Im getting close to finishing up my my supra and I need to know how I should break it in. I have replaced the crankshaft and bearings, and changed to a metal headgasket. I also will be putting in a new clutch and flywheel. My haynes manual says to go to an empty parking lot and go full throtle for a couple passes. But that is to seat the piston rings and I didnt touch those. Plus should I crank the motor with the spark killed to that the oil can make its way through the car before I start it. Thanks alot for any help
Break in....?
- Thread starter socc924
- Start date
Lots of schools of thought on this subject.
If you've replaced the clutch Boosting hard for the first 4>500 miles can be bad as it could slip and glaze the clutch.
To break the motor in I first crank it till I see pressure with no ignition then fire it check for leaks then run it around the block come home and recheck everything.
Change out the filter as it fills up with assembly lube fairly quick.
I then go back out and vary the speed keeping it below 3000.
Once I'm happy nothing is going to fall off/break/explode I'll start bumping the rpm's a bit, after 2>300 miles I'll dump the oil and filter by this time the clutch should be good to go.
Good luck with it!
If you've replaced the clutch Boosting hard for the first 4>500 miles can be bad as it could slip and glaze the clutch.
To break the motor in I first crank it till I see pressure with no ignition then fire it check for leaks then run it around the block come home and recheck everything.
Change out the filter as it fills up with assembly lube fairly quick.
I then go back out and vary the speed keeping it below 3000.
Once I'm happy nothing is going to fall off/break/explode I'll start bumping the rpm's a bit, after 2>300 miles I'll dump the oil and filter by this time the clutch should be good to go.
Good luck with it!
should I keep it at low rpm's for the first 2-300 miles? After that is it ok to push it? If not how long till I can safely push it - ie higher rpms and boost? Thanks for the help. Very good info IJ
Socc: If it's built correctly with good clearances yes after the first 2>300 you can start leaning on it!
It's important to NOT stay at a constant speed during this time and avoid letting it idle too long.
I also use a single weight oil to break it in as 5 qt's of single weight is 5 qt's of oil not 4 oil 1 VSI (Viscosity Index Improver the gloop that makes it thicker when hot and thinner when cold)
Just about any of the modern single weight oils will work but stay away from anything with Friction Modifiers as these will prevent rings bedding in (I know you didn't replace the rings this is just in case someone else reads this with new rings)
An old school builder once said to me "From the first time you turn the key the motor is running out not in" The way I break em in is just to give the rings a chance to seat and to make sure everything else is perfect before leaning on it hard as if something is going to go wrong it's best if it happens close to home and at low revs!
It's important to NOT stay at a constant speed during this time and avoid letting it idle too long.
I also use a single weight oil to break it in as 5 qt's of single weight is 5 qt's of oil not 4 oil 1 VSI (Viscosity Index Improver the gloop that makes it thicker when hot and thinner when cold)
Just about any of the modern single weight oils will work but stay away from anything with Friction Modifiers as these will prevent rings bedding in (I know you didn't replace the rings this is just in case someone else reads this with new rings)
An old school builder once said to me "From the first time you turn the key the motor is running out not in" The way I break em in is just to give the rings a chance to seat and to make sure everything else is perfect before leaning on it hard as if something is going to go wrong it's best if it happens close to home and at low revs!
Break in? Oh....I thought my engine builder said "break it" LOL. I beat the shit out of mine right away. He told me that babying it just prolongs seating the rings. Like IJ said there are many schools of thought on this. Just letting you know that if you feel the need to give it some right foot don't be worried, mine was floored from mile 0. Also as IJ said use single weight oil. You the man IJ!
this is my take on it...you replaced bearings and thats it correct?
bearings dont need break ins...nor to "seat" the only thing you should be breaking in is your clutch...
and in that case as long as you have no hard shifting...and your varying your rpms and speeds IE: when highway driving dont stay at a constant speed/rpm for longer then a few minutes.... thats it.... drive like your grandmother and very your speeds for about 500 miles and that clutch is broken in....
then drive it like you stole it
bearings dont need break ins...nor to "seat" the only thing you should be breaking in is your clutch...
and in that case as long as you have no hard shifting...and your varying your rpms and speeds IE: when highway driving dont stay at a constant speed/rpm for longer then a few minutes.... thats it.... drive like your grandmother and very your speeds for about 500 miles and that clutch is broken in....
then drive it like you stole it