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Old 01-11-2020, 01:00 PM   #1 (permalink)
dannhepannhe
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Low oilpressure egen warm

Hello!
Im having some problems with my suburban 6.5 turbo diesel.
When the engine is warm my oilpressure is about:
2.8 psi @idle
34 psi @2000rpm
I know this is low.... but what is the limit for the engine to tanke no damage?
What should the pressure be and what could be the problem?
I have an external sensor and the original and Both says low pressure.
The dieselpump under the car is wired to the lights thats why i still can run the car i guess.

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Old 01-11-2020, 01:29 PM   #2 (permalink)
OkDually
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Quote:
Originally Posted by dannhepannhe View Post
Hello!
Im having some problems with my suburban 6.5 turbo diesel.
When the engine is warm my oilpressure is about:
2.8 psi @idle
34 psi @2000rpm
I know this is low.... but what is the limit for the engine to tanke no damage?
What should the pressure be and what could be the problem?
I have an external sensor and the original and Both says low pressure.
The dieselpump under the car is wired to the lights thats why i still can run the car i guess.
Try replacing the Oil Pressure Switch with AC Delco: D1808A
Your lift pump should not be wired to the lights to run.

The OPS supplies power to the lift pump for it to run correctly.
When the OPS goes bad the lift pump will not run correctly.
You will also get inaccurate oil pressure readings.

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Old 01-11-2020, 01:31 PM   #3 (permalink)
Tommygunner
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Minimum oil pressures according to manuals for your engine. Is idle, 10 PSI, and 40 PSI at 2000 RPM. Low oil pressures like yours are usually caused by worn bearings in the engine. Did the low oil pressure happen suddenly. Or appear over time? What oil pressure connection did you install the second gauge or sensor to?
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Old 01-11-2020, 01:39 PM   #4 (permalink)
dannhepannhe
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I allredy tried to replace the ops with a New one and the gauge were at the red part. I tried a external and i installed it in the hole the original ops is. Så i dont have the original inserted right now. I dont know when this happend because i bought the car over a year ago with other problems that i fixed and now when the car finally ran i saw this problem.... but i guess thats why somone wired the liftpump to the lights instead of the ops...
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Old 01-11-2020, 02:08 PM   #5 (permalink)
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Quote:
Originally Posted by dannhepannhe View Post
I allredy tried to replace the ops with a New one and the gauge were at the red part.
If you use an aftermarket part you will get a false reading.
You must use the AC/Delco brand part
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1996 K3500 6.5L,( "F" Eng #141 cast block) 5 speed manual, crewcab, dually longbed: 208,000mi.
Diamond Eye 4" Turbo Back Exhaust w/2.5" Flo-Pro Crossover
AirDog II DF165 w/ tank sock delete - XDP
TD-Max boost controller - Kennedy Diesel
OPS extension hose - Leroy Diesel
Glow Plug Harness- PT Wiring Solutions
Glowshift Maxtow EGT,Boost, Fuel gauges
Boost & Fuel Pressure Bolts - Leroy Diesel
2/0 Battery Cable Upgrade - PT Wiring Solutions
PMD w/#9 resistor and Re-Location Kit, mounted to bumper - Leroy Diesel
GM-5 Turbocharger
4.10 gear ratio
OptiLube Winter Formula


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Old 01-11-2020, 03:26 PM   #6 (permalink)
dannhepannhe
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Quote:
Originally Posted by OkDually View Post
If you use an aftermarket part you will get a false reading.
You must use the AC/Delco brand part
It was the same as the old one at the gauge. 2 ops and 1 external shows low pressure so i guess it really is low pressure in the engine....
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Old 01-11-2020, 11:35 PM   #7 (permalink)
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Quote:
Originally Posted by dannhepannhe View Post
Quote:
Originally Posted by OkDually View Post
If you use an aftermarket part you will get a false reading.
You must use the AC/Delco brand part
It was the same as the old one at the gauge. 2 ops and 1 external shows low pressure so i guess it really is low
pressure in the engine....
Time for a rebuild. But if it's a beater and no long term hopes, put 50 weight oil in it to boost pressure. Valves might starve for oil during startup, and maybe oil lines (Achilles heel with 6.5) will be under more stress, but if it's a rusted out, beat up rig you just need to run sometimes on the farm or similar situation, heavy oil. Or pull it and get check book ready, it's not cheap like rebuilding a 350 sbc
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Old 01-12-2020, 05:08 AM   #8 (permalink)
dannhepannhe
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So the problem probably isnt the oilpump?
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Old 01-12-2020, 08:40 AM   #9 (permalink)
jnlperformance
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Have you tried a mechanical gauge? Use a tee. Hook up a mechanical (10/15 bucks at any ole auto parts store) + standard ops (dually is right. Delco is the only one that will readout correctly - you're dealing with a 6.5 specific pcm so alot of the sensors are not universal like gasser stuff)

See what you're hitting on with a mechanical gauge.

Also... the oil pressure switch could be stuck open (maybe a chunk of rtv is lodged in switch... or debris of sorts??)

Tommygunner is correct. 10psi is absolute minimum but it should be around 25psi idle in optimal conditions. 40psi at 2k.

You start doing damage to the turbo impeller shaft and bearing races below 20psi.

hope this helps.
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Old 01-12-2020, 01:24 PM   #10 (permalink)
dannhepannhe
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But every sensor i tried showed a good pressure when the engine was cold and the it got lower and lower the warmer the engine got. if i got wrong sensor shouldnt it be wrong pressure even when cold?

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