C4 Whine
Thread Starter
Intermediate
Joined: Nov 2003
Posts: 29
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From: Templeton California
C4 Whine
I purchased a 94 LT1, 6 speed one year ago with 8,000 miles. Drove it home over a distance of 1,500 miles. On the way home noticed a very audible whine between 60 and 75 MPH. Immediately upon touching home base the water pump let go and ruined the optispark. Having replaced them I'm at a loss as to the reason for the whine. I would say it is in the key of E and is E Sharp under power and E Flat when decelerating. Wheel bearings seem tight at 12 and 6 as well as 3 and 9. No visible signs of universal joint deterioration. By feathering the throttle at 60 to 70 MPH I can make the car sing. Checked the level of fluid in the pumpkin and changed the fluid in the transmission. No visible signs of bearing wear in the transmission fluid. I have no reason to doubt the authenticity of the mileage of this car. Anyone have this experience and what was the solution?
Race Director
Joined: Aug 2000
Posts: 14,130
Likes: 7
Cruise-In II Veteran
Im not sure but have you Changed the rear end fluid?The reason I ask is because I once started to have a whine and it was most pronounced when going around turns,not the speed you said and it was the rear end oil needed changing.It kinda sounded like the power steering pump was screeching.
DO some figure 8's in a parking lot and see if its still there.If it is,then its a good chance the rear fluid needs changing.Remember,just because its full doesnt mean its not contaminated and needs changing.
Dont forget to check the engine accessories and their pulleys and be sure the belt is good.Sometimes,taking the belt off and starting the car and revving the engine for a brief time can help narrow down a noise.
Maybe some others will chime in.Can you tell where the noise seems to be coming from?
DO some figure 8's in a parking lot and see if its still there.If it is,then its a good chance the rear fluid needs changing.Remember,just because its full doesnt mean its not contaminated and needs changing.
Dont forget to check the engine accessories and their pulleys and be sure the belt is good.Sometimes,taking the belt off and starting the car and revving the engine for a brief time can help narrow down a noise.
Maybe some others will chime in.Can you tell where the noise seems to be coming from?
Instructor
Joined: Apr 2005
Posts: 208
Likes: 0
From: Wheaton Illinois
Originally Posted by Bill's86Coupe
Im not sure but have you Changed the rear end fluid?The reason I ask is because I once started to have a whine and it was most pronounced when going around turns,not the speed you said and it was the rear end oil needed changing.
Is the whine still there after replacement of the water pump and the opti? I thought that is what you said.
Thread Starter
Intermediate
Joined: Nov 2003
Posts: 29
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From: Templeton California
It appeared as though the differential fluid had been changed due to oil on top of C beam and exhaust pipe when I first checked car on a lift. Level was right at fill plug hole and clean. Noise/whine does not occur at low speeds, only between 60 to 75 MPH. Whine does diminish significantly at speeds above 75 MPH under load and will stop when clutch is depressed. At first I thought perhaps a problem with transmission countershaft because of the range at which the whine occurs, fifth and sixth gear. However, I can cause the whine in fourth gear simply by accelerating to the speed range at which it occurs.
Thread Starter
Intermediate
Joined: Nov 2003
Posts: 29
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From: Templeton California
I don't think the water pump or opti has anything to do with the whine. The car is in showroom new condition. Really pristine, which may be the problem. Seals dried out due to prolonged storage without startup to operating temperature and I suspect this whine was there all the time and never got worked out because it was stored most of the last 11 years.
Instructor
Joined: Apr 2005
Posts: 208
Likes: 0
From: Wheaton Illinois
as annoying as it might be, i would just drive it. your already stuck with the car unless you sell it. I can't really see it damaging anything else really even though you dont know what it really is. The problem may fix itself (stranger things have happened). When and if it does show, be prepared to fix it. Thats about all I've got.
I would probably look into having the rear end looked at. Probably a bad seal. Find a mechanic that you can trust with your car and let him drive it a bit and see what he thinks after an inspection.
I would probably look into having the rear end looked at. Probably a bad seal. Find a mechanic that you can trust with your car and let him drive it a bit and see what he thinks after an inspection.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Are the tires original? If they are the original Goodyear GS-Cs, ditch them. They came from the factory hard as hell, and only got worse.
Check the air pressure... and check the insides of the tires. I would bet money this is a tire roar.
Check the air pressure... and check the insides of the tires. I would bet money this is a tire roar.
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Thread Starter
Intermediate
Joined: Nov 2003
Posts: 29
Likes: 0
From: Templeton California
No, this is not tire noise nor is it the usual whine associated with corvettes, especially the ZF six speed. I have a couple of ZR1's and they are noisy mechanically, but nothing like this. On a scale of 1 to 10, 10 being as loud as you can turn the volume on your radio, this is at a 5. Yes I can take it to a certified mechanic but I'd rather know what the likely answer is before I ask the $uestion. Surely, someone out there has encountered a similar problem?
