Could It Be.......Piston Slap?
Thread Starter
Racer
Joined: May 2000
Posts: 363
Likes: 0
From: Eureka CA
Could It Be.......Piston Slap?
I have a 97 A4, purchased it used with 29,000 miles on it. Currently has 36,000 miles. No cold startup noises at all. I recently put 6,000 miles on it during an extended road trip, still no cold start up noises.
A few days after returning home, I start it up and it sounds like a rod is about to come through the side of the engine!!!!! This loud, annoying noise lasts for a few moments then goes away. Car runs fine and is quiet when warm. Just seems to happen after sitting overnight. I have read many articles on the dreaded "piston slap", but normally does this happen just out of the blue?
Sure is embarassing upon a cold startup with people standing around!!!!
Do any of you have to deal with this noise?
Something GM should be proud of! :auto:
A few days after returning home, I start it up and it sounds like a rod is about to come through the side of the engine!!!!! This loud, annoying noise lasts for a few moments then goes away. Car runs fine and is quiet when warm. Just seems to happen after sitting overnight. I have read many articles on the dreaded "piston slap", but normally does this happen just out of the blue?
Sure is embarassing upon a cold startup with people standing around!!!!
Do any of you have to deal with this noise?
Something GM should be proud of! :auto:
Le Mans Master
Joined: Feb 1999
Posts: 6,269
Likes: 1
From: Richmond Ca
Re: Could It Be.......Piston Slap? (silverhead)
Yep! :mad
Mine started under the same circumstances. After a 2000 mile road trip. 25,000 miles on the odo!
I'm on the verge of going to the dealer about it. I have to get some vasoline first though! :( :sad:
[Modified by wwashing, 11:39 PM 9/4/2003]
Mine started under the same circumstances. After a 2000 mile road trip. 25,000 miles on the odo!
I'm on the verge of going to the dealer about it. I have to get some vasoline first though! :( :sad:
[Modified by wwashing, 11:39 PM 9/4/2003]
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Re: Could It Be.......Piston Slap? (wwashing)
I had the same problem at 10K miles after returning from the 50th in Bowling Green. Someone on another forum who specializes in C5's recommended a carbon cleaner by GM, part #12345515. I put it in for two tanks of gas, one bottle per tank. I also drove the car a little more aggressively, i.e., I didn't run it in higher gears all the time but rather kept the RPM's up at around 2K. No more noise as of right now. I think that during my trip the extended use of 6th gear helped build some carbon on the pistons. Not sure it will help you guys, but it might be worth a shot since the cost is so low and no-one has to rip apart your motor.
Just noticed you are both from CA so you likely have the highly oxygenated fuel as we do in New England. I don't think that helps the situation at all plus you you 10% of your fuel mileage.
[Modified by vettenuts, 6:31 AM 9/5/2003]
Just noticed you are both from CA so you likely have the highly oxygenated fuel as we do in New England. I don't think that helps the situation at all plus you you 10% of your fuel mileage.
[Modified by vettenuts, 6:31 AM 9/5/2003]
Le Mans Master
Joined: Feb 1999
Posts: 6,269
Likes: 1
From: Richmond Ca
Re: Could It Be.......Piston Slap? (vettenuts)
I had the same problem at 10K miles after returning from the 50th in Bowling Green. Someone on another forum who specializes in C5's recommended a carbon cleaner by GM, part #12345515. I put it in for two tanks of gas, one bottle per tank. I also drove the car a little more aggressively, i.e., I didn't run it in higher gears all the time but rather kept the RPM's up at around 2K. No more noise as of right now. I think that during my trip the extended use of 6th gear helped build some carbon on the pistons. Not sure it will help you guys, but it might be worth a shot since the cost is so low and no-one has to rip apart your motor.
Just noticed you are both from CA so you likely have the highly oxygenated fuel as we do in New England. I don't think that helps the situation at all plus you you 10% of your fuel mileage.
[Modified by vettenuts, 6:31 AM 9/5/2003]
Just noticed you are both from CA so you likely have the highly oxygenated fuel as we do in New England. I don't think that helps the situation at all plus you you 10% of your fuel mileage.
[Modified by vettenuts, 6:31 AM 9/5/2003]
Thread Starter
Racer
Joined: May 2000
Posts: 363
Likes: 0
From: Eureka CA
Re: Could It Be.......Piston Slap? (wwashing)
There is another GM process, decarbonization, with what they call, Top End Cleaner, I think. There is a Tech Tip about doing this on this forum. This could be another option.
My 2000 Silverado with a 5.3 developed "piston slap". Unfortunately, GM feels this is "normal" and will not harm the engine so they would do nothing in my case.
I found a good write-up at this site: http://www.idavette.net/hib/02ls6/page5.htm
Thanks for the tip, as well. :auto:
My 2000 Silverado with a 5.3 developed "piston slap". Unfortunately, GM feels this is "normal" and will not harm the engine so they would do nothing in my case.
I found a good write-up at this site: http://www.idavette.net/hib/02ls6/page5.htm
Thanks for the tip, as well. :auto:
Burning Brakes
Joined: Feb 1999
Posts: 1,165
Likes: 1
From: San Jose CA
Re: Could It Be.......Piston Slap? (silverhead)
I've been reading this forum for over 4 years now and learned that piston slap last about 1 - 2 minutes after startup in the morning.
If you hear the noise for only a few seconds in the morning I would check how fast your oil pressure builds up. There have been reports of oilpump bypass valves sticking open (on 97 - '99 C5s) which give you very low oil pressure upon startup and causes excessive wear on the rod bearings. Some members here even got new engines from GM because their dealer said "this noise is normal" :) I think there is even a TSB on this.
:cheers:
If you hear the noise for only a few seconds in the morning I would check how fast your oil pressure builds up. There have been reports of oilpump bypass valves sticking open (on 97 - '99 C5s) which give you very low oil pressure upon startup and causes excessive wear on the rod bearings. Some members here even got new engines from GM because their dealer said "this noise is normal" :) I think there is even a TSB on this.
:cheers:
