Lb7 compound turbo lacking oil feed

Gman327

New member
Apr 12, 2016
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Kakabeka falls, Ont
So I built an s475 over stock for my 03 Sierra and when I checked the oil flow out of the oil gallery plug the truck was warm (had lines installed before build) I had all kinds of oil coming from the -4an feed but after I built the rest of the kit I primed the turbo pulled the drain off the bottom and barely any oil coming out was around -5 c did not allow it to run more than a few seconds just wondering if the oil prv has anything to do with it or any ideas what to look at? Oil psi is good on guage and guage seems to be functioning fine. Any input would be great thanks
 

Gman327

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Apr 12, 2016
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Kakabeka falls, Ont
I ended up disconnecting the compound system for now anyways, the ran out of time had to go back to work but I checked it coldish again the next day straight out of the line again and it was pretty sad had it plugged in with a magnetic oil pan heater also. Thanks for the quick feedback appreciate it.
 

Burn Down

Hotrodder
Sep 14, 2008
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Boise Idaho
Pull the feed line off of the top of the turbo and stick it a small bucket. Have someone start it while you hold the line. You should have a steady stream coming out. Then hook it back up. I don't think you let it run long enough with cold oil to see any flow the first time.
 

Gman327

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Apr 12, 2016
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Kakabeka falls, Ont
Ya that's how I've been checking the flow I think the 15 40 rotella will not be good in the winter was showing 70 psi on the -4 an line as well. Any cold weather warriors have input on winter oil was gonna start runnin 0 40 syn all year when I get it back runnin
 

dirtydmax

<---up shit creek
Sep 1, 2013
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muskoka,Ont Canada
The first time i checked for oil pressure from the feed line for my twins it shot a 20 ft stream from a 6an line immediatly from front pass galley plug.even cold you should have a big mess with the line open.This was with rotella 15 40 and a cold start.Somethings not right if your only getting a slow stream.
 

kiwilml

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Nov 4, 2015
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The first time i checked for oil pressure from the feed line for my twins it shot a 20 ft stream from a 6an line immediatly from front pass galley plug.even cold you should have a big mess with the line open.This was with rotella 15 40 and a cold start.Somethings not right if your only getting a slow stream.
Ok wow this is something I've wondered about.. I've got -4 feed and it definitely wasn't shooting out like that.. Had it stuck in a 20oz coke bottle and started truck for a second and shut it off again and it definitely wouldn't have squirted very far at all, maybe put an inch in bottle.. Thought that was normal but maybe not..

Don't mean to derail here so carry on..
 

Burn Down

Hotrodder
Sep 14, 2008
7,093
28
48
Boise Idaho
Ya that's how I've been checking the flow I think the 15 40 rotella will not be good in the winter was showing 70 psi on the -4 an line as well. Any cold weather warriors have input on winter oil was gonna start runnin 0 40 syn all year when I get it back runnin

5-40 rotella t6 is what I have run in my truck from day one, summer or winter no issues. -40f winter to upper 80's in the summer up here.

I run -4 to my twins from the top of the 4094 in the valley. I think -4 is plenty for supply but others will argue -6 is needed. I had to restrict a S475 that was -6 from the galley for pushing oil out the turbine side.
 

Gman327

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Apr 12, 2016
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Kakabeka falls, Ont
Rite on great info. Was thinking about switching to -6 feed line but I don't know if my -10 drain will suffice, also worried that much flow might rob oil for the rest of the engine. I have a little over a week until I get home gonna try switch to synthetic, I know the pressures there I checked it rite off the line. Anyone know what the big frame turbos need for oil volume at idle?
 

kiwilml

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Nov 4, 2015
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I'm just running the 468 as a single but I had it installed last summer and then here a couple months ago it grenaded on me.. Shaft broke and compressor wheel went to little pieces so was a bad deal for sure.. Not sure how many miles I had on it but pry around 15k..

When I got my new turbo this second time is when I checked for oil flow like I posted earlier here.. Pry 3 or 4k miles ago already though..
 

Gman327

New member
Apr 12, 2016
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Kakabeka falls, Ont
Thanks again all very useful information, noticed it was a single when I zoomed in ur filter looked like a comp housing for a sec, decided to run -6 an from
The gallery up to the turbo then keep my -4 feed flange I would think I would see better cold flow with that but truck Is here parts are there kinda deal. All I know is that I don't want my turbo feeding aluminum peices into my
Other turbo!. Gonna make some calls to see what the adequate flow should be but I think the fitting"s" I used have too small I.d
 

Gman327

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Apr 12, 2016
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Kakabeka falls, Ont
Just to close up this old thread. after having many other malfunctions got the twins whistling, oil psi was there the whole time. Need some real tunes for it now l