oil cooler nuts locked on tight; help - PeachParts Mercedes-Benz Forum

HowellK · #1 06-07-2007, 09:56 AM

Working on the '85 300TD (290k mi), studied posts on oil cooler lines, dieselgiant info, and I soaked the ends of the hoses with wd40, then PB blaster several times over two days.... I have the 1 1/16 wrench, and I can't budge any of the ends. I tried tapping...grunting...teeth gnashing...
The wrench even slipped over the nut; the wrench opened up a bit to slip.
What about drilling into a nut ? What about using a chisel? I'm worried about damaging the oil cooler.
Any ideas?

vstech · #2 06-07-2007, 10:04 AM

why are you pulling the lines? many here have found the hard way that replacement of the cooler is the only way once the threads have locked themselves. I would start searching for a junkyard containing these cars. good luck.

vstech · #3 06-07-2007, 10:10 AM

I hear that you can CAREFULLY use a cut off tool to cut through the nut on the lines and once the pressure is off, the nut comes off pretty easy, but if you have already rounded the edges/distorted the line nut, all bets are off.

rs899 · #4 06-07-2007, 10:20 AM

Yes, try using a dremel or cutoff tool across the flats of the nuts. Try to cut it into two semi-circular pieces and pry them apart with a screwdriver in the cuts.

I have hacksawed several of these and haven't ruined any yet. You can cut into the male thread of the cooler a bit without ruining it, but dont go too far or you will cut into the beveled flange that seals with the oil coller hose end.

Rick

techguy512 · #5 06-07-2007, 10:55 AM

Quote:

Originally Posted by vstech

many here have found the hard way that replacement of the cooler is the only way once the threads have locked themselves

The oil cooler fittings are repairable should you strip the aluminum threads.

PatricdeBoer · #6 06-07-2007, 11:27 AM

I used a soldering torch to heat mine up, they came off nice and easy.

HowellK · #7 06-07-2007, 12:02 PM

I did try some heat on two nuts; the two by the filter are hard to get to with a torch.
I'll try cutting into them next; I do remember a post about that... and the one about being able to repair the threads on the oil cooler (though I would like to find another cooler just in case). How do you repair the threads btw?
Thanks for the ideas.

SD Blue · #8 06-07-2007, 12:04 PM

Are you using a "modified" box end (slight cut-out to make it a flare-nut wrench)? I would avoid using the open end to prevent rounding the nut.

Sometimes, I have found that alternating PB Blaster and brake cleaner helps to allow the penetrant to work into the threads.

BTW, ditto the heat idea just be sure to clean the area with brake cleaner before using a torch.

rs899 · #9 06-07-2007, 12:07 PM

Sounds like you are committed now.

Best to cut the rubber lines with a knife and work on the oil cooler issue on the bench.

mcguirjf · #10 06-07-2007, 01:50 PM

I just pulled the oil cooler lines of my 1990 300D because the bottom row was smashed and leaking oil. I sheared the fittings off the oil cooler! I then had to take a plumbing wrench and 27mm socket and breaker bar to separate the fittings from the hoses.

Now I have to pay 250-300 for a new oil cooler

techguy512 · #11 06-07-2007, 02:00 PM

Quote:

Originally Posted by mcguirjf

Now I have to pay 250-300 for a new oil cooler

Please see the below thread (post #10) about repair of the hose fittings on the aluminum coolers. It works. My cooler has been working fine for a year after this repair.

http://www.peachparts.com/shopforum/showthread.php?t=152383&highlight=screwed+nipple

SD Blue · #12 06-08-2007, 12:22 PM

Quote:

Originally Posted by mcguirjf

..........because the bottom row was smashed and leaking oil................

It sounds like you had a replacement coming anyway. You might be able to find one in a bone yard for less. Double wrenching and penetrant is definitely the key, and a couple of prayers to help calm the nerves.

d.delano · #13 06-08-2007, 02:17 PM

Use copious amounts of penetrant, maybe heat the fittings with a torch for a bit. Let it sit overnight, and repeat. After a few days of this, put the proper wrench on the hose fitting, put the proper backup wrench on the cooler fitting, and perhaps have a helper smack the hose wrench with a rawhide hammer or something while you hold your mouth in a grimace biased toward the right side of your face, not the left. You want to break that fitting quick, not slow.
I used this strategy and it worked for me without any damage to the cooler fittings.

HowellK · #14 06-08-2007, 03:12 PM

I'm on day three or four of penetrating oil and heat... still trying.
Many of us needed that post of Bob/Techguy about tapping and screwing in the nipple (sounds like the tapping goes on the inside of the stripped nipple is on the oil cooler, is that right?). I haven't gone beyond no return...may have to reload oil and take it to an indie...
I'll see if I can get someone to tap while I hold and grit it out. (An impact wrench with the flare nut fitting would be great.)
thanks.

techguy512 · #15 06-08-2007, 09:56 PM

Quote:

Originally Posted by HowellK

sounds like the tapping goes on the inside of the stripped nipple is on the oil cooler, is that right?

Hard to explain.....

The threaded section extends out from the face of the cooler, and is made of the same aluminum
as the cooler body. The entire threaded extention is cut off flush with the face of the cooler, and
the tap cuts threads below the face of the cooler.

It all makes sense once you see one of the replacement steel nipples.