slap sound when cold
Thread Starter
Staging Lane
Joined: Aug 2005
Posts: 93
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slap sound when cold I have a 2000 trans am and when i start it up after it has been sitting for a while and the motor is cold it almost sounds like a piston slap or something like that. It does go away as soon as the car warms up and builds oil pressure. I know that these are noisy motors and was wondering if anyone has the same problem, know what it would be and if i should worry about it???
Thanks in advance guys, jay
Thanks in advance guys, jay
TECH Apprentice
Joined: Dec 2004
Posts: 393
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Yea, they knock and burn oil. Not much you can do about it, short of new pistons, machine work etc..Just run inexpensive 5w-30 dino oil and drive it.
80k on my 01, bought it brand spanking new and heard the "slap" about a week after I took it home. I complained over and over, GM wouldn't fix it; gave me a 100k mile engine warranty instead.
Watch it throw a rod at 105k
80k on my 01, bought it brand spanking new and heard the "slap" about a week after I took it home. I complained over and over, GM wouldn't fix it; gave me a 100k mile engine warranty instead.
Watch it throw a rod at 105k
Thread Starter
Staging Lane
Joined: Aug 2005
Posts: 93
Likes: 0
^^^isn't that the way it always works out???
I have noticed the sound more ever since i went to synthetic oil at the begining of this year, kinda wish i didn't now...
thanks for the info fellas..........
I have noticed the sound more ever since i went to synthetic oil at the begining of this year, kinda wish i didn't now...
thanks for the info fellas..........
TECH Apprentice
Joined: Dec 2004
Posts: 393
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Just run regular 5w-30 oil. mine uses a quart every 3000 miles, and I couldn't justify the expense of synthetic oils.
I've been changing the oil every 5000 miles, and 80k miles later It still runs like the day I drove it off the lot.
They will knock cold and use some oil, but they keep on going. GM had enough "faith" in it to give me a 100k mile warranty, so I'm not worried about it and neither should you guys.
I've been changing the oil every 5000 miles, and 80k miles later It still runs like the day I drove it off the lot.
They will knock cold and use some oil, but they keep on going. GM had enough "faith" in it to give me a 100k mile warranty, so I'm not worried about it and neither should you guys.
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Mine chuckles all the time but burns zero oil. You
have short skirt pistons and loose enough in the
bore to let this big a motor spin efficiently up to
7000+ RPM. I'll take that tradeoff.
have short skirt pistons and loose enough in the
bore to let this big a motor spin efficiently up to
7000+ RPM. I'll take that tradeoff.
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Yeah the cold start piston slap is nothing to worry about. I work in the service department at a pontiac/buick dealership and have seen a few engines come apart for really loud piston slaps to have different pistons put in to take care off the noise. Every engine I have seen torn down has had no visible scuffs or scares to the cylander walls.
My understanding of why this happens it that in attempts to reduce roataing mass they made the skirts on the pistons shorter. And while the piston is cold in the cylander it rocks back and forth a little until it expands a little with heat.
But anyways really not something to worry about. My firehawk does it and will till
I take the motor apart to build it up
My understanding of why this happens it that in attempts to reduce roataing mass they made the skirts on the pistons shorter. And while the piston is cold in the cylander it rocks back and forth a little until it expands a little with heat.
But anyways really not something to worry about. My firehawk does it and will till
I take the motor apart to build it up