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Discussion Starter · #1 · (Edited)
I have seen several threads about this issue. I just ran into this and I wanted to document my experience for any others that run into this. Please let me know if there is an open / active thread I should be posting on instead.

I bought my Malibu second hand in 2017 at roughly 25K miles. Since then the car has been fairly well maintained and only serviced at official Chevrolet service centers. Before this specific issue I had not had any mechanical problems with this car.

While I was driving on a fairly long trip (100 miles in) I noticed the car was idling rough while stopped at a light. Over several more stops the idling got rougher and a Stabilitrak warning flashed up. I drove straight to a Chevy service center and while I was describing the issue the check engine light came on. My car was under 45K miles.

The service center checked compression and guessed that a piston had failed. They did an inspection and a day later they told me they needed to replace all 4 pistons. Interestingly the service center said the problem with the original piston design had been resolved and it was not likely to recur with the replacements. They confirmed the car had received the ECM update to reduce the risk of this specific failure. They told me my car was out of warranty and they gave an initial estimate of ~$4.5K for the repair. The service center suggested I contact GM customer services. I called GM and explained the issue. GM did an investigation and a few days later they agreed with the dealer to cover the majority of the repair. My portion of the cost was under $900.

After the repair my car is running great. I was told that the work is warrantied for 2 years. I feel a bit more nervous about the long term reliability of the car now, so I'd be open to any specific maintenance recommendations for Malibus that have been through this. Or should I sell the car while it is still running well?

As a random aside. I used to hear coolant "gushing" when I shut off the car sometimes. Since the repair I have not heard it. I'm not sure if it is related but I remember seeing this discussed somewhere before so I'm mentioning it just in case.
 

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As a random aside. I used to hear coolant "gushing" when I shut off the car sometimes. Since the repair I have not heard it.
That's it right there. Based on piston failure reports here, and a couple I know locally, all of them had the coolant air pockets. The rushing coolant is caused by initial coolant being low and air gathering in the heater core. When Auto stop engages, the aux pump starts and you get a the symptom of rushing or gushing of coolant. Air pockets in coolant create hotspots and you exacerbate LSPI issues. Excess heat causes a cylinder to ignite at the wrong time and you blow pistons. That's my theory. There is also the possibility batches of pistons used in some 2016-2017 cars that are either defective or too borderline on the mfg spec. GM offered a program that specified specific chronological build dates for "predictive piston replacement". It was about 1800 cars they just tore apart and replaced before something happened. And updated pistons.

I know spending $900 is a lot of money but it is a decent deal cut by GM. GM has negotiated prices ranging from 500-2000 on these repairs (which are an all day sometimes multi-day job). Some people just get a "tough luck" and the full $3500+ bill.

I'd probably keep the car and re-evaluate when the warranty expires. Make sure you always use top tier licensed fuel and dexos1 2nd gen oil. When gen3 comes out, use that.
 

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Discussion Starter · #3 ·
Thanks for the reply.

initial coolant being low
Does this mean that the coolant just needed to be topped off or is this something more fundamental than that?

Make sure you always use top tier licensed fuel and dexos1 2nd gen oil.
I will continue getting my car serviced at Chevy service centers. Is this something I should specifically ask for?
 

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Does this mean that the coolant just needed to be topped off or is this something more fundamental than that?
Sometimes topping off is enough to fill the air pockets. Other times a full coolant drain and fill is done. There is a bulletin about the rushing coolant outlining the cause and correction. Unfortunately, many owners believe the noise is normal because so many cars start that way. It's not normal and not your or any owner's fault. I'm not even sure how it initially happens. Some cars do it from day one, some start sometime in the first year. Perhaps in the fill they don't account for the aux pump since it wasn't common at the time... Or perhaps the first time that aux pump fires it sucks air into the system because it isn't pre-filled. I don't know. Either way sounds like they got it right on your repair work.

I will continue getting my car serviced at Chevy service centers. Is this something I should specifically ask for?
A GM dealer will/should always use dexos1 licensed oil during oil changes. It's just if you do your own changes or visit a quick lube you need to double check.

Good luck in the future.
 

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2016, pre owned, 1.5L Chevy Malibu. Approx 87000 miles on it. i’ve only had it one year. codes popping up P0301and P0300 and P050D. It drives fine when cruising. but at any stop or or original parking it horrible rough idling and heavy resistance to accelerate
 

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2016, pre owned, 1.5L Chevy Malibu. Approx 87000 miles on it. i’ve only had it one year. codes popping up P0301and P0300 and P050D. It drives fine when cruising. but at any stop or or original parking it horrible rough idling and heavy resistance to accelerate
Thanks for that information. Has this already been diagnosed (actual inspection, not just guess) with piston failure or is that the fear?

That behavior doesn't lead me straight to piston failure - engines don't usually cruise fine with loss of compression in one or more cylinders - especially cylinder 1 as your P0301 indicates. The wild card is P050D - it doesn't usually come with a cracked piston. If you search gen9 you only find 2 posts and one was a broken spark plug insulator. It certainly could be and if it was diagnosed with a compression and leak down test I'd trust it.
 

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not diagnosed but fear by the mechanic who looked at it. did a compression test. cylinder 1 was at 100 cylinder 2 was at 205. but didn’t do a leak test. they wanted me to bring it to the dealer bc they didn’t have the special tools to really get into everything.
 

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I have to look up the psi readings to be exact but that is too wide of a variance. I thought it was 180 but could be 200. 100 does seem low and it isn't so low it shows at speed - perhaps a tiny crack. Still need to isolate carbon or a valve issue. If this is a piston at that mileage in that year, I don't have much. Based on what I have read here GM never shows mercy for multi-owner cars. I would get the diagnosis, talk to the service manager; if pistons and the price is extreme, try and be reasonable, contact Chevy, then decide if you can absorb the hit or want to try the nuclear route via lawyer. The bulletins above discuss GM's own documentation of the preemptive piston replacement some cars received and "updated pistons". Someone with legal knowledge could always try and make the case GM knows of defective pistons in some cars and can nudge them take some case by case responsibility.

What sort of maintenance has been done over the last few years? Brakes? Coolant? Plugs?
 

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Hmmm.... That gets trickier. Coolant needs to be changed at 5 years. Plugs are due at 60,000 miles. Do you have any idea if these were done before you got the car? The brake booster sensor bothers me a bit too - that is an common misdiagnosis of a failing vacuum pump. Did you have a hard brake pedal or clicking/clunking when braking? Or was it a warning light that led to that?
 

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it was clunking and grinding that led to the brake booster. no warning light. and i’m not sure about what was done before i got the car. they said it was kept up maintenance wise but i never got specifics.
How long ago was that? Has the braking been normal since?
 

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about 2 months and it’s been fine since
That's good news. If it was more recent or you have felt the hard pedal or the clunking/grinding intermittently or a couple times I would be concerned about the pump. The pump failing can cause the problems you are experiencing by throwing off timing. The pump wouldn't heal by changing the booster vacuum sensor so that was a good diagnosis from your first mechanic.

I think I am out of questions. Keep us updated with what you decide to do or what the diagnosis is.
 
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