system on any of the repairs. I am now wondering how to tell if the system needs to be bled.

To put it another way...What symptoms would one be experiencing if there was air trapped in the system?

warmblood58 · #96 06-19-2011, 04:21 PM

Quote:

Originally Posted by kerry

NAPA refused to make mine when it started leaking, saying they did not have the correct hose. It's not worth paying NAPA. If you have the skill to unscrew the hose from the pump, you have more than enough skill to replace the fittings on the hose.
Other people experienced what I experienced; hose shops saying they couldn't reuse the ends and wanting to cut the end off and braze it to one of their fittings. This is entirely unnecessary since MB made these fittings so easily reusable.

Yep did mine with high quality high pressure hose from a hydraulic shop -had to use a cut off wheel to cut the stuff!Hey kerry -what do the little plastic inserts do? Help maintain pressure surges? I put all back in save for two (accident on my part in reassmbly)

KenB · #97 07-01-2011, 05:32 AM

What is normal to use for the *low* pressure hose? Fuel hose ok?

vstech · #98 07-01-2011, 10:09 AM

on the return hose, I just used hydraulic low pressure braided hose.
fuel hose might be ok, but I don't know about the iso 46 reactivity to the fuel rated rubber...

upliftmovement · #99 07-12-2011, 11:27 AM

Quote:

Originally Posted by macdoe

Yes, the steel reinforced hose worked with the old fittings....or at least I can tell you so far, so good.

I should also mention that I put all those little plastic pieces back into the replacement hose. I figured that they should be there for whatever reason they were put there in the first place.

Before replacing with the new steel reinforced line, I did patch together the old hose with a couple of hose clamps and a double ended barbed fitting until I had time to properly replace the old hose. I removed all the plastic bits when I did the temporary fix. I did drive the car like this for awhile and I think the rear suspension was actually better without those plastic bits in the line. (could be that my nitrogen sphere's are getting worn out?)

In hindsight, if I were to do it again I am not sure that I would put those plastic bits back in the line. I never did get a straight answer as to why those plastic pieces are in the line. If they are there for backflow prevention, fine ...but if they are meant to prevent the line from collapsing.... then with this newer steel reinforced line they are not necessary as you cannot compress the newer steel line.

As far as bleeding the system....what Kerry said. I did not bleed my system on any of the repairs. I am now wondering how to tell if the system needs to be bled.

To put it another way...What symptoms would one be experiencing if there was air trapped in the system?

awesome, did you have to grind or file taper the ends of the hose to get the old fittings to thread in?

i temporarily patched up my hose as well untill it blew out on me on the road one hot day, thats when i noticed those plastic inserts, well i finally am at the point of rebuilding using the new hose, and am now contemplating reinserting those plastic inserts for the same reasons that you mentioned....

either way thanks for this thread and everyone else that has responded as well, it has been empowering and inspiring, and i am not feeling so alone and lost, lol, down here on the southern borderlands...cheers.

upliftmovement · #**100** 07-12-2011, 01:40 PM

**************.com/node/7760
just stumbled apon this Mercedes Self Leveling Suspension (SLS) High Pressure Hose Replacement Kit w/ Instructions on this other site, and they refer to those little plastic inserts as plastic restrictor (anti cavitation) plugs.

I just pulled out my plugs and realized that when my hose originally blew, i lost a few of those white pluga and THE RED ONE.

I am trying to track some down, so far with no luck as to tracking down a part# for those little buggers...almost had luck here http://mb.ilcats.ru/part/class/1/ccode/F/cat/68M/type/123/subtype/193/group/32/subgr//vers//imgno/6
but the site is in some other language...

any one on this forum have a few of these including the red one that youd be willing to part with? sale, barter, trade, whatever...

thanks

eduardo.

Viggo · #**101** 03-11-2013, 05:22 AM

Quote:

Originally Posted by pclark71

Anyone ever figure out what causes a whining noise from the engine bay after replacing the SLS hydraulic hose. I replaced the cracked OE hose with a Gates 6G2 this afternoon. While the SLS is now working like a charm...I realized that there's a whining noise now coming from the engine bay. I believe someone else posted a similar issue with a W124. Any ideas what's causing this gang?

By the way, anyone preparing to make this update would be well served to have bence vice handy. It makes the job MUCH easier than doing it by hand. Also, I highly recommend partially threading the outer collars, then partially threading the inner line prior to completly threading the outer collars. The inners are nearly impossible to get threaded if the outer collars are all the way on.

Sounds as if you are experiencing exactly the same as me.
I just did this job last weekend, carefully inserted the plastic flow limiters, everything works fine - but the car is sounding like a Formula 1 race car now. Or maybe, like a car with a shot muffler.

My feeling is that these steel-braided hoses are not suitable for this purpose. They are durable and can stand the pressure - but they don't dampen the noise from the pump, on the contrary, they amplify it.

That is why MB used fibre-braid in the original hose. They new what they were doing :-)

/Viggo

warmblood58 · #**102** 03-11-2013, 11:35 AM

I did mine several years ago - the hardest part of the job was using a cutoff wheel to cut the hose - did not have one so I had to run out and buy. This is a very satisfying repair, just make sure to remove all the little plastic pieces inside (count them) and put in the new hose the same way/direction.

vstech · #**103** 03-11-2013, 12:50 PM

Quote:

Originally Posted by Viggo

Sounds as if you are experiencing exactly the same as me.
I just did this job last weekend, carefully inserted the plastic flow limiters, everything works fine - but the car is sounding like a Formula 1 race car now. Or maybe, like a car with a shot muffler.

My feeling is that these steel-braided hoses are not suitable for this purpose. They are durable and can stand the pressure - but they don't dampen the noise from the pump, on the contrary, they amplify it.

That is why MB used fibre-braid in the original hose. They new what they were doing :-)

/Viggo

I disagree. if your steel braided hose is noisy, either you didn't use the damper balls/hose inside, or your hose is routed where it vibrates something that the old hose did not touch. is the hose too long? is it not in the brackets with grommets?

macdoe · #**104** 03-11-2013, 02:10 PM

My hose did'nt make any noise, either and I lost the brackets with the rubber grometts plus I made my hose longer. I agree, you got something else wrong there. Maybe you put the plastic inserts in backwards.

Orv · #**105** 03-11-2013, 02:26 PM

I just replaced mine using the steel braided hose kit from "the other site"...I put the old inserts in the new hose (except for one that I found on the garage floor, later) and it's no noisier than before. The old hose had swelled up inside so much that I had to hack it into one-foot chunks to get the inserts out of it. BTW the pointy ends of the inserts go toward the pump (banjo fitting end of the hose), with the red one going in first. I re-used all the grommets from the old hose and routed the new one through the same brackets.

BTW, I don't care what the kit says, you do not want to try to cut the steel braid hose with a hacksaw. You'll be there all day. That stuff is TOUGH. An angle grinder with a cutoff wheel makes short work of it. An electric drill with a cutoff wheel would work too, but it'll be slower. Hacksaw works a treat on the old fabric braid hose, though.

Hardest part of the job, for me, was getting the fittings threaded back together on the new hose. The steel braid hose has less give. I ended up having to stop when the small portion of the fittings was still about 1/8" from fully seated, because they just wouldn't tighten any further. So far it hasn't leaked. I figure if it ever does I can tighten them up a bit more, since the hose will have compressed a bit by then.