oil cooler line replacement, w124 om602
 

Hi,
One of my oil cooler lines failed at low speed (luckily), turned it off before low oil level or oil pressure dropped. Anyhow I removed the old hose and tried to find a replacement at a local parts store. The best they had was 5/8 hydraulic hose, but it looks too narrow to fit over the barbs. I haven't put on the gloves and really tried but it seems tight, and by the look and feel of the hose it doesn't have any stretch. Does anyone know if this engine uses the same oil cooler hose diameter as the w123 ? There are lots of write ups about the w123 300d, but not much for w124. I am thinking maybe I should go with the cohline, if I can find it anywhere.

I'm looking at the cohline 15 mm oil cooler hose. It is designed to be fastened with the metal crimps, but am hoping I can use the shielded high pressure clamps. I don't think I am going to use the 5/8 hydraulic hose that I just bought, because after doing more research, hose clamps don't work on those hoses.

Have you tried Belmetric?

No, I haven't. For the clamps, I am guessing?

I see they have the hoses too. It doesn't look like they have the right size.

I see. I recall they carried 15mm cohline hose. But that was a long time ago.

I ended up using Goodyear Galaxy #12 barrier hose. I am very happy running this setup since 2019.

https://www.peachparts.com/shopforum/3941331-post149.html

On my SD I did manage to find replacement hoses with cohline. But this was in 2010. And it was already hard to find good hoses back then. Perhaps a call to Belmetric will put you on the trail of a cohline distributor.

I did not read all of the posts so this could be a repeat. My experience is with w123s.

Please note that 5/8 inch is a larger OD compared to 15mm.

On a W123 removing loosening and unscrewing the Hose nut on the aluminum oil cooler frequently results in stripped threads on the oil cooler nipple. It happened to me. One a W123 there is a factory repair for that.

After you cut the collar off of one end of the hose find something to measure the high spots on the hose jag on the tubing. That measurement will let you know what size ID of hose you need.


I ended up getting 15mm hose from Bellmetric however some have said you can buy the same hose from Porsche dealers, and they will do one cut to length.

Post 10 has a pic of the correct Choline part number for the 15mm oil cooler hose.

http://www.peachparts.com/shopforum/diesel-discussion/414669-w123-123-oil-line-part-numbers.html

There is a thread of mine and another thread that eventually coves all manner of oil cooler hose replacements.

I used 2 shielded clamps per end, I next went to 2 normal clamps per end with 2 oteiker type clamps on the oil cooler side. I wanted to go all oteiker clamp, but my tool did had on feature to crimp from the side.

I ordered a 15 mm cohline hose, hopefully it will fit. Should be here in a few days. I have high pressure hose clamps that should be quite a bit better than regular ones. Hopefully will be good enough.

What exactly are high pressure hose clamps?

Not sure on your engine but on my 84 300D turbo diesel the highest pressure can be 110 psi. And that is what the oil pressure relief valve in the oil pump is set to open at.

In practice with the oil cold at idle I had 96-97 psi when I revved up the engine. I cannot recall the hot oil reading. In the hydraulics world that is low pressure.

Looks like my memory is slightly off.

This is from an older post of mine: In the below pic is what I got with and idle speed of about 750rpm and the Engine Cold; 80psi.

When I reved the Engine hot or cold the highest pressure I could get is about 97psi.

In one of the Manuals it has the Oil Pump Pressure Relief Valve relieving pressure at 101.5psi (7bar).

I did the fab your own oil cooler line, kept as close to OE as possible. Detailed here: http://www.peachparts.com/shopforum/4307411-post14.html. Learned from others here who blazed this trail. Working well so far. It's a timely post because I had a little seepage at the oil cooler, looks like I didn't have the pipes tight enough (27 mm nuts). That takes some finesse. Get them tight, but don't strip the aluminum cooler! ;)

Most NAPA stores can rebuild them.

The clamps I am using have a bolt on the end for tightening, and the majority of the clamp is shielded so it doesn't chew up the hose.
I am finding that the 15mm cohline hose is really really tight. I've only got one side on and spent several hours. Will try again soon.

Most of the infomation and threads are about 300D's with turbos. Those are the ones the choline 15mm hoses fit. I have no information on other engines and that is why I recommended measuring the OD of the nipples on the tubing.

If you continue to use the 15mm hose going to walmart and get some generic STP and coat the nipples with that before trying to put the hose onto the nipple. It is extremely slick stuff. Keep it off of your hands or the outside of the hose.

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.

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.