lulubarcello

my 02 tb made a bang noise in the rear when i slowed to make a turn. I took it to the dealer and of course it did not make the noise. I went to pick it up and drove about 25 minutes and it did it again. my husband was working so my son who is a jaguar tech took the truck to the dealer and had someone go on a road test and my son got it to make the noise. They let truck sit a day and then had 3 techs and could not get the noise to happen. The 4th tec got it to do it but unsure of what it is since it does not make it often. Has anyone had a banging noise come from the rear and only do it occasionaly? The dealer finance guy said to me and my husband" Thats what you get for buying a used car" I almost fell over. We have not even had it a year. not to mention the service guy treated my son like he was a idiot and new nothing.

jack0723

You didn't by any chance just install only two new tires on a 4wd did you? If your Trailblazer is 4w and the selector switch is in the "Auto" position, the transfer case will try to engage since the traction control system sees the wheels are spinning at different RPM's due to the different tire heights (it doesn't take much of a difference to cause this). If this is a 2wd, do you have a limited slip differential? They usually "tell" you it's time for a differential fluid change by doing exactly what you described. This will only get worse - fast. It will cause the driveline to sound as if the drive shaft is going to come through the floor. If this is the case, have the differential fluid changed and the friction modifier added. The problem should go away almost immediately. I highly recommend using GM fluid and friction modifier. I am not pushing GM products, but I tried other brands and they just don't last. The difference in cost is well worth the aggravation.

Hope this helps,

Jack

jack0723

Sorry, I forgot to mention, even if your Trailblazer is 4wd it may have a limited slip differential in the rear. It will do the same thing as a 2wd.

Jack

lulubarcello

I do have 4 wd.. I drove it home from the dealer last night and it did not make the bang noise after driving it a hour. I thought I hear like a swoshing noise..lol if that makes sense down by the shifter. Other wise no banging noise. I dont get it, but I will try your suggestion. Thank you

jack0723

For your noise near the shifter, you may be running with very low lube in the transfer case. I would also check the level in there. It may be running dry. Actually, I would check all your driveline fluids.. Another thing to consider is a dry universal jiont. It could be binding, causing those noises you hear. It's tough to diagnose without actually hearing the noise, but these checks will eliminate those possibilities.

Jack