6.9 suspension repairs - progress on trusty rusty

[s class]

Well this weekend I got going on the blue car's hydraulics in ernest.  I had been VERY worried about the state of neglect of the system, plus signs of butchering which led me to suspect there could be potentially damaging foreign particles inside.  I decided that I would remove all the hydro lines, and either replace them or have them cleaned and plated, according to the condition. 

It turns out this is a VERY ambitious project.  I suspect the factory installed the hydro lines first, before the rear suspension, engine etc.  Removing the lines now proved VERY difficult.  I resorted to dropping the rear subframe, exhaust system and all fuel system components at the rear. 

Also, the system is very complex with many, many lines.  I spent fully an hour photographing the system and making notes of where everything went. 

This first pic shows the area next to the diff.  The 4 lines you see go to the rear levelling valve, which I had removed.  This is the sort of condition of the lines that prompted me to want to replace them. 





A very long while later I had this :







The three long lines are the pressure feed, pressure return and leak return from the rear of the car.  The shorter lines are all located around the diff and link to the spheres and leak return tubes. 

IN this photo they have all been degreased and scrubbed, and from a distance look reasonable.  BUT : check this closeup



This type of corrosion is prevalent in the hoses at the rear of the car.  The front ones in the engine bay are much much better. Also, check that bodged join in the line.  Yuk.

All these lines will be replaced. 

Now I must say that during the removal process, I becan to question the sanity of it all, but I was lucky, and quite by chance discovered that one of the shorter lines is BLOCKED almost completely buy a jagged piece of metal inside.  Presumably from past carlessnesses.  THat might explain why the rear end was not functioning correctly.  So this has definately been a worthwhile exercise.  Otherwise I would have NEVER found that blockage in the line, and probably would have torn my hair out trying to get the suspension to operate correctly. 

[CraigS]

Would it not be better to forget about having them plated, and to buy copper pipe and sweat new fittings onto them ? I'm sure this would be considerably cheaper - especially if you buy a roll of it, AND it will be flexible AND clean - something that your existing lines will not be. You would need to anneal them again also to get them soft.

[WGB]

You're a braver man than me Gunga Din.

Bill

[s class]

I have taken it all on board, and realised that I know nothing about plating.  The concerns about remaining acids, plus bending of the lines are real concerns that pretty much dissuade me from that course of action. 

The lines you see in these photos are all going to be replaced with made-up items from a local hydraulics place.  The lines in the engine bay are in much better condition, and I will be removing them to be ultrasonically cleaned at the avionics hydraulics specialist. 

I decided to do the system in 2 or three 'phases', because I felt that if I reoved ALL the lines from the car at once and mixed them up, my chances of figuring out what went where again would be slim. 

[CraigS]

Why not make them up yourself ? You seem more than capable, and need no more than a flairing tool. One thing that you should probably look at buying is a rotisserie so that you can turn the car 90 degrees and work on it standing up, You can get these for not much more than a couple of spheres or a strut, and makes life so much easier. I saw a great one in Germany that was EUR 650 and wound up with a standard electric drill. All you had to remove from the car was the battery.

The lines you see in these photos are all going to be replaced with made-up items from a local hydraulics place. 

[s class]

Craig, thanks - as to making up the lines, it is so cheap to get it done here there is no motivation to do it myself.

I was under the impression these lines are all NLA - can anyone confirm this?  If they are available new I will feel guilty for 'cheaping out' on made-up lines. 

[CraigS]

It appears as though they are, although replaced with a 123 part number. It also looks like they are quite cheap. One that I looked at has a (US) list price of $20.50. This is described as "Line from triple distributor to rear self levelling unit".

[s class]

Indeedy it seems that most if not all of the lines are available - some locally too.  Prices seem around $10 to $30 per line.  I bought one of the long ones today.  and guess what - it has none of the bends in it.  it's just a straight tube, coiled up, with the fittings on the ends.  One must duplicate the original one's self. 

The new line is painted? coated? in the correct olive green, which now brings me to a point of indecision - the olive green look is authentic, but the cad plated look of the new stuff from the hydraulics shop is visually much more attractive and impressive.  I don't know which way to go now.   

[s class]

no that's not helping at all..... I'm building this car for my self first of all, resale is a lesser concern.  In anycase, I seriously doubt there are too many people who would know the lines are supposed to be green.

The red car, which is much more original and better cared for, still shows a lot of green on the lines, but its actually all flaking off and looks terrible - one of the reasons I thought shiny metal may be more durable. 

[CraigS]

One day, and that may be a long time away, you will sell it. I think I would go the original route, if only for reasons of correctness, and the price is certainly right. I don't think they would make them up for that. When I mentioned originally to go copper, I didn't think that they would be available, and certainly not at that price. Shiny metal will only be shiny for a while don't forget, and I can't see you getting under there with a tin of Brasso !

[s class]

OK guys, just to confuse it further, I have spent the last 45 minutes studying the hydro lines on both cars. 

The red car clearly shows lots of the green coating on the lines, albeit flaking a lot.  Crucially, it is always in tact under the rubber mounting blocks. 

Now examining the blue car, I am fairly convinced its lines never had this green coating for three reasons :

a) there is no sign of it anywhere on the pipes, not even in 'protected' areas in the engine bay.  The general state of corrosion of the pipes throughout suggests its been this way for at least a long time.

b) there is no trace of green even under the rubber mounting blocks

c) the bands of red paint that some lines have near their ends as some form of coding are in tact, with no sign of green underneath. 

I'm quite happy for someone to prove me wrong, but for now I'm happy to accept that the blue car never had this green coating, and this may be explained by the fact that it is a very early car ('76)

Ryan

[CraigS]

It would be interesting to know what the Green coating is, and why it is there. It may have been an addition early on, but it is a bit hard to understand why, as there would not be any evidence of corrosion in the first 2 years of production, or perhaps they learnt something from the W123 with self levelling suspension. More importantly, as far as originality is concerned, the current lines do have the coating, so whether it had it originally is probably not really an issue. Generally, Mercedes will only make a change for a specific reason. Unfortunately, we do not know the reason for it, but you can assume that it was an improvement for some reason. Maybe someone has the Mercedes bulletins and can answer this.

[s class]

Craig, I have no doubt the coating is an improvement, but I would like to go with shiny metal, and if I can verify that the car was originally delivered without the coating, I will feel less guilty about going that route. 

[CraigS]

That is entirely your choice ! We all make minor adjustments along the way, so no harm done, and it would be hard for anyone to disprove that it shouldn't be there.

[s class]

Craig I have another concern about the long line I bought from the dealership today - it has a lot of slight kinks in it and I think I have bugger all chance of getting it really straight again.  A bit like trying to straighten a piece of old fence wire.