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Old 08-04-2005, 06:37 PM
dieseldiehard's Avatar
Join Date: Oct 2002
Location: Bay Area No Calif.
Posts: 4,298
new ends on oil cooler lines OM603 '87 300D turbo Ouch!!!!

OK, I am in process of "restoring" my newest project, an '87 300D turbo. Actually getting it to run after being in storage for over 18 months. The problem of a missing cylinderhead is now solved! A used one is being readied with new guides and triple angle valve seats being cut as we speak.
So this morning I yanked the water pump, cleaned the fan and repainted it. I removed the alternator to prep it for a new regulator chip. As I was removing the front antisway bushings (one was loose in its clamp and half of it was chewed up!) I saw that the oil cooler was pretty dirty.
So to clean the cooler fins and an added measure of draining the oil I removed the cooler lines from it and took it out and dunked it in the solvent tank. Admiring it as I blew out the fins w/ compressed air I discovered that the aluminum threads from nipples was GONE, it stayed in the nuts Why did they design the stupid thing using aluminum threads?
Has anyone been down this road b4?
Has anyone heard of a method for removing the stuck aluminum from the threads in the nuts? I tried using a pick awl but its stuck on what looks to be permanently.
How about new nuts? If available, could they be relaced after swaging new fitting on or will that shorten the lines too much to fit?
I see MB has replaced the upper and lower with one size fits all. Darn I wonder if I should have even started this mess! W124 cooler Lines are EXPENSIVE! Like worth more than I paid for the car!

'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!
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Old 08-04-2005, 06:41 PM
Hatterasguy's Avatar
Join Date: Nov 2002
Location: Milford, CT
Posts: 19,307
I have been down that road before! Don't worry the new lines have aluminum fittings to prevent this problem in the future.

I would try to find used ones, or bend over and buy new ones.

I bent over and it only hurt when I got the Visa bill at the end of the month!

Or you could have a shop crimp on new lines and metric fittings. Then you would just need a new cooler.
2020 GMC Sierra Denali
2007 Tiara 3200
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Old 08-04-2005, 06:51 PM
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Join Date: Jul 2002
Location: S. Texas
Posts: 1,237
If the fittings are steel you can heat them to a dull red and the al. should come out. A. melts at aout 500deg.
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Old 08-04-2005, 11:19 PM
dieseldiehard's Avatar
Join Date: Oct 2002
Location: Bay Area No Calif.
Posts: 4,298
thanks for the tips, I was trying to think of a caustic that would etch the aluminum without attacking the steel.
Whatever I do, you can bet I'll use anti sieze on the threads. I also have alunox for aluminum stuff (similar to anti sieze but made for electrical work and antennas that use aluminum).
I will try heat before giving up. I don't recall if there were signs of any leaks on the hoses, oddly I have replaced them on 123's they seem to get attacked from within and the rubber seeps oil. The 603's I have worked on don't show that kind of failure maybe they found a better rubber by 1987.

While I've got the cooler lines out I plan to R&R the starter, and maybe put a "new and improved" gasket under the filter housing, well on second thought the adage "leave well enough alone" has taught me something on this car, the first real money pit I've owned
Oh yes, what about tapping the oil cooler and putting a drain in it? Like a petcock or something? If the end ranks are brass I might solder one on. I had a 115 300D that came with a drain plug on the oil cooler, I like that feature it lets you get more of the stagnant oil out when doing an oil change.
Here's a link to the story on the $400 car: By it so I dont 87 300d $400
'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!
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Old 08-05-2005, 12:25 AM
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Join Date: Jun 2001
Location: Santa Monica, CA
Posts: 2,053
I copied the following off one of the forums or mailing lists, but I can't remember which one. Applies to a 617, but has some applicable info for your oil cooler, I believe. It's interesting that MB even offers this replacement part (screwed nipple). Whoever came up with that name?

The correct metric size is 27mm or you can use 1 & 1/16 inch. Be very careful removing the oil lines from the oil cooler. The threaded nipples on the cooler are soft aluminum and will strip or gall easily. I replaced my oil cooler lines last May. Despite slowly working the coupling nut with lots a penetrating oil, I still galled the threads on the cooler. A new oil cooler is $300. I planned for this and expected something like this to happen. I bought new threaded fittings for in between the oil lines and oil filter housing because I expected the old fittings to strip when I took them off the line couplings. These fittings are less than $5.00 each. I reused the original fittings so I have an extra set now. All I had to do is cut the aluminum threads off the oil cooler, drill a pilot hole, tap new threads, and install the new fittings. The thread tap size is 18mm by 1.5mm. The drill size for the pilot hole is 21/32 inches, I don't know the metric equivalent. It took a local machinist 15 minutes to cut off the aluminum threads back to the nut part, drill the pilot holes (there's plenty of metal there), and tap the new threads. It took longer to rinse out all the aluminum filings and grit out of the cooler than it did to work on it. Here are the MB part numbers for the threaded oil line fittings and copper washers. MB Part # Description 915013-013002 Screwed Nipples (That's what the label said.) 007603-018101 Ring, General, Metal "

After reading this, I ordered two new "screwed nipples" to have on hand from the dealer and they are copper fittings that were not unreasonably priced. FWIW
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1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)
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Old 08-05-2005, 12:31 AM
dieseldiehard's Avatar
Join Date: Oct 2002
Location: Bay Area No Calif.
Posts: 4,298
Great! Thanks jbaj007
I am usually one that uses the search feature (and promotes newcomers to use it!) but today I am frazzled, and too tired to see straight after the mess I got into on the '87 I have a vacation for a few days then I'll collect the parts I can and see if I can repair the darned things!
I'll post what I eventually do later,.
thanks again
'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!
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Old 08-05-2005, 10:24 AM
WANT '71 280SEL's Avatar
I'll Go Upside Your Head!
Join Date: Jan 2003
Location: Dallas, TX
Posts: 3,378
I had to repair the threads on the cooler of the 116 I sold not too long ago. Just make sure that you drill straight and not into an angle so the replacement fitting will fit flush. The worst part is cleaning out the metal shavings after the work is complete. Do the cleaning after the drilling and tapping but before finally threading in the new fitting. Good luck and I hope this applies to the 603 cooler as well. I wouldn't know as my cooler was bypassed by the PO, like 6 years ago. Still alive and kicking!



2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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