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Engine Break-in question(s)


RC K9

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Something I have wondered about for years on and off is factory engine break in. Basically, when a dealer has a new cars on the lot with like 2mi on it, was that engine broken in at the factory? Or are all the people test driving this thing essentially breaking it in? I ask because on the DSM motors I have had in the past, I pretty much follow the motoman break in procedure and it's worked great for me in the past.

 

http://www.mototuneusa.com/break_in_secrets.htm

 

Initial start run some cheap conventional oil in for a few min to flush any crap in there out. Drop in some Amsoil or whatever 30W break in oil. And I go beat the piss out of hit. Varied throttle/rpm and running it up top. I remember one motor in particular I beat the snot out of it for essentially 10mi worth of driving, got back to the garage, no smoke coming out of the tail pipe at all. Rings seemed to have sealed nicely. Never had any issues with that bottom end.

 

So basically what I am asking is, do factories run these engines prior to installation and break them in, or is the customer breaking them in?

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No, I can tell you GM specifically puts them together and drives them off the assembly line. They don’t have us do anything related to engine break in before they are sold, and just want you to bring the car in for it’s first oil change at 5-7k miles.

 

It’s like when I replace pistons and rings in an engine burning oil, slam them in and ship it. That’s it, that’s all I get paid for and all they want.

 

According to GM the machining and tolerances are very good (lol) and they don’t need any special treatment. Of course they also say to not change any fluid other then your oil for the first 100k miles, and that’s about as big of a joke as going 10k miles on regular bulk oil.

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on old stuff where machine tolerances were not as great, metallurgy wasn't all that super, and cars had big ol' honking carbs that occasionally would wash your cylinder walls down with gasoline, a break in period was part of the process of a new car or engine assembly to make sure you didn't lunch something down the road.

 

In this modern age, I question whether it is necessary at all. Fuel and oil control has gotten a lot better, tolerances are more precise and the rangers are smaller, better materials has led to less heat expansion and mfg processes have improved how it gets accounted for in the design. It's a different world.

 

The last "new" vehicle I can remember being around that had a serious break in period and had demonstrable catastrophic results if you didn't was a 2009 Royal Enfield Bullet with the AVL engine. these were basically 1957 design engines with minor updates over the years, were air cooled so they ran really loose tolerances, had carbs, and were made in a country known for using metals of questionable metallurgy to meet a price point. It was so bad with those bikes that it wasn't hard to find a blown engine RE that wasn't properly broken in with less than 1000 miles on it. As soon as they went to the Austrian designed modern EFI engine, the break in procedure stopped being a religion and the engine failures stopped being an issue.

 

Engine break in really starts at operating temp, because that is when heat expansion is at it's fullest and the real wear will start to happen. I don't know where this idea came from that you need to be "gentile" with an engine during break in, the engine needs to experience the forces it will see during hard use to really get a good wear pattern going. the worst thing you can do for a new car is to hold it at steady rpms, in top gear on the highway, like you are heading for your morning commute.

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I've always done about the same as you RC K9. Run it up and let it pull down on vacuum. The rings are pretty much seated when you fire it up. Change the oil after and it is what it is. With roller cams, change in oils and metals with tighter tolerances than 80 years ago, they'll be fine.
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Nothing more satisfying than getting a zero-ish mile car up to operating temp and beating the piss out of it

 

I've done it on every vehicle I've owned/built. I specifically remember picking up my F150 from Jordan back in 2011 and on the way back from Cambridge to Columbus, topping it out a few times, ha ha. Let that bish rip.

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