C5 chirping underhood
Thread Starter
Intermediate
Joined: Jun 2005
Posts: 28
Likes: 0
From: McGaheysville Virginia
C5 chirping underhood
I have a base 98 C5 A/T with around 95K. Everything runs and works fine till temp. reaches 189 and then a chirping starts under the hood. It fluctuates with engine rpm. I actually sounds like detonation but will fluctuate with rpm even at idle ( no load at all} so I have ruled that out. It also runs just as good ( no knock sensors affecting timing). I have been under the hood with a stethoscope while my wife works the throttle ( damn fly by wire ! ). I have loosened the belt and tried to spin the pulleys that have no load to no avail. I did replace the tensioner as it seemed a little rough but chirping still there. I can keep driving and sometimes the chirping will quit. I am at a loss- anyone else have this problem ?
Instructor
Joined: Sep 2012
Posts: 156
Likes: 9
From: Sprint Car Territory
I have had that problem with my PU. The belt needed replaced. After replacing the belts the chirping stoped. Sounded like a bird was under my hood. Try the belts if you haven't already. Hope this helps.
The Outlaw
The Outlaw
Race Director
Joined: Mar 2001
Posts: 11,405
Likes: 26
From: Whippany NJ
CI 6-7-8-9 Veteran
St. Jude Donor '08-'09
NCM Sinkhole Donor
Same issue i had as well, mine turned out to be AC tensioner pulley. The main belt idler tensioner also is notorious for this. GM made an updated design tensioner.
Thread Starter
Intermediate
Joined: Jun 2005
Posts: 28
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From: McGaheysville Virginia
Thanks-the A/C was not working anyway so I think I will just cut that belt off and see what happens since cold weather is here anyway.
Instructor
Joined: Oct 2014
Posts: 195
Likes: 7
From: Greenfield In
St. Jude Donor '16
I've heard chirping from three things: belt tensioner, water pump bearing and lastly and the worst a lifter. The stethoscope is your best friend for this diagnosis. The lifter wheel ceases turning and starts to create a tremendous amount of friction on the cam lobe.
Hopefully it's not the last two items.
Hopefully it's not the last two items.
Thread Starter
Intermediate
Joined: Jun 2005
Posts: 28
Likes: 0
From: McGaheysville Virginia
I've heard chirping from three things: belt tensioner, water pump bearing and lastly and the worst a lifter. The stethoscope is your best friend for this diagnosis. The lifter wheel ceases turning and starts to create a tremendous amount of friction on the cam lobe.
Hopefully it's not the last two items.
Hopefully it's not the last two items.
Le Mans Master
Joined: Apr 2001
Posts: 5,941
Likes: 281
From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
MY first thought is going to be the pulleys. You said you replaced the tensioner, but what about the idler? Normally, when one goes out they are all shortly going to fail after that. You should have one idler and one tensioner on the main belt, and the same on the AC side. I would look first at all the pulleys and tensioner and see if you missed one.
Team Owner
Joined: Mar 2002
Posts: 24,160
Likes: 78
The chirping does not start till the temp reaches 189 degrees. I drove and drove the other day and could not get the temp past 185. I had no chirps. Finally I pulled over and idled to 195 and the chirping appeared. I can drive awhile and sometimes the chirping will go away. It sounds exactly like a loud detonation but will do it in neutral so I rule it out. It seems like a heat expansion related noise. I will try the stethoscope on the valve covers and see what happens.
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Thread Starter
Intermediate
Joined: Jun 2005
Posts: 28
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From: McGaheysville Virginia
Believe me in my lifetime I have owned 8 corvettes, 4 Camaros, 3 impalas, 1 Firebird and 1 chevelle. Five were big block block cars. I definetly know what detonation sounds like. I used the word chirp to get more response. If I had used the word PING everyone would say detonation.
Team Owner
Joined: Mar 2002
Posts: 24,160
Likes: 78
Believe me in my lifetime I have owned 8 corvettes, 4 Camaros, 3 impalas, 1 Firebird and 1 chevelle. Five were big block block cars. I definetly know what detonation sounds like. I used the word chirp to get more response. If I had used the word PING everyone would say detonation.
Racer
Joined: Mar 2011
Posts: 337
Likes: 1
From: Mechanicsville Md
To rule out the water pump, and all the pulleys take the belt off when it begins to chirp. If it stops than you have a better idea where to focus. Because of the heat being generated in the front of the engine, it could be the AC belt, pulley and tensioner. They are separate from the serpentine belt. You can turn your AC on when the chirping starts to see it that changes anything.
Melting Slicks
Joined: Feb 2001
Posts: 2,791
Likes: 355
From: Northville, MI
In addition to the above, you might check the tightness of the tensioner and idler pulleys. I had a similar problem and it involved one of the bolts was getting loose. It started first when the engine was warm and quickly moved to shortly after the start. I was almost ready to replace the water pump when I check the idler pulley.
Thread Starter
Intermediate
Joined: Jun 2005
Posts: 28
Likes: 0
From: McGaheysville Virginia
In addition to the above, you might check the tightness of the tensioner and idler pulleys. I had a similar problem and it involved one of the bolts was getting loose. It started first when the engine was warm and quickly moved to shortly after the start. I was almost ready to replace the water pump when I check the idler pulley.