Garage > Mechanicals

Flushing 6.9 Suspension

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daantjie:
I looked in the service manual and the tightening torque is 45nm so you may need to snug it up more.  That hose was still available a while ago.  They tend to leak inside out after a while but leaking at the connection would be unusual.

PosedgeClk:

--- Quote from: Rolo on 16 October 2020, 06:57 PM ---What a warming thought -- rubber, that will all need replacing.

I got a serious problem now.  The high pressure hose from the pump to the valve on top of the tank is weeping.  The fitting is the cone type, but it's not very tapered.  Torqued to spec, 30 nm.  I looked in my factory shop manual and it says the connection was superseded in May 1978 with a cone and the photo shows another fastener on the hose fitting, I think.

Is there a newer fitting that won't weep?

--- End quote ---
What is weeping is the rubber itself. The fittings are likely fine. I had a high pressure hose rebuilt locally and simultaneously purchased a new one from ECS or someone like that. I got a bunch of emails for months that the high pressure reservoir hose was NLA, and I was OK with that, and after I had installed the rebuilt one, a package mysteriously arrived with a bunch of NOS stuff. I was annoyed, and at the same time, I was kind of charmed. I was making so much money a year and a half ago and was so busy that I didn't have any time to complain to ECS and just laughed it off that they had wasted $500 of my money but had found probably the last X of what I was looking for by calling every dealer in North America. I'm probably way off, but that is how I rationalized it at the time.

Not too long ago, I had an issue with a hose on a Honda product, and it was a similar scenario. It was a high pressure power steering hose with a right-angle bend. The slight seep of hydraulic oil always looked like a problem either at the crimp or at the fitting going into the pump, but that was never the case. Something in the rubber had split, and it was causing oil to leak around the crimp in the fitting.

Do you see a spray, a drip, or just a loss of fluid? Don't run your hand near the exit of the hydraulic pump. I have heard some bad stories of people injecting themselves with fluid from a pinhole leak.

Rolo:
It's the fitting.  I used talcum powder to leave a trail.  The shop manual says 30 nm, but I'm going to try a little more torque.  It's scary because there's no place for a counter hold and the top of the tank is flimsy.

Rolo:
Sorry to be responding to my own posts.  An update on leak.  I traced with talcum to the connection and assumed that it was incorrectly torqued.  It is correct.  It is the fitting on the hose going into the tapered fitting.  The hose is leaking, but not the rubber.  It's cadmium plated fitting itself.  Not at the hose, but on the fitting where the two halves meet.

Probably repairable, but another update is that the hoses are available from Classic Center.  Ships from Germany

raueda1:

--- Quote from: Rolo on 08 December 2020, 04:19 PM ---Sorry to be responding to my own posts.  An update on leak.  I traced with talcum to the connection and assumed that it was incorrectly torqued.  It is correct.  It is the fitting on the hose going into the tapered fitting.  The hose is leaking, but not the rubber. It's cadmium plated fitting itself.  Not at the hose, but on the fitting where the two halves meet.

Probably repairable, but another update is that the hoses are available from Classic Center.  Ships from Germany

--- End quote ---
I'm not entirely clear what this means, but in the end it likely amounts to the same thing.  The fitting is a compression fit on the hose.  Over time the rubber compresses and loses elasticity ("compression set").  Then the fitting, in effect, becomes loose, even if torqued correctly, and can't hold the same pressure.  The fitting then leaks or weeps.  The answer is to replace the hose.  It's not hard.  In many cases the hose can get so compressed that fitting will become loose enough to take it all apart by hand!  I think I posted the specs on the hose, try a search.  I think Uncle Ken at Mercedes Source sells the hose.  Be careful though.  The anodized ferrule is brittle and can be easily cracked unless care is taken.  To reassemble wrap the ferrule in duct tape or similar and used a vise grip with curved jaws.  At least that's what I did and it worked fine.  Cheers,

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