Break-in method for just new rings

[Squaremaxfan]

So I'm replacing rings and bottom end bearings on a 07 lbz with 235k miles. What should I do for a break-in process for the rings? Does it have to be like a whole new motor?

The other side note is that it's going into a project pickup that Is not driveable yet probably for another year.

 

[DAVe3283]

Everyone has their own theory on how to break in engines. One thing I like to point out is every new Duramax is started by an engine dyno prior to going in the truck, so even GM thinks a bit of load is good for them.

If the motor will sit for a year before the first start, put a ton of assembly lube everywhere you touch, and use fogging oil on the cylinders.

The way I break in my motors is do a short idle to look for any leaks or issues, then shut it down and cool off. Start it again, easy drive around the block to keep looking for leaks or problems. Shut down, cool off. Finally, go drive in the mountains or tow a trailer (usually one than the other) to put some hard load on the motor with varying RPM.

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[2004LB7]

Everyone has their own theory on how to break in engines. One thing I like to point out is every new Duramax is started by an engine dyno prior to going in the truck, so even GM thinks a bit of load is good for them.

If the motor will sit for a year before the first start, put a ton of assembly lube everywhere you touch, and use fogging oil on the cylinders.

The way I break in my motors is do a short idle to look for any leaks or issues, then shut it down and cool off. Start it again, easy drive around the block to keep looking for leaks or problems. Shut down, cool off. Finally, go drive in the mountains or tow a trailer (usually one than the other) to put some hard load on the motor with varying RPM.

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I concur. Pretty much just drive it normally.

Most say to avoid sustained consistent rpms like the highway. I'm not sure it really makes any difference either way

 

[Squaremaxfan]

Everyone has their own theory on how to break in engines. One thing I like to point out is every new Duramax is started by an engine dyno prior to going in the truck, so even GM thinks a bit of load is good for them.

If the motor will sit for a year before the first start, put a ton of assembly lube everywhere you touch, and use fogging oil on the cylinders.

The way I break in my motors is do a short idle to look for any leaks or issues, then shut it down and cool off. Start it again, easy drive around the block to keep looking for leaks or problems. Shut down, cool off. Finally, go drive in the mountains or tow a trailer (usually one than the other) to put some hard load on the motor with varying RPM.

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I had planed on doing first initial start up to check leaks, etc.
Do you have to all that break-in if your just replacing ring?

My other question is since my project won't be ready drive for a year can I go out and start once in a while even though it won't be fully broke in yet or will

 

[DAVe3283]

I had planed on doing first initial start up to check leaks, etc.
Do you have to all that break-in if your just replacing ring?

My other question is since my project won't be ready drive for a year can I go out and start once in a while even though it won't be fully broke in yet or will

IMO 90% of breaking in an engine is seating the rings, so yes, if you replace the rings, you need to break in the engine again. If you swapped heads (for example) no break in is needed. But the rings will need to bed in after you have the block honed.

What finish are you targeting on the cylinder bore when you hone it? You might look through some of the more extensive discussions on rings & bore prep we've had here over the years. For example:

• https://www.duramaxdiesels.com/forum/threads/piston-rings-not-seating.88807/
• https://www.duramaxdiesels.com/forum/threads/cylinder-wall-honing-surface-finish-ring-gap.55809/
• etc (use search, lots of great tech here)

I would personally avoid putting much time on the engine until you can get cylinder pressures up (aka high load) to seat the rings and bed them in. A bunch of short idles probably won't hurt, but won't really help anything either. I'd just lube the engine up during assembly, then store it in as dry of a place as possible until you're ready to run it.

 

[OleBlackyLBZ]

I don't know as much as a lot of these guys here, but I done a whole lot of reading before I broke mine in. I came to pretty much the same thing DAVe3283 said. But if I had to choose between babying it or driving it like I stole it, I'd drive it like I stole it. Too many stories of people having seating issues with babying them, but the guys breaking them in at the dragstrip seem to have no issues. In other words don't be shy about driving it

 

[TheBac]

Used pump sprayer with hose/fitting into the side oil galley access to prime engine oil. Easy peasy.

As Dave did, ran truck for a bit to check for leaks. Filled coolant, checked for leaks again. loaded up the kids and went for ice cream first trip. After that, ran as normal back and forth to work. Didnt baby it, but didnt beat on it either. After a week or so of that, then came the first WOT runs, then dragstrip runs.

Truck still runs fine (other than injector haze) with good oil pressure and no blowby.

 

[Chevy1925]

I hope the cylinders are being honed and/or specs checked before you pop new rings in there. If you are re-using pistons and honing cylinders, p to w clearance will become quite large for cast pistons and it’s going to eat some oil even after ring break in.

Now as far as break in. Just finished one up last weekend. My way that I do on every engine:

Fire it up, check for leaks, let it warm up, shut off and let cool down. Make sure you got a good tune in the truck (the hotter the better but again, needs to be a good tune), start her up, go to Mexico and give her the beans through all the gears. I’ll do that for about 15-20 min of driving with cruising between WOT runs.

Got 200 miles on this engine and barely used any oil so far (if any). Pretty sure the leaky drain plug and then quick swap from crap drain plug to new good plug lost more oil than it ate.