Drivetrain growl

[Nitrous]

Got something funny going on with the drivetrain and haven't had time to trouble shoot the problem but will start this weekend. I can hear a growl coming from the drivetrain and it actually gets softer under a load put increases with time. I have a new transmission and converter with a used Typhoon transfer case. When I pulled the tranny I drained the fluid out of the tranfer case and I did notice some small metal shavings but opted to flush the case out with solvent and filled it with Royal Purple. The truck has had the growling noise since I purchased it but has progressively gotten worse with the new tranny build. I keep reading on the viscous coupling and vibration issues and it sure sounds like this could be my problem along with something else wearing to put out the shavings.

Yesterday I took a ride to Circle D and everything was fine until I was on my way home and 60 miles of driving. I could accelerate and the truck would barely move like there loss of friction somewhere. I pulled over and checked the fluid and it was fine without a burnt smell to it. I drove the truck home, checked fuel pressure just for the hell of it which was 50psi at the rail and let the truck cool down. I got back in it a couple of hours later and it drove like all was well again. I drove it to work this morning and still no problems. Can someone explain how the viscous coupling works and tell me if anyone else has had a similar issue. If you have any knowledge or experiences similar to mine please feel free to post.

Thanks

 

[TxSy1430]

Re: Drivetrain growl

The shavings could be from the planetary...thats where mine was from. once i pulled the case open the planetary was about to come apart. And the viscous was shot...

 

[sy2675]

Re: Drivetrain growl

my truck started growling at me when the rear pinion bearing went.

 

[Nitrous]

Re: Drivetrain growl

The pinion nut was loose when I put the transmission in so that might be the culpret but that doesn't explan the power loss during accelleration. Maybe it's a combo of things..........

 

[Try Me]

Re: Drivetrain growl

The viscious consists of a an input and output shaft with discs on them (but not like clutch discs). There is a silicon based fluid inside that when heated it solidifies causing the two sets of discs to lock together. The heat is made when one shaft spins faster than the other.

Most viscious failures are from the silicon fluid "burning" to where it is in a constant solid state, locking the two shafts together. This usually causes the truck to be very hard to make sharp turns, will make the front tires "skip" and can even pop axles out of the front diff or even cause more permanent damage.

As DaveP said, the viscious would not cause power loss. I just recently swapped out my transfer case because of a froze up viscious. From what you described it sounds like something slipping in the trans when getting hot.

When you tightend the pinion nut, how much did you tighten it and with what? If i remember correclty our rears have crush sleeves and if you went crazy with a big impact gun you could have crushed the sleave a little more causing a change in the pinion bearing preload.

Also did you check the front and rear diff fluids? "Growling" sounds to me like a bearing noise though more than a tranny noise.

 

[midnightbluS10]

Re: Drivetrain growl

I was at school yesterday looking for a drivetrain growl. We tracked it down to the DS wheel hub assembly. Probably not what's causing your noise, but ....

 

[powercat6]

Re: Drivetrain growl

I think DaveP's comment about the differential is probably the problem. My brother's '88 S10 Blazer had a differential go out and the sound coming from the back was a loud "growl" of sorts.

 

[Nitrous]

Re: Drivetrain growl

Well I finally put theSy in the air and got to look at the drivetrain in motion. All of the noise went back to the rear end so I decided to pull the rear cover and see what was going on. I could see the pinion gear moving up and down so DaveP hit it right. I decided to R&R the complete rear end and found 4 out the 6 bearings bad. Both pinions and carrier bearings were shot. It's a wonder the housing didn't explode with the 1/16" chucks out of the rollers on the pinion bearings. LOL I'm hoping to put it back together tonight when I get off work. This was probably alot of my drivetrain vibration also. I did see some tire out of roundness that could also be contributing to the vibration. Once I get this knocked out I'll go back to the power loss issue which I'm hoping is something different from the transmission since RPM didn't climb during the power loss.