Engine Knock
Thread Starter
2nd Gear
Joined: Sep 2004
Posts: 2
Likes: 0
From: St. Catharines ONTARIO
Engine Knock
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We have just completed Route 66 driving our '01 6-speed convertible. Part way thru the trip, I noticed a knock on cold start in the morning, similar to lifters. Once warmed up, this knock would not reappear until the next morning. Also, in driving the 7,000 miles the car used 2 quarts of Mobil 1, although it had not used oil before. The knocking does not seem to impact on performance or economy. Does anyone have a similar sympton? What should I do? I really don't want the local dealer to tear into the engine unless necessary.
We have just completed Route 66 driving our '01 6-speed convertible. Part way thru the trip, I noticed a knock on cold start in the morning, similar to lifters. Once warmed up, this knock would not reappear until the next morning. Also, in driving the 7,000 miles the car used 2 quarts of Mobil 1, although it had not used oil before. The knocking does not seem to impact on performance or economy. Does anyone have a similar sympton? What should I do? I really don't want the local dealer to tear into the engine unless necessary.
Le Mans Master
Joined: Jun 2004
Posts: 6,269
Likes: 50
From: Dallas Texas
St. Jude Donor '06-'07-'09-'10
If it's a tapping sound like valve lifters, it probably piston slap, which has been discussed on numerous threads here. If your still in warranty, then it's up to you if you want to go thru the hassle of getting it fixed. Otherwise, drive it. Also, 3500 miles per quart usage is good as far as I'm concerned, though others may disagree. 
Heel & Toe
Joined: Mar 2004
Posts: 16
Likes: 0
From: Stockton IL
I feel your pain. FWIW. Last October we also drove Old Route 66 from Chicago to L.A. and towards the end of the trip we developed a cold start knock (the dreaded Piston Slap 
) that disappeared after about a minute and a half of warm up. We never noticed oil consumption probably because I changed oil twice on the trip. I checked with my dealer when we got home and told me that it's normal, and that it's not a durability problem. Ours was a '98 Silver A4 with 19K on when we finished the trip. I traded it off in Jan. 04. I wonder if I caused mine from leaving it in drive instead of 3rd because of the long ascends and 55mph and less speed limits on Old 66. I think I was lugging the engine with only 2.73 gears in it and the LS1 pistons barely have a skirt. I know this is of no consulation but wanted to share the similarity. Other than that, the 66 trip was probably the most memorable trip ever . Best of Luck!!!
Team Owner
Joined: May 2001
Posts: 36,836
Likes: 243
From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
There is a big difference between "engine knock" and "lifter noise". Various "lifter noise" on cold starts have been associated with the Evaporative Purge Solenoid on some vehicles. It makes a clicking sound when operating. It's located on the driver's side underneath the fuel rail cover and may only operate in "open loop" status. Once the engine warms up, and goes into "closed loop" status (for emission control reasons), this solenoid isn't so active anymore. Try popping off the fuel rail cover when it's cold and see if it is where the "lifter" noise is coming from when you start the engine. Mine used to make a little more noticeable noise in the past until I reformed the bracket a bit to make sure the solenoid assembly wasn't contacting anything which will make the solenoid sound louder while it's operating.
BTW, this will have nothing to do with any oil usage issues you spoke of.
HTH,
Robert
BTW, this will have nothing to do with any oil usage issues you spoke of.
HTH,
Robert
