I have a pair of garret t3/t4 turbo ar.48 I put new bearings and seals in both using garret parts. I have them mounted below the oil level in the oil pan. I am using full synthetic oil. Hoping this will help to prevent oil cooking. Yesterday I started it up for the first time. Oil was dripping from the compressor side and it smokes like crazy. This happens almost imediatly after start up. So i thought maybe i had somthing wrong i took it apart again and every thing was fine. Tried it again and still leaks. My engine runs 25 lbs oil pressure at idle and 60+ at 3,500 rpm. I smashed the barbed fitting greatly restricked the amount of oil going to the turbo. It still leaks and smokes. That's when I found oil was mixed with water. The oil is new and the oil I drained out before the turbo install was not mixed. Is it possible for oil to mix in the turbo? Is the root cause of my oil leak because the turbo mounted so low?

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85 gt 350 longitudal
twin garret t3/t4 in the works

Not an expert here but isn't the turbo supposed to be mounted above the oil level? Otherwise it cannot drain back.

Also not sure if the center section can mix coolant and oil. Anyone else?

any time you mount a turbo without a direct gravity drop drain to the oil pan ,its going to leak oil .you need to use a scavenger oil pump on the return side to prevent leaks .turbocharger oil seals are very weak .i dont know about your water problem .the coolant seals are not affected by mount position .

yes they need to gravity drain back to the oil pan

I am unsure if thats also the cause of the oil / water problem
as the water should be seprate from the oil with no connection
that could happen but should not but I donot know what happens when you over fill the turbo with oil that really has no outlet it may even crack inside to mix with the water cooling

once the oil seals blow [and they will with your low mounts]
as the oil has nowhere to go out and willnot flow up
unless you get expence scavenger pumps to suck it out
and one way valves to prevent pan oil from flowing down in to the turbo
as all fluids want to go DOWN if they can

eazy/cheap fix is move the turbo a bit above the oil pan
and pressure test the water part
remember oil is slung all over a crankcase
it is not just sitting at the oil level when parked

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Question wonder and be wierd
are you kind?

You can get oil and water mixing in a turbo if the housing is cracked into the water jacket and yes if the turbos are mounted in a manner that allows oil to build up into the oil drain and back up into the turbo it will more willingly pour out the rear seal into the exhaust and smoke like crazy, usually on a worn turbo you can get oil seapage into the compressor housing but the seal on that side is a good bit more resistant to leaking otherwise the vacuum created when pulling air through the filter at certain points would allow oil to be sucked passed the seal into the compressor housing.

oil in the compressor housing is usually a sign of too much oil pressure
so the restriction on the oil input is a good idea and the same applies to
the turbine side... but in yoiur case i agree that you need to either
scavenge the oil up to the pan above full mark or mount the turbo above
the pan.

oil in the water or water in the oil may not be a turbo specific problem
blowing a head gasket or a cracked head could also do this as well

hope that helps

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87 Fiero GT 5sp with Vortec L35 4300 Turbocharged V6
Bully Stage 2 clutch
Syclone intake manifold and engine management with Moates adapter and chip burner
Air/water intercooler and Devil's Own progressive water/alky injection
50lb injectors, 3 bar map sensor, Walboro fuel pump and Jabasco Intercooler pump
LM1 wideband on custom manifolds and 3" stainless exhaust system
T31/T04B S4 turbo with a Super T61 in the box
S10 caliper conversion.
Murphy's Constant Matter will be damaged in direct proportion to its value
Murphy's Law of Thermodynamics Things get worse under pressure.
Arthur C. Clarke "Any significantly advanced technology is indistinguishable from magic"

The answer was provided by Hudini. A turbo must always be mounted higher than the oil pan and a generous size return line that runs continually downward to the oil drainback point at the pan must be utilized. If oil is not drained from a turbo as quickly as it is fed to it, oil will flow past the seals and the result is smoke and more smoke.
The most usual mounting place for a turbocharger on the Fiero is to the left side of the engine compartment above the trans. You can consider a scavenger pump if you leave your turbo low mounted but you're adding cost, wiring, & more plumbing ,........ and there is no guarantee that it will work.

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87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
re-programming & odd electronics stuff
" I'M ON THE LOOSE WITHOUT THE JUICE "

scavenger pumps work very well .all of the new rear mount turbo kits use them .i have been using a simple shurflo aggie pump for 4000 km now .i dont reccomend this pump for the long haul but its available from any TSC store and i have read about one person with 15000 miles on one .i have a gear pump from RB Racing that i am going to put on next rainy day and that will fix any reliability problems .my turbo leaked out of the compressor side as well before i put my pump on .the local turbocharger rebuilder told me that turbo oil seals are so weak that a dirty oil filter will cause a leak .