Auto trans cooler hoses?

[twistedtree]

I have the front of the engine compartment mostly apart on my '64 230SL chasing oil leaks, and while I'm at it I'd like to replace the flexible hoses for the auto transmission oil cooler.  Mine are metal pipes and fittings attached to the radiator, and metal pipes coming from the transmission, then maybe 12" of flexible hose with hose clamps joining the metal sections.  I think in later model cars these were fully formed hose assemblies with crimped fittings on the ends.  But mine are not, and I have no reason to believe it's not original.  If anyone knows otherwise, please let me know.

But my question is what type hose to use?  I have a bunch of fuel hose with the woven outer jacket, and one of the existing hoses uses that material.  The other appears to be a more common smooth fuel hose.  My plan is to use the woven fuel hose unless anyone knows otherwise.  I'd also like to confirm that the cooling loop is on the low pressure side of the transmission hydraulics.  Other than originality, pressure rating is my real concern.

Thoughts?

Thanks,

Peter

[wwheeler]

Hi Peter,

Does your trans hose look like this? If so, it is original as far as I know. I have seen this green braided hose with the replaceable hose fitting ends used on original trans cooler lines.

As far as using a fuel hose for ATF, you are in luck. Both of those use Nitrile (NBR) as the inner rubber material. You have to be very careful though, that the hose material is compatible with the fluid you are using. Most do not interchange as easily as this. FYI, fuel lines have a cloth braided cover or use another rubber material on the cover because Nitrile is very poor in ozone or UV. The different cover material will be something that resists ozone and UV.

[twistedtree]

Thanks.  I wouldn't have guessed that was a replaceable fitting on the green hose, but that's more like what I have seen listed as replacements.   Yet mine are still different.  I snapped a couple of pictures yesterday.

Ignoring the hose clamps, the swivel hose ends didn't just come from a hardware store, which is what makes me think it's original.  Unless the previous owner got the hose ends from something else and made these assemblies?  I don't know.

I checked and 3/8" hose is a good fit, so my current plan is to use "fuel injection hose" which is just fuel hose with a 50 psi pressure rating.

[Pawel66]

I am for sure not qualified to judge, but I looked at 113042 spare parts lists and all I have seen was factory assembled hose from the metal line to the cooler, like on the picture from wwheeler.

The connector reminds me fuel line connector or vacuum line connector. Certainly clamps are not original.

[wwheeler]

The original oil cooler hoses and trans cooler hoses were all rebuildable. Meaning you reuse the fittings and just use a new piece of hose. That green hose pic is from 280SEGuys W108 car and it is has many very original parts on it, this being one.

I have all of the pieces that I have gathered over the years in order to convert the factory crimp hose to the original reusable fittings. The new factory hoses are an assembly and crimped and not reusable. Attached is a pic of the hose you see in my first picture disassembled. It isn't easy and why most throw them away and use the crimp style.

[twistedtree]

Thanks for the picture.  That's very different from the hose ends that I have.  The one in the picture is conical, and mine are straight tubing, but with a bulge near the end, typical of a fitting meant to have a hose and clamp over it.

So I'm thinking it's either original, but different, as many little things are on these very early 230s.  Or it's something the PO cobbled together from other parts, from other cars.

Yet another Mercedes Mystery.

[wwheeler]

In order to get the fitting you have, all you have to do is cut the metal crimp on an assembled crimped hose and remove the old hose. It has just the same fitting you have. Then use a new piece of hose and an adjustable hose clamp like you have. I have done that many times. I would say it is very likely this was done by a PO and is not original.

However it works just fine and the advantage is that now it is a reusable fitting of sorts. Meaning you can easily replace the hose and re-plate the fitting to make it look new.   

[Shvegel]

Wallace,
I have spent hours upon hours looking for the correct green hose.  Has anyone ever found a supplier?

[Aaron h]

Wallace,
I have spent hours upon hours looking for the correct green hose.  Has anyone ever found a supplier?

Aeroquip, as well as other manufacturers that made this type of hose in Europe, quit making this hose in this color many many years ago.  However, you can still buy some like it, but it'll be black in color.  You'll need the inner diameter and outer diameter measurements to match up exactly what you need. Maybe someone somewhere has some of the original green hose lying around, but given how old it is would you want to put 30-40 year old hose back on?  It's a bit of a catch-22. 

[wwheeler]

The picture above is from an owner who still has the original hose. I agree with Aaron that I would not buy a NOS hose that would see service because you have no idea where it has been stored all of these years. No, I am guessing that hose will never be found again unless someone decides to reproduce it. I for one have not seen it. About the closest I have ever got was a green plastic braided cover that fits over the hose. The material is in a tube and kind of like Chinese finger trap. It just didn't look good though. 

Aaron is also correct in that you have to get the exact size hose. The most critical dimension is the cross section (or width) of the hose. Because you are "threading" both the ID and OD on the fittings, it cannot be too loose or too tight. You also need a softer hose that can be compressed like that. Wire reinforced hose will not work. 

[Aaron h]

What about that blueish cloth covered hose that Mercedes, VW, Audi, BMW, etc., used for the fluid supply from the brake fluid reservoir to the clutch master cylinder? It would be a really close match if the dimensions of the hose are correct, but ONLY if the hose itself can stand up to transmission fluid.....that's what I'm not certain about.  Brake fluid and transmissions fluid are very different in composition, so I'd want to make sure that the hose is compatible with both. 

[wwheeler]

Good thought on the hose. If it would work (compatibility and size), I would use it and call it close enough.

BUT......There is no one material that will work for both Dexron (trans fluid) and DOT 3 Brake fluid. So very doubtful that hose would work as a trans hose.

[Shvegel]

I did know of a braided hot oil hose that was green but the OD was too large.  If I could find a braided hose a little paint might just do the trick.

[Shvegel]

Found a Rein N203591 hose.  Bought a couple meters from Belmetric under there RH9 part number.  It is black so I will try to paint it green and see what happens.  Specs look good.

[wwheeler]

Excellent! I will get some as well. Let us know what paint you decide to use. It may be better to paint once installed for fear of the paint cracking when the hose is getting shaped?

I need some metric stainless pan head sheet screws anyway, I'll get it all at the same time.

Thanks.

[Shvegel]

Dyed a lot of carpets with spray cans. It should stick to the fabric cover just fine.  I noticed Cohline has the same part # as well.  The hose arrived and is stamped “NBR”  (Nitrile Rubber) and made in Germany.

[Shvegel]

I think I got it.  Rustoleum Meadow Green Gloss (Home Depot)

Here is how to apply:

One medium coat the wipe with paper towel in one direction to stick down all the fibers then let dry.

Soak it with paint and wipe down again and let dry. 

Apply a third light coat to bury the white lettering if needed.

[280SE Guy]

Excellent job ! ! !   Looks like the original.

[wwheeler]

Wow! That is nice and great job. I was just about to order that hose but needed some stainless metric interior screws as well and making my list now. You gave us perfectionists new hope!!!!!

I remember way back when 280SE guy showed a picture of this hose and Joe A. pointed out that it was original. I certainly had no idea Mercedes used that at the time. If you don't learn something new everyday, you have your eyes closed.

I am no good at posting info, but someone more capable than I should put that in the tech manual for eternity.

 

[Shvegel]

This is another contender but being double braided the sizes are not spot on.

https://www.bdiexpress.com/pl/en/Fluid-Power/Hose-Flexible-Tubing-And-Assemblies/Hoses/FC647-10GRN/p/9001816352

[wwheeler]

Well and more than that, the extra braided row will make it almost impossible to thread on the fittings being more rigid. The construction really cannot be any more than an outer cloth braid and inner rubber. I once tried a hose that was the correct size but had a steel braid in the middle. It just would not fit over the fittings and thread. I think you have it with the first hose you found. 

[Shvegel]

You are probably right.  I think it might be a tough one to get too.  I am looking for cleaner yellow sleeves and the 90 degree elbow fitting if anyone has some laying around.

[wwheeler]

Those trans fittings are hard to come by. I tried to get extras, but could only get one set. The oil cooler fittings are much easier to come by and I guess because the automatic trans was optional.

The sleeves are aluminum and should be anodized with that funky yellow. I gave up trying to find someone to anodize those in small volumes and ended up zinc plating them with a yellow chromate.

Yes you can zinc plate aluminum with what is called "Zincate" from Caswell. It is an acidic solution and puts a sacrificial zinc coating on the part right before it goes into the plating tank. The process is a bit persnickety but works. The aluminum zinc plated part turned out quite differently from the steel ones. Close enough for me.   

[Shvegel]

Plans being formulated to make new ones when I get home in April.

[MikeSimon]

Someone in one of our motorcycle communities has used this product to make small parts appear anodized. I will try this out on some of my parts.