Break in for stock rebuild motor

[wadbus]

Thoughts and input on proper way to break in a old motor with new std bearings, new std rod bearings, new std rings, reworked head.

[MR 325]

Drive the hell out of it! :D

[Pdxseth]

For real??

[jlevie]

Here is how I do it:

1) Remove the cover of the boss where a conventional distributor would mount on the left side of the engine and pick out the gear. Using a 3/8" electric drill, extension and socket that fits the oil pump shaft, spin the pump until the drill loads down and then for 30 seconds more. The filter is now full and oil has been pumped to all bearings.

2) Start the engine and let it warm up. While warming up bleed the cooling system and check for leaks. The front of the car needs to be up in the air for the bleed and for the leak checks (so you can get underneath.

3) Once the engine is at normal temperature lock the throttle for an engine speed of 2500rpm and hold that for 30 minutes. Monitor engine temperature and oil pressure during the break run.

The engine is now broken in. Change the oil/filter after the first 500 miles.

[Alex Mc]

Jim, any experience with break-in oils? Essentially, high Zinc content oil (~2000ppm as opposed to <800ppm).

[jlevie]

I only use oil with a high ZDDP content in an M20 engine. The engine was designed for those oils. Valvolene VR-1 is readily available and has a good ZDDP level. But I use Brad Penn 20w50 which has a higher ZDDP level. I think that there is a Joe Gibbs racing oil with a high ZDDP content. I don't use a special break-in oil because the engine will always have a high ZDDP content.

On a related subject the Mobil 1 oil filter got the best marks at bobistheoilguy.com, and is what I use instead of the OE filter.

[MR 325]

Exactly. Prime it, run it, make sure everything is good, and drive!

As said change the engine oil after a couple hundred miles. I personally use Valvoline VR1 20w50 which also has high zinc.

[wadbus]

Thanks this was my first for a BMW motor and I didn't want to screw up on break in.