How do you break in an engine properly?

Years ago my first new car was a Datsun B210. The day I got it I drove it until 4am, at different speeds, gently, stepping on it, winding it up, cruising, easy takeoffs, high speed passing. IOW, all kinds of loads, and a good amount of them against common sense.

Result? An engine that

1. did not burn any oil between oil changes, despite driving it daily on the xway at up to 80mph commuting ~100 miles. This car had no overdrive gear either.

1. did not discolor oil between changes! I could never believe it, but what I drained was always "clean looking"!

My bro in law had the same engine in an F10, and he said his oil always darkened alot. He did nothing special during breakin except drive it "normally".

Yes, I could have gotten a lucky engine, but I am convinced the stresses I put it through caused it to breakin nicely.

I miss that car, not a rattle even over the railroad tracks.

Theres many a way that people break in engines. My race car engine builder told me to start it up and run for at least 2mins at minimum 2500RPM and then flog the crap out of it. Engine never missed a beat but when I did pull it down (at 20,000kms on the motor) it had glazed the bores somewhat. Same motor (Toyota 2TG) different car was run in while putting around a race track at various speed and accelerations, he pulled his down after 5,000kms and it was worse than mine at 20,000kms.

get in drive it normally and hope like hell that your engine builder was a good one and got layed the night before.

The most important thing is to get the rings to seat properly. This web page has some info on the process to use.

Although the site is for motorcycles it pertains to all engines. I got the same advice from a machine shop when I rebuilt my first engine 20 years. It has always worked well for me.

I always like to change the oil and filter after 100 miles. Then go with

500, 1500 and 3000.

You don't want to lug the engine anytime, even after break in. That can be hard on bearings.

Ah, driving hard?? Very subjective indeed. It's actually good for the engine to get on it "hard " while breaking it in. It is necessary to seat the rings. First thing to remember is to do this with a fully warmed engine. By fully warmed I mean drive it around normal for at least 20 minutes. Say you have an auto tranny. Start out from a dead stop and hold the throttle to the floor. Run it up to 60mph or so and let off. Let it slow down on it's own without hitting the brakes. When you get down around 20mph floor it again to 60mph. Do this 2 or 3 times and then just drive it normal for a few miles. Then floor it again a few times. If you have a manual trans try accelerating in 3rd without lugging the engine.

You do not want to run it at sustained high rpms for an extended period of time. It's ok to go from 50mph to say 80 mph at full throttle ( like passing another vehicle) as long as you slow back down to 50mph. What you don't want to do is cruise at 80mph for hours on end. Try to vary your speed as much as possible, don't cruise around at just one speed. City driving is actually pretty good for this as you are always starting and stopping and varying engine load and rpm.

RPMs I would say to try and keep it under 4,000 rpms for the first 500 to

1000 miles. If you go a little over it's no big deal.

One important thing to do is check for fluid levels DAILY. You want to catch a problem as soon as possible. Check your oil level but also check for coolant or gasoline in the oil. Check you coolant level at the radiator not the overflow jug. Check it cold. I ALWAYS check fluid levels daily for a few weeks or so until I am satisfied everything is OK. It also doesn't hurt to check all your radiator and heater hose clamps to make sure the were all tightened properly.

If the vehicle is equipped with gauges for water temp and oil pressure keep an eye on them also. If you spot a problem, shut the engine off. It has been my experience that a new or rebuilt engine will run a little hotter at first so don't be alarmed if the temp gauge reads a little higher during break-in. By a little higher I mean just a needle width or two.

Good luck with your new engine. Let us know how it turns out.

Can't do that on many new vehicles with crank-hold. OTOH, vehicles with crank hold will actually crank until THEY feel the oil pressure is up for starting.

This is insanity. Change it at 3,000, and then every 5,000 after that with a good synthetic and she'll last forever.

set cruise control

Absolutely no towing for the first 1000. You CAN run the cruise, so long as you vary your speed. If you have a road trip during the first

200 or so miles, just make it a point to get off of the freeway every 10-15 miles. Just pull off of an offramp, come to a complete stop at the bottom, and continue back on. All you need is to avoid running the engine at a constant steady speed for extended periods.

Not using the cruise for 1000 miles is more insanity. Extended steady speeds should be avoided for anywhere from 200 to 500 miles. At that point, you're broken in.

As far as "driving it hard", I'd say any throttle setting that forces the auto trans to downshift, or where you feel the need to downshift in a manual.

Max RPM is a good gauge, but nobody can give you a solid number. For the Tundra V8, I'd say 2,500 is a good top-end number to shoot for, and in fact, unless I'm in a hurry or passing someone, I rarely exceed

2,500-2,800 during routine driving.

--- Rich

A lot of good advice in this thread already, so I'll just add a couple of points that haven't been covered:

1. I recommend changing the oil at the first 100 or so miles as this will help clear out any crud left in the engine from the build. My next change would be at around 3,000 miles (again with dinosaur oil), and then synthetic every 5,000 after that (or per the manufacturer's recommendations). During that first 100 mile change, replace your oil drain plug with one that has a magnetic insert (if your engine is not already equipped with such a plug). That will trap metal shavings which is useful because: (1) it will save them from scoring the insides of your oil pump; (2) it allows you to monitor the health of your engine. Basically, with each oil change after an engine build (or re-build), the quantity of shavings should decrease until it gets to a constant very minimal amount. If after that, you see an increase in accumulation of metal on the plug, you know something is wrong. Oh, and never change the oil without also changing the filter: that is, as the Brits say, "a false economy."

1. When breaking in your engine, always make sure it gets to full operating temperature on every drive (actually, this is good even after the engine is broken in). So if you have a short trip, say to pick up a jug of milk, take the long "scenic route" so that you aren't shutting down a cool engine.

- Michael

Well, just my two cents, but ... I did a complete overhaul on my bro's 20R in his Celica a year+ ago and it has been driven over 10,000 miles very vigorously and still burns no oil (leaks some at the valve cover gasket, but hey).. What we did for break-in was the following:

1. Made sure valves were adjusted a bit loose, since I was unable to heat up the engine for the initial adjustment. (This statement may seem like common sense, but *NEVER* assume the valves are adjusted properly when you buy a crate motor and definitely not when taken to the machine shop)
2. Cranked for a while with hi-tension lead grounded (no-spark)... was waiting for oil pressure to come up, but didn't see an indication, so I connected the coil wire again.
3. Cranked the engine and when it fired, adjusted the idle speed so that it would be at least 1500 RPM. (low speed is a new engine's worst enemy)
4. Checked for leaks as the engine warmed up.

1. Let the engine warm up completely and run for about 20 minutes (hot air at the defroster vents inside the car).

2. Shut down and changed the oil and filter.

1. After refilling the oil and installing a new filter, we went for a

100-mile drive or so. (The whole time, the idle speed remained set at 1500 RPM) We did what others were talking about where you floor the pedal and build speed, slow down, then floor it again... did this a bunch of times. I followed in another Celica and we did nice bursts of speed on the highway.

1. Went back to the garage and changed the oil and filter again at ~100 miles. Reduced the idle speed finally.

2. Warmed the engine up again completely with a drive around town and adjusted the valves to the proper spec's.

1. Drove normally from then on. Changed oil and filter again at 500 miles.

The engine runs like a top. The car will pin the speedometer (speedo reads to 85, needle goes around to 6 o'clock position before stopping) and keep accelerating.

Recently, the gearshift screws all fell out (i attribute it to someone replacing the shifter bushings and not using lock-washers on the screws). I burnt the transmission because my bro ran all the fluid out and I didn't realise it until too late. Anyway, 4th gear still worked (1:1) and he drove all the way from VA --> GA and back again in 4th gear.. he said he ran the engine 4300 rpm all day long with no problems.

Now, I've helped rebuild a couple Detroit 4-71 diesels (i did the three-angle valve jobs) and when it was time to break them in, we hooked up a load bank to each one (basically an expensive shunt) and ran them at "rated speed" (read: full-throttle) for 4 hours to run them in. This conflicts with the statements above and in the previous messages, but that's how we did it and as far as I know, they are still generating power on the Henry Knott of Salisbury Towing fame.

Wow. I never intended to be in conversation today. But the thread proved too interesting to resist, and such great advice. Thanks guys. I just stumbled in here from a search engine. Just completely rebuilt my

22R ?81 SR5 pickup engine. I?ve got about 250 miles on it. Wish I?d have seen that ring break in info before, I?m a believer. I had a new cam, so I read folks that told me to run it at 2000-2500 RPM for 30 minutes, that?s what I did. Parked. Changed the oil, it looked like new. Then I put about 100 miles on it, all in semi-rural residential areas, never much above 40 MPH. Tach long broken, but I don?t think I ever put it past 3000-3500 RPM. Checked the oil (of course, been watching fluids all along) and it?s got some gray cast to it. Hmmm, wonder what that is? Changed it a few miles later. Now I?m about 130 freeway (60-70MPH) miles on that oil, looks new still. I have to take a 500 mile trip soon, I?ll take my oil change equipment with me and change it on the way at 500. Bet it?s got a little more gray in it by then. It runs great. I need to rebuild the carb, sat with gas in it for 2 years waiting for engine to be fixed, gunked, but that?s understandable. Idles a bit rough and power range is a little pipey. Otherwise, no complaints. I Plastigaged everything, etc., and everything is in spec, closer to the tight side. She feels like it. Before it died at 250K + miles (wife overheated it, you all know that story, otherwise it had much more to give) the old 22R gave a consistent 21 MPG on the highway. Now I?m getting somewhere between 24-30, sorry haven?t quite put my finger on it yet. I?ve been mixing highway with city miles and the city driving MPG is much worse, around 19. Still, I wish I had broken in the rings that way, I feel sure he?s on the mark. Sigh. Well, next rebuild. I sure can?t complain about this one, it?s ol? reliable again. The main thing I want to communicate is the oil thing. I can?t see how it would be false economy to do the 100 mile oil change, or even next time for me, the 20 mile change that the motorcycle engine guy says to do. I know exactly what?s in my engine, ?cause I put it together like Frankenstein. Nothing but pure clean engine lube and Castrol. When that Castrol turns gray, I can?t believe that?s anything but metal. Well, I guess it could be the lube. But still, I?m sure there were tiny bits of worn metal. And certainly, as little of that floating around your system as possible has got to be a better thing. Spend the extra 30-40 $ on your baby you spent so much time making it all that it can be. I don?t think anyone will argue the fact that the lion?s share of metal wear on your new engine is concentrated in the first miles of driving. Where do those tiny pieces of metal go? I think it?s false economy to run that metal thru the bearings to save a $15 oil change. I want my baby tight for a long time.

Wow. I never intended to be in conversation today. But the thread proved too interesting to resist, and such great advice. Thanks guys. I just stumbled in here from a search engine. Just completely rebuilt my

22R ?81 SR5 pickup engine. I?ve got about 250 miles on it. Wish I?d have seen that ring break in info before, I?m a believer. I had a new cam, so I read folks that told me to run it at 2000-2500 RPM for 30 minutes, that?s what I did. Parked. Changed the oil, it looked like new. Then I put about 100 miles on it, all in semi-rural residential areas, never much above 40 MPH. Tach long broken, but I don?t think I ever put it past 3000-3500 RPM. Checked the oil (of course, been watching fluids all along) and it?s got some gray cast to it. Hmmm, wonder what that is? Changed it a few miles later. Now I?m about 130 freeway (60-70MPH) miles on that oil, looks new still. I have to take a 500 mile trip soon, I?ll take my oil change equipment with me and change it on the way at 500. Bet it?s got a little more gray in it by then. It runs great. I need to rebuild the carb, sat with gas in it for 2 years waiting for engine to be fixed, gunked, but that?s understandable. Idles a bit rough and power range is a little pipey. Otherwise, no complaints. I Plastigaged everything, etc., and everything is in spec, closer to the tight side. She feels like it. Before it died at 250K + miles (wife overheated it, you all know that story, otherwise it had much more to give) the old 22R gave a consistent 21 MPG on the highway. Now I?m getting somewhere between 24-30, sorry haven?t quite put my finger on it yet. I?ve been mixing highway with city miles and the city driving MPG is much worse, around 19. Still, I wish I had broken in the rings that way, I feel sure he?s on the mark. Sigh. Well, next rebuild. I sure can?t complain about this one, it?s ol? reliable again. The main thing I want to communicate is the oil thing. I can?t see how it would be false economy to do the 100 mile oil change, or even next time for me, the 20 mile change that the motorcycle engine guy says to do. I know exactly what?s in my engine, ?cause I put it together like Frankenstein. Nothing but pure clean engine lube and Castrol. When that Castrol turns gray, I can?t believe that?s anything but metal. Well, I guess it could be the lube. But still, I?m sure there were tiny bits of worn metal. And certainly, as little of that floating around your system as possible has got to be a better thing. Spend the extra 30-40 $ on your baby you spent so much time making it all that it can be. I don?t think anyone will argue the fact that the lion?s share of metal wear on your new engine is concentrated in the first miles of driving. Where do those tiny pieces of metal go? I think it?s false economy to run that metal thru the bearings to save a $15 oil change. I want my baby tight for a long time.