Cold Startup knock
Thread Starter
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Cold Startup knock
I was traveling during the holidays and out in the midwest, cold morning, I started it up and got some serious knocking. It was not a lifter tapping. I shut her down immediately and checked the oil, it was at a normal level. Restarted, the knocking continued briefly then went away on its own. An hour later, I had the oil changed as it was down to %9 life left. No problems since. It was 26 degrees outside at the time this happened. Thoughts?
Le Mans Master
Joined: Jan 2005
Posts: 5,611
Likes: 5
From: Thousand Oaks California
I believe this is normal due to the extended vehicle park time plus the cold temperatures. It takes time to build up oil pressure when the oil is cold. If something is wrong mechanically, most likely you will get the knock on every cold start up.
I assume you are using the correct synthetic SAE 5w-30???
I assume you are using the correct synthetic SAE 5w-30???
Last edited by calemasters; Dec 31, 2009 at 02:15 PM.
Burning Brakes
Joined: Jan 2009
Posts: 975
Likes: 67
From: Pleasant Hill Ca.
I was traveling during the holidays and out in the midwest, cold morning, I started it up and got some serious knocking. It was not a lifter tapping. I shut her down immediately and checked the oil, it was at a normal level. Restarted, the knocking continued briefly then went away on its own. An hour later, I had the oil changed as it was down to %9 life left. No problems since. It was 26 degrees outside at the time this happened. Thoughts?
(Accusump Oil Accumulator - Canton - TREperformance.com)
However, most of us use these to help prevent oil starvs on high G
cornering; while there is an added benefit of preventing cold knocking when the engine is cold
Melting Slicks
Joined: Feb 2004
Posts: 3,307
Likes: 111
From: Tucson AZ
Hopefully the knocking was a collapsed hydraulic lifter. Even with 0 oil pressure there should not be enough clearance for a connecting rod to knock. After it runs for a short period the lifter plunger pumps up with oil pressure and removes the excess clearance between the lifter/pushrod/rocker.
A rod knocking is loudest when letting off the throttle (decelerating) and a lifter will be fairly constant even during acceleration. A rod knocking will shake the entire car and you can really feel it in the pedals and the steering wheel.
Does this car still have warranty?
A rod knocking is loudest when letting off the throttle (decelerating) and a lifter will be fairly constant even during acceleration. A rod knocking will shake the entire car and you can really feel it in the pedals and the steering wheel.
Does this car still have warranty?
Thread Starter
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Nah, out of normal warranty other than the 5yr/100K warranty which will cover this for sure. Its possible it was a collapsed lifter. Yes, I'm using the standard Mobil1 5W-30 oil as called for. I had just completed the trip out there the morning before, 1457 miles one-way and it was started that afternoon briefly too. It had been shut down for only about 16 hours or so when this happened. This car is an '07 with now 82K miles on it. Engine was started and idled only. I did not rev it at all.
Supporting Vendor
Joined: Sep 2007
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From: Pensacola Florida GO GATORS!!! www.rlsebring.com www.c6c7vette.com
St. Jude Donor '17
I have a similar noise upon cold start up. As it's been colder lately the noise is more prevelent. Only last about a minute until things start getting warmed /pumped up then it's it's gone until next cold start up.
I've been told it's cold start piston slap. I have HP Tuners and have adjusted the piston slap table. It's not as bad but cannot seem to adjust further as other things start to happen.
I've been told it's cold start piston slap. I have HP Tuners and have adjusted the piston slap table. It's not as bad but cannot seem to adjust further as other things start to happen.
Thread Starter
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Piston slap table...lol. This was a lot more than piston slap, almost a rod knock type sound, but not quite that deep but not a light tap sound from a lifter either. A collapsed lifter, maybe...
3rd Gear
Joined: Aug 2022
Posts: 3
Likes: 1
Mine is a knock coming from the back of the engine, not any particular piston. Noticeable when engine is cold and under a load (going up a hill). Goes away when the engine temperature warms up. After that, it’s fine.
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2023 C6 of the Year Finalist - Unmodified
The most common culprit would be piston slap though, which isn't a cause for concern imo. At least its not rod knock man!
Last edited by BlissfulC; Feb 23, 2024 at 04:40 AM.
Race Director
Joined: Dec 2013
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If your going to leave the car sit for months at end, then when you go to start it the first time after sitting, hold the gas pedal all the way down when you go to start the car.
This will turn off the injectors so the starter turns the motor for about 5 seconds them stops without starting the motor. This will allow the pump to push oil through all the motor parts to pre-lube the motor, before you go to start it again (this time, do not touch the gas pedal).
As for motor oil, it gets change yearly, or every 12K miles. Never play the oil life percentage game unless the car is a DD, and before you go to start the car sitting that long, check the amount of oil in the system before hand.
This will turn off the injectors so the starter turns the motor for about 5 seconds them stops without starting the motor. This will allow the pump to push oil through all the motor parts to pre-lube the motor, before you go to start it again (this time, do not touch the gas pedal).
As for motor oil, it gets change yearly, or every 12K miles. Never play the oil life percentage game unless the car is a DD, and before you go to start the car sitting that long, check the amount of oil in the system before hand.
