Lower oil pressure with new turbo?

[DrCharles]

A couple years ago I put a factory turbo setup on my 7.3NA and promptly was reminded that the turbo needed a rebuild. So I bought a Chinese $200 cartridge. Worked great for a year, and the oil pressure (dash gauge with resistor jumpered and a variable sender mounted on the turbo oil feed casting) was actually higher.
Initially when fully warm (on 15W-40 diesel oil) the pressure would get so low at idle that the variable sender would "disengage" and the dash gauge would drop to zero. Above 800-900 rpm it would pop back up onto the low end of the scale. The sender is rated to read 4-70 psi but I've never checked with a mechanical gauge. Planning to now!'

The Chinese junk made 10 psi but started to emit an occasional raucous "scraaaawk"... had to replace it before it ate the impeller and shrapneled the IDI. So I got a $900 CDD factory turbo with upgraded wheel and just put it in, now correcting a massive slip joint leak.

Anyway, the oil pressure is back to the old habit of falling to "zero" at hot slow idle, and even at 2000 rpm and with a fresh oil change and FL-1995 filter, the needle is perceptibly more to the left. Oil change place swears they saw it come out of the 15W-40 bulk drum.

I feed the turbo with a couple of AN fittings and about a foot and a half of #4 Teflon braided hose from the rear gallery port, and the "bell" sender mounts to the bolt-on feed casting.

Does my brand-new turbo require more oil flow to the bearing, and that's why the pressure reading dropped (due to resistance in the feed line and fittings)? Or maybe my unknown mileage (almost certainly replaced PSOM) IDI needs an oil pump? What do you think @Thewespaul? Thanks for any advice.

Edit: I've read various oil pressure threads here, and most of them recommend using a mechanical gauge. I will get to it, I promise! What worries me is the *change* in the reading. thanks

 

[Nero]

Definitely do a mechanical gauge. My dad's truck did the same thing, and his is non turboed. Mechanical gauge proved it was actually OK and was a wiring issue.
Between my truck and my dad's, mine is turboed and his isn't, oil pressure with mech gauge both read the same.

 

[hacked89]

I have an aftermarket electronic gauge, no unusual oil pressure. Turbo is a factory ATS093 turbine housing machined for a garret t350 wheel. Compressor side, GTX3584r. The housing is a T04Z. I use AN fittings from the driver side galley.

 

[DrCharles]

Thanks. Where do you access that gallery? It must be a relatively long run of hose from a port on the driver's side all the way to the top of the turbo?

 

[Nero]

There's two common places that are used. I personally got the oil feed from the side of the block on the drivers side. Just used a 1/8th 90° elbow and a steel braided line up to the turbo. Second option would be to tap into the oil pressure sensor bung.

 

[hacked89]

Thanks. Where do you access that gallery? It must be a relatively long run of hose from a port on the driver's side all the way to the top of the turbo?

See below. Longer than factory but not bad. I angle it so that it rides up the firewall and away from any areas of concern from the head and manifold heat.

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[DrCharles]

Hacked, where is your oil pressure sender (stock location on the top, all the way at the rear of the engine)? I seem to recall that the original "idiot light" sender was screwed in there, but it's been a while.
If you're using a mechanical gauge too, where'd you tap it?

 

[hacked89]

Hacked, where is your oil pressure sender (stock location on the top, all the way at the rear of the engine)? I seem to recall that the original "idiot light" sender was screwed in there, but it's been a while.
If you're using a mechanical gauge too, where'd you tap it?

Stock location you described correct. No idiot light. I run the engines first on my engine run stand I built with a mechanical gauge and then move them over to the electronic. Some pics of the gauges in the truck and the engine run stand during the design and build.

15ish hot idle

 

[DrCharles]

Thanks.
I didn't mean it was an actual light... but the original sender was a switch, not a variable resistor, so at any oil pressure over about 7 psi, the gauge in the dash read right in the middle. So it was not even as useful as a red light to catch the eye.
I fixed it by replacing the sender with a variable one, and jumpering out the resistor on the dash cluster PC board. Although not calibrated in psi, it now shows relative pressure changes!

 

[IDIoit]

i had chineese turbos that flowed too much oil,
i sent them out to get the oil seals replaced and had them restricted down.

 

[DrCharles]

Doesn't surprise me, their machining tolerances are hit-or-miss a lot of the time. But mine is fresh from CDD and I expect it's "right" the first time

 

[Nero]

Doesn't surprise me, their machining tolerances are hit-or-miss a lot of the time. But mine is fresh from CDD and I expect it's "right" the first time

What because it's a no name turbo? Yeah I noticed too. But so far working just fine.

 

[DrCharles]

My no-name Chinese turbo worked great out of the box too! Until it started introducing the impeller to the housing at random intervals... I don't think it lasted even 4K miles of light use.

 

[Old Goat]

There is a chinese auto part supplier with the name "URO", means You replace often.
Vacuum Pumps, Lift Pumps and now Turbo`s too?
High failure rate on all these parts.


Goat

 

[DrCharles]

oh yeah, I'm acquainted with URO parts.
Rarely if ever will I buy that brand, and then only if it's easy to replace and non-critical.

Here is a brand-new valley pan that I installed on one of my BMW M62 V8's to fix a slow coolant seep from the built-in gasket... by the next morning it had filled up and coolant was dripping on the floor. I had to do the entire job again (which includes removing the intake manifold, water pump and its piping, neither of which are simple tasks on that engine). Never again.

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