Rear End Noise

[02silveradols]

I'm getting almost a humming and griding noise coming from the rear of my truck. I thought it could be the G80 going but I'm not entirely sure. It only does it when the truck has been parked and doesn't last all that long. It's almost like something is getting dry and then it gets oiled and quiets down. Any ideas of things to check? No leaking fluid either. Thanks

[dlstewart01]

When is the last time you checked or changed the diff fluid.

[Xtremski74]

When is the last time you checked or changed the diff fluid.

 

I agree...the diff. fluid is most likely shot or needs to be topped off. Might want to check it soon! Sounds like the bearings may be suffering! Good Luck!

[dlstewart01]

LOCKING DIFFERENTIAL LUBRICANT (SERVICE INFORMATION) #91-4-109

SUBJECT: LOCKING DIFFERENTIAL (G80) LUBRICANT - (SERVICE INFORMATION)

VEHICLES AFFECTED: ALL LIGHT TRUCKS EQUIPPED WITH G80 REAR AXLE ALL YEARS

Some light duty trucks equipped with locking rear axles (G80) may exhibit rear axle chatter, especially when turning a corner from a stop.

This condition of alternate engagement and disengagement of clutches in differential assembly is usually caused by contaminated axle lubricant.

To correct this condition, drain and refill the rear axle with SAE 75W-90 GL5 (P/N 12378261). The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.VEHICLES/COMPONENTS INVOLVED: ----------------------------- Some light duty trucks equipped with locking rear axles, RPO G80.

SERVICE PARTS INFORMATION:

Part Number Description ----------- ------------------ 12678261 Lubricant, Rear Axle (1 litre)

Parts are currently available through CANSPO.

WARRANTY INFORMATION:

As specified in Light Duty Truck Maintenance Schedules, locking rear axle fluid drain and refill is required owner maintenance at the first engine oil change. Failure to drain and refill the rear axle as specified may contribute to a later axle chatter condition. Refer to the appropriate Light Duty Truck Maintenance Schedule or service manual, section OB, for further details on change intervals.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.

© Copyright General Motors Corporation. All Rights Reserved.

[02silveradols]

Do you guys recommand any specific brand and is there a replacement gasket I can put in or do you just RTV? It just started after a snow storm with a lot of wheelspin. I was thinking something could have went out. Thanks

[Stevens03]

My 03 had a gasket. I tried the RTV and it leaked and ended up getting the gasket.

 

Anyways... Put GM synthetic back in. It comes stock and works the way it should for the factory lockers.

[dlstewart01]

Do you guys recommand any specific brand and is there a replacement gasket I can put in or do you just RTV? It just started after a snow storm with a lot of wheelspin. I was thinking something could have went out. Thanks

 

Any GL-5 synthetic 75W90. Mobil 1. castrol syntec, Valvoline synpower, They all will work well. I always use a gasket. Well not any more. The Mag-hytec diff cover I have has an o-ring.

 

I have used Castrol Syntec for the last 5 years, with no issues. the G80 is as happy as a G80 can be. I would use Mobil 1 as well.

[02silveradols]

Where do you get the gasket? That is more then likely a dealer trip. I'll have to wait until Monday. Hopefully it will be okay. Do you use a little rtv on the gasket as well? Thanks for all the help.

[Stevens03]

Nope, I cleaned the surface real good and just the gasket. Worked great after I got the gasket. It only leaked after towing. I got the gasket from the dealer.

[02silveradols]

Whats the torque spec on those bolts? I will have to work on it next week. Hopefully nothing else fails.

[Stevens03]

Maybe someone else can help you with the tq spec's. I just did a cris-cross pattern and made them good and snug.

[02silveradols]

Thanks for all the info. I'll try Napa tomorrow and see if they have any in stock. Then I can get it down quicker. I haven't been out under my truck in a bit, is that as hard to fill as the transfer case?

[dlstewart01]

Thanks for all the info. I'll try Napa tomorrow and see if they have any in stock. Then I can get it down quicker. I haven't been out under my truck in a bit, is that as hard to fill as the transfer case?

 

Make sure you get the fill plug out before you take the diff cover off. Yeah its hard to fill it with that small fill hole. I usually cut the tip off the bottle and put a short piece of plastic hose on it. When it gets going I punch a hole in the bottom of the bottle. It will be up-side down when filling.

 

I have the torque specs in the garage. I have locked up for the night. I'll get them for you when I go out there again.

[02silveradols]

Thanks for all the info. I'll try Napa tomorrow and see if they have any in stock. Then I can get it down quicker. I haven't been out under my truck in a bit, is that as hard to fill as the transfer case?

 

Make sure you get the fill plug out before you take the diff cover off. Yeah its hard to fill it with that small fill hole. I usually cut the tip off the bottle and put a short piece of plastic hose on it. When it gets going I punch a hole in the bottom of the bottle. It will be up-side down when filling.

 

I have the torque specs in the garage. I have locked up for the night. I'll get them for you when I go out there again.

 

 

 

Thanks for the quick reply. I take it you just fill it up until its at the height of the drain plug?

[dlstewart01]

Thanks for all the info. I'll try Napa tomorrow and see if they have any in stock. Then I can get it down quicker. I haven't been out under my truck in a bit, is that as hard to fill as the transfer case?

 

Make sure you get the fill plug out before you take the diff cover off. Yeah its hard to fill it with that small fill hole. I usually cut the tip off the bottle and put a short piece of plastic hose on it. When it gets going I punch a hole in the bottom of the bottle. It will be up-side down when filling.

 

I have the torque specs in the garage. I have locked up for the night. I'll get them for you when I go out there again.

 

 

 

Thanks for the quick reply. I take it you just fill it up until its at the height of the drain plug?

 

 

The torque is 30 ft lbs.

 

I personally fill it to the bottom of the hole. The manual will say not to fill it that full, but from many years of experience, I recommend it. It will not be over-full or cause any seal problems. there is a vent tube to relieve any pressure.

 

I haven't had one go out yet, and I started driving in 1960...