Chirping Noise
Thread Starter
Advanced
Joined: May 2019
Posts: 53
Likes: 6
Chirping Noise
I recently purchased my first C4. It is a 1987 with 21K miles.
Right after purchase I had the alternator replaced as it was bad and a new belt put in.
I then had some work done by a corvette restore shop. The front mono spring was replaced (it was failing), the intake was removed and resealed (it was leaking), new valve guide seals (they were bad), new water pump (leaking), new (rebuilt) smog pump, thremostat and gasket, a new heater hose and an oil change. They warned me that the new (rebuilt) smog pump could be noisy for a while. That it said so on paperwork that came with the smog pump and they mentioned "around 500 miles".
They also said that the car has been well maintained, that things were clean under the intake and valve covers.
I got the car back a few days ago and I am happy with the work that was done, the car is running good and all is well, except for a chirp/clicking noise. I first noticed the day after I got it back after the car was idling next to a wall. The injectors have always been loud (clicking), that isn't new but this noise can best be heard under the car. The noise speeds up and slows down with the RPM of the engine.
I ran it by the shop that did the work today and the mechanics listened to the valves and accessories with a stethoscope and said the engine is healthy. They think it is either the noise from one of the injectors just being directed down or an exhaust leak. I would like to track it down if possible.
I have included a video and the noise can best be heard after I put the phone under the car. The phone didn't pickup how loud the noise is but I think you can hear it. The clicking when the phone is above the engine is definitely the injectors, they have been loud since I purchased the car.
Any idea where I might start to troubleshoot this? Might it possibly be the new (rebuilt) smog pump being loud as was warned?
I don't remember the noise before I took the car in for the work but I am starting to second guess myself on that as I am not sure what else could be left that hasn't been changed already.
Note: you might see a small spot of liquid on the ground in the video, it is water (I checked), my A/C was on.
Right after purchase I had the alternator replaced as it was bad and a new belt put in.
I then had some work done by a corvette restore shop. The front mono spring was replaced (it was failing), the intake was removed and resealed (it was leaking), new valve guide seals (they were bad), new water pump (leaking), new (rebuilt) smog pump, thremostat and gasket, a new heater hose and an oil change. They warned me that the new (rebuilt) smog pump could be noisy for a while. That it said so on paperwork that came with the smog pump and they mentioned "around 500 miles".
They also said that the car has been well maintained, that things were clean under the intake and valve covers.
I got the car back a few days ago and I am happy with the work that was done, the car is running good and all is well, except for a chirp/clicking noise. I first noticed the day after I got it back after the car was idling next to a wall. The injectors have always been loud (clicking), that isn't new but this noise can best be heard under the car. The noise speeds up and slows down with the RPM of the engine.
I ran it by the shop that did the work today and the mechanics listened to the valves and accessories with a stethoscope and said the engine is healthy. They think it is either the noise from one of the injectors just being directed down or an exhaust leak. I would like to track it down if possible.
I have included a video and the noise can best be heard after I put the phone under the car. The phone didn't pickup how loud the noise is but I think you can hear it. The clicking when the phone is above the engine is definitely the injectors, they have been loud since I purchased the car.
Any idea where I might start to troubleshoot this? Might it possibly be the new (rebuilt) smog pump being loud as was warned?
I don't remember the noise before I took the car in for the work but I am starting to second guess myself on that as I am not sure what else could be left that hasn't been changed already.
Note: you might see a small spot of liquid on the ground in the video, it is water (I checked), my A/C was on.
Last edited by Regen; Sep 17, 2019 at 07:53 PM.
Le Mans Master
Joined: Dec 2005
Posts: 8,582
Likes: 968
From: Communist Colorado
Im not really hearing anything either... Is the car a stick? Could be T/O bearing related.... or possibly the idler pulley, they will chirp sometimes... But, as I said, I dont really hear much of anything in the video. Go drive the **** out of it for a while.... get the rpms up and see what happens. Youll be suprised how much better the car will run after a good romp.
Le Mans Master
Joined: Oct 2004
Posts: 6,314
Likes: 508
From: South-central Missouri
"Chirp" makes me think BELT. But, to be sure, pritz some window washing fluid on the inside of the belt while the engine is running (e.g., Windex is great for this). If the squeak goes away, and the belt is new, then I wouldn't worry about it. it will go away.
Just a thought: You can buy an inexpensive mechanic's stethoscope at your favorite auto parts store - money well spent too, I might add. And, here's a tip on how to use it (c/o Marc Haibeck, our ZR-1 guru): To investigate noised on the front of the engine, remove the steel probe and the diaphragm from the rubber hose. Then use the open end of the rubber hose to locate the source of that squeak. If you have a bearing, or power steering pump, etc. issue, you'll quickly isolate the source.
John mentioned the TO bearing, but you'd only hear that when engaging the clutch pedal. And, long as we're "down there", if you hear a squeak ONLY WHEN IDLING OR THE CAR IS IN NEUTRAL or when changing gears, the PILOT bushing should be on the list of "suspects". (Course you'd have to have a manual trans for that to apply.)
And, then there's the ol mechanic's adage: "Drive it. If it is serious, it will make itself better known and you can find it. Otherwise, turn up the radio and don't worry about it!"
Just a thought: You can buy an inexpensive mechanic's stethoscope at your favorite auto parts store - money well spent too, I might add. And, here's a tip on how to use it (c/o Marc Haibeck, our ZR-1 guru): To investigate noised on the front of the engine, remove the steel probe and the diaphragm from the rubber hose. Then use the open end of the rubber hose to locate the source of that squeak. If you have a bearing, or power steering pump, etc. issue, you'll quickly isolate the source.
John mentioned the TO bearing, but you'd only hear that when engaging the clutch pedal. And, long as we're "down there", if you hear a squeak ONLY WHEN IDLING OR THE CAR IS IN NEUTRAL or when changing gears, the PILOT bushing should be on the list of "suspects". (Course you'd have to have a manual trans for that to apply.)
And, then there's the ol mechanic's adage: "Drive it. If it is serious, it will make itself better known and you can find it. Otherwise, turn up the radio and don't worry about it!"
Le Mans Master
Joined: Dec 2005
Posts: 8,582
Likes: 968
From: Communist Colorado
"Chirp" makes me think BELT. But, to be sure, pritz some window washing fluid on the inside of the belt while the engine is running (e.g., Windex is great for this). If the squeak goes away, and the belt is new, then I wouldn't worry about it. it will go away.
Just a thought: You can buy an inexpensive mechanic's stethoscope at your favorite auto parts store - money well spent too, I might add. And, here's a tip on how to use it (c/o Marc Haibeck, our ZR-1 guru): To investigate noised on the front of the engine, remove the steel probe and the diaphragm from the rubber hose. Then use the open end of the rubber hose to locate the source of that squeak. If you have a bearing, or power steering pump, etc. issue, you'll quickly isolate the source.
John mentioned the TO bearing, but you'd only hear that when engaging the clutch pedal. And, long as we're "down there", if you hear a squeak ONLY WHEN IDLING OR THE CAR IS IN NEUTRAL or when changing gears, the PILOT bushing should be on the list of "suspects". (Course you'd have to have a manual trans for that to apply.)
And, then there's the ol mechanic's adage: "Drive it. If it is serious, it will make itself better known and you can find it. Otherwise, turn up the radio and don't worry about it!"
Just a thought: You can buy an inexpensive mechanic's stethoscope at your favorite auto parts store - money well spent too, I might add. And, here's a tip on how to use it (c/o Marc Haibeck, our ZR-1 guru): To investigate noised on the front of the engine, remove the steel probe and the diaphragm from the rubber hose. Then use the open end of the rubber hose to locate the source of that squeak. If you have a bearing, or power steering pump, etc. issue, you'll quickly isolate the source.
John mentioned the TO bearing, but you'd only hear that when engaging the clutch pedal. And, long as we're "down there", if you hear a squeak ONLY WHEN IDLING OR THE CAR IS IN NEUTRAL or when changing gears, the PILOT bushing should be on the list of "suspects". (Course you'd have to have a manual trans for that to apply.)
And, then there's the ol mechanic's adage: "Drive it. If it is serious, it will make itself better known and you can find it. Otherwise, turn up the radio and don't worry about it!"
Not necessarily... my son has a Toyota pick up that when its idling, T/O chirps... engage it , it stops from the pressure... The T/O is always spinning...
Last edited by 81c3; Sep 19, 2019 at 06:47 PM.
