oil cooler line replacement, w124 om602 - Page 2 - PeachParts Mercedes-Benz Forum

JHZR2 · #1 10-14-2025, 12:39 AM

Quote:

Originally Posted by martureo

I'm still an advocate of going the more appropriate and serviceable route.

Remove the old hoses, cut off the old rubber and compression fittings and braze AN lines to the steel portion. Cut off the threaded nipples on the oil cooler and install AN nipples. Then create braided stainless hoses with AN fittings.

You'll never have to source new lines again apart from a few feet of braided stainless hose and you'll never have to remove the hard line sections.

I did this with my 240D oil cooler hoses. Used some really good Parker hose.

The issue is that if you don’t braze, and don’t know someone who does, it’s a $$$ proposition…

Diesel911 · #2 08-18-2025, 10:39 PM

Quote:

Originally Posted by Hoijaun

The OM602 in the W124 does have slightly different oil cooler line specs than the W123 300D. The W123 used 16mm ID hose, but the W124 often needs 17mm or even 18mm depending on the barb style. 5/8" hydraulic hose is close to 16mm, but if it feels too tight, you risk damaging the hose or not seating it properly. Cohline 2134 is the OEM-style hose and worth getting—it’s rated for oil and high temps.

My 84 300D used 15mm Choline oil cooler hose with no issues. I have no idea on the other years and engines.

jdulle · #3 08-29-2025, 01:12 PM

I didn't measure it, but the 18mm cohline works great. I do realize I would have saved some money by measuring, so will do that next time around. There is a hole in the metal line now too, so I need that fitting that screws into the cooler. There is rust on the metal fitting and I guess removing the ferrule was enough to create a hole. Looks like it will be difficult to find.

jdulle · #4 10-07-2025, 04:18 PM

I finally got this all buttoned up. I bought a used oil cooler (mainly for the rust free fittings), but ended up installing the whole thing since the fittings are hard to remove. The 18 mm cohline hose is working great.

Diesel911 · #5 10-08-2025, 12:49 PM

Quote:

Originally Posted by jdulle

I finally got this all buttoned up. I bought a used oil cooler (mainly for the rust free fittings), but ended up installing the whole thing since the fittings are hard to remove. The 18 mm cohline hose is working great.

2 thumbs up.

JHZR2 · #6 10-14-2025, 12:41 AM

Quote:

Originally Posted by jdulle

I finally got this all buttoned up. I bought a used oil cooler (mainly for the rust free fittings), but ended up installing the whole thing since the fittings are hard to remove. The 18 mm cohline hose is working great.

How did you crimp/secure it?

I’ll probably need to do this on my w124 and my two w126 350sd cars at some point…

Any photos?

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