Humming from engine

Hi, I hope someone can help, I got a 1996 Blazer a little over a month and a half ago, I took it from St. Pete to Orlando (not that far) and when I got to Orlando there was a loud deep humming noise coming from the engine but mainly only when going slow or when stopped, it sounds like it is coming from the fan or the belt, anyone have any suggestions? Thanks a bunch1! :wink:

I would try to pinpoint where the sound is coming from. It could be the belt needs replaced, idler pully, tensioner pully, alternator, power steering pump(check level), water pump, or a/c clutch.

Hey, thanks for the info, we were thinking it might be the belt, should we get belt dressing or just try to replace it? Thanks again!! :smooch:

Just replace the belt, don't waste your money on belt dressing. THe cost of the belt is fairly inexensive, ~$35.00, and it will save you trouble in the long run.
The change out of the belt is quick, maybe 15 minutes tops, and is really easy.

Thanks once again!! But can I tell if it is the actual belt that is bad? Is there some way to tell? And how easy is it to switch out, would that be in my manual by chance? Thanks again! :wink:

The change out of the belt is very easy, all you need is a 3/8" breaker bar or ratchet handle. Put the breaker bar on the tensioner, it has a 3/8" opening in the center, and turn counter clockwise about 1/4 turn. Remove the old belt, replace with new belt following the diagram located on the fan shroud. You're done.
It is in the Haynes and Chiltons manuals, and is so easy you'll wonder why you didn't do it earlier.

:wink: Great! thanks again... im going to go to the store tonight and we will try to get it switched out, thanks again, you were a huge help! I really appreciate it! :cheers:

While you have the belt off you can check for play on most of the pullys, if you feel something funny thats probably were the noise is coming from.

Will do! thanks!! But then, im assuming that if it does feel a little weird or if the sound keeps up, I should just go ahead and bring it to a pro.? Oh and do you think this is ab-normal for a 96'? (it has a little over 85,000 miles):smokin:

Since you don't know the source of the noise:
Start and run the engine for a minute while the belt is removed. If you hear the noise, then you know it is internal and not related to belt or accesories. If noise is gone, but comes back after you install the belt, you know it is one of your accessories.

:) Great idea, makes complete sense, thanks once again... to all of you for all your info. and help!! youre all great!

If you find that you're getting noise from the pulleys themselves, they are not that hard to replace. As long as you have access to some standard tools, and a Haynes or Chilton manual it can be done in a parking lot or garage failrly easily.
Good luck, and let us know what you find out. These posts help others that search for similar symptoms.

I dont know if we will go that far, a real mechanic might be our best bet if its not the belt... actually it is now making the noise off and on, not every time its driven... but im still going to check the belt anyway, cant hurt!
I will definitly let everyone know what happens, thanks again!

I dont know if we will go that far, a real mechanic might be our best bet if its not the belt... actually it is now making the noise off and on, not every time its driven... but im still going to check the belt anyway, cant hurt!
I will definitly let everyone know what happens, thanks again!

You may want to check your PVC hoses/crankcase hoses. I had my upper intake seal done this week and when I got the truck back I was experiencing a buzzing/humming at idle and slow speed. I thought it was coming from the PVC hose in the driver side rocker. Dealer thought it was a cable vibrating against the firewall, but 2 minutes after leaving the dealership the noise was back. It ended up being the hose that runs from the passenger side rocker to the plastic cap on top of the throttle assembly. There was a rubber elbow which was not tight and leaking air. I just reversed the elbow and it went back on tighter. The buzzing was driving me nuts.

On that PCV after the intake done, the throttle cable plastic connector to the intake (on rear drivers side) bracket always ends up broken so I had to use a plastic tie to secure - the cable conducts the noise and also moves the PCV on acceleration as the engine torques up. The top of the intake can where the PCV hose goes into the intake is a removable top that you rotate to lock on 98 up, same with the power brake vac to intake.

On that PCV after the intake done, the throttle cable plastic connector to the intake (on rear drivers side) bracket always ends up broken so I had to use a plastic tie to secure - the cable conducts the noise and also moves the PCV on acceleration as the engine torques up. The top of the intake can where the PCV hose goes into the intake is a removable top that you rotate to lock on 98 up, same with the power brake vac to intake.

Thanks!! Well,I have good and bad news, I found out the problem, it is a pully that is going to the belt, the bad news.... it is going to cost $625.00 to fix!

Oops, sorry its not a pulley, its the motor that runs the belt that we need to replace, does $625 sound right?

Which "motor" has gone bad?? Is it the alternator? or the AC Compressor? Water pump?
In order to tell you if you are getting robbed or not we need a little more info, it may be able to be repaired at home with less cost.

More info required , but yes at the dealer an alternator can run that much with labor and the belt. About $150 do it yourself in an hour - easy.

sounds like the front diff is partially engaged.

Make sure your 4x4 system is working properly.

Also, do you have the same tires on the front on either side??

ok, well, I got to see the receipt last night, it was the a/c pump??? they fixed or replaced, does that make sense though since we havent even touched the A/C since getting the truck...and it says they put some dye in it as well?? :banghead:

AC Systems will sometimes spring a leak. It has nothing to do with wether you touch it or not. Yes, it could cost upward of $600+. A new AC Compressor runs about $250, the cost of the troubleshooting, freon, new gaskets for the lines coming into the compressor, orifice tube, etc.
The dye is used to determine if there are any leaks, and where they are at. It is an ultraviolet dye that they look at under a blacklight.
The sad part is that you probably could have gotten a good used compressor for about $75 to $150, and the change out is only four bolts and the lines coming in after you remove the belt. Putting the system under vacuum and recharging at a service center is fairly cheap.
I did this to my truck over the summer and the total cost was about $150, and its working great. I was able to get a compressor from a junk yard for $75 with a 90 day warranty.

ok, well, I got to see the receipt last night, it was the a/c pump??? they fixed or replaced, does that make sense though since we havent even touched the A/C since getting the truck...and it says they put some dye in it as well?? :banghead:

If you use defrost, you use the AC system.

Try not to use the defrost of blend function so your AC system doesn't run or only use it when you need it.

You will save fuel too.

Well, even though i could have saved a ton of money doing it myself, it really really makes me feel a lot better knowing that I probably didnt get screwed and that it was a valid problem, because i sure was concernced as to why they fixed the "A/C" it just didnt seem right, thanks again for all your info, it really helped me!!! I really appreciate it all!! :cheers: :thumbsup: