Belt Squeal Mystery - Need Help

5.0L Miata

Member
May 3, 2005
121
0
17
Ontario, Canada
www.cardomain.com
Hey Everyone,

I have a 95GT with bolt-on's that I've been having accessory belt issues with for the past two seasons. Last summer the car was making a ticking noise which turned out to be a bad belt tensioner. I replaced it this winter with an aftermarket unit from Summit Racing.

This spring my first trip with the car it threw the belt off which I thought was really odd. It destroyed the belt in the process, so I purchased a new Goodyear Gatorback belt. I also noticed that the belt was riding on the front of the new tensioner pulley which I thought was maybe why the belt came off.

So I used a 1/4 spacer behind the tension to push it out so the belt rode on the middle of the pulley. The belt no longer flew off but now I had horrible belt squeal at startup and a slight chirping at idle. I figured maybe my spacer meant that the tension was not 100% straight and thus causing the squeal, so I went back to no spacer and the squeal is still here.

So three things come to mind now. One; my new belt could be glazed from the squealing and needs to be replaced again. Two; the aftermarket tensioner is crap and I should replace it with a Ford unit, or Three; I noticed a lot of rubber build-up around the alternator and perhaps my alternator is the cause? It is charging find and spins freely, but there is a lot of build up around it. Pictures attached to maybe help.

Thoughts?
 
  • Sponsors(?)


jozsefsz

5 Year Member
Aug 11, 2013
1,149
273
114
49
Cleveland OH Area
Shimming the tensioner pulley should not cause any problems, I've had to do so before as well as not all aftermarket parts are created equal. I'd be surprised if that was rubber dust on the alternator, usually metal dust collects there due to magnetism.

If you're getting squealing, either the tensioner is inadequate, the belt is too long, or one of your accessories is binding. Remove the belt and spin each one by hand. The idler pulley, air pump, A/C, power steering, water pump, or alternator could be binding. They should all move absolutely freely, make no noise, have no spots where they 'stick', and have little if any free-play in any direction.
 

5.0L Miata

Member
May 3, 2005
121
0
17
Ontario, Canada
www.cardomain.com
Thanks for your response, I appreciate it. I had zero squealing issues last year before I replaced the tensioner. Ever since I installed it I have belt squeal and a thrown belt. My first instinct is to throw the $70 I just spent away and buy a $110 Ford tensioner (or an aftermarket piece that someone can recommend). Here is the Ford one on CJ Pony Parts: Ford Mustang Belt Tensioner W/ Pulley 5.0L 1994-1995

I am running a 90.2" belt. I have all stock accessories (including A/C) but no smog pump. I have spun all the accessories and they seem good. The only one that maybe suspect is the idler. It spins but maybe only two rotations by hand before it stops again. I'm wondering if it should spin more free than that?

Any other suggestions let me know.
 

jozsefsz

5 Year Member
Aug 11, 2013
1,149
273
114
49
Cleveland OH Area
Usually when an idler is brand new it will spin a little tight, if it's well-worn it usually free-wheels pretty well. It may be worth a shot before you spend the money on a tensioner since they're pretty cheap. But it's hard to argue with the history you have -- if it was fine before, it's quite possible the tensioner isn't up to snuff. It's also important to check that the tensioner isn't bottoming out because the belt's loose. I also have a smog delete, and some brand belts seem quite a bit bigger than others. It should have some marks on it to tell you if you're within an acceptable range (the one you linked has two hash-marks on the top, between which the other one should sit when the belt is installed)..
 

toyman

SN Certified Technician
Jul 19, 2007
1,944
54
79
Vernon BC
I would remove the spacer to see if the squealing stops. If it does, you have the problem solved. The tensioner has a belt wear indicator on it. If the marker is in the good zone the belt length is okay. Also, using a soap bar, apply the soap to the belt to see if the squealing stops.
 

5.0L Miata

Member
May 3, 2005
121
0
17
Ontario, Canada
www.cardomain.com
Thanks again for the responses. I have removed the spacer from the tensioner but the squeal continues. I am now getting a constant chirp as well that increases with the speed of the engine. I may try a new smaller belt to see if that helps. The aftermarket tensioner does not have a mark to indicate if it is in the right range, but I do see it on the original OE piece I still have.
 

jozsefsz

5 Year Member
Aug 11, 2013
1,149
273
114
49
Cleveland OH Area
Awesome glad to hear it, that ticking you heard is actually the tensioner reaching its limit and bottoming out. No harm from it for a short time, and the proper length belt will keep that from happening again.
 
Thread starter Similar threads Forum Replies Date
E Engine High rpm belt squeal Fox 5.0 Mustang Tech 4
Eilermoon Engine Serpentine Belt Rubbing Near Tensioner SN95 4.6L Mustang Tech 3
K Engine Belt Squeal that I can't seem to fix... Help Pls! SN95 V6 Mustang Tech 1
W Squealing belt 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 7
B Throttle Body Squeaking 1996 - 2004 SN95 Mustang -General/Talk- 0
B Squeal when tapping Gas, Not belt or Pulleys 1996 - 2004 SN95 Mustang -General/Talk- 0
J 03 Gt belt squeal 1996 - 2004 SN95 Mustang -General/Talk- 1
Bob Hughes Forced Induction Case Of The Squealing Belt.... SN95 4.6L Mustang Tech 1
GTpowerwithin Squealing Belt Or Pulleys?? 1996 - 2004 SN95 Mustang -General/Talk- 8
Platonic Solid Belt Squeal at Startup Classic Mustang Specific Tech 4
strattoc Squealing belt is driving me insane 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 1
9 Help me get rid of this annoying belt squeal! Fox 5.0 Mustang Tech 4
H Serpentine Belt squealing 2.3L (N/A & Turbo) Tech 4
merc123 Serpentine belt rub and pulley squeal SN95 4.6L Mustang Tech 0
R belt squeal on startup Fox 5.0 Mustang Tech 3
flashback87 3g alt.......belt squealing Fox 5.0 Mustang Tech 7
Slo5Oh89 Belt Squeal with Underdrive Pulleys Fox 5.0 Mustang Tech 12
H squealing belt Fox 5.0 Mustang Tech 13
OregonMustang Horrendous new belt squeal....how to get rid of it? SVT Tech Forum 8
R squealing belt Fox 5.0 Mustang Tech 2
B People with powermaster alternators, did you have belt squeal? Classic Mustang Specific Tech 10
jtfairlane Help - Belt Squeals Only During Startup - Already Searched Fox 5.0 Mustang Tech 4
5.0L Miata Belt Squeal - Help Needed! Fox 5.0 Mustang Tech 14
L why the hell wont my belt stop squealing? Fox 5.0 Mustang Tech 25
DarkProphet belt is squealing, a/c + smog delete quesiton 1994 - 1995 Specific Tech 7
stangboy35 Belt Squeal SN95 4.6L Mustang Tech 5
S belt squeal 1994 - 1995 Specific Tech 1
old_blue Squealing belt, tensioner bad?? Fox 5.0 Mustang Tech 3
88306stang Belt squeal Fox 5.0 Mustang Tech 5
Lawman85 Fan Belt Squeal SVT Tech Forum 0
T Squealing Belt tensioner 99 Cobra SVT Tech Forum 5
DemonGT Door belt molding 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 4
M Seat belt question for 97 GT convertible. (Resolved) 1996 - 2004 SN95 Mustang -General/Talk- 1
T Questions about power steering delete!! Need help!! 1996 - 2004 SN95 Mustang -General/Talk- 5
9 So my idler pulley and serp belt disintegrated. 1996 - 2004 SN95 Mustang -General/Talk- 0
M Engine Belt tension Fox 5.0 Mustang Tech 9
Habu135 For Sale 1993 Front Seat Belts in gray Interior Exterior Parts 0
M Engine Need help on belt with V3 Fox 5.0 Mustang Tech 4
B Serpentine Belt Re-route 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 9
R Blue wire connected to Seat belt Fox 5.0 Mustang Tech 8
BNF861 Vortech Underdriven Crank Pulley Belt Size 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 0
EX-SSP Engine Belt Tensioner Broke? Fox 5.0 Mustang Tech 5
A 1978 302 Serpentine conversion 1974 - 1978 Mustang II Talk & Tech 3
kamikaze5.0 V-1 Supercharger Belt Questions 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 3
S Interior and Upholstery Looking for new seat belts for my 92 convertible 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 2
C Squeeking noise at idle but it's not the belt or the pulleys SN95 4.6L Mustang Tech 1
Mr.Roush02 2002 Roush mustang Allen Supercharged serpentine belt routing SN95 4.6L Mustang Tech 0
Diesel1277 Engine Serpentine belt length Fox 5.0 Mustang Tech 9
Hudson N Belt tensioner wearing a hole in timing cover. Help 1996 - 2004 SN95 Mustang -General/Talk- 0
HighLife7 Upper door belt line trim advice needed 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 21
Similar threads