I found these AC style clamps and I think they are a good option for repairing the oil cooler lines. They are a perfect fit with the 15mm hose and the tab should help keep them from blowing off.

The clamps are SUR&R AC6816 clamps which state they are good up to 600psi and I purchased a 5 pack from Zoro and was very happy with their customer service.

https://www.zoro.com/surr-clamp-set-for-12-ac-hose-pk5-ac6812/i/G6392526/

I purchased the hose here. It is sold by the meter. 1 meter is enough to do both oil cooler hoses.

https://www.belmetric.com/smooth-high-pressure-oem-c-14_139/rh15hp-smooth-high-pressure-15mm-p-962.html

video of the repair here.
https://youtu.be/e3gBh8Ozeak

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1985 Mercedes 300D bought for $400 work in progress. Video Playlist: https://www.youtube.com/playlist?list=PLeYmvdiw3Xm87mFck3FjQ12ZoTSFXZ0Rr

The hose only being capable of 284F for short duration has me concerned... oil can exceed 300F...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I am looking at a pic of the Clamps and in the pic there is either internal grooves or internal ridges on the Clamps. I do am not sure that is helpful. Next is, is the spacing of the clamps going to be good for the Oil Cooler application?

I have no answers for either because no one has used those particular clamps before that I know of. Nor do I know what a common AC nipple looks like.

From what I have read on the forum most of the clamped hose failures (and unknown hose quality to fit the application) have been from worm gear type clamps that a previous owner had installed and the forum member bought the car and seemed never to have occasionally tightened the clamps to be sure they were tight.

When the sock crimped collar hoses fail it seems to be due to the Hose shrinking under the crimped collar or possibly cracked off at outermost crimp. Almost always preceded by Oil seeping between the Hose and the crimped collar.

I assume that the same hose srinkage occurs under any type of clamp.

Clearly on the crimped collar of the stock lines it is not that the collar moved. That means if you used clamps with that tab to keep the clamps from moving if the hose srinks under the clamp the tab is not going to matter.

One thing the clamps with the tabs have going for them is that at a later date you can squeeze the camps together to tighten them (as can the worm gear type clamps) and that cannot be done on the crimped collar.

There is different types of Oeticker Clamps that are similar to the pictured clamps but have a better internal setup so that there is near continious smooth clamping surface inside.

I think double Oeticker Clamps are the colset you can get to a crimped collar and they can be squeezed tighter at a later date.

On mine because I left the lower hose tubes on the vehicle I found my lack of a Oeticker Clamp tool did not allow enough room to crimp them so I used Norma double worm gear type clamps on those and the Oeticker Clamps on the Oil Cooler ends.
The real Oeticker clamp tool allows you to use crimp with the tool parallel to the hose as well as 90 degrees from the hose.

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84 300D, 82 Volvo 244Gl Diesel

Can they be further tightened? I took a close look at similar clamps and it seems to me that clamping force is established by the three pins locking in the three slots. Deforming the bridge creates an overcenter so the clamp doesn’t come apart on its own. But it can’t get tighter than the pins in the slots allow.

In the picture of a crimped bridge, you can’t crimp it further if the clamp was sized correctly.

Sixto
98 E320s sedan and wagon

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I was not able to open the belmetric site. But if it is the same hose I bought from them; Choline 2633 wich has a 15mm inside diameter that is the same hose that is coming on some of the factory made Oil Cooler Hoses.
The temp for that is listed as minus 40 degrees C to 125 degrees C.

If that temp does not seem sufficient remember that is the hose beinused on some of the factory made oil cooler lines for W123s so in reality it must work.

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84 300D, 82 Volvo 244Gl Diesel

We will see how it holds up. It’s the hose I’ve seen recommended in other threads on here. Supposedly it’s the exact same hose that is used on the trucktec oil cooler line.

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1985 Mercedes 300D bought for $400 work in progress. Video Playlist: https://www.youtube.com/playlist?list=PLeYmvdiw3Xm87mFck3FjQ12ZoTSFXZ0Rr

I’ll try to get a picture of inside the clamp but that groove you see is for an opposite piece of metal to slide into on the other side of the clamp when you squeeze it together. I checked the spacing and bothe clamps are located on the metal tube with extra tube after the last clamp.

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1985 Mercedes 300D bought for $400 work in progress. Video Playlist: https://www.youtube.com/playlist?list=PLeYmvdiw3Xm87mFck3FjQ12ZoTSFXZ0Rr

The clamping force is achieved by crimping the bridge. My crimper could not crimp these tight enough that the 2 bridge parts were touching. So if these loosen up I can crimp them tighter.

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1985 Mercedes 300D bought for $400 work in progress. Video Playlist: https://www.youtube.com/playlist?list=PLeYmvdiw3Xm87mFck3FjQ12ZoTSFXZ0Rr

Yes it is the choline 2633 hose. I think it should be fine.

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1985 Mercedes 300D bought for $400 work in progress. Video Playlist: https://www.youtube.com/playlist?list=PLeYmvdiw3Xm87mFck3FjQ12ZoTSFXZ0Rr

125 C = 257°F I can't remember but I believe that the Manual only indicates what temp at wich the Oil Cooler Thermostat is fully open. Not sure that is an indication of the typical temp of the Oil before it goes through the Oil Cooler.

I also on a W123 I don't recall anyone actually measuering the temp of their Oil.

In any event as I have said the same hose is used on some of factory made Oil Cooler Hoses for W123. So it is a commonly used hose.

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84 300D, 82 Volvo 244Gl Diesel

I have used the Cohline 15mm ID hose for about 20 years now on my '83 300TD, changing it out every 5 years. I use T-bar clamps that have a completely smooth inner surface and they are wide enough to bridge two adjacent"barbs"(actually, rounded humps)on the stock metal fittings. It does appear necessary to tighten the clamps periodically, especially after the initial installation of new hose.

Removing the old hoses is not easy as they seem to become formed to the "barbs". I would be surprised if one could come off due to oil pressure--has not happened yet, anyway.

The Cohline hose also appears to be used on some air cooled Porsche motors for conecting to oil coolers.

If you go to a hydraulics store, they should have some metal coil spring like material that you can slip over the hoses to protect them from an errant ps pump belt.

Peter

My 135i, which sees far higher oil temperatures than a low power w123, only gets to around 250F under cruising conditions.

I will try to see what the spec is for the lines on my 135i. Seems they would have the appropriate design margin.

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)

As the hose gets damaged by heat and other factors. The rubber portion of the hose softens or relaxes. For added insurance the addition of a simple safety wire under the clamp. With the end taken to the nearest solid area. Or if not available to another clamp on the hard tubing line.

Basically if the clamp of whatever type. Cannot go off with the hose. The hose and clamp are far more likely to remain on. So simple to do yet I am not aware of anyone doing this.

I have seen too many fittings not prevent blow offs where the hose material is far more stable than the rubber outer layer of hose. Again even with those materials the clamp goes with the hose.

There is no clamp that can equal the applied pressure of a hydraulic crimped setup. My thought is that with a safety wire you will see leakage far earlier than a potential blow off can occur. Actually it may not be possible at all unless the rubber becomes totally rotten.

Personally I find the average screw type clamp very weak. All too common to strip them out when trying to get a decent clamping pressure out of them. It is neither costly or rocket science to incorporate a safety wire.

Or another way to look at it. Anything that reduces the chances of a blow off is worth the effort on these oil cooler lines. The original clamp has a safety device for the same reasons. The clamp has to get over the bubble in the line to slide off. So in effect by not putting a safety wire on you are further reducing the original integrity of the clamping system.

I wish people would give some serious thought to this. A blow off of these hoses is an engine failure event in most cases. Where less than a dollar can provide at least some insurance against it. Just a piece of stainless steel wire and sometimes another clamp.

Pex failures are common enough on hard plastic domestic water systems. The clamping system used by this poster is very similar to them.

Pex fittings are used on pretty stable material compared to the rubber outside layer of these oil cooler hoses. I do not use pex devices as I do not trust them enough by experience.

They have been replaced by a much superior device. Pex fastened hose would not blow off if they had a safety wire either. With no safety device incorporated it is like playing with fire.

Even the hydraulic swaged end has a safety system that works if the clamping pressure relaxes over time. Without it we would have a lot more blown off hoses. Of course when the rubber layer totally disintegrates nothing can stop the hose from blowing off even with their system of attachment.

I have to add that the safety wire must be mechanicaly secure at both ends. Not just slid under whatever clamp you are using. On some types of clamps there might be a way to do this without going under the clamp. This for those that may already have clamps installed.

If for some reason a member does not get a clear understanding of this. Bring it up on this thread. . Also the easiest method of doing this may come to some members thoughts.. To me it is not optional not to have a safety for the clamping system.

For example to keep it neat. I would take some flexiable stainless wire rope. Perhaps 1/16 or smaller. Take a swaging fitting and hammer it closed on one end or both. Put it under the clamp with the hammered on fitting just past the clamp. Take the other end and clamp it to the hard line. Even this is a 100 percent better than no restraint system.

The Choline Oil Cooler Hose is used on more then one of the factory made Oil Cooler Hoses for Mercedes.

I used double Oetiker Clamps on the upper ends of the Oil Cooler Hoses. I wanted to use them on the bottom also but there was no room on the bottom for the pincer/nail cutter type tool to fit in.

Note that the real Oietiker and some other makers make a pincer type tool that also has a portion on the side of it so that the tool can be used parallel with the Hose as well as 90 degrees to the hose as a Nail Cutter/Nipper does but the real tool is about $40+.

ButThere is another type of tool that has the Jaws mounted on a threaded rod and you turn a nut and it pinches the crimp inwards. That would have worked as it does not take up much space.

So I used Normal Worm Gear type clamps on the lower Hoses.

Not a good pic of Oetiker Clamps on the upper hose.

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84 300D, 82 Volvo 244Gl Diesel

In page #9 post #130 My original Hose replacement (with the sloppy fitting 5/8" ID Hose) lasted 6 1/2 years and I decided to change it.

The replacment of that hose with the 15mm Choline was done around 05-18-2014 so that was 4 years ago now.

The is pics of the Oeitker and Norma Clamps on the hoses.

Note that nearly all of the people that had factor made likely the original hoses fail saw that seeping wetness of Oil coming out of the factor crimp. So when you see that don't ignore it.
http://www.peachparts.com/shopforum/diesel-discussion/205012-cheap-oil-cooler-hose-replacement-9.html

Unfortunately the hose failure often happened within the first year of someone buying a used Car (likely the orginal hoses) and the owners might have wanted to change the hoses but other stuff to get the car on the road like brakes and so on were done first.

I read one account on a different Mercedes Forum where a man bought a Car in AZ and tried to drive it back to CO and one of the oil cooler hoses failed on the way.

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84 300D, 82 Volvo 244Gl Diesel