View Full Version : New Engine Break-In

04-27-2007, 08:40 AM
I posted this in the rebuild thread, but it might not get much traffic, so here's a new thread. Still hoping to get the time to finish putting the engine back together and start it this weekend. Any recommendations on the break-in? So far the engine's been assembled and filled the crankcase with GTX 10W30, cranked and oil pressure built. A friend of mine said to fill the cooling system with water and start it. Then keep the RPM above 2000 for about 15 minutes, basically enough to burnish the rings, but not overheat. Then do a coolant and oil change (and I'd check the head bolt torque) and just drive it reasonably, at least not to baby it but no long pulls up Floyd Hill. Another oil change at around 500 or 1000 miles and call it good. Never having a new engine to break in, this will be the first one with zero miles that I have to do this.

04-27-2007, 09:02 AM
Wow Dave, those are pretty detailed break-in proceedures.

I started to post on the other thread, but never finished it.

The don't baby it part I have to agree with. We used to say, "Break it in a dog and it will always be a dog."

Here is what we used to do with the race engines, (right or wrong)
Crank until you have oil pressure (Some engines we could spin the oil pump with a drill, or we would use a pressurized accusump if the car had it.

Start it and warm it up at minimum rpm. (always warmed up up at minimum RPM, but that was usually around 2000 on the big cam motors)

Take the car out for 5 2000 to 5000 rpm pulls (without lugging it, but in a tall gear) This would seat the rings. You needed the load to establish enough pressure.

on the race cars, there wasn't much else you could do. go out for easy practice laps if you could, otherwise, well, you just gave 'er the spurs and raced it. The mule mazda inline 4 motors I built lasted the same whether they were broken in hard, or had a couple of hours of practice laps. Hmm, 1 broke an oil control ring, and I think that one was broken in racing.

On the street engines I built, I tried to run easy for the first 500 miles, then oil change and drive normally. It seems like the engines would break in in about 10,000 miles.

Head bolt torque: We didn't touch the bolts after the engine was built.
Water: We ran water wetter and water. If you run straight water, you get fungus and corrosion. There is enough low velocity holes at the bottom of the radiator and block for solids to settle out. I've never seen anything significant come out of a coolant system on a new engine.

04-27-2007, 09:56 AM
It is important to seat the rings, and that won't happen with synthetic and won't happen with no throttle. Getting to operating temperature is important. Not overheating is important. Not lugging is important. Not being too easy on it is important. Changing the oil after about 100 miles, and again at 500 and 1000, is also important (you'll giggle with glee at all the metal shavings. Not.).

Google Motoman Break-in if you want a break in procedure that you won't find in any manual, but which has been proven in experience. Not unlike Spanky's.

Most rings don't seat very well under the factory procedure!

04-27-2007, 10:05 AM
Oh, yeah!
Be sure to check your valves early and often. The clearances WILL change, and quickly. DAMHIK. It involved my wife's motorcycle and a very interesting trip through Seattle.

04-27-2007, 01:30 PM
After the head gasket was replaced on my '89 22RE, I later checked the head bolt torque (after 1000 miles) and all bolts were 10% below spec, so I think I would check the head bolts when you do one of the valve adjustments, after a few miles.

04-27-2007, 02:39 PM
My buddy who races BMWs told me to keep the RPMs variable for the first 1000 miles. In other words, don't use cruise control.

06-07-2007, 10:40 AM
I wouldn't be all that concerned, just avoid lugging it. Perhaps an easy run? That's just me though. Running fine yet?