All of a sudden, after I put about 700 miles on my 1996 Dodge Ram 1500 4x2 5.9L (195,000 miles) this weekend I have a new noise.....

After a cold start (for about 2-3 minutes) I hear a noise...

The best way I can describe this noise: It's the same type of noise my old 1980 carbureted boat engine makes at startup....sounds like a bunch of air rushing through the flame arrester....

but, I am not conviced it's "air" related. I am thinking it may be bearings in one of the pulleys.....

Can I remove the serpentine belt completely and start the engine to isolate pulley noise?

thanks,
Chris
Austin, TX

update 7-6-06, 11am: I fixed the noise. It was the idler pulley. It was very hard to determine if it was an "air" related noise or bad bearings....but after the belt was off and I could spin them by hand - it was very noticeable the tensioner pulley was the culprit. $24 at advance auto. 2 minute install.

 

I guess I don't see how removing the belt would help you isolate pulley noise since none of the pulleys (except the crank pulley) will be turning without the serpentine belt being attached to them. You could remove the belt and turn the pulleys by hand to see if they make noise, but it is unlikely you will be able to, by hand, reach the speed and pressure that is exerted on a pulley during normal engine operations. I have had success identifying bad pulley bearings on other vehicles by starting the vehicle, waiting for the noise to start, then spray wd-40 on the center of the pulleys. Most are not completly closed bearings, so even if you get a little in there, the noise will go away almost immediatly, identifying that pulley as having bad bearings.

If it is an air rush type noise, and it only lasts a few minutes on cold start, my first guess would actually be the airhat assembly gasket. If the airhat becomes loose, or the gasket is warn, broken, or out of place, you will hear a very noticable air suction sound when you first start up. It is the air rushing by the partially closed/choked throttle body blades. It goes away quickly (few minutes) as the blades open, and as heat expansion seals the gap that might exist due to the loose air hat or bad gasket. Second guess would be a vacuum leak of some sort. Third guess would be you need a new serpentine belt. It may be worn and/or stretched, causing your pulleys to "chatter" until the belt heats up.

 

thank you Silver_Dodge.

The gasket you speak of....airhat assembly gasket.....is that the round gasket between the air box and the TB? Advance auto parts is suggesting p/n 60038.

I was going to remove the belt so that I could determine if it was a pulley related noise or something else. If the belt was off and I didnt hear the noise, I'd assume that a pulley is the culprit. I suppose it would be ok to run 30 seconds w/o the serpentine belt right?

thanks again, -C

 

Not sure about that part number, but yes, that is the location of the gasket I am refering to.

I can't think of anything that would be hurt by it if you only run it for a few seconds. Pumping water would be the only think you should probably be most concerned about. 30 seconds won't be enough to drain your battery (since the alternator will not be turning), and power steering and ac won't matter. I wonder if the lack of resistance usually created by the belt would cause issues with how the engine runs? Never tried this before.

 

Get used to the noises, one of the worst put together trucks on the road.........10 yrs running

 

I fixed the noise. It was the idler pulley. It was very hard to determine if it was an "air" related noise or bad bearings....but after the belt was off and I could spin them by hand - it was very noticeable the tensioner pulley was the culprit. $24 at advance auto. 2 minute install.

 

Good to here. Inexpensive fixes are always the best.