I have a 97 two door tahoe, 5.7L, 4x4, 149000 miles. From the day I got it, It has a grinding noise at interstate speed, in between letting off the gas and pressing the gas. It is still there when letting off the gas, but not as loud as when in between on and off gas. Heres the list of things I have had done, and its still there. New brakes all around. Rear axle seals and fluid. New transmission and transfer case. New universals front and rear drive shafts. New plugs, wires, cap and rotor. Fuel and air filter. rebalanced the tires. It has not changed. It sounds as though in is right under my feet and drivers seat area. Any ideas, Im stumped. Also if on the interstate and you put it in Nuetral the grinding goes away.
97 tahoe, grinding noise
- Thread starter nhbluevip
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
Bad bow tie
Grizz Straight FTMFW
Drive shaft or wheel bearing is all I'm coming up with.
SunlitComet
OBS Jedi-Do Good
SInce you have eliminated the tranny and t-case is the noise rate consistant with vehicle speed or engine speed increase or decrease as well?
99Yuk
Full Access Member
Auto-trac 4x4 or manual shifter on floor? Maybe a malfunctioning 4x4 actuator? It sounds like mine does when I'm in 4x4 on the highway. I can make the same sound. Mine is a 99 with a manual shifter on the floor. What if for some reason your 4x4 is not disengaging? I first thought wheel bearing, but it doesn't stop making noise when in neutral rolling along at speed. Then I thought leaky exhaust manifold gasket, but I'm unsure.
It is push button 4x4, not on the floor. I thought wheel bearing as well but as already stated, that would be constant, and not go away when put in neatral. It is consistent with vehicle speed, not engine speed.
---------- Post added at 09:20 PM ---------- Previous post was at 09:19 PM ----------
I also forgot to mention, I though it may have been the exhaust hitting somewhere on the body, so I replaced from the muffle back with new stock exhaust. Still the same.
---------- Post added at 09:20 PM ---------- Previous post was at 09:19 PM ----------
I also forgot to mention, I though it may have been the exhaust hitting somewhere on the body, so I replaced from the muffle back with new stock exhaust. Still the same.
96ProCompTahoe
Full Access Member
Is you front shaft spinning with the truck in drive? Front shaft or diff would be my guess if it sounds like it's in the front end and not wheel bearings, drive shafts, trans, brakes, or t-case.
SunlitComet
OBS Jedi-Do Good
What has happened when you shift your transfer case?
I dont know if the front drive shaft is spinning while in drive or not. I don't think it is wheel bearings, due to the fact it goes away if put in neutral. I don't believe it is trans or t-case, because it has a completely different trans and t-case then before, and nothing has changed, as far as the grinding noise. Im at a lose. Also not the breaks because i have put all new pads rotors and rear drums on the truck, and still no change. Also if it were the tires, it again would still make the noise wether it was in drive or neutral.
---------- Post added at 01:42 AM ---------- Previous post was at 01:41 AM ----------
I also forgot to mention it goes into 4x4 fine, no noises.
---------- Post added at 01:42 AM ---------- Previous post was at 01:41 AM ----------
I also forgot to mention it goes into 4x4 fine, no noises.
SunlitComet
OBS Jedi-Do Good
Do I understand your to say that when you switch to 4x4 the noise goes away? If so when you replaced your t-case did you use the existing shift motor or a new one?
SunlitComet
OBS Jedi-Do Good
you should be able to do highway in 4hi but not low if you don't want valves flying out of your hood like a sparkler. Just do it a short period of time on drive payment. Until you figured out the noise I would not shift on the fly at speed just yet. It maybe worth trying.
If the shift motor is the existing one my thought was something was wrong with its encode or the gearing inside causing a partial engagement. Just a thought.
If you have the nv243 t-case (RPO code NP1 I think-Check on the inside of your glove box face.) I have about 2 dozen papers on that system. Including T-case control module tech data. I can only fax it right now though.
If the shift motor is the existing one my thought was something was wrong with its encode or the gearing inside causing a partial engagement. Just a thought.
If you have the nv243 t-case (RPO code NP1 I think-Check on the inside of your glove box face.) I have about 2 dozen papers on that system. Including T-case control module tech data. I can only fax it right now though.
I forgot to mention, the old tranny that was in it had a hair line crack in the case, just in front of the pan, which obviosly leaked bad and I believe burn out the tranny over time. Im thinking what ever this grinding vibration is, may have been what caused the crack before. I would like to figure this out, before it cracks another tranny or t-case.
SunlitComet
OBS Jedi-Do Good
In that case it has got to be somewhere from the driveshafts outwards. Rings or pinions bearings or teeth - axle bearings. I do not know if a a malfunctioning locker could do it but maybe the front axle shift mechanism. Maybe something hitting the reluctor rings for ABS on the front wheels. Or maybe a plastic body piece hitting a moving part at speed. The sound is probably just traveling through the parts that will carry it the easiest. Can't think of much else unless you have it put on a rack with some one inside on the throttle.
Agreed. I have had the rear end opened up to do the axle seals, all looked good. I agree it has to be something with the front, and vibrating the front axle? I don't understand why it woud go away the minute it is put into neatral, and your coasting?
SunlitComet
OBS Jedi-Do Good
Is there any evidence that maybe a collision with parts has shifted the mounts on equipment cuasing binding problems. Page 98 of the document below might help if you want to do some basic measurements. There are more I just don't have them now.
http://www.sunlitcomet.com/pdf/auto/ck.pdf
---------- Post added at 06:18 PM ---------- Previous post was at 06:11 PM ----------
Wear on the driving side of gear tooth or synchonizer face and none on the other face that makes contacts when coasting with no force.
Something like that.
Last edited:
Similar threads
