line leaking at oil cooler
 

85 300D at the bottom line at the jam numt I have a leak. Is there an o ring o seal that goes in there to replace to stop it. I tried gently tightening it but it would not move and didnt want to snap it. If I replace the line how much oil will come out if much at all?

Its a compression fitting.

Don't worry about the little oil you will loose, replacing the oil line is a PITA and you may damage the aluminum oil cooler fitting when you unscrew the hose.

There is no o-ring. These oil lines seal on a metal to metal flare. Try tightening it carefully. These fittings are famous for stripping the threads. If that happens MB has a repair fitting you can buy but it needs to be drilled and tapped. Are you sure that the fitting is leaking and it is not the hose? May be time to replace the oil lines.

If the rubber portions should be soft enough to squeeze. If they're hard, they're probably cracking and weeping or getting ready to. On my wagon, it was the rubber that was leaking. Use plenty of penetrating oil on the fittings to try and keep from galling the threads on the cooler. If you're going to replace the lines, use a dremel with a cut wheel and split the nut on the end of the lines so you can save the threads on the cooler completely.

I wish I had cut the nuts off the lines on mine. I was able to use the cooler again, but the threads were galled a bit.

I soaked the fittings on my oil cooler lines (both at the cooler and the oil filter housing) daily for a week with Kroil before my indy replaced the lines earlier this summer. I don't know if the shop did anything other than wrench the nuts loose, but I got lucky and they came off without any problem.

Good luck with yours.

Charlie

I took out the oil cooler with the line attached. A bolt holds it in at the bootom. On mine the weld nut broke its weld, so I had to take off the bottom chin part. No big deal. I could get to the wrench slots on the oil cooler easier then. I saw one post where they just cut off the old hose cap crimps and replaced the rubber oil lines, then used hose clamps. I had some line made up, but they are leaking. I might not have the compression fittings tight enough. Not the most inmortant problem at the moment, I'm working on the clutch line. I hope Phil come through for me.
Tom

I would degrease the area good with brake cleaner and re-check to be sure where the oil is leaking from. The cooler itself could have a hairline crack in it.

As Chad said, if the hoses are hard, it is time to replace. the rubber should be soft. most of the leaky ones I have seen always seem to be the bottom hose around the crimp. If it is weeping, get on it soon and replace.

when I changed mine they were as hard as the metal line, but were the orginals with the date of 84 stamped on them. so 20 years worth of use:eek:.

Those are not Jam nuts on the cooler, they do not turn, but if they do, you are in deep DO-DO. I use a 7/8 open end to take the pressure off that nut, and use a 1 1/6 flare nut wrench on the cooler nut. (have to make the wrench).
I lucked out, mine came right off. use Anti-seze in the threads when replacing them.

If you mess up the threads on the cooler, MB has a fix for them. do a search for "Screwed Nipples".

I think the reason the bottom hose starts to leak first, is the hot oil comes in from the bottom from the engine. so the top will be cooler exiting the cooler.

Charlie

I have 2 sets of good oil cooler lines. No leaks. Let me know

I thought the oil flow through the cooler is like the radiator, hot oil enters at the top and exits at the bottom.

yeah

Well now you guys got me doubting myself:confused:. so i went out a took a lookie see. and sure enough, goes in the bottom, comes out the top.

the line coming out the bottom of the oil filter housing goes to the bottom of the oil cooler. and the upper to the top.

Also in the "Service Manual Engine 617.95 Turbo Diesel" Section 18 "Engine Lubrication" a Diagram showing the oil circuit, lays out the oil flow.
Oil in from the bottom and out the top.

so when going on a drive down the highway and getting the oil good and hot, the top of the oil cooler will not be hot. but that all depends also on the out side air temp.

The Thermostat inside the oil filter housing starts to open @ 110C (230F), and is fully open @ 125C (253F).

on the 617.950 eng. the temp is 95C (204.8F) and fully open @ 110C (230F).

Charlie

Thermostats start to open 20 before stamped degrees on them. So what post makes sense.

:confused:

Charlie