Guess it was bound to happen. Today while driving my daily driver 83 300D home on the highway I started to get a little bit of burning oil smell. I checked the gauges and they were all fine, oil pressure gauge was pegged at 3 bar, and temp read about 90C. As I slowed to turn off the highway onto a side road, I lost the feel of power steering and heard a bit of a groan from the pump. I figured the low pressure hose that I just changed worked loose or something. I drove the remaining 2 miles home and each time I slowed to make a turn it was as if I had no power steering. Well, I got it home, glanced at the gauges again before I shut it off and all was still normal, oil pressure was about 1.5 bar at idle, temp at 90C and no weird noises from the engine. Anyway I shut it off and popped the hood only to be greeted with motor oil all over everything on the drivers side of the engine, including the radiator fan shroud, the entire power steering pump and belt (which was slipping due to all the oil on it hence the steering issue! The passenger side of the engine, the valve cover and the air cleaner are all still clean and dry but the drivers side is an unholy mess. I pulled the dipstick and near as I can tell I lost all but about 2 quarts of oil.....I'll recheck in the morning to see for sure.

Now for the questions. First, where do you think I have a leak? Without being able to clearly see because of all the oil, I'm thinking the dreaded oil cooler hoses as they have been a little weepy the last few months. Right now my plan is to let it sit until the weekend when I can work on it, and then, use de-greaser and a pressure washer set on low pressure to clean off as much oil as I can. Then, once it is dry, top it up with oil and fire it up to see if I can find the leak. Good plan?
I will re-read some of the threads on oil cooler hose replacement, but any tips ahead of time would be most welcome. I have heard the fittings where they go into the oil cooler are a caution area and I remember reading where one forum member simply cut the old hose off the oil cooler fittings and used double hose clamps to hold the hose in place and never touched the fittings on the oil cooler.

__________________
2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

It sounds like oil cooler hoses would be the first place to look. Since MB is no longer offering them direct, we are all forced to scrounge around. You could remove the hoses and find a competent hydraulic hose repair shop to make you new hoses. Also, (because I'm dealing with similar issues.....) the best way IMHO, to clean an engine that has a lot of greasy oil is to use a hot water pressure washer. Start checking in your area for companies that provide hot water pressure washing services and ask if they can come to you. You could also spray the engine REALLY WELL with Sam's Club degreaser just to loosen up things.......

Be sure and stuff a rag or towel into the air cleaner intake and wrap large two gallon freezer bags around your starter and alternator before letting anyone turn a hot water pressure washer loose on your engine......

I've seen a few aftermarket hoses but I'm not sure I would trust them over what a competent hydraulic hose shop could do for you........

Sounds like oil cooler hose. The issue is that the fittings on the lines can gall the cooler threads when you remove them. I cut the fitting on the old hose with a cutoff wheel to relieve the tension on the threads before removing and had no issue. Just make sure you dont cut into the threads on the cooler.

__________________
1985 300 TD 448K
1984 300 TD 278K

1983 240D euro 240k
1994 f-250 idi turbo 330K
1986 f-350 IDI
1987 F-350 IDI

1985 JD 1050 4wd
1965 IH 3660

Ok, I kinda feel like the boy that cried wolf. After dinner I went out again and looked things over. I put my finger in some of the oil residue and it was dirty but rather thin. Looked around more now that the engine was cool and determined it was more like hydraulic fluid than engine oil. Pulled the dipstick and the oil level had risen back to near normal level (I guess a lot of oil is in the engine right after shutting it off).

So without boring you too much......I looked over the two power steering hoses and they were fine, but damp with sprayed oil. I pulled the cover off the power steering reservoir, and sure enough......completely empty. So, I found my source of the oil mess. So, the plan is the same, clean it up, fill the reservoir fire it up and look for leaks. I'm suspecting the gasket behind the pulley, but I also noticed the gasket for the cover is missing so it may have come off unnoticed when I refilled it after replacing the hoses last week.

Can these pumps be easily rebuilt with regular tools or???? sure hope I didn't kill the pump.

__________________
2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

Great news! That said, I know I'm going to go for replacing the oil cooler lines in the very near future. I've had the car for 25 years so who knows when they were last replaced?

Glad it was the PS vs oil cooler lines… but that said, the oil cooler lines are getting old, and if you don’t know the history, it’s likely prudent to change them… or get a qualified hydraulic shop to modify your OE lines with replaceable fittings.

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)

Can these pumps be easily rebuilt with regular tools or???? sure hope I didn't kill the pump.
__________________

I have resealed a few with just normal tools.

__________________
92 e300d2.5t
01 e320
05 cdi
85 chev c10

A company called "C&M Hydraulics" offers remanufactured power steering pumps for our cars. I would think it would be easier to purchase a reman power steering pump than trying to rebuild it yourself. You can check pelican parts for parts availability.....

They can be rebuilt in the sense you mean re-sealed.
Are you sure you didn’t damage the steering box?

__________________
1981 240D 4sp manual. Ivory White.

Yes, Pelican Parts sells a nifty P.S. pump kit with the better quality blue input shaft seal Mercedes no longer sells .

The only difficulty is removing the drive pulley, it's the same as all others : just be careful and gentle with it .

There's also a large, thin O-Ring that seals the sheet metal case to the cast iron guts, it rarely fails but often weeps / drips .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

I recall borrowing a free loan a tool puller from Autozone to get that pulley off. I’m trying to find my photos. I think I needed their bearing splitter to hold the pulley and then a standard puller to pull on that with the included 3/8” bolts.

Too bad MB doesn’t sell the blue seal anymore. This part can probably found in the CR Seal or National, Federal Mogul or other catalog though if availability becomes an issue. Relevant specs will be fluid compatibility, outer diameter, shaft diameter and thickness. It’s great that
Pelican has put together a kit. They do eventually leak.

ETA - hold it…I just checked, they still have the MB PN 0189976047 which is black. Are you saying the blue one is superior?

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

Well, after checking it out, the pump is definitely leaking a decent amount of fluid from the shaft seal behind the pulley. Call me crazy for throwing money at an old daily driver, but I am going to get either a rebuilt pump or a low mileage used one off of a friend that offered (his 300D was totaled with only 160K on it). I'm also going to replace the high pressure hose; I just replaced the low pressure hose a week or so ago, Finally a new belt, filter and cap gaskets, and I should be ok.

I doubt I hurt the steering box as at the most I drove probably 5-7 miles on flat and straight roads without much if any fluid, and it was only in the last mile where I had to make 3-90 degree left and right slow speed turns that the pump made audible groans and the steering got stiff.

__________________
2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

Yes indeedy ! .

They're much better and longer lasting too .

This is a dead simple job .

Plus, no more ATF dripping and getting blown all over the engine....

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

You ought to be able to tell what leaked by checking your engine oil level.

The Steel Oil Cooler Nuts tend to corrode onto the aluminum oil cooler nipple. When it happened to me, I turned the oil cooler nut and the corroded piece stuck to the nut threads and acted as a cutter and stripped 2-3 threads off of the nipple.
There is a repair for that, but you need to remove the Oil cooler, cut off the stripped threaded area and drill and tap for the replacement fitting.

Frequent spraying of the nipple threads with Kriol or the PB blaster catalyst penetrant may or may not works even if in combination with heat from a propane torch.

There is this thread and one other that lists a lot of alternative methods to factory oil cooler hoses. In the thread you can see that I left the Oil Cooler hose ends on the Oil Cooler. If you do that you are not removing them hence you cannot strip threads on the nipples.

Cheap oil cooler hose replacement.

__________________
84 300D, 82 Volvo 244Gl Diesel

You need to tell him the direction of the cuts and damages the oil cooler nuts he needs to already have the replacement hoses in hand.

If you nick into the threads that is not where the sealing is done. The sealing is done on the face of the nipple and the rounded acorn end of the oil cooler hose.

__________________
84 300D, 82 Volvo 244Gl Diesel