Incontinence (in continents? in contents?)

gmctd · **Posted:** Sun Jul 13, 2008 11:56 am

Just found the perennial leak, causing the little mule to go thru a gallon of coolant every other month - or, rather, found it last year, but just now fixed it (ownership thing, don't you know): courtesy of yer local Mr MoService, prolly due to extenuating circumstances of 4xEGR replacement, the rubber outer ply had an eighth inch split on the top side where connected to the EGR solenoid cooler - bummer! - hadda drain the radiator, which will result in installation of an eighth inch air bleed tap in the t-stat housing, if I can't find my sixteenth inch tap

Next: Provent drain port in the turbo oil-drain line

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

gmctd wrote:

Next: Provent drain port in the turbo oil-drain line

Looking forward to seeing that.

Bill.Barg · **Posted:** Sun Jul 13, 2008 5:40 pm

Pablo wrote:

gmctd wrote:

Next: Provent drain port in the turbo oil-drain line

Looking forward to seeing that.

Me too..

I was thinking it might be easier to go over to the dipstick port on the other side ?!?

gmctd · **Posted:** Mon Jul 14, 2008 1:32 pm

Remember: liquid must seek it's own level - that's a mighty fur piece, with many ups and downs, to be a-runnin' a aqueduct, wouldn't you say?

Bill.Barg · **Posted:** Mon Jul 14, 2008 2:53 pm

Ya it is a long way to the dip stick, but at least there I am sure it is at atmospheric pressure, no?

What is the pressure at the turbo oil return?

gmctd · **Posted:** Mon Jul 14, 2008 3:32 pm

Any access port opening into the crankcase area will be at the same pressure level: oil filler, dipstick, turbo drain, CCV - what makes it all work is that the compressor inlet is at some level of depression, compared to blowby and Baro, due to piston displacement and intake path\air filter restriction - dirty air filter = greater restriction = greater depression (also known as vacuum), measured in "H2O, as compared to "HG at the vacuum pump inlet - it'll work - trust me............

Bill.Barg · **Posted:** Mon Jul 14, 2008 3:52 pm

I trust ya man!
Just being cautious with the turbo lubrication system, ya know.
At this point I could not identify which is the supply side of the turbo lubrication pipework, for instance.

I take it that the turbo bearing system is not "pumping", or pressurising the return oil, somehow. That was my concern.

gmctd · **Posted:** Mon Jul 14, 2008 4:16 pm

The top-side line is engine oil at system pressure - from there it enters the cartridge, separates into two paths, one to the compressor bearing, one to the turbine bearing - each bearing has 6 holes in a circumferential channel in the center of the bushing - cartridge construction is of the free-floating bearing concept, as the turbine shaft could never achieve the rpm necessary to compress air, otherwise - the shaft rotates in the bushing-type bearing on a film of oil bubbles, the bushing rotates in turn inside the cartridge bore in a film of oil bubbles - shaft touches not the bushing, the bushing touches not the cartridge bore, very little oil touches bore, bushing, shaft - shaft rotates at designed 125000rpm, bushing rotates at half that - thus the circumferential oil supply - oil enters the cartridge bore at engine oil pressure, reduces to almost 0 in the rotating bearing channel, less than half that as it surrounds the shaft - the combination of the spinning bushing and spinning shaft whips the oil to a golden froth consisting of billions and billions* of tiny bubbles which allows the high speeds of the bushing and shaft - this froth is at zero pressure, and oozes into the oil drain gallery, then slides down the turbo drain to the crankcase - this is why most turbos of the full-floating persuasion have a very large-tube drain system, to allow the froth easy access to the crankcase - this is why you don't see intricate seals on the turbine end, as Exhaust Gas Pressure keeps the oil from escaping - the seal is simple centrifugal with a piston-ring type seal in a groove on the shaft - as Diesels do not develop great levels of vacuum in the intake, there is also no requirement for an elaborate seal on the compressor end - simple centrifugal labyrinthine seal and Boost pressure prevents oil from escaping on that end - Diesel turbochargers thus rotate with much less friction on the turbine shaft than that other type, which we need not specify, here..........................

ibid: Carl Sagan; also that bathroom bowl cleanser on TV

Bill.Barg · **Posted:** Mon Jul 14, 2008 4:47 pm

Complete answer, as usual, from the man who knows.
Ya, i suspected the 1/2"tube coming down from the turbo area was for oil return. I did not understand why it had to be so large, but your froth explanation makes sense now.

Incontinence (in continents? in contents?)

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