# Squealing belt - 99 Sentra



## petercc (Dec 27, 2005)

I have a 1999 Sentra with 1.6 engine. When I put the defrost on, the belt often squeals horrendously for a few seconds and wil sporadically continue. Any idea why this is happening?


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## wildmanee (Nov 21, 2004)

You need to check your tension on your belts. I had the same thing happening to me, and all I did was tighten my belts up back to spec. Problem solved. Does it do it when you're coming to a stop? And sometimes while idling? It could also be one of your pulleys, but check your belt deflection first, it's an easy fix if it's your belts.

This should help (don't worry about the oil seal part, just look below to the process for adjusting tension on the belts):











The tensioner for the alternator belt is a little hard to get to, it's a long bolt near the alternator. By taking off one of your front splash guard panels underneath the alternator, you should be able to access the tensioner with a 10mm or 12mm socket wrench.. I forget which size.


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## petercc (Dec 27, 2005)

*Thanks for the diagram very helpful*

Yes, it does it mostly in idle or when I come to a stop. 



wildmane said:


> You need to check your tension on your belts. I had the same thing happening to me, and all I did was tighten my belts up back to spec. Problem solved. Does it do it when you're coming to a stop? And sometimes while idling? It could also be one of your pulleys, but check your belt deflection first, it's an easy fix if it's your belts.
> 
> This should help:


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## wildmanee (Nov 21, 2004)

By the way, here are the Belt deflection numbers
All of them are in *millimeters*

The number are Limit */ * Deflection After Adjustment */ * and Deflection of New Belt

The numbers you want to be looking at are mostly the middle numbers, although if your belts are within the limit range, then they should be good. I would still suggest tightening them up to the middle number range specs. 

*Generator(Alternator)* 
With A/C Compressor - 9.5*/*6-6.5*/*5-6
Without A/C Compressor - 11.5*/*7.5-8*/*6.5-7

*Water Pump*
With power steering pump - 7.5*/*4-6*/*3-5
Without power steering pump - 6*/*3-4.5*/*3-4

Applied Pushing force is 98 newtons (10kg, or 22 pounds)


Also, you do not need to loosen anything.. only tighten those adjustment screws until the belt deflection is in spec!


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## Twiz (Aug 24, 2004)

petercc said:


> I have a 1999 Sentra with 1.6 engine. When I put the defrost on, the belt often squeals horrendously for a few seconds and wil sporadically continue. Any idea why this is happening?


Which defrost... front windshield or rear ? It can't be the rear windshield defrost I don't see any connection in between the belt and the electrical grid on the rear windshield. The front defrost could cause the A/C to kick in, depending on your HVAC settings, meaning the compressor belt is loose.


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## petercc (Dec 27, 2005)

I just printed them.
Thanks again.

Peter




wildmane said:


> By the way, here are the Belt deflection numbers
> All of them are in *millimeters*
> 
> The number are Limit */ * Deflection After Adjustment */ * and Deflection of New Belt
> ...


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## wildmanee (Nov 21, 2004)

It could be possible that it's putting stress on the alternator, and thus making the pulley slip from the loose belt, but I think I'm gonna have to go ahead and assume it's the front defrost.

No problem Pete.


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## petercc (Dec 27, 2005)

*Its the front defroster*

Yes, I believe the A.C. is kicking in and that is when the squealing begins. I hope its just a loose belt and not something in the A.C. unit. The heat resistor is shot and needs to be replaced as well. Thanks.





Twiz said:


> Which defrost... front windshield or rear ? It can't be the rear windshield defrost I don't see any connection in between the belt and the electrical grid on the rear windshield. The front defrost could cause the A/C to kick in, depending on your HVAC settings, meaning the compressor belt is loose.


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## wildmanee (Nov 21, 2004)

Yeah, when my A/C kicked it, it'd squeal. I wouldn't worry about the A/C, I would definitely put money on your loose belts though.


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## Twiz (Aug 24, 2004)

petercc said:


> Yes, I believe the A.C. is kicking in and that is when the squealing begins. I hope its just a loose belt and not something in the A.C. unit. The heat resistor is shot and needs to be replaced as well. Thanks.


I'm assuming it's cold so you need warm air, just turn the A/C off from the switch in your dash , set the blower on WARM or pull the fuse out and deal with it later, I'm sure you can figure a way to stop the A/C.


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## enigmatic_carlos (Dec 31, 2005)

*problems*

hey...am experiencing same problems??could unsteady electric flow cause problems wif the belting??i have already changed the entire belting....could it be because it is stressing the alternator???10q


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