Break-in Procedure

[Kdubski]

Just rebuilt a motor with 111,xxx miles. Did a head gasket and rod bearings, as well as a short list of other wear and tear items. BMW suggests not exceeding 5,500 RPM or 105MPH for 1,200 miles. Other argue that the rod bearings don't require a break-in, especially seen on unregistered track cars.

What have you guys done in the past? A 1,200 mile break-in procedure in the middle of summer is going to be a tough one!

[jbfrancis3]

Hasn't this been debated enough in the other threads from which you are quoting data points, or wouldn't it make sense to keep that dialog going? Why fragment?

[heinzboehmer]

Might not be necessary, but I would personally do it (and did when I changed my rod bearings) for the peace of mind. I wouldn't want to have to tear down the engine again just because I wasn't patient.

[Obioban]

I would follow BMW's recommended break in.

[enjoy_m3]

It's really up to your confidence on the rebuild. Did you replace the piston/rings/cams/followers? Those are the main areas requiring good break in when new.

[Estoril]

Just do the break-in procedure.

[Obioban]

It's really up to your confidence on the rebuild. Did you replace the piston/rings/cams/followers? Those are the main areas requiring good break in when new.

Bmw also says to do the break in procedure as part of the rod bearing replacement SIB

[Jimbo's M]

BMW suggests not exceeding 5,500 RPM or 105MPH for 1,200 miles.

You forgot no WOT as well...

[2004LSB]

If anything now is the perfect time to log in the break in miles since traffic is light due to the pandemic. Drive about 250 highway miles per day every other day and you'll hit the 1,200 mark pretty quickly.

[Nick_P]

I followed the break-in procedures as well...certainly doesn't hurt and for peace of mind

[cbean]

Currently in the break in period process from my ROD bearing install.

One point of view was track only cars that go from shop to track . . . No break in period

Mine is not a track car ( hopefully it will see a day or two ) . . . I the Nick_P said it best . . . "certainly doesn't hurt and for peace of mind"

[Estoril]

If anything now is the perfect time to log in the break in miles since traffic is light due to the pandemic. Drive about 250 highway miles per day every other day and you'll hit the 1,200 mark pretty quickly.

Thats not the break-in procedure.

[Jimbo's M]

Thats not the break-in procedure.

Concur. Should be driven in conditions more indicative of load variance on the motor...other than WOT that is.

[digger]

once the oil is hot drive it like you stole it

[Arith2]

Rod bearings have wear patterns. I believe it says dont exceed like 50% or 60% load along with the other stuff. I don't really think it matters about load variation, just that a certain amount isn't exceeded. Most of my break in miles were highway miles. Our engines are known to have tighter clearances so it'd be better to heed the warning. BMWs in general have tight clearances so do follow the TSB. It's not just talking about engines break in, it specifically refers to bearings needing 1200 miles.