What is the best way to break the engine in? When can I mash the gas and not worry about messing up the engine?

2004 FX4 Screw Dark Shadow Gray, 5.4 V8, 3.73 Ls, Power Moonroof, PS Rear Window, Power Pedals, Tow Package, Heated Mirrors, Captains Chairs, 18" Wheels

 

In my experience, it's good to drive it normally (light) for the first 500 miles or so, then beat the S@#T out of it for the next 2-3k miles... punch it at every chance you get.. merging onto the freeway, open road (with no cops), etc., then drive it normally after that. You'll probably have pretty poor gas milage during the break in, but after break in is complete you should see it increase significantly.

 

Just break it in per the owners manual. If you ever have any problems after that then you are covered because you did exactly what the manual said. Just my .02

 

Engines are "broken" in at the factory mash the gas leaving the lot and never look back.

 

Did some salesman tell you that?

No mainstream production vehicle has engines pre-broken in at the factory. They do a wet test fire before they are installed to make sure they work, but that's about it. That's why they have a break-in period in manuals.

Can you imagine a huge factory with thousands of engines on dynos running hours each all burning lots of gas and time before they are installed in our trucks? Especially for a high volume truck like the F150!!!

I used to work for Porsche, and even limited production cars didn't have pre-broken in engines, only replica racers for homologation got "special care" engines.

 

Well then since you worked for Porshe then I think you would agree with me that engines are indeed "broken in" at the factory. This is a very controversial topic to discuss. However the term "broken in" really applies to the first things that are done once you run a new motor. In all truth Several factors make the older information on break-in obsolete.There is not much that any consumer out there can do to "break in" an engine. The biggest factor is that engine manufacturers now use a much finer honing pattern in the cylinders than they once did. This in turn changes the break-in requirements, the window of opportunity for achieving an exceptional ring seal is much smaller with newer engines than it was with the older "rough honed" engines. In addition, there is a lot less heat build up in the cylinders from ring friction
due to the finer honing pattern used in modern engines.
The other factors that have changed are the vastly improved metal casting and machining technologies which are now used. This means that the "wearing in" of the new parts involves significantly less friction and actual wear than it did in the distant past. The Best Way To Break-In A New Engine ?? The Short answer: Run it Hard ! Nowadays, the piston ring seal is really what the break in process is all about. Contrary to popular belief, piston rings don't seal the combustion pressure by spring tension. Ring tension is necessary only to "scrape" the oil to prevent it from entering the combustion chamber.
If you think about it, the ring exerts maybe 5-10 lbs of spring tension against the cylinder wall ... How can such a small amount of spring tension seal against thousands of PSI (Pounds Per Square Inch) of combustion pressure ?? Of course it can't.
How Do Rings Seal Against Tremendous Combustion Pressure ??
From the actual gas pressure itself !! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear into the cylinder surface, to seal the combustion pressure as well as possible.
The Problem With "Easy Break In" ... The honed crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly wear down the "peaks" of this roughness, regardless of how hard the engine is run. There's a very small window of opportunity to get the rings to seal really well ... the first 20 miles !! If the rings aren't forced against the walls soon enough, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again. Again some live by this rule like I do others will not. Like I said this is a very hot topic and everyone has there own view on it. If you not sure I would do some in depth research and talk to a few wrenches in your area (if you know one you can trust).

 

wingn8ive,

You mentioned 500 miles above...I was always told at least 1000 miles to get it nice and broke in before the peddle should meet the floor.

Fact? or Fiction?

 

FWIW.....

I've owned seven new F-150's since 1987 and have driven all of them fairly hard since day one and have not experienced a single engine problem. I not here to say that my new vehicle driving habits are correct. I will say that a few short duration full throttle blasts, even on brand new vehicles, hasn't had a noticable negative affect on any of mine. Hard driving with a cold engine isn't something I would ever recommend and towing a heavy load on a fresh motor is a no-no, but "babying" your vehicle for the first 1000 miles is a bit over the top. Just my opinion.......

 

ok....Fiction then.

 

Has anybody seen a vehicle driven off the line? At some plants, they floor it - it is the start of the break-in process. And all plants, do not baby them.

I agree with Clem, no heavy towing. Also, try not to do a long initial run with the cruise control, vary your speed lightly.

High rpm engine breaking helps in breaking-in.

 

Alrighty.

I learn something new everyday.

Thanks for the info Storm.

 

My father worked for Ford for 30 years. They hammer them from the start........

 

I agree, the manual is all you need to do..

That said, to add needlessly to jcollins28's post, i do remember an old VW repair manual, late 70s early 80s era haynes manual, that described an intricate process of being in top gear, on an open road, and accelerating hard from 30 to 50, then backing off the gas letting it engine-brake to 30 again, and repeating several runs of this, this was mentioned in the engien rebuild section and referenced the new piston rings.

You have to realize thought that a 70s era vw motor had the rough cross hatch pattern and somewhat archaic metallurgy that was earlier mentioned.. NOTHING like the computer designed not-hand-built consistent close-tolerance modular ford v8..

Anyway, that's where that wive's tale comes from, experience with older types of engine design..

 

How many miles should I put on before a long run with cruise control? I'm picking my up in NC and driving to Phoenix. We'll be spending a few weeks running around NC visiting relatives before the long drive so I should get at least 1000 before the long trip.

 

Thayer, you should be fine with 1000 miles before your road trip.

I trailered my 4000# boat from Maryland to Florida with only 919 miles on the clock at takeoff. All high speed Interstate travel with plenty of long strectches of cruise control mixed in. Aside from less than stellar mpg, I had no ill effects. I averaged about 11 mpg on the first 1100 mile leg. On the return trip I pulled 12.5 mpg, so I guess she had loosened up a bit. Not bad mpg for hauling a 21' boat at 75-80 mph to whole way.

Bad pic but here's the rig........