A Simple Diff Fluid Change

98 Z71 SLT · June 25, 2009

Great story for you guys. True story. And, I'm sure many of you have been here...

Just bought myself a 1991 Sierra 1500, 2wd, Longbox SLE with a 5.7

Truck has 151k on it. Previous owner did tons of work to this thing. Except...

By the amount of crud and rust on the rear diff cover bolts, I decided I wanted to change the rear end fluid; probably never done. Never know - with 151k miles...how does it look in there??

So, in the process of taking the rear cover off, one bolt snaps on me. So, after alot of drilling, a light bout of cussing, and using some reverse-thread extractor bits, that is repaired.

To get the cover off, you have to lightly push the steel brake lines upwards, to slide the diff cover off the diff. OK.

Turns out the previous owner replaced ALL steel brake lines on this truck, EXCEPT for the left rear section of steel line. So, with me putting the LIGHTEST amount of pressure on the line, in order to remove the diff cover to change fluid, it starts leaking brake fluid. I just shake my head, and chuckle to myself.

OK. Diff fluid is drained out. Old rusty brake line is out of the way. Diff cover bolt hole is ready again. Diff cover back on, new gasket. New section of steel line installed (new section is about a foot too long, so I got a bit crafty with how it is routed.)

So, I got the rear brake bleeders soaking with some GM Penetrant. In the meantime, lets fill up the diff. Yeah, right.

It took a 4-foot long half-inch breaker bar, with a three-eights adapter, and about all my strength to crack open the diff fill plug. I have another 2 seconds of laughing...to myself. Well, diff is now full and sealed up.

Let's get these rear brake bleeders opened up. Yeah...right. It took another bout of strength and vise-grips to open up those SOB's...so I run to the parts store, get 2 new bleeders, and then I bleed the rear brakes.

All of this for a 15-minute diff fluid change??

Sure ain't nothin' like our GM Trucks !!

MS3DALE · June 25, 2009

Been there,Done that

brims · June 25, 2009

Great story for you guys. True story. And, I'm sure many of you have been here...

Just bought myself a 1991 Sierra 1500, 2wd, Longbox SLE with a 5.7

Truck has 151k on it. Previous owner did tons of work to this thing. Except...

By the amount of crud and rust on the rear diff cover bolts, I decided I wanted to change the rear end fluid; probably never done. Never know - with 151k miles...how does it look in there??

So, in the process of taking the rear cover off, one bolt snaps on me. So, after alot of drilling, a light bout of cussing, and using some reverse-thread extractor bits, that is repaired.

To get the cover off, you have to lightly push the steel brake lines upwards, to slide the diff cover off the diff. OK.

Turns out the previous owner replaced ALL steel brake lines on this truck, EXCEPT for the left rear section of steel line. So, with me putting the LIGHTEST amount of pressure on the line, in order to remove the diff cover to change fluid, it starts leaking brake fluid. I just shake my head, and chuckle to myself.

OK. Diff fluid is drained out. Old rusty brake line is out of the way. Diff cover bolt hole is ready again. Diff cover back on, new gasket. New section of steel line installed (new section is about a foot too long, so I got a bit crafty with how it is routed.)

So, I got the rear brake bleeders soaking with some GM Penetrant. In the meantime, lets fill up the diff. Yeah, right.

It took a 4-foot long half-inch breaker bar, with a three-eights adapter, and about all my strength to crack open the diff fill plug. I have another 2 seconds of laughing...to myself. Well, diff is now full and sealed up.

Let's get these rear brake bleeders opened up. Yeah...right. It took another bout of strength and vise-grips to open up those SOB's...so I run to the parts store, get 2 new bleeders, and then I bleed the rear brakes.

All of this for a 15-minute diff fluid change??

Sure ain't nothin' like our GM Trucks !!

If that's a stab at the GM trucks, I wouldn't say it's the previous owner's fault that they didn't do the proper maintenance. If it isn't, disregard.

Stevens03 · June 25, 2009

That kind of stuff always happens to me. Never is a simple job simple...

Glad you got it worked out.

ffthornton · June 25, 2009

It never fails. Every time you try to fix something it always seems to be more to it. That has always been my luck.

98 Z71 SLT · June 25, 2009

No, no stabbing of any GM trucks !! You must be mis-understanding.

Funny thing is this...this 91 Sierra could easily go another 151k........

It is not a clunker / junker by any means...it is a super nice truck, BUT it's 18 years old.

Hey guys...here's what the previous owner has done, in let's say the last 25k miles.....

1. New Transmission

2. All New Tires

3. New Front Rotors,Pads, and Calipers

4. New Water Pump, New Coolant, Thermostat

5. New exhaust...COMPLETE exhaust...new downpipe, new 0-2 sensor, Turbo muffler, new tail pipe

And, this past weekend I just installed 4 new shocks, and today the diff fluid change, and brake repair.

txab · June 25, 2009

Sounds like you should be in great shape now.

MarkD · June 25, 2009

Sounds like a typical remodel job.

brims · June 25, 2009

No, no stabbing of any GM trucks !! You must be mis-understanding.

Funny thing is this...this 91 Sierra could easily go another 151k........

It is not a clunker / junker by any means...it is a super nice truck, BUT it's 18 years old.

Hey guys...here's what the previous owner has done, in let's say the last 25k miles.....

1. New Transmission

2. All New Tires

3. New Front Rotors,Pads, and Calipers

4. New Water Pump, New Coolant, Thermostat

5. New exhaust...COMPLETE exhaust...new downpipe, new 0-2 sensor, Turbo muffler, new tail pipe

And, this past weekend I just installed 4 new shocks, and today the diff fluid change, and brake repair.

Hard to judge tones online. Sounds like your truck is ready to go for a long time.

bigredmariner · June 25, 2009

Those "quick" jobs always get me too. Lots of cussing and skin lost over that stuff. Glad you got 'er did.

Bowler807 · June 25, 2009

If that rear brake line was that bad it's a great thing that it broke when it did. At least you weren't hauling a load down a hill when it let go.

Sounds like with a little TLC you will have a good truck for quite a while.

superjim · June 25, 2009

Great story for you guys. True story. And, I'm sure many of you have been here...

Just bought myself a 1991 Sierra 1500, 2wd, Longbox SLE with a 5.7

Truck has 151k on it. Previous owner did tons of work to this thing. Except...

By the amount of crud and rust on the rear diff cover bolts, I decided I wanted to change the rear end fluid; probably never done. Never know - with 151k miles...how does it look in there??

So, in the process of taking the rear cover off, one bolt snaps on me. So, after alot of drilling, a light bout of cussing, and using some reverse-thread extractor bits, that is repaired.

To get the cover off, you have to lightly push the steel brake lines upwards, to slide the diff cover off the diff. OK.

Turns out the previous owner replaced ALL steel brake lines on this truck, EXCEPT for the left rear section of steel line. So, with me putting the LIGHTEST amount of pressure on the line, in order to remove the diff cover to change fluid, it starts leaking brake fluid. I just shake my head, and chuckle to myself.

OK. Diff fluid is drained out. Old rusty brake line is out of the way. Diff cover bolt hole is ready again. Diff cover back on, new gasket. New section of steel line installed (new section is about a foot too long, so I got a bit crafty with how it is routed.)

So, I got the rear brake bleeders soaking with some GM Penetrant. In the meantime, lets fill up the diff. Yeah, right.

It took a 4-foot long half-inch breaker bar, with a three-eights adapter, and about all my strength to crack open the diff fill plug. I have another 2 seconds of laughing...to myself. Well, diff is now full and sealed up.

Let's get these rear brake bleeders opened up. Yeah...right. It took another bout of strength and vise-grips to open up those SOB's...so I run to the parts store, get 2 new bleeders, and then I bleed the rear brakes.

All of this for a 15-minute diff fluid change??

Sure ain't nothin' like our GM Trucks !!

That sounds like some of the nice and simple jobs that I get involved with... way too often.

builderpaul · June 25, 2009

Good lesson learned. Always remove the fill plug before draining anything (rear end, transfer case, etc). I learned the hard way and had to re drain a rear end to remove the stripped, then drilled out fill plug, pieces, and debris that fell into my new oil.

Bostonsfavson · June 25, 2009

Haha, yea, these things tend to happen. On a related note, I had a hell of a time getting the bleeder screws loose on *my* truck. Jeez. It's like they were welded on.