pentosin leak - who are the "usual suspects"?

[ByMW]

The ’93 850 has developed a slow but persistent pentosin leak. Not the brake booster. Not the pressure switch on the ABS/traction unit. The fluid pools toward the front left of the car – actually drips off of the shelf below the radiator and fan. It happens at rest, so it isn’t pressure dependent. I’m thinking it is most likely one of the hoses coming off the reservoir itself.
So my question: anyone have experience with the most likely culprit here? I’ve not been able to see the actual leak in action, so I’m mostly guessing at this point.

[killian665]

Just look at it? If it’s leaking and you can see it, fire some brake cleaner all over that shit then check again. It’s probably just one of the lines.

[M6csi]

Likely, the leak(s) is from the steering fluid oil cooler that is mounted in front of the radiator. There are 2 short rubber hoses that are connected between the cooler and the metal feed/return lines. Not that difficult of a job as I did this recently. The leak was from the same general area as you described. Both hoses leaked off the oil cooler connector nipples. Believe the BMW oil hose is 12x18mm. Parts 18 on diagram.

[ltbrett]

Likely, the leak(s) is from the steering fluid oil cooler that is mounted in front of the radiator. There are 2 short rubber hoses that are connected between the cooler and the metal feed/return lines. Not that difficult of a job as I did this recently. The leak was from the same general area as you described. Both hoses leaked off the oil cooler connector nipples. Believe the BMW oil hose is 12x18mm. Parts 18 on diagram.

Yup, I recently fixed the same problem. The hoses are nothing special. No bends or anything. Just open the plastic cowling atop your radiator and go to your local auto parts store for new hoses and clamps. The upper clamps are easy to reach from above while the lower ones can be reached through the lower air inlet. Watch your knuckles on the radiator.

Brett

[toomanyparts]

My leak was the bottom hose from the housing to the pump. Not too bad to change and did the rest of the hoses for peace of mind while I was there.

[ByMW]

thanks everyone - I'll tackle this as soon as it warms up a bit...

[Gregsgroup]

I found a leak at the power steering cooler. There are two rubber hoses which connect to the hardlines. Upon visual inspection you cannot see them unless you remove the driver side plastic cold air ductimg in the nose of the car.

[Max Lumens]

Ancient history comes back around 8^) Almost none of the PS lines are high pressure, even tho they look like it. Nothing connected to the reservoir is. Replace the rubber portions, using wide SS hose clamps. You can cut the rubber hose off the barbed end fittings in situ; ignore the crimped collars, fakes. Double up the hose clamps, can't hurt.

My Pentosin substitute has evolved, now that I'm also pouring it thru a couple of big British cars. Been using ISO 10 or ISO 15 hydraulic oil from the tractor dealer, works great, costs pennies.

[ByMW]

Thanks, everyone, for the tip about the fluid cooler lines in the nose of the car. I actually never knew the car had a “power steering cooler” up there. It looks like the rubber lines harden/shrink over time and start leaking past the original clamps. Typical 8 series repair: looks simple but devilishly difficult to access easily. I hope this cures my pentosin leak.
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