Odd noise when powering off motor
Thread Starter
Cruising
Joined: Jul 2022
Posts: 13
Likes: 9
Odd noise when powering off motor
Hey guys,
'74 Stingray owner here. Hearing an odd noise as I shut the motor off. It's more aggressive the longer the drive. This time I just went for a spin around the subdivision and tried to capture in the video. It's right at the end. Any idea what this could be?
'74 Stingray owner here. Hearing an odd noise as I shut the motor off. It's more aggressive the longer the drive. This time I just went for a spin around the subdivision and tried to capture in the video. It's right at the end. Any idea what this could be?
Le Mans Master
Joined: Jun 2019
Posts: 7,640
Likes: 2,460
From: Indiana
Sounds like Engine run on.. or dieseling.
possible causes
- tune up
- throttle plates opened too far at idle
- not sure youryear has idle solenoid
take some good pics of carb area linkage etc..
possible causes
- tune up
- throttle plates opened too far at idle
- not sure youryear has idle solenoid
take some good pics of carb area linkage etc..
Team Owner
Joined: Mar 2002
Posts: 44,621
Likes: 1,826
From: Huntsville AL
As Interpon pointed out this sound like engine run on (dieseling). The 74 was equipped with an idle stop solenoid that when powered on (car ignition switch on) the solenoid extends and sets the base idle for the engine and when the car shut off (car ignition switch off) the solenoid is released and the idle is dropped to keep the engine from trying to keep running. I would inspect / adjust that first to see if that fixes your problem.
On a side note, I had a 74 back in the mid 90's that did the same thing and one day for whatever reason I filled up with premium gas and the problem went away. My run-on condition was worse than yours.
On a side note, I had a 74 back in the mid 90's that did the same thing and one day for whatever reason I filled up with premium gas and the problem went away. My run-on condition was worse than yours.
Racer
Joined: Jul 2018
Posts: 331
Likes: 123
From: Sandusky, OH
Two ways to stop the diesel problem. Used to do that way back with drag car with too much idle speed and initial advance:
One: Stick it in gear with the brake on and kill the key. Looks cool with a stick shift. And tests your coordination.
Two: Double flip the key to Off. From on to off, on, off. Always sounded sweet with open headers, too.
Or you can fix the problem like has already been explained. I always make the stall-brake-clutch move when the choke high idle is going. The rumor was you’ll break the crank letting it diesel…
Steve O.
One: Stick it in gear with the brake on and kill the key. Looks cool with a stick shift. And tests your coordination.
Two: Double flip the key to Off. From on to off, on, off. Always sounded sweet with open headers, too.
Or you can fix the problem like has already been explained. I always make the stall-brake-clutch move when the choke high idle is going. The rumor was you’ll break the crank letting it diesel…
Steve O.
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
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What are you running for octane and when was the last oil change and tuneup?
