Do i have to drop front differential on a 2002 chevy tahoe 4x4 to replace oil pump

No hubs on 2002 Chevy 2500. I'd check the front axle actuator (engages front axle when 4WD is engaged). Belive it's on the passage side axle tube of front differential. Could be wrong, but that's what it sounds like. Or the front ring/pinion is shot. They don't turn when not in 4wd.

ask the dealers what ratio was put in the rear diff
sound like the incorrect ratio against the front differential is used

remove the drain plugs from the diff units and check for metal bits. Check for metal in the transfer case oil as it sounds like a bearing in the diff section of the transfer case has failed.. There is a small diff here to allow the front wheels to travel at a different speed to the rear unit to allow for driving over un even surfaces or speed bumps.

It can be faulty 4x4 wd switch.

4X4

On these issue, there are few solved help links for troubleshooting the issue easily.-------

Click the link below: ---

No 4x4 light on dash?

http://repairhelpcenter.blogspot.com/2011/12/no-4x4-light-on-dash.html

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4X4 Truck makes roaring noise in the front end?

http://schematicsdiagram.blogspot.com/2012/01/4x4-truck-makes-roaring-noise-in-front.html

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Car will not go into 4WD high or 4WD low?

http://schematicsdiagram.blogspot.com/2011/12/car-will-not-go-into-4wd-high-or-4wd.html

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No 4x4 light on dash?

http://repairhelpcenter.blogspot.com/2011/12/no-4x4-light-on-dash.html

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4 wheel drive system will not disengage?

http://technoanswers.blogspot.com/2012/01/4-wheel-drive-system-will-not-disengage.html

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4WD light is flashing and beeping? NO 4WD high?

http://schematicsdiagram.blogspot.in/2012/02/4wd-light-is-flashing-and-beeping-no.html

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2002 Jeep Wrangler: 4WD Idiot Light is ON?

http://technoanswers.blogspot.in/2012/06/2002-jeep-wrangler-4wd-idiot-light-is.html

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Traction control switch will not engage on 4WD High or Low

http://whoisbyme.blogspot.com/2012/10/traction-control-switch-will-not-engage.html

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4WD light flashing and 4WD will engage after few minutes

http://repairhelpcenter.blogspot.com/2012/10/4wd-light-flashing-and-4wd-will-engage.html

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2008 Toyota Tundra: 4x4 Wheel Drive Light is Flashing?

http://technoanswers.blogspot.in/2012/05/2008-toyota-tundra-4x4-wheel-drive.html

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4x4 front differential will not engage the axle on ford?

http://technoanswers.blogspot.in/2012/02/4x4-front-differential-will-not-engage.html

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4x4 will not engage on Ford F150?

http://technoanswers.blogspot.in/2012/02/4x4-will-not-engage-on-ford-f150.html

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Dodge Ram 4x4 light keeps flashing

4X4 LOW LIGHT IS FLASHING ON DASH

http://technoanswers.blogspot.in/2012/09/dodge-ram-4x4-light-keeps-flashing.html

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Ford 4x4 front wheels will not engage?

http://technoanswers.blogspot.in/2012/02/ford-4x4-front-wheels-will-not-engage.html

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These details will help.

Thanks.

on a lift its about a 4hr job on you back in the ground plan on the day the front diff needs to be removed or at least dropped down but before replacing the pump are you planing on this due to the gauge dropping down to zero?gn had a problem with the sending units that read the pressure thats a 20min job and a $30 part

It involves removing the trans from the vehicle pulling the pan off the bottom of the trans removing the tcc solenoid from the pump then removing all the bolts from the pump and pulling it out the front ... chances are though if the pump is bad so is the rest of the trans .. if its just a convertor seal leaking u need to drop the trans pull the convertor pry out the old seal from the pump and replace it with new .

did you change oil brands or motor engine oil weight ? it even could be a bad oil sending unit / oil pump

this truck is equipped with an aluminum oil pan you could have 1 or several things going on... a stripped drain plug which is causing it to leak or it may be a leaking front seal or a rear main seal. If it is a front seal it is not to labor intensive. But if it is a rear main seal leaking it will require the transmission to be removed since the seal is a 1 piece rear main

oil pump might be going bad

i think what you are talking about is the front differential. you will wanna put gear oil in it. the correct weight would be found in your manual.