3rd Generation Specific (1993-2002) 1993-2002 Discussion including performance modifications and Technical Support Sections.
Sponsored by:

Knocking sound for 10 seconds at startup

Thread Tools
 
Search this Thread
 
Old 02-02-21, 04:29 PM
  #1  
Senior Member

Thread Starter
iTrader: (2)
 
Badappex's Avatar
 
Join Date: Aug 2001
Location: Florida
Posts: 372
Likes: 0
Received 0 Likes on 0 Posts
Knocking sound for 10 seconds at startup

Helping a buddy out. Anyone had this issue before? Seems to be coming from towards the rear of the engine.
Length of the knocking varies with the cold weather so quesitoning if it s a oil thing. Checked for loose heat shields, bolts, the usual.

Last edited by Badappex; 02-02-21 at 07:04 PM.
Old 02-02-21, 05:11 PM
  #2  
half ass 2 or whole ass 1

iTrader: (114)
 
cr-rex's Avatar
 
Join Date: Nov 2011
Location: okinawa to tampa
Posts: 3,425
Received 480 Likes on 350 Posts
does it change whether or not youre on the clutch or with rpm?
Old 02-02-21, 05:20 PM
  #3  
Senior Member

Thread Starter
iTrader: (2)
 
Badappex's Avatar
 
Join Date: Aug 2001
Location: Florida
Posts: 372
Likes: 0
Received 0 Likes on 0 Posts
Sometimes. It lessens when the clutch is pressed in/ let out or revved. Cant put the exact timing of what gets it to stop.
Old 02-02-21, 05:39 PM
  #4  
half ass 2 or whole ass 1

iTrader: (114)
 
cr-rex's Avatar
 
Join Date: Nov 2011
Location: okinawa to tampa
Posts: 3,425
Received 480 Likes on 350 Posts
next time its cold, take the inspection plate off the bottom and start the car. just watch the clutch spin until it stops. its possible it could be coming from inside the transmission but i think you would notice something wrong if it were. how heavy of knock sound are we talking here? can you post a video?
Old 02-02-21, 06:18 PM
  #5  
Senior Member

Thread Starter
iTrader: (2)
 
Badappex's Avatar
 
Join Date: Aug 2001
Location: Florida
Posts: 372
Likes: 0
Received 0 Likes on 0 Posts
Pretty heavy. Checking on the slave cylinder to see if the rod might be sticking or anything else. Ill try and post a vid
Old 02-02-21, 08:48 PM
  #6  
Senior Member

Thread Starter
iTrader: (2)
 
Badappex's Avatar
 
Join Date: Aug 2001
Location: Florida
Posts: 372
Likes: 0
Received 0 Likes on 0 Posts
video attached.
Attached Files
File Type: mov
IMG_3257.TRIM.mov (4.66 MB, 143 views)

Last edited by Badappex; 02-03-21 at 12:11 PM.
Old 02-04-21, 01:58 PM
  #7  
Senior Member

Thread Starter
iTrader: (2)
 
Badappex's Avatar
 
Join Date: Aug 2001
Location: Florida
Posts: 372
Likes: 0
Received 0 Likes on 0 Posts
no opinions?
Old 02-04-21, 03:01 PM
  #8  
half ass 2 or whole ass 1

iTrader: (114)
 
cr-rex's Avatar
 
Join Date: Nov 2011
Location: okinawa to tampa
Posts: 3,425
Received 480 Likes on 350 Posts
thats not a knocking sound homie..... i dont mean knock in the technical term either. im saying it in the literal sense as in *knock knock*. thats a rattle. this is important because a sound like that is either an exhaust leak or a loose heat shield.
Old 02-04-21, 04:26 PM
  #9  
Racecar - Formula 2000

 
DaveW's Avatar
 
Join Date: Sep 2002
Location: Bath, OH
Posts: 3,850
Received 277 Likes on 198 Posts
Originally Posted by Badappex
no opinions?
Sounds to me like a metal door rattling (heavier than a heat shield) - maybe the wastegate or similar.

Last edited by DaveW; 02-04-21 at 04:31 PM.
Old 02-04-21, 06:32 PM
  #10  
Original Owner

iTrader: (1)
 
Retserof's Avatar
 
Join Date: Mar 2005
Location: America's Dairyland
Posts: 549
Received 82 Likes on 61 Posts
I would try using a mechanic's stethoscope to locate the source of the noise. Or you can use a 3 foot section of garden hose, or even a large screwdriver as a listing device.
Old 02-04-21, 07:41 PM
  #11  
Senior Member

Thread Starter
iTrader: (2)
 
Badappex's Avatar
 
Join Date: Aug 2001
Location: Florida
Posts: 372
Likes: 0
Received 0 Likes on 0 Posts
Yeah, we tried looking for a loose heat shield or bolt. Its strange because it goes away after a few seconds. Perhaps whatever is loose is settling.
Old 02-04-21, 07:52 PM
  #12  
half ass 2 or whole ass 1

iTrader: (114)
 
cr-rex's Avatar
 
Join Date: Nov 2011
Location: okinawa to tampa
Posts: 3,425
Received 480 Likes on 350 Posts
exhaust leaks do that too
Old 02-05-21, 08:33 AM
  #13  
RX-7 Bad Ass

iTrader: (55)
 
DaleClark's Avatar
 
Join Date: Jan 2002
Location: Pensacola, FL
Posts: 15,399
Received 2,438 Likes on 1,509 Posts
Can't listen to the video at work, but I would suspect the turbo control door in the exhaust manifold. If the actuator isn't preloading it slightly it will rattle when the car is cold and shut up once the car warms up and the metal expands.

Dale
Old 02-05-21, 08:44 AM
  #14  
Newly Rebuilt
 
Axton's Avatar
 
Join Date: Aug 2020
Location: Australia
Posts: 111
Received 42 Likes on 26 Posts
Had a similar sound years ago when the clutch was depressed. It's possible that the front transmission cover has broken and is rattling around between the throw out bearing and the input shaft.

Jump under the car and open the clutch inspection plate, check to see if the cover has broken off.


Old 02-05-21, 08:59 AM
  #15  
Newly Rebuilt
 
Axton's Avatar
 
Join Date: Aug 2020
Location: Australia
Posts: 111
Received 42 Likes on 26 Posts
Originally Posted by DaleClark
Can't listen to the video at work, but I would suspect the turbo control door in the exhaust manifold. If the actuator isn't preloading it slightly it will rattle when the car is cold and shut up once the car warms up and the metal expands.

Dale
Dale's definitely onto it here, it does sound very much like ceramic knocking against cast iron.
Old 03-15-21, 07:09 PM
  #16  
Senior Member

Thread Starter
iTrader: (2)
 
Badappex's Avatar
 
Join Date: Aug 2001
Location: Florida
Posts: 372
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Axton
Had a similar sound years ago when the clutch was depressed. It's possible that the front transmission cover has broken and is rattling around between the throw out bearing and the input shaft.

Jump under the car and open the clutch inspection plate, check to see if the cover has broken off.

Thanks. Hard to tell through the inspection plate with the clutch and flywheel in the way. But i believe its gotta be in the clutch area. Sound goes aways after several clutch pumps.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Cordt
2nd Generation Specific (1986-1992)
3
02-26-11 11:07 PM
IceRain
2nd Generation Specific (1986-1992)
5
07-28-05 05:08 PM
Marxxpress
1st Generation Specific (1979-1985)
13
11-21-03 01:37 AM
jrc240sx
Interior / Exterior / Audio
4
11-27-02 01:23 AM



Quick Reply: Knocking sound for 10 seconds at startup



All times are GMT -5. The time now is 09:46 PM.