ok guys im in the middle of replacing my oil cooler lines on the sd. actually i would be done but i cant get the bottom cooler line to stop leaking. all the othersbare fine. i tried removing and retightening but still leaks. is there a trick i dont know? thanks

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual

two things... CLEAN the fittings super well.
and use a good backup wrench on the fittings!

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I was able to get it to stop leaking but it seemed like it had to be much tighter than what the last hose was. In fact all of the lines came off without a hitch and the only really tough one to get off was the lower fitting on the oil filter housing. Anyway I got it all back together and drove it about 20 miles and when I went to fill up I noticed it dripping again. I guess I need to loosen it and try again but that won't be until next weekend. Sigh.

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual

I just noticed your sd is orient red and palomino. I'd really like to see a picture of that. My SD is Anthricite and palomino, and also an eighty four.

Is it leaking at the Oil Cooler end or the Oil Filter Housing end?

The fittings that go into the Oil Filter Housing have their own Crush Washers.
I have also read where someone cracked their Oil Filter Housing by not useing a backup Wrench on the Fittings.

A few people have recieved Oil Cooler Hoses where the Crimped area leaked.

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84 300D, 82 Volvo 244Gl Diesel

It leaks at the lower oil cooler fitting not the crimped area. I did use a backup wrench and a modified wrench to do the job. I just cant get that last hose to seal. All the others didnt even need a retightening. The whole job isnt the nightmare I was planning on, except for this one reluctant fitting.

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual

Try completely unscrewing the lower fitting (hopefully you can do it without having to undo the upper one.) this time with you tighten the lower fitting, try to press the beveled end into the threaded piece before you start tightening the nut on the cooler line. Try to keep the pressure on that beveled pend of the line while you tighten the nut. It should make it easy to finger tighten most of the way. Then check for leaks.

I will try that. I ran out of daylight and got tired of working by flashlight. Next saturday I will let you know how it goes. Also I try to snap a few pics of the car for ya. It just sucks that whenever the lower line comes of it makes a terrible oily mess. So far this is the dirtiest job I've done yet.

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual

I know how you feel. When I did theoilcooler lines on my sd one of the threaded fittings had been basically welded in place by some sadistic ****er with loctite. I ended up applying so much torque to the nut on the cooler line that I sheared the line. Having passed the point of no return, so to speak, I cut the copper part of the line and kept at it and eventually the brass nut broke free. I was using a heavily modified 1 1/16 open end. I managed to get it done, but it took something like ten hours. I have a feeling when yup try unscrewing it entirely and then keeping the beveled end of the line seated while you finger tighten the nut you'll get it. The trick is keeping the beveled end seated while you then pickup the mod wrench and apply the final torque.

I always use a thread sealer when dealing with oil lines. Rector seal #5 is good to 10000 PSI and it's what I used to seal the HPOP lines on the HEUI setup in my old Powerstroke.

It say flexible and is oil rated.

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The Oil Cooler Hoses do not seal on the threads they seal on the rounded end of the hose and the inverted cone shaped end of the Nipple.

The Oil that goes in and out of the Oil Cooler is dirty Oil so you do not have to worry about any particles getting into your Enigne; because before going into the Engine the Oil has to pass through the Oil Filter.

This means it is possible to use some Teflon Pipe Tape on the end of the Hose or even to use something like a coating of non-hardening Permatex on the rounded portion of the Hose end.
Or some other type of sealant.

Another thing I have done before; but not on Mercedes is I have put a thin Copper (Aluminum would work) Washer between the 2 surfaces and tighten them together.

Attached Thumbnails

   

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84 300D, 82 Volvo 244Gl Diesel

Please note the rounded ball compression/seal face.

It is a compression fitting = thread sealer has no effect on compression face leaks.

Never use thread lock/sealer on these compression fittings, it makes future repairs difficult or a disaster..






.

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Is a touch of that copper antiseize paste o.k.? On the threads I meant? I thought I read somewhere that the threaded male bung or fitting coming off the cooler itself is aluminum which would make a dis-similar metal connection at that point since the female connector that threads onto it is steel. Some have had a heck of a time cracking these loose and even had the fitting twist out of the cooler if a backup wrench is not used. I used the antiseize on mine over a year ago and it is fine....comes apart nice.

Yes, that is what I use.

1984 300SD
I have a lower line leaking at the crimp so must replace.
What are the problems for getting that line out and back in.
Is it all one piece?
Do these crimp leaks usually get worse over time?

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1984 300SD turbo 126
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