Serpentine squall

[Mark Rinker]

Today a new noise began emanating from under the hood. Thought maybe some grit or gravel from snowplowing had made its way under the hood, but it continually got louder and more consistantly present today. By the time I got home, it was enough to cause me to pop the hood and investigate.

Its 100% coming from the serpentine belt, near the left (of two dual) alternators, possibly from the tensioner mounted below...but...how to tell which one???

How about a can of WD-40 with straw engaged, starting with squirting the tensioner? Then...if not the tensioner, a small burst behind the pulley on the alternator?

What say ye for my test methods to ISOLATE THE SQUEAKER?

[richp]

Hi Mark,

I ignored a similar noise on my '01, and ended up with a fried belt when the tensioner siezed up in the middle of nowhere.

Given that there were more than 125k miles on it at the time, I think now that I probably should have replaced the tensioner pre-emptively when I did the alternator the week before.

FWIW.

[DmaxMaverick]

With the belt removed, you should be able to feel the bad one turning by hand. They should turn smoothly with a little resistance (the grease and seal). If it spins freely and/or makes any noise (like metal roller skates), it's bad. It is, however, good practice to replace all the idlers, tensioner (at least the bearing) and the belt as soon as one fails. Keep the serviceable (not necessarily "good") one(s) and the belt for roadside spares.

If it's an alternator, it should be noisy as well if bad, turning by hand.

Spraying WD40 in there is not a good idea. It'll lubricate the belt, which will cause issues for a long time coming, and probably not tell you anything. It will also sling the stuff all over.

[Mark Rinker]

Thanks for the input. I'm on it today. Probably the tensioner - but unusual at only 85K miles?

[GMC D-Max]

I had the same issue with mine, shortly after I picked it up (with 33k on the odo). First, I found that the alternator (single) was squeaking... pulled the plastic cover off the back of it, and a few drops of oil took care of it. Second was the belt, which was looking a little worn. I put on a Goodyear Gatorback when I added the second alternator, and it's been silent since.

[SoTxPollock]

So Mark, what did you do? I've noticed that I hear a squeek anytime I drive in rain and then park overnight. When it first starts up I hear the squeek, but after a while it goes away. I'm suspecting the bearings are going dry and there probably is a very slight overnight corrosion that gets worn away after that little while. It's been that way now for about a year. I wish there was a way to lube those bearings, but I don't know of any. The guys out here used to add grease to their sealed bearings on the John Deere combines by using a syringe and needle filling it with grease and puncturing thru the seal and injecting the grease, my nephews say they have kept old bearings running for many years by doing that, seems the rubber or neoprene seals seem to reclose after you withdraw the needle. I've never tried it, but they swear it works just fine.