I have been in Cleveland this past week visiting family and my upper oil cooler line on my 85 300TDT is dripping about a drip every 3 seconds at idle. It started as a very minor weep before I departed from FL last week and I fear my snugging of the line a couple days ago started a stronger leak. It's too much of a leak for me to comfortably drive almost 1,000 miles at highway speed.

The leak is predominately coming out at the back of the nut on the oil cooler line. I am using two wrenches, with one ground down for clearance on the oil cooler nipple. I cleaned and decreased both ends of the coupling and used 600 grit Emory to very carefully clean the chamfered/beveled mating edges. It almost seems as if I am running out of the thread. The coupling is snug and tight but still leaks. The oil cooler nipple front thread looks suspect and kind of chewed, very minor but not suspect.

I am going to try and find a 22x1.5 die to redress the oil cooler nipple threads and possibly find a new upper oil cooler line locally. I am in the Old Brooklyn area of Cleveland near Memphis and Fulton. If anyone has a spare upper cooler line and possibly an oil cooler if needed I would be greatly appreciative
I can be reached at nine oh four three five two six five three oh

Anyone know what size tap I would need to redress the threads inside the nut on the upper cooler line?

Any other suggestions....pipe dope, jb weld? I need to leave Cleveland ASAP to be back at work Tuesday morning.

High temp RTV maybe? Just as a temporary patch? If it's just a drip that might be okay...

quick update.....

ran a 22x1.5 die over the oil cooler nipple threads with an improvement of the threads but upon reassembly the leak is much worse, now a steady stream instead of a drip

no luck finding a new upper oil cooler line locally today

I also bought some permatex 1 minute set gasket in a tube

You could loop the oil cooler line(s) using constant tension hose clamps and a barbed fitting in a pinch. It would probably get you home.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

can you explain this method or a pic of the clamps you mention....Thanks

here are some pics

Plumbers tape?

Cut both rubber lines, buy a double ended barbed fitting (maybe a 90 degree fitting would work best given the OE bends in the hoses), slide hoses on the fitting and clamp each end with two constant tension clamps. constant tension hose clamps are available to NAPA.

Constant Tension Hose Clamps

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I also might try a coating of 5 minute epoxy on both sides of the fitting before looping the hoses.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

by looping the cooler I would be bypassing the oil cooler from functioning, correct? not sure if I want to drive 1000 miles without one in this heat

Sounds like it may be a combination of things:

1)Galled threads on the oil cooler itself.
2)Galled threads in the hose fitting.
3)Hyper-tightened hose fitting.

It is starting to sound as if the hose fitting has been over-tightened. (The nut portion of the fitting is no longer keeping the mating surfaces together.) If this occurs, the only solution may be replacement of both the cooler and hose fitting.

As Kerry suggested, the temporary solution may be bypasssing the cooler and cutting the lines off to accept a double-barbed fitting. If the upper hose fitting is damaged, you will be looking at replacement of the hose, regardless.

Is there someplace nearby that does custom hoses for hydraulics? They may be able to help if the bypass idea doesn't sound appealing. Temperature will be the big factor with this. Driving at night and cooler parts of the day may overcome that obstacle.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

The Oil Cooler Hoses do not seal on the Threads. The Hose seals in the tapered ID of the Oil Cooler Nipple and the rounded Face of the part that attaches to the Hose.

On the surface it sounds like the Hose Fitting has a crack somewhere or something else is cracked like the Hose Nipple having a split in it.

__________________
84 300D, 82 Volvo 244Gl Diesel

X2. aka flare fittings. I'd suggest look at the fittings for cracks with a magnifier and flare seating surfaces for nicks. If no cracks and minor nicks, scuff it up smooth with Scotchbrite or 600 wet dry paper.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

the trip home went quite well in regards to the oil cooler line....NO leaks at all!

I plan to purchase the replacement nipples and redo a spare oil cooler I have in stock. The permatex and self sealing tape held up quite well!

Just came across this thread and want to give an update. The permatex and survival tape is still holding quite well. Have maybe 20k miles since the "fix"