Transmission (oil) Cooling Lines - metal, rubber, metal

[jdcaples]

This isn't Sprinter specific, so I put it in "off topic."

What is the engineering reason for fluid conduits being made partially of rubber and partially of metal?

For instance, oil cooling lines on a GM 6.2 L diesel are essentially a length of rubber sandwiched between two (bent) metal tubes with threaded fasteners on the ends and stamped metal crimping at the metal/rubber joining. The power steering lines, I think, also were made of both rubber and metal.

Having donated my '93 GM 1-ton cargo van to a dear friend in need, I don't have another handy example, save my Sprinter's transmission oil cooler lines.

Yet again, I'm staring at the same implementation.

Why not make the whole thing out of rubber? The rubber's not just hanging in the air, so its at risk for abrasion at the strapping points.... The metal is immobilized too, presumably to prevent crimping and holes from fatigue.... I can see how an all metal tube would be a hassle to remove and replace. I figure that an all rubber situation would be would be too weak... but these things always fail where the metal meets the rubber.

There must be a reason this technology hasn't changed in decades, but I'd like someone to explain it to me.

-Jon

[sikwan]

My guess would be "less likelihood of deterioration of the entire line" especially considering the length of these lines.

[mobileoilchange]

jon,
i replace those oil and tranny lines on the gm trucks and vans all the time for reasons of leaks just as you said. right where its crimped to the rubber and metal. the reason is for engine movement. since the motor and tranny are mounted on rubber mounts, the motor and tranny move. if the lines were all metal they would fracture. although some gas gm and fords are steel tranny lines.

last week i replaced 3 tranny lines, 3 oil cooler lines, 1 tranny cooler, and 1 oil cooler on a 2002 chevy 3500 express van with a 6.5 diesel. all 3 oil cooler lines were leaking, the oil coolers fittings were rotted. the tranny lines were rusted and leaking badly. in all, the total in parts alone was nearly $335.00 my cost and $575.00 list. plus 4 hours labor. ive seen the oil cooler lines on a brand new 2008 GMC sierra 1500 with 13000 miles already leaking at the crimp. enough to Piss a owner off!

[jdcaples]

thanks for the info, guys. i'd still like to know why they use metal at all?

it seems to me rubber hoses pushed onto brass, barbed air hose adapters (see below) would be smarter, avoiding the whole metal crimping thing.


7976

I've cut hoses off of these kinds of adapters; they hold high pressure transmission lines really well.

A clamp would be a good idea, of course, but honestly, I've never been able to uncouple a hose from one of these things. I always have to cut the hose off the brass fitting.

Obviously, there's a reason these are not used instead, but I'd still like to know the engineering reasons for electing metal-rubber-metal contraptions.

-Jon

[mobileoilchange]

ok i know what youre asking now, they could of used high pressure hose such as a R1 (rubber over 1 braided strand) good for 2000 psi which is pretty cheap. who knows why engineeres do what they do at time. sometimes i think engineeres can be smart and other pretty dumb. example: steel brake line. all brake lines in my opinion should be made of stainless steel. its a safety issue!

but like all car manufactures will tell you, "we build cars to sell them, not to repair them"

[jdcaples]

Thanks, mobileoilchange. I appreciate the info.

[mobileoilchange]

info?