Screeching noise similar to failing belt tensioner

[romeroom]

CAR: 1995 MX-3 (not MX-2), 120K Miles

PROBLEM: Loud screeching, high pitched noise from under hood. Difficulty narrowing down exactly where it's coming from.

SYMPTOMS:
- sounds like a bad belt or when tensioner is going bad. Belet is good.
- happens when car is cold
- can last beyond 3 minutes while idling; lasts for up to 2 minutes while driving. HOWEVER,
- will dissipate or totally go away if engine is turned off and restarted 1 to 3 times.

ASSISTANCE NEEDED: The noise has been getting worse by the week for the past 6 - 8 weeks. Concerned about serious damage being done.

MECHANIC EXPERIENCE: Have been a "backyard mechanic" for over 10 years. Have worked on every major systems on my cars, with the exception of replacing or rebuilding an entire engine.

[Ryan]

Sorry, I don't know a single thing about MX-2's.


...


But really, tighten up your alternator belt, and check the voltage across your battery terminals at idle. If its closer to 12 than 14.4, your alternator may just be old and weak and over-working, putting that extra load on the belt.



If you want to narrow it down for sure (although I'm pretty sure) get a spray bottle full of water and spritz the belt when its squeaking. It should shut up.

[wytbishop]

I'm going to go ahead and guess that you're car is a 4cyl.

It's the alternator belt. 100%. I went through 4 of them on my old RS in about 3 months. It would squeal and I would check it and check it. It was always tight but wouldn't stop squealing. Finally it will snap.

The only solution I found was to go to the dealership and purchase a factory belt. Solved the problem immediately.

[romeroom]

Thank you all for such prompt responses. I will look into both suggestions and get back to you.

[romeroom]

I just remembered another detail: I did replace the alternator approximately a month a go. No change in the "squealing factor." I will try to replace the belt and see what happens.

[wytbishop]

Seriously just suck it up and get a factory belt. I tried 3 different aftermarket belts including a Gatorback and they all quealed. The factory belt was twice the cost...but it never quealed once.

[Dark_Rider2k3]

same issue with my BP. I even was bugging Ryan thinking I'm crazy.. kept snapping alty belts. Funny thing was that my Power Steering/ AC belt was perfect!

Seems Alternator belts can go easily...

[Josh]

YEP same with me... I have gone threw so many belts. Alt belts mainly.

How I resolved it is I sanded the inside of the pulleys, yes I sanded them. if they slip for a while they tend to get a bit polished. Then I scored the underside of the belt (it was used) with a straight edge while running, a flat blade screwdriver will work (just dont get your fingers taken in between the belt and pulley ). Then I used belt conditioner, this can be purchased at the hardware store, we used it a lot in HVAC and when I was in the gym industry we used it A LOT on treadmills. and BAM it was gone. I never had another issue after that.

In many cases you can just use belt conditioner and it will go away.

[Daninski]

Ok I would never tell people to never do this as WD40 has a lot of limitations as a lubricant however. A couple different mechanics told me to spray my belt with WD40. I sprayed the hell out of more than one belt on more than one vehicle and in every instance (where it wasn't belt tension) the squealing stopped for good. WD40 has a tendency to soften the rubber and I assume that's the magic. I know belt dressing is out there but it is about 3X as much. So go ahead and spray the living sheet out of the belt while the engines running.

[romeroom]

By the way, I recently replaced the belts as recommended and problem has dissapeard. Thank you all for your interest and suggestions.

[wytbishop]

Factory belt FTMFW!!!