Engine break-in procedure

[ryan_george]

I'll be installing my new 'b25 soon, and was wondering what the correct break-in procedure is. It's a complete rebuild with new pistons, rings, bearings, clutch, etc...

Regular or synthetic oil?
Stay under what rpm for how long?
Any other important stuff to keep in mind?

Thanks.

[DaN]

Regular oil, there has been some controversy as to what is the correct break in procedure. Some actually say run it hard.

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

[ryan_george]

Regular oil, there has been some controversy as to what is the correct break in procedure. Some actually say run it hard.

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

That's a pretty interesting article.

I've heard from someone else that it's good to do some WOT runs, but not to go near the redline.

[Jordan]

Regular oil, there has been some controversy as to what is the correct break in procedure. Some actually say run it hard.

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

This is how I plan to break my motor in.

[dwforum]

I still have a sticker with break-in instructions on my windshield. I can check it later today and post what it reads if you'd like.

[ryan_george]

I still have a sticker with break-in instructions on my windshield. I can check it later today and post what it reads if you'd like.

That would be swell.

[crazy]

I still have the orig sticker as well. Reads something like observe owner's manual, no kick-down, no full-throttle...

very interesting article.
thanks for posting it.

[DaN]

No problem

[f u z z]

break it in like your going to drive it.

[nando]

I have buddys that used to break their engines in back in the day by driving the piss out of them from the start. they all said it worked great.

I have broken in one motor myself, I did it the manufacturers way by idling the motor for a certain time (might have been 45 minutes) at a set RPM (1500 if I remember correctly). of course the motor didn't start at 1500 rpm, it roared to life at nearly full throttle. still, I ended up loaded it up for 30 minutes until the neighbors were coming over to complain about the loud exhaust, :twisted: and shut it off. then I drove it normally, it wasn't a revving motor anyways. not bad in a 3100lb car though. :)

Oh and by the way, I used synthetics from day one and I NEVER had a problem with the car, untouched motor for the 5 years I owned the thing except for changing the air filter, adjusting the timing once or twice (mopars are especially bad about this) and changing the oil. it did leak a little bit, but never enough to worry about (not any more than my M20, anyway). I don't think there is anything wrong with starting up with a synthetic.. use something heavier to start with if you think it's going to cause problems.

anyway this motor was not exactly a high revving power machine, but it had the torque curve of a big truck motor. personally I would probably run the motor at a slightly higher speed than idle for 20 minutes to break in the cam, change the oil (flush shit out), then tune it if you need to, and drive the piss out of it for a while after. hope you don't have noisy exaust.. ;)

[Axxe]

Well, I guess my Dad's 5-er was broken in right. Leaving the dealership we drove pretty much full throttle the whole way home. Then he changed the oil the next day at the dealer. Haha, that poor V8 is ragged on by the whole family, but it never misses a beat and pulls like hell.

[dwforum]

I still have the orig sticker as well. Reads something like observe owner's manual, no kick-down, no full-throttle...

very interesting article.
thanks for posting it.

Also says not to overdo 2/3 of permissable speed in any gear.
I would guess that depends a bit on the engine since they are all a bit old, but then again I don't know all that much about our cars. I can drive my car tommmorrow though and see where each gear redlines at if you would like (mph wise through 3rd or 4th, I never pass about 95 or so).

(also my car has about 15k on a rebuild top end)

[b00b00]

It's an interesting read.

A few things came to mind:

Our engines we're designed and manufactured 15-20 years ago. The manufacturing tolerances we're looser than they are now.

When an engine is rebuilt, one usually follows the original specs with regards to clearances etc. so I don't see how/why one should apply a newer break-in method even though we have an older specification engine. Additionally, have all engine rebuilders changed the cross-hatch pattern on their honing machines? Is this something specific to bike engines or is also common with cars as well?

Bikes are also different animals than cars and operate on average at higher engine speeds. Can this have an effect on the way we should break an engine in?

Then there are the individual testimonies where some will say, "I ran the piss out of it since day one and it was fine blah blah blah..." or I did it this way, put a melon over my head and and waved a rubber chicken over the intake manifold and the car has never missed a beat.

Yes, I'm exagerating and it could be that the method you used appeared to give you good results
or you maybe you got lucky
or maybe there are several break-in methods that can have good results.
or maybe modern engines are so well built now, that regardless of how we break them in, it really doesn't make that big of a difference...
(or maybe we're too insensitive to tell the difference) :roll:

Without a methodical testing procedure, it's very difficult to say what techniques work and what techniques don't. Until this is done, much of what is being said are observations and nothing more.

I'm not saying that the method discussed in the article can't work (what is being said has certain merit) but before I risk the large amount of $$$ I invested in a rebuild, I might want the opinion of a few experienced engine builders. (Noteably, some who have built car engines) as this is the opinion of one person on the internet. There are just too many aspects that are brought up that make me want to say "This is a good question..."

As for the synthetic vs. dyno oil debate, I don't really want to get into it as it's been debated to death but if it came from the factory with synthetic, then run it in like that. (The engineers that create Porsches, Corvettes etc, have obviously taken this into consideration and the rings will seat fine) If it's a rebuild of an older engine, conventional wisdom would be to break it in with dyno oil and then switch to synthetic.

My. 0.02
~andre~

[ryan_george]

Should I be redlining at all? Probably not... but might as well ask. Or just some full throttle runs to like 5k or something?

[BahnE30]

i'd heat cycle it a couple of times, to break in the cam, drive it hard for about the first 20 or so miles to seat the rings, then change the oil, drive it easy for the next 500 and call it broke in, at least thats how the old man broke in his new e30 and it's got 380,xxxkms on it and hasn't been rebuilt or burn oil, it's seen probably 3-4 autocrosses a year for the past 4-5 years and hasn't had an easy life but has been well maintained.

always break in a new motor with dino oils as synthetic's are to "slippery" and make the break in process last longer.