Light tapping or knocking sound
Thread Starter
Burning Brakes
Joined: Sep 2006
Posts: 985
Likes: 0
From: Cumming Georgia
Light tapping or knocking sound
Hi,
Just got my 2000 Mag Red Coupe last week, and absolutely love it! My wife is out on a trip in it right now, and loves it too
.
My question is that when the engine is cold, I hear what sounds like a tapping or light knocking sound coming from the engine compartment, which gets a bit quieter in a few minutes, and is almost undetectable after the engine has been at operating temp for about ten to fifteen minutes.
Oil pressure shows about 50 psi cold, and 35-40 psi hot. Uses Mobil1 5W-30 (I have known the previous owner for a year, and he took excellent care of the car).
As best as I can tell, the knock or tap happens once each revolution, and the frequency goes up with the engine rpm. It doesn't start until somewhere between 800-1000 rpm.
Has anyone had any experience with this type of noise? I am hoping it is just an innocent sound, but aware that it could be more expensive to repair. Jim gave me a great deal on the car, and then spent about $850 on tires, key fobs, and other items before he would let me take possession, so I have no complaints or regrets whatsoever. Also, the car is still covered by a Maxcare warranty until April 2007.
Thank you in advance for your input.
Tim Glover
Just got my 2000 Mag Red Coupe last week, and absolutely love it! My wife is out on a trip in it right now, and loves it too
.My question is that when the engine is cold, I hear what sounds like a tapping or light knocking sound coming from the engine compartment, which gets a bit quieter in a few minutes, and is almost undetectable after the engine has been at operating temp for about ten to fifteen minutes.
Oil pressure shows about 50 psi cold, and 35-40 psi hot. Uses Mobil1 5W-30 (I have known the previous owner for a year, and he took excellent care of the car).
As best as I can tell, the knock or tap happens once each revolution, and the frequency goes up with the engine rpm. It doesn't start until somewhere between 800-1000 rpm.
Has anyone had any experience with this type of noise? I am hoping it is just an innocent sound, but aware that it could be more expensive to repair. Jim gave me a great deal on the car, and then spent about $850 on tires, key fobs, and other items before he would let me take possession, so I have no complaints or regrets whatsoever. Also, the car is still covered by a Maxcare warranty until April 2007.
Thank you in advance for your input.
Tim Glover
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
Sure, it's called "piston slap", and it is benign; enjoy the car and don't sweat it.
You can read more about this here at www.pistonslap.com but realize it's not harmful, more a function of "high performance" piston to cylinder wall clearances.
You can read more about this here at www.pistonslap.com but realize it's not harmful, more a function of "high performance" piston to cylinder wall clearances.
Last edited by Dan_the_C5_Man; Nov 28, 2006 at 11:20 PM.
Le Mans Master
Joined: Feb 2006
Posts: 5,488
Likes: 4
From: USA
My car did the same thing when I bought it 10 months ago. The problem was I was using regular gasoline. As soon as I started using 91octane gas, the problem got much better. Then I started using Chevron with Techron and then it stopped.
I've noticed the problem coming back lately so I think it is because few are using 91 octane with the gas so expensive or they are not adding the Techron to the gas.
I say this b/ I put a bottle of Techron from PepBoys in a full tank and the problem all but stopped again. Hope this helps
I've noticed the problem coming back lately so I think it is because few are using 91 octane with the gas so expensive or they are not adding the Techron to the gas.
I say this b/ I put a bottle of Techron from PepBoys in a full tank and the problem all but stopped again. Hope this helps
Thread Starter
Burning Brakes
Joined: Sep 2006
Posts: 985
Likes: 0
From: Cumming Georgia
Thank you all for the input
Hi everyone,
I really appreciate the info. I noticed I cannot hear what I have learned is piston slap if the radio is on, so that's what I will do. We look forward to enjoying the car. If it ain't broke, I'm happy not to fix it .
Dang! I was looking to use regular gas, either Chevron or Texaco, but wanted a couple of weeks first to get used to the car, so I filled it with Texaco premium the day I picked it up. Now I'm not so sure about using regular. I don't hot dog the car, I just love the appearance, and the cool factor. That is why I bought my '69 (the picture on my avatar) 26 years ago. The house and then new wife were well worth giving it up; I just didn't know then it would take this long to get another.
On the plus side, it is averaging over 24mpg, and that is half freeway and half side roads. That is really cool!
Tim Glover
I really appreciate the info. I noticed I cannot hear what I have learned is piston slap if the radio is on, so that's what I will do. We look forward to enjoying the car. If it ain't broke, I'm happy not to fix it
.Dang! I was looking to use regular gas, either Chevron or Texaco, but wanted a couple of weeks first to get used to the car, so I filled it with Texaco premium the day I picked it up. Now I'm not so sure about using regular. I don't hot dog the car, I just love the appearance, and the cool factor. That is why I bought my '69 (the picture on my avatar) 26 years ago. The house and then new wife were well worth giving it up; I just didn't know then it would take this long to get another.
On the plus side, it is averaging over 24mpg, and that is half freeway and half side roads. That is really cool!
Tim Glover
