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Tim's Auto Repair
Tim's Auto Repair, Mechanic
Category: Car
Satisfied Customers: 12787
Experience:  Have owned a repair shop for 25 yrs.
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Hummer H2: 2003 Hummer H2 6.0L: 70k miles, well kept maintenance,

Customer Question

2003 Hummer H2 6.0L:
70k miles, well kept maintenance, original owner
oil pressure had sudden drop from normal operating psi. Now operates at 5psi at idle 35psi at high rpm. replaced oil pressure sensor. checked oil pressure with manual gauge at dirver side block near front of motor, confirmed same oil pressure as the dash. changed oil to 50W straight Kendell oil. no change in oil pressure. engine runs perfect (no knocking or lifter noise) engine goes into reduced power after few days from "low oil pressure" warning. is it common for bypass to be stuck open at oil pump? has engine oil cooler, is this thermostatically controlled? can you refer me to where i can acquire oil diagram? could there be another check valve or bypass open that im not aware of in the system?
Submitted: 11 months ago.
Category: Car
Expert:  Tim's Auto Repair replied 11 months ago.

tims auto repair :

hi

tims auto repair :

yes..it is possible for the oil pump check valve to be stuck open just a little to cause the low oil pressure

tims auto repair :

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tims auto repair :

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tims auto repair :

you may just want to replace the complete oil pump while you are there at it

tims auto repair :

OIL PUMP, PUMP SCREEN AND DEFLECTOR REPLACEMENT

REMOVAL PROCEDURE








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1. Remove the oil pan.
2. Remove the engine front cover.
3. Remove the oil pump screen bolt and nuts.
4. Remove the oil pump screen with O-ring seal.
5. Remove the O-ring seal from the pump screen.
6. Discard the O-ring seal.








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7. Remove the remaining crankshaft oil deflector nuts.
8. Remove the crankiest oil deflector.








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9. Remove the oil pump bolts.

IMPORTANT: Do not allow dirt or debris to enter the oil pump assembly, cap end as necessary.

10. Remove the oil pump.
11. Clean and inspect the oil pump.

INSTALLATION PROCEDURE








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1. Align the splined surfaces of the crankshaft sprocket and the oil pump drive gear and install the oil pump.
2. Install the oil pump onto the crankshaft sprocket until the pump housing contacts the face of the engine block.

NOTE: Refer to Fastener Notice in Service Precautions.

3. Install the oil pump bolts.

Tighten
Tighten the oil pump bolts to 25 N.m (18 lb ft).








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4. Install the crankshaft oil deflector and nuts until snug.








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5. Lubricate a NEW oil pump screen O-ring seal with clean engine oil.
6. Install the NEW O-ring seal onto the oil pump screen.

IMPORTANT: Push the oil pump screen tube completely into the oil pump prior to tightening the bolt. Do not allow the bolt to pull the tube into the pump.

7. Align the oil pump screen mounting brackets with the correct crankshaft bearing cap studs.
8. Install the oil pump screen.
9. Install the oil pump screen bolt and nuts.

Tighten
9.1. Tighten the oil pump screen bolt to 12 N.m (106 lb in).
9.2. Tighten the crankshaft oil deflector/oil pump screen nuts to 25 N.m (18 lb ft).
10. Install the engine front cover.
11. Install the oil pan.

tims auto repair :




Customer:

how common is it that the check valve in the pump is stuck open? and is the oil cooler system thermostatically controlled or does it simply work off a bypass valve?

tims auto repair :

the cooler is open

tims auto repair :

it flows all the time

tims auto repair :

it isnt that common but it does happen

tims auto repair :

another thing that will happen sometimes on this year

tims auto repair :

is the o-ring on the pick-up strainer

tims auto repair :

it will break

tims auto repair :

causing the oilpump to suck air

tims auto repair :

ass long as the engine isnt knocking...i would think replacing the complete oil pump would fix your problem

tims auto repair :

as

Customer:

ok, would you recommend replacing with a high pressure only or high pressure & high volume pump? and do you have any suggestions on best way to remove the oil pump on this vehicle? replaced pump on similar motor but in a sandrail car so i know its not exactly easy to get to the pump since the hummer has the front-flip hood...

tims auto repair :

i would just use an oem pump

tims auto repair :

it doesnt need anymore

tims auto repair :

unless you just want to add it

Customer:

alright, woiuldn

tims auto repair :

the pump isnt to bad to replace on this engine

tims auto repair :

it just takes a little time

tims auto repair :

i gave you instructions above on replacing it

Customer:

wouldnt cause other complications if i did though correct? and ok, do you suggest removing the hood to have easier access or do you think it wont make a difference?

tims auto repair :




i always like removing the hood,,just to get it out of the way

tims auto repair :

and let in more light

tims auto repair :

but,,you really dont need to

tims auto repair :

no...a high pressure/volume would cause any trouble

Customer:

ok good to know

tims auto repair :




Customer:

alright, thank you for all your help. just wanted to check all my options before going and tearing into the motor

Tim's Auto Repair, Mechanic
Category: Car
Satisfied Customers: 12787
Experience: Have owned a repair shop for 25 yrs.
Tim's Auto Repair and 4 other Car Specialists are ready to help you

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