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Discussion Starter · #1 ·
As the title says, I have a 2020 with 36k miles. Last month, I heard a slight knocking/tapping sound under acceleration. (usually, between 1200-1800 rpm or up to approx 30mph.) It was due for an oil change, so I made an appointment with the dealer. They investigated, and long story short, they ended up replacing the engine under warranty (they found meta l shavings in the oil, and 'after about 10 calls to the GM tech line, GM chose to replace the engine'. Without really uncovering the underlying cause) The car was parked all holiday weekend, and I drove it to work this morning. I heard the exact same noise, under the exact same circumstances. This is about 170 miles on the brand new GM 'crate motor', installed by the dealer.

I called the dealer this afternoon, and I will be returning it to them in the next two days.

Has anyone else had a similar experience? Is this a widespread issue?
 

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Happened to a friend of mine 30 years ago. He bought his wife a Oldsmobile Calais, with the exact same description of events.

It turned out to be the core of the catalytic converter rattling.

It's a wonder car companies can stay in business at all.

Let us know what happens.
 

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Discussion Starter · #3 ·
I will update as this unfolds. Curiously, the loaner car that I was given was also a 2020 Traverse. I tried to replicate the noise in the loaner car, I couldn’t. I don’t think the trim level (LT for the loaner, and LS for mine) would make any difference, would it? Maybe more sound deadening materials?
 

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You may have had two issues, one of which was remedied because they found metal shavings in the oil. The sound--which led to discover of metal shavings, evidently is from something other than the "oil/shavings" problem; as indicated by AlisoBob, could be the catalytic converter or something else external to the engine. However, keep us posted.
 

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Discussion Starter · #5 ·
The Dealer just called.
The culprit, according to the mechanic, was a baffle inside the intake manifold. This engine has a plastic intake manifold, as so many newer engines do, and apparently when it warms up, the baffle that is broken (or has come loose somehow) rattles in relation to engine speed. They replaced the manifold, and (hopefully) checked everything out.
I’m curious if the broken baffle had anything to do with the original engine failure, specifically, if any piece of it had broken off and ended up in the combustion chamber. And if so, how are they sure that another piece hasn’t done the same damage to the new engine.
I did get the extended power train warranty, as I knew that I would be putting major miles on this car. Honestly, my faith in this vehicle has been shaken.
Has anyone else had a similar experience?
 

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99.99% sure nothing was wrong with the OEM engine. If was a slow week, the dealer swapped engines on GM's dime to give the Mechanics something to do. They tried that BS on my wife's 2012 Tahoe. They said the transmission was leaking out of the front pump and the whole thing needed to be rebuilt at 2200 miles. (The car was there to get rear glass latch fixed). So I go down there and march straight to where the car is to see the "leak" for myself. The mechanic tried to shoo me out of his bay, and I told him to pound sand. Of course, there was no leak. I called the Service Manager out and reemed his ass. I told him I was going to GM with this if he did not give me a free parts dept shopping spree. He literally begged me not to go to GM, and I got a few hundred bucks worth of maintenance. Dealerships are so friggin' slimy.
This was at Connell Chevrolet in Costa Mesa Ca.
I suggest no one ever goes there.
 
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