97 knock
Thread Starter
Racer
Joined: Sep 2005
Posts: 383
Likes: 0
From: Michigan
97 knock
Well brought our 97 coupe home sunday it has 27,000 miles on it. The wife drove it home so I could see it rolling down the road. Trip was 150 miles. everything worked fine but when we got home and my wife was setting in the driveway I noticed a knocking noise. Not a lifter tick (I know what that sounds like) It was kind of a dull kind of knock. I'm thinking (rod). But when she put in park or nutural the noise quit. I started it the next afternoon and let it run for say 10 min. But I couldn't get it to make any noise. I emailed the previous owner to ask him about it. He told me he took it in and was told it was exhaust noise and that it is common for C5s and there wasn't anything they could do about it. Is this true? It doesn't sound like any exhaust noise I ever heard. Our 2000 C5 never made any noise. What do you think?
Melting Slicks
Joined: Feb 2006
Posts: 2,172
Likes: 104
From: Des Moines Iowa
Assume it's an automatic, since you referance park/neutral. What you describe, is a knock when @ idle, but under transmission load.....hence the no knock when in neutral/park situation.
When it was making the knocking noise, did it speed up with increase in engine speed and was it consistant with the increased engine speed?
Suggest you whip out the trusty old engine stethoscope the next time you hear the knock and open the hood and try to loccate isolate same.
Good luck
When it was making the knocking noise, did it speed up with increase in engine speed and was it consistant with the increased engine speed?
Suggest you whip out the trusty old engine stethoscope the next time you hear the knock and open the hood and try to loccate isolate same.
Good luck
Thread Starter
Racer
Joined: Sep 2005
Posts: 383
Likes: 0
From: Michigan
Assume it's an automatic, since you referance park/neutral. What you describe, is a knock when @ idle, but under transmission load.....hence the no knock when in neutral/park situation.
When it was making the knocking noise, did it speed up with increase in engine speed and was it consistant with the increased engine speed?
Suggest you whip out the trusty old engine stethoscope the next time you hear the knock and open the hood and try to loccate isolate same.
Good luck
When it was making the knocking noise, did it speed up with increase in engine speed and was it consistant with the increased engine speed?
Suggest you whip out the trusty old engine stethoscope the next time you hear the knock and open the hood and try to loccate isolate same.
Good luck
Thread Starter
Racer
Joined: Sep 2005
Posts: 383
Likes: 0
From: Michigan
I listened to the knocking sounds from your post but it dosen't sound like any of those. it's more of a dull sound that seems like it's coming from deep in the engine.
I talked to 2 diffrent people at work and the both said trhe same thing. "cracked flywheel" of course a flex plate in a automatic. What do you think about that? Is this common?
I have pulled the battery it was no good. I didn't want it to freeze and crack in the car. I won't be running it until spring now, it's too nasty in Mich. in the winter. I will let everyone know what is going on when I find out.
I talked to 2 diffrent people at work and the both said trhe same thing. "cracked flywheel" of course a flex plate in a automatic. What do you think about that? Is this common?
I have pulled the battery it was no good. I didn't want it to freeze and crack in the car. I won't be running it until spring now, it's too nasty in Mich. in the winter. I will let everyone know what is going on when I find out.
Racer
Joined: Dec 2005
Posts: 426
Likes: 0
From: Northern Virginia
There have been a couple of threads about knocking noises of late. One posted a link to a site that talks about piston slap and has a recording of what that sounds like. The site was
http://pistonslap.com/
A second thread was about a spun rod bearing . Here's the video and sound track of his engine:
http://www.youtube.com/watch?v=gRSrUQudaP0
The thread about this persons problem is here:
http://forums.corvetteforum.com/c5-t...d-bearing.html
Check them out and compare to the noise you are hearing.
Of course there are othger things that it may be as well like broken exhaust parts that are vibrating when under load etc.
Keep us posted..........
http://pistonslap.com/
A second thread was about a spun rod bearing . Here's the video and sound track of his engine:
http://www.youtube.com/watch?v=gRSrUQudaP0
The thread about this persons problem is here:
http://forums.corvetteforum.com/c5-t...d-bearing.html
Check them out and compare to the noise you are hearing.
Of course there are othger things that it may be as well like broken exhaust parts that are vibrating when under load etc.
Keep us posted..........
Aren't thaose cause by missing a shift and over revving? I just can't imagine piston slap being so bad on 4 cylinders that it leaves valve reliefs on 3.
Congrats on the 97 Steve! They are always fun to figure out what's going on with the first model year.
Thread Starter
Racer
Joined: Sep 2005
Posts: 383
Likes: 0
From: Michigan
Are the pictures on piston slap. com of the pistons withthe valve marks in them supposed to be caused by piston slap?
Aren't thaose cause by missing a shift and over revving? I just can't imagine piston slap being so bad on 4 cylinders that it leaves valve reliefs on 3.
Congrats on the 97 Steve! They are always fun to figure out what's going on with the first model year.
Aren't thaose cause by missing a shift and over revving? I just can't imagine piston slap being so bad on 4 cylinders that it leaves valve reliefs on 3.
Congrats on the 97 Steve! They are always fun to figure out what's going on with the first model year.
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Thread Starter
Racer
Joined: Sep 2005
Posts: 383
Likes: 0
From: Michigan