curt05
Thread Starter
Heel & Toe
Joined: Jul 2007
Posts: 24
Likes: 0
curt05
have a c5 and have wondered if anyone has ever tried to undercoat the pans underneath to reduce road noise. also have that diesel knock until it warms up--unmodified with 40000 miles. have heard every thing from carbon buildup to throttle body cleaning and not really sure what causes it but it is an unpleasent sound until hot. any ideas??
Racer
Joined: Sep 2006
Posts: 464
Likes: 2
From: New Bern NC
I've never heard of anyone putting an under coat on their C5 before. Dynamat yeah but it adds a lot of weight to the car so I'm not sure if you want to do that. Knocking until it warms up.... sounds like spark timing to me. Does your check engine light come on? Have you checked your codes?
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
have a c5 and have wondered if anyone has ever tried to undercoat the pans underneath to reduce road noise. also have that diesel knock until it warms up--unmodified with 40000 miles. have heard every thing from carbon buildup to throttle body cleaning and not really sure what causes it but it is an unpleasent sound until hot. any ideas??
with noahdr, most guys try two things to reduce noise. Get rid of the stock tires and suddenly the noise levels drop instantly. The next step is Dynamat in the cockpit and trunk.The noise on start is fairly common with the Vette. Most guys suggest its either the dreaded GM piston slap or the lifters dropping when cold. A bottle of Techron or a treatment with Sea Foam can't hurt. Generally, most agree that unless it gets really bad it's nothing to worry about.
Try pistonslap.com for background info.
Le Mans Master
Joined: Feb 2002
Posts: 6,937
Likes: 21
From: Waldorf MD
Those "pans" have honeycombed balsa wood inside them, so I don't think noise gets transmitted by them.
If you want to reduce noise, stuff 4 Inch home fiberglass insulation into plastic garbage bags and stuff the rear 3 compartments. You will be amazed. Low cost, no weight, very effective.
The noise you hear is probably the dreaded pliston slap. Read about it at pistonslap.com
Good luck.
If you want to reduce noise, stuff 4 Inch home fiberglass insulation into plastic garbage bags and stuff the rear 3 compartments. You will be amazed. Low cost, no weight, very effective.
The noise you hear is probably the dreaded pliston slap. Read about it at pistonslap.com
Good luck.
Team Owner
Joined: Oct 2006
Posts: 65,010
Likes: 133
From: Title town, Champs live here.
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16-'17-'18-'19
Undercoat=no lessing of noise. As stated search piston slap for your dieseling problem, losing the runflats will help w/ interior noise ,I have heard, but I just went with headers and exhaust never hear the run-flats
