PeachParts Mercedes-Benz Forum - View Single Post

rs899 · #1 07-23-2002, 02:26 PM

I just replaced the oil cooler hoses on my 83 300D Turbo this last weekend after watching my lower hose weep over the last four months since I got the car. I had read all the posts on this and other websites and talked to a mechanic or two and finally decided to take the plunge. It was bad, but not as bad as I had expected. For those of you who have this action ahead of you, I offer a few words of advice. This is not intended to be a detailed step-by-step procedure, just some tips/observations of the things I did that worked for me. Keep in mind that I have done this only one time, and I am sure there are several ways to do this successfully, but this worked for me THIS TIME.

1. Remove the left hand motor mount . This was tricky. It is difficult to even understand the concept of how the mount works and see the three fasteners holding it. From the bottom there is a hole to stick an 8mm allen key or socket on a bolt that holds the engine to the mount. After this is out, you jack up the engine and can access two bolts with 6mm socket-headed bolts that hold the mount to the "frame" Be very careful with these because if you strip out the socket heads it will be a nightmare to get these out.

2. Try to loosen the lines at the oil cooler, using a wrench on the line and one on the flange on the cooler. Do not apply much force here because you may strip the threads (aluminum to steel interface can corrode)or bend/break the soft cooler housing (I have done this on a Triumph). If they don't budge (mine didn't- rats), I would suggest you cut the rubber hoses , remove the cooler and bring it to the workbench. There, you can carefully cut across the threads of the female steel coupling nuts. Cut as deeply as you need to, but try not to dig into the aluminum of the flange. When you have weakened the connector sufficiently, stick a screwdriver in the cut and twist, expanding the coupling slightly. Then, you can carefully loosen and take the coupling nut off and dress the threads for the new hose. If you have been careful and have not cut into the flange much, the cooler can be reused. The seal is made by the bevel inside the male flange compressing with the oil line , not the threads.

3. On the block, under the IP , there is an L-shaped bracket that holds the lines together in front of the oil filter. I removed this (two 13mm bolts hold it to the side of the block) and it really seemed to make life easier to remove and replace the lines. Once I had the lines routed , located and secured loosely to the oil filter housing , I replaced the bracket (which was difficult because your arms aren't hinged properly- you'll see what I mean).

4. I tightened the lower oil line on the filter housing before the upper. There is very little room in there to swing a wrench (I used a 1 1/16th- it works). If I had a wrench to sacrifice I would cut it down to fit (maybe needs to be 6 or 8") or possibly cut out a piece of the box end (make a sort of tubing wrench).

Anyway, I got it over and done with. It doesn't leak and I didn't ruin the $300 oil cooler. Took me the better part of a weekend but I work slow. Any I didn't utter any German oaths.

To those of you who are destined to tackle this- best of luck. It can be done. And now...ONWARD... to the front end work...