1976 240d oil cooler lines

[240Dude]

My lower oil cooler line is starting to leak and it seems like all of the parts I see on line are for 123's. I saw Deisel911's thread on replacing just the hose so I thought i'd give that a try. I bought a meter of Cohline 2633 15mm and some good clamps in hopes that I could at the very least stop the leak until I find a new line. The hose came in today and I thought it would be a good idea to test fit it on some old hose fittings I took off a car in a junkyard a few years ago. I was kind of surprised when the hose was way too big. Like a dope I figured that a 115 and 123 would use the same diameter lines. Now I must admit that I can't remember what car I took the fittings off of. It could have been a 220. Has anyone done the hose only fix on a 115 and if so what size hose did you use?
john

[Diesel911]

Ya, my thread was for a W123 with a 617.952.

I am not sure what goes on the 240D especially a 1976.

But, the issue with the Oil Cooler Hoses has change because on some years and models it seems like the poorer quality companies are making the Hoses.

Can you measure the Hose fittings OD? Also are the threaded Nuts on the 2nd set of used hoses the same size and threads.

When I first did the job I used 5/8" (15.8750 mm close to 16mm) GoodYear Slip Fit Hose. And, that was just a shade too large of ID.

[240Dude]

I checked the fittings in the car and the tube is 12mm which is the same as the old fittings. The barbs on the old fittings are 13.5mm.

[Diesel911]

Originally Posted by 240Dude

I checked the fittings in the car and the tube is 12mm which is the same as the old fittings. The barbs on the old fittings are 13.5mm.

15mm ID Hose ought to fit over it.

[240Dude]

the 15mm is way too loose. it actually slides easily over the stop on the fitting. Belmetric has some Cohline 2633 in 12mm so I'm going to give that a try.

[BillGrissom]

Don't confine yourself to metric sizes. Like others, I used 5/8" ID AC hose (-12, I recall) for the oil cooler hoses on my W123 300D. Sounds like 1/2" ID (-10 I recall) would work for you. If you don't have ferrules and crimper (an AC shop would), next best is Oeticker step-less ear clamps (ebay). If like my cars, cut the top hose 1" longer so it stays farther from that evil p.s. belt. I used "reduced barrier" hose to be more elegant, but "std barrier" would work. Lookup the specs and you will see the hose is rated fine for hot oil, and for higher pressure.

[Diesel911]

1/2" = 12.7mm. Regular autoparts stores sell 1/2" Oil Cooler hose. However, it might be best to go to the Store and find out what brand they sell and the number on the Hose and look up the specs as to temp and pressure.
There is a speck in the Mercedes Service Manual on when the Oil Pump Pressure Relief Valve is supposed to open and also the Temp when Oil Filer Thermostat (if there is one on a 1976 opens).

Going to the Auto Parts store allows you to try out the fit before buying.

https://mdmetric.com/tech/cvtcht.htm

If not a regular auto parts store then NAPA would be another likely source.

this site appears to have an online service manusal http://eva2.homeip.net/W115/program/

It has the oil pressure relief valve opening on a 615 Engine at 5 Bar 616 engine at 8 or 7 bar so that would be the max possible oil pressure.

The max temp with the thermostat opens all the way is 110 +or minus 4 degrees C

I only did a cursory look so recheck.


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