Strange Sound

[beachrover]

My '93 has 55,000 on the clock. I decided to drive it to work today as the weather was beautiful. I noticed while sitting at a stop light that I could hear a "ticking" or slight "knocking" sound. When I accelerated, the sound went away. My oil pressure was fine and didn't see anything noticible. When I got to the office, I raised the hood and really couldn't hear it but as I walked back toward the driver's door I began to hear it again. It appears to be coming from underneath the car on the driver's side right around the floor pan area. One other note, when you rev the engine, the sound does increase in speed but not relative to the engine RPM's. its slower.

Any suggestions?

 

[sargevette]

Exhaust leak or rattle?? Is the car an automatic?

 

[Robertwav1]

I noticed some strange noise comming up from underneath the car at one time. Can't remember what the noise sounded like but, my fuel was around a 1/4 and I was parked on a slant. Turned out to be the fuel pump making noise. It sounded like it was comming from the trans (auto) but wasn't the case.

 

[vee93]

Check and make sure the battery terminals are screwed in tight. Did you maybe pick up a stray piece of paper, plastic bag, twig, leaves, etc. Oh, check and make sure a neighbor's cat isn't missing!!!

 

[jfcupolo]

I had this issue

Been there, bought the tee shirt. I had EXACTLY the same issue with mine right after I bought it. It turned out to be that the fuel filter although allowing the engine to run fine was beginning to reach the end of it's usable life span. The sound was a lagging in modulaton related to the engine because it was the throbbing of the fuel pumps response to racing the engine. In other words you race the engine and the ticking increased after the engine sped up but seemed to be in concert matching the increase. It was not until the fuel filter finally plugged and I changed it that the sound went away and the ticking is gone now and I figured it out. Try changing the $7.00 fuel filter and I'd bet it will solve the ticking issue.

My '93 has 55,000 on the clock. I decided to drive it to work today as the weather was beautiful. I noticed while sitting at a stop light that I could hear a "ticking" or slight "knocking" sound. When I accelerated, the sound went away. My oil pressure was fine and didn't see anything noticible. When I got to the office, I raised the hood and really couldn't hear it but as I walked back toward the driver's door I began to hear it again. It appears to be coming from underneath the car on the driver's side right around the floor pan area. One other note, when you rev the engine, the sound does increase in speed but not relative to the engine RPM's. its slower.

Any suggestions?

 

[beachrover]

Stopped by the dealership on my way home Friday. The vette mechanic there is really good and a very honest person. After driving and listening to it for about 30 minutes he said that it was either a cracked flywheel or a lower end problem (rod bearings). He said that if he had to bet, he would put his money on a cracked flywheel. He did tell me if it ended up being the bearings he wouldn't spend the money having them repaired, he would just buy a short block and drop it in. I asked him was it normal for the flywheel to crack or rod bearings to go with so low mileage on the engine and he said "On a vette, almost anything is normal".

 

[John Robinson]

Second opinion

I find it hard to believe that the bearings are shot at 55K. He shows his prejudice to wards Corvette's with his statement. I wonder how he feels about Camaro's or TransAm with the same engine? Can you tell us what the oil pressure is like when the engine is hot at idle and road speed. Do you have an auto or standard trans?

 

[beachrover]

I find it hard to believe that the bearings are shot at 55K. He shows his prejudice to wards Corvette's with his statement. I wonder how he feels about Camaro's or TransAm with the same engine? Can you tell us what the oil pressure is like when the engine is hot at idle and road speed. Do you have an auto or standard trans?

Again, he feels the same as you, he said he would bet that the flywheel is cracked but that it "could" be rod bearings. The oil pressure is one of the things that he looked at closely while we were out. It maintains around 10 to 12lbs at idle and he said that if it was the bearings, it should drop to almost nothing or nothing at all. He als had me "power brake" it. I put the car in reverse, held down the brake and reved the engine up to about 2500 RPM's and held it there. He then had me slowly decelerate and the "knocking" sound would come back at exactly 1500 RPM's. He said that this points more and more to the flywheel. He also initially thought it could be a CAT going out but said it didn't have the right sound. By the way it is an automatic.

I don't think he feels negative about the Corvettes, he was just making a slight joke.

 

[JEFNLSA]

I would not rule out a bad cat. Get under there w/ some kind of listening tool and check each cat...

 

[GuyzVette]

I had the same thing. A clicking sound. Turned out to be a small hole in the header gasket. When I would accelerate, the pressure would cause the exhaust to go out the hole, making the popping sound. Unfortunately, it's labor intensive, and cost a few hundred, so I hope it is just the neighbor's cat...

 

[beachrover]

Follow up:
mechanic just called and it was the main CAT. Flywheel & bearings looked fine.

 

[Robertwav1]

Interesting and thanks for sharing. We all need to know where strange noises can actually come from. Cheers!

 

[ANDY199afd]

noise

I have a simular noisw sounds like a knock to me. Dealer said it is injector noise and don't worry about it but it is driving me nuts...........