Hello and sorry to bother

1998 Blazer 2WD 4door 4.3L V6 105,000 miles

Recently(since it turned colder here in Ontario Canada) there has been a "howling/moaning" sound coming from what sounds like its coming from the area of the rear end. It starts after the truck sits for a period of time(say overnight). I start it in the morning when it is cold and or damp out, I put it in REVto back out of my drive way and it howls. I back up a few feet and it howls..put it in drive and move away and it will howl for maybe 15 feet and then quit. By the time I get to the end of my street it disappears(less than 50 feet). It will not do it again for the rest of the day until it sits for overnight or longer. I have read that this could be caused by low or worn out grease/lube in the rear end. The lube in the rear end has never been changed as far as I know

I hope I have explained this well enough

This is going to be a PITA to trouble shoot because after it starts moving it does not happen so by the time i get it to a mechanic it will be gone.

Any suggestions what this could be or any leads?

Thanks in advance

 

I would get the truck up on jack stands and check for play in the pinion bearings (where the driveshaft attaches to the rear axle). While you have the rear end up on jack stands, it would be a good time to check for play at the outer wheel bearings to see if they may be at fault, but I can't see a problem there going away after you drive it 50 feet (which isn't very far at all). Play in any of these bearings will require disassembly of the rear axle. If the pinion bearings have play, then you are looking at either rebuilding the axle or swapping it out for another from a scrap yard.

Are you sure that the sound is coming from the rear end? Have you had someone else move the truck while you lay on the ground next to it to determine the source? Is there any way that you can take a quick cellphone video and post it to youtube for us to watch. Some people go nuts with videos, but actually hearing the noise can give us more direction to help you pinpoint the problem.

If you do not recall the rear axle ever being serviced, it won't be a wasted effort. If you do decide to service the rear axle, be sure to get the fill plug out before you crack the pan. It can be a bear and it sucks to fill the axle through the vent tube port. I wrote a post several years ago on servicing the rear axle (CLICK HERE).

 

Hello again

I will do my best to capture the sound on video. The truck had been sitting since about noon yesterday. Went out at 0900 EST this morning. Set up the camera and backed out and drove away. Nada. Silencio, squat. f***

Anyway I will keep trying and post when I get it up on Youtube.

Regards,

Don

 

It turned a little colder overnight last night and the blazer sat since about 1200 yesterday. Took it out at 1800 tonight and it made the same howling sound. I had the camera on my cell phone rolling but the sound was not picked up very well by the microphone. Going to try a couple of more times with a better camera and see what happens. If that don't work good enough so I can post it on YouTube I will take this post down I guess and not waste any more time

Thanks anyway

 

I sought out some advice from my neighbor/Mechanic friend about this issue and he got it up on his hoist last night. Rear brakes pads were seized up in the calipers. There apparently there was enough play once I got moving they freed up enough to stop howling. Let it sit and they froze up again. He took the rear brakes apart and serviced them without replacing a part(Maybe I should have but that can wait until spring). I do need to look into a pair of rear calipers thought. The pistons in both sides are sticking pretty good.

Next job I guess

Thanks for the input swartlkk

 

I was going to say you should check the rear brakes /emergency brake cables. The cables tend to seize up and cause the rear brakes to make all sorts of strange noises. The E. brakes operate the rear brakes only---whether caliper or drum type. The cables are subject to freezing up due to the salt on the roads. I would try to spray them, but you may end up replacing those cables. Many in the salt belt never apply the emergency brakes and depend on the Auto trans 'Park' to hold the vehicle. Not a recommendation, but a fact.

 

I was going to say you should check the rear brakes /emergency brake cables. The cables tend to seize up and cause the rear brakes to make all sorts of strange noises. The E. brakes operate the rear brakes only---whether caliper or drum type. The cables are subject to freezing up due to the salt on the roads. I would try to spray them, but you may end up replacing those cables. Many in the salt belt never apply the emergency brakes and depend on the Auto trans 'Park' to hold the vehicle. Not a recommendation, but a fact.