Weird noise coming from rear

papo020

Original poster
Member
Dec 19, 2011
12
Ok so if I'm sitting on a slight incline (sometimes doesn't even have to be inclined) and I begin to move slowly I hear a sort of grinding noise. It doesn't matter if I have my front wheels turned or not and it doesn't always do it. I know I'm not giving much of a description here, but was hoping someone may be able to chime in here and give me some kind of an idea. Thanks ahead of time.
 

strat81

Member
Dec 29, 2011
399
papo020 said:
Ok so if I'm sitting on a slight incline (sometimes doesn't even have to be inclined) and I begin to move slowly I hear a sort of grinding noise. It doesn't matter if I have my front wheels turned or not and it doesn't always do it. I know I'm not giving much of a description here, but was hoping someone may be able to chime in here and give me some kind of an idea. Thanks ahead of time.

Check the fluid level in your rear differential.

Inspect your brakes.

Inspect your u-joints and slip yoke.

A search of the site will show info on all of those.
 

papo020

Original poster
Member
Dec 19, 2011
12
strat81 said:
Check the fluid level in your rear differential.

Inspect your brakes.

Inspect your u-joints and slip yoke.

A search of the site will show info on all of those.

Thanks for the quick reply. I'll try and give this all a look tomorrow. I know it's not the brakes because it's only been a few months since I changed them all the way around (but I'll give it a look anyway).

Rear differential I'll also look at. My only worry with that is I'm at roughly 134k and had bought the truck with 116k. I'm not sure of any of the service that was done before and am not sure what to do when it comes to the rear diff since I don't know the history. Advice?

U-joints I'll also look at but the slip yoke I've never heard of :confused: but i'll do a quick search to see what I find. Thanks again.
 

McGMT

Member
Jun 17, 2012
621
papo020 said:
Thanks for the quick reply. I'll try and give this all a look tomorrow. I know it's not the brakes because it's only been a few months since I changed them all the way around (but I'll give it a look anyway).

Rear differential I'll also look at. My only worry with that is I'm at roughly 134k and had bought the truck with 116k. I'm not sure of any of the service that was done before and am not sure what to do when it comes to the rear diff since I don't know the history. Advice?

U-joints I'll also look at but the slip yoke I've never heard of :confused: but i'll do a quick search to see what I find. Thanks again.

The slip yoke is where the driveshalf "Slips" into the transfer case...
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
I'd suspect emergency brakes. Does the sound change at all when you move with the ebrake lever changing position? Do your ebrakes work at all?

Does the sound change when you back up versus go forward?

And the transfer case needs its fluid changed every 50K miles, and many lazy owners assume it's 100K and the even lazier ones never change the fluid at all and then sell you a ticking time bomb.

Now would be a good time to schedule ALL the 100K fluid and filter changes and spark plugs if you don't have the maintenance history.
 

strat81

Member
Dec 29, 2011
399
papo020 said:
Rear differential I'll also look at. My only worry with that is I'm at roughly 134k and had bought the truck with 116k. I'm not sure of any of the service that was done before and am not sure what to do when it comes to the rear diff since I don't know the history. Advice?

Trust no one. Assume the prior owner did nothing but put gas in it.

I'd drain and fill the crankcase, transfer case, front differential, rear differential, master cylinder, transmission, and radiator. New air, fuel, engine oil, and transmission filters too. Spark plugs were due at 100k miles as well. New accessory belt, thermostat, and coolant temp sensor too. Clean your throttle body and dump some Techron in the tank while you're at it.

Dex6 for the transmission.
GM Auto-Trak II for the transfer case.
Mobil 1, Valvoline SynPower, or similar quality synthetic 75w-90 for the differentials.
Dex-Cool or Prestone All Makes All Models for the radiator.
Your favorite brand of quality engine oil for the crankcase.
Synthetic DOT3 fluid such as Valvoline for the master cylinder.

100k miles is a pretty major service interval on many cars. That's why many people dump them at that point - they don't want to pay for the maintenance.

ETA - Dang it, roadie beat me by a minute. That's what I get for being so verbose.
 

papo020

Original poster
Member
Dec 19, 2011
12
the roadie said:
I'd suspect emergency brakes. Does the sound change at all when you move with the ebrake lever changing position? Do your ebrakes work at all?

Does the sound change when you back up versus go forward?

And the transfer case needs its fluid changed every 50K miles, and many lazy owners assume it's 100K and the even lazier ones never change the fluid at all and then sell you a ticking time bomb.

Now would be a good time to schedule ALL the 100K fluid and filter changes and spark plugs if you don't have the maintenance history.

No, the sound doesn't change at all. Yes the ebrakes work. When I replaced the brakes a few months ago I did them as well.

No change in sound no matter which way I drive. But same as I said before it's not a constant sound. It does it sometimes and sometimes it doesn't.

I'll get on the fluid changes asap, I'm trying to think back to about a year ago and I'm pretty sure I did the transfer case already. But since I'm not sure I'll add that to my to do list again anyway. Are these trucks safe to do the transmission fluid and filter at my mileage?

Hopefully this will help me gain some of the gas mileage that I've lost. I'm at about 13.5 would love to at least get back to the estimated 15 or more....Thanks Roadie!
 

papo020

Original poster
Member
Dec 19, 2011
12
strat81 said:
Trust no one. Assume the prior owner did nothing but put gas in it.

I'd drain and fill the crankcase, transfer case, front differential, rear differential, master cylinder, transmission, and radiator. New air, fuel, engine oil, and transmission filters too. Spark plugs were due at 100k miles as well. New accessory belt, thermostat, and coolant temp sensor too. Clean your throttle body and dump some Techron in the tank while you're at it.

Dex6 for the transmission.
GM Auto-Trak II for the transfer case.
Mobil 1, Valvoline SynPower, or similar quality synthetic 75w-90 for the differentials.
Dex-Cool or Prestone All Makes All Models for the radiator.
Your favorite brand of quality engine oil for the crankcase.
Synthetic DOT3 fluid such as Valvoline for the master cylinder.

100k miles is a pretty major service interval on many cars. That's why many people dump them at that point - they don't want to pay for the maintenance.

ETA - Dang it, roadie beat me by a minute. That's what I get for being so verbose.

I've done all the filters minus trans. So that's on the list. I usually do as you say and trust no one before me. I run only mobil 1 fully synthetic and mobil 1 filter, spark plugs are the recommended ac-delcos. I have to do all the fluid changes minus oil right now. Accessory belt I also did as well as the throttle body.

I'm going to jack my own thread here and ask a separate question. My temp gauge isn't right at the middle. It's actually about 2 lines not to the left....but to the RIGHT. I know I've read and seen that if it's to the left it def needs the new t-stat. Is it the same case for me with it being to the right? I've had this truck going onto 3 years now and it's been good to me so time to return the favor and give her what she needs. Thanks for all the advice guys. Much friendlier here than the OS.:thumbsup:
 

strat81

Member
Dec 29, 2011
399
papo020 said:
I'm going to jack my own thread here and ask a separate question. My temp gauge isn't right at the middle. It's actually about 2 lines not to the left....but to the RIGHT. I know I've read and seen that if it's to the left it def needs the new t-stat. Is it the same case for me with it being to the right? I've had this truck going onto 3 years now and it's been good to me so time to return the favor and give her what she needs. Thanks for all the advice guys. Much friendlier here than the OS.:thumbsup:

To the right indicates it's running slightly hot, or at least the coolant temp sensor thinks it's running slightly hot. The best way to check is to buy/borrow a scanner that will provide real-time output of what the sensor is seeing. Replace the coolant with fresh Dex-Cool and distilled water (contains no minerals that may harm the cooling system, about $1 a gallon at any supermarket). Replace the thermostat and the coolant temp sensor. This may help with your mileage as well. But, usually it's an engine running too cool that has lousy mileage.

papo020 said:
No, the sound doesn't change at all. Yes the ebrakes work. When I replaced the brakes a few months ago I did them as well.

No change in sound no matter which way I drive. But same as I said before it's not a constant sound. It does it sometimes and sometimes it doesn't.

I'll get on the fluid changes asap, I'm trying to think back to about a year ago and I'm pretty sure I did the transfer case already. But since I'm not sure I'll add that to my to do list again anyway. Are these trucks safe to do the transmission fluid and filter at my mileage?

Hopefully this will help me gain some of the gas mileage that I've lost. I'm at about 13.5 would love to at least get back to the estimated 15 or more....Thanks Roadie!

Never hurts to check the brakes anyway. Some gravel or something may be stuck somewhere it doesn't belong.

My opinion is that if a transmission fluid change kills your transmission, it was on its death bed to begin with. Others disagree.

If that's 13.5 on the highway in fourth gear, something might be wrong. What gears are you running?

Newer fluids have better lubricating properties, so it is very possible you'll see an improvement in fuel economy. In the drivetrain, that's your F&R diffs and your t-case. The incorrect fluid may cause issues too - some guys put 140 weight gear lube in their diffs which is not recommended. Wheel bearings can cause economy to decline if they're shot and these trucks have a reputation for eating front wheel bearings. Lazy O2 sensors can also cause poor fuel economy. Again, some scan tools can read the O2 sensor output to see if it's getting lazy.

I'd also go with at least 35psi per tire (assuming your tires can handle it). Remove any excess junk to reduce weight.
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
IMHO, you should be safe doing a pan drop and filter change. Just stay away from a trans flush.
Also definitely use the Dexron VI trans fluid.
 

papo020

Original poster
Member
Dec 19, 2011
12
Thanks for all the advice. I'm going to try and get on all of this asap! The 13.5 I'm getting is city. Is that about what is expected? I'm not sure about what gear ratio I have.

I was also going to mention that the other day I turned on my ac and I got the check gauges, low oil pressure and stop engine warning in the DIC. :/
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
papo020 said:
Thanks for all the advice. I'm going to try and get on all of this asap! The 13.5 I'm getting is city. Is that about what is expected? I'm not sure about what gear ratio I have.

I was also going to mention that the other day I turned on my ac and I got the check gauges, low oil pressure and stop engine warning in the DIC. :/

The gear ratio will be on the info list in the glove box:
GU6 = 3.42
GT4 = 3.73
GT5 = 4.10

The problem, when turning on the AC, is probably a gummed up throttle body. An hour and a can of t-body cleaner is the usual cure.
 

papo020

Original poster
Member
Dec 19, 2011
12
Wooluf1952 said:
The gear ratio will be on the info list in the glove box:
GU6 = 3.42
GT4 = 3.73
GT5 = 4.10

The problem, when turning on the AC, is probably a gummed up throttle body. An hour and a can of t-body cleaner is the usual cure.

I'll have to take a look at the throttle body since its been less than a year since I cleaned it. But who knows. Thanks! I'll get back in a few minutes with the gear ratio.
 

strat81

Member
Dec 29, 2011
399
papo020 said:
Thanks for all the advice. I'm going to try and get on all of this asap! The 13.5 I'm getting is city. Is that about what is expected? I'm not sure about what gear ratio I have.

I was also going to mention that the other day I turned on my ac and I got the check gauges, low oil pressure and stop engine warning in the DIC. :/

That mileage in the city would not concern me no matter what gear ratio you have.
 

papo020

Original poster
Member
Dec 19, 2011
12
Wooluf1952 said:
The gear ratio will be on the info list in the glove box:
GU6 = 3.42
GT4 = 3.73
GT5 = 4.10

The problem, when turning on the AC, is probably a gummed up throttle body. An hour and a can of t-body cleaner is the usual cure.

I almost forgot to answer this question. Gear ratio is 3.73
 

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