Author Topic: Oil sump hose specs?  (Read 131 times)

raueda1

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Oil sump hose specs?
« on: 25 August 2019, 01:37 PM »
The various 6.9 oil system hoses don't seem to bear any markings with the spec or type designation - no DIN, ISO or SAE indications of what they are. Same goes for the smaller transmission hoses going to the cooler.  I want to replace them all on principle given their age.  The fittings are in fine shape and easy to replace, just gotta use the right hose.  Need to know:
  • diameter -easy to measure
  • temp rating - oil starts decomposing above about 275°F so 300° (~150°C) would be OK
  • pressure.  Per Wikipedia, "The oil pressure generated in most engines should be about 10 psi per every 1000 revolutions per minute (rpm), peaking around 55-65 psi" so 100psi (~6.8 Bar) would be fine.
  • reinforcement is textile, not steel
From all that it would be possible to back into the DIN/ISO spec but I'd prefer to just have the spec itself.  If anybody has any hard info it would be very helpful.  If not then I guess I'll have to reverse engineer it with these guys https://www.belmetric.com/metric-hoses-c-14.html.  Many thanks to Rumb for the source!  Cheers,
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

daantjie

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Re: Oil sump hose specs?
« Reply #1 on: 26 August 2019, 08:10 AM »
Dave I cannot offer too much info here, but as you have discovered, the pressure handled by these hoses is not nearly as extreme as the hydro suspension hoses, thus I would guess as long as you match the ID properly, then any half decent hydraulic shop would be able to fab up some hoses chop-chop.  Most important of course is to reuse the fittings as they would be metric, and here in NA you usually have a helluva time getting metric hydro fittings in my experience.  Cohline/Continental should be the go - to I would think.
Daniel
1977 450 SEL 6.9 - Astralsilber

raueda1

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Re: Oil sump hose specs?
« Reply #2 on: 26 August 2019, 12:06 PM »
Dave I cannot offer too much info here, but as you have discovered, the pressure handled by these hoses is not nearly as extreme as the hydro suspension hoses, thus I would guess as long as you match the ID properly, then any half decent hydraulic shop would be able to fab up some hoses chop-chop.  Most important of course is to reuse the fittings as they would be metric, and here in NA you usually have a helluva time getting metric hydro fittings in my experience.  Cohline/Continental should be the go - to I would think.
I foolishly paid to have my rear strut hoses "rebuilt."  After doing my own high pressure power steering hose I'm kicking myself in the butt.  The hoses themselves are commodities and the fittings can be reused.  It's just a matter of knowing how to read the specs or, as I'm doing, backing into the spec based on the application.  I can't believe that MB got custom hoses, the hose guys hate that stuff.  But I wouldn't be surprised if they overspec'd on pressure or temp ratings.  MB is just a car, after all, not a transwarp plasma wormhole capsule.  Then it's just a matter sourcing the hose itself.  ooking a specific spec just makes it a bit easier.  I spent years in the rubber industry with Gates, Dayco, Goodyear et al as customers - I guess some of that stuck with me.  ;D

So.....    I'll certainly reuse fittings.  They're all in perfect shape, so why not?  No need for a shop that I can see.  I plan to to measure hoses and will seek substitutes per Rumb's excellent source for all things metric.  I'll post the results.

-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0