1982 300SD Oil Cooler Hoses Internal Pressures-Operating Pressure?
 

Hello,

I am in the process of renewing both of these lines and have had some help already from Rhodes. I'm awaiting the 2nd hose out of Miami.

The replacement hoses I got from Miami off of Ebay. They look OK but the Rubber Part looks thinner than the original hoses that I will be taking off. The new hoses are more like the thickness of a Radiator Hose rather than what is coming off. The ones coming off are real thick and hard of course with leaks at Rubber/Metal fittings. Drips. The connections on new hoses are nice and tight which I like and the bends look fine.

Does anybody know the operating pressure on these hoses? The hose material is stamped "Oil Service" but I'm just checking prior to changing these due to hose thickness of the new ones.

If operating pressure is minimal ie "orificed" they appear to be OK to me but I'm new at this so I'm not sure. . Any response would be appreciated.

Sincerely,

Steve

The max pressure in the oil system is regulated around 7bar (101PSI). I currently have a set of oil cooler hoses on my car that are exactly like you describe and have a little over 3000miles on them. The only issue I have is some oil seepage at the lower tubing flare (metal) on the oil cooler connection.

If it's rated pressure is at least 100psi, burst pressure is 250psi+ and it's rated for oil use, I see no reason why they won't last another 20 years. Rubber technology has come a long way since the 70's.

Yeah Right,

Good point, rubbers have come a long way! lol

I feel better now. I was worried about them not being as thick as the old hoses but since you have similar thinner hoses and they are stamped Made in Germany and are supposed to be OEM Equiv. I'm thinking now I'm good to go. I'll look closer for a pressure rating on hoses but if made in Germany with all the correct bends I'm thinking they are OK but I'll examine closer for pressure rating.

I would think that this line is orificed so under less than engine operating pressure anyway, but I have no clue.

I'll monitor at ends at this is where you ended up with drips.

Thanks for quick response.

Steve

AFAIK these hoses operate at full oil pressure. When I had mine replaced (right before a cross-country trip) one of the fittings was a tad loose, made a huge mess. Make sure you keep an eye on them for a few days.

The issue with the hoses is never the hose itself. The problem always occurs where the hose is crimped to the hard line.

Many folks have found that the aftermarket hoses won't go more than 30K before the crimp connection fails.

Maybe you'll be more fortunate than most.;)

Thanks for replies,

Hose says conti OLN-T 15X (Something more but ran out)

Not sure what it means but this is what I got off the hose on the new assembly.

I will sure monitor connections at ends and at junction.

I might redo the old ones as spares with something better.

At least on my 220D the oil cooler is thermostatically regulated, so not just zero or full flow. Plus, at least with my hoses, the hose i.d. is greater than the feed into it, so there is a drop in pressure as soon as the oil passes this neck into the rubber portion; then the drop in pressure is much greater yet to the return hose as much pressure is lost in the oil radiator itself. "Oil Rated/Resistant" doesn't speak to the pressure rating, per se, unless it is written or provided on paper, but I think that the temperature of the oil in combination with the pressure is the true measure; i.e. It's burst pressure is much less with hot oil than cold oil and vice versa. Since Brian C has seen a ton of this stuff over the years and how they perform, just keep an eye on the metal crimp.

Thanks fellows for replies,

I got the job finished this weekend. I was lucky as the new hose hasn't produced a drop of leakage anywhere yet. I will monitor it from time to time.

It isn't a pleasant job but a DIY'r if you have the required tools.

steve

lol, I cheated. I did them when the engine was out of the car. :D

Yeah, that job is a royal PITA with the engine in the car. Make sure you watch you oil pressure like a hawk. One of our 300sd's bit the dust after the crimp came undone on some aftermarket lines.

I don't really understand the presence of the hard lines on the oil cooler circuit... is it vibration or heat related?

I worked at a hydraulic shop and our heaviest duty 4 wire flex hose that probably had a higher burst than those hard lines, not to mention a working temperature well in excess of what my 617 will ever see.

Any good reasons why I shouldn't go with the 4 wire with a ballistic nylon/kevar sheath?

I'd keep an eye on the crimps of those aftermarket lines. A few members have had them fail at the crimps within 30k miles of replacement.


The OE hoses are identical to the original ones in every way.

I would just keep a watchful eye on everything. You have just a few seconds to shut the car off if one breaks.:eek:

Yogi Bera could not have said it better!!!