LLY Rebuild - Break in Procedure

NevadaLLY

Adam B
Feb 24, 2019
305
27
28
Reno, NV
I wanted to kick this over to a new thread from my build thread. What are the recommendations for break in on a built motor? Its going to tow heavy and I've seen recommendations everywhere from tow immediately to load the engine, to don't touch a trailer for 10k. I've also seen recommendations for initial start to idle to operating temp then change oil, then do 300-500mi break in drive.

All of these are all over the map. Looking for what you all have done for reliable builds? What oil did you use, how did you break in, did you have any blow by following break in, and how long before you started towing?
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
18,206
440
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Phoenix Az
first start, i usually have no coolant in the truck and its mainly a quick look for oil or fuel leaks. truck runs for a quick 30-45 sec. during this. if all looks good, ill finish out putting it back together and top fluids off, start truck and let it idle up to temp or atleast as far as it will go. let it cool down over the next couple hours or till the next day and if the tune it has is a fairly good one off the bat, she sees no remorse. ill start being hard on it once temp comes up a bit and varying engine rpm constantly. the idea is to help seat the rings right away and if something is going to fail, i need to know now, not later. the first time you go WOT and having that worried feeling never changes though. i prefer that over no worries at all.

oil, just use what ever diesel oil off the shelf, you will be changing it very soon. i prefer a 100 mile oil change to split the filter and look for any major issues starting. it also gets the glitters out as it breaks in. then at 500, another change and oil filter split. that then tells me if we have any small issues coming up as you shouldnt find much of anything. from there, its how every long you like keeping oil in it.

towing, id maybe throw 100+ miles on it first. Not due to break it but to find the clamp you missed tightening, the boost leak thats slowing you down, or so on. after that, let her sing. i still try to vary rpm if possible if it aint got atleast 300 miles on it. so if its a long flat stretch, drop it to 4th for a bit, then back to 5th and so on. if you have lots of hills, not much to worry about.

ive done this with many dmax engines over the years and even did this with my new 2020. had 160 miles on it and took it on a 600 mile tow trip up the mountains. she saw foot to the floor for miles at a time up some of the grades. granted, its stock but im not a nice guy to my engines 🤣
 

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
2,755
46
48
Central OH
Just break it in how you will use it. Chances are you'll never see a difference one way or the other, people have greatly varying rituals and none of them cause any direct issues

At the tech center they always ran a torque curve test on all new engine / fresh rings & liners. 2hr test at full load doing an RPM sweep.
 

Bdsankey

Vendor
Vendor/Sponsor
Feb 1, 2018
2,647
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Neenah, Wisconsin
It's like asking if your a boobs or ass man, there will be answers all across the board.

Personally I treat them similar to James. I run them quickly to check for fuel/oil leaks then plumb the cooling system and high idle them until operating temp and let them fully cool while also doing an oil change to remove any potential contaminants. I then usually take them on a 50-100mi drive to ensure the file is good varying the rpm/load. After that I treat them how it's going to be used. My LLY motor got a 464/83/0.90 put on to tow a trailer 100-120mi before I put the 475 on it the first go around.
 

NevadaLLY

Adam B
Feb 24, 2019
305
27
28
Reno, NV
LOL. Clear as mud.

So what does "full load" mean? Should I throw a backup truck on a trailer, and go for a spin through the Sierra Nevada's (that's probably a 9-10K load) or go unloaded and just lug it in 5th with constant variation of RPM - probably vary the speed between 55 - 80 as well?

Also - why without coolant? any risk of warping/damage without coolant? To me, heat would transfer way too fast or unevenly with the jackets empty??
 

Bdsankey

Vendor
Vendor/Sponsor
Feb 1, 2018
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Neenah, Wisconsin
LOL. Clear as mud.

So what does "full load" mean? Should I throw a backup truck on a trailer, and go for a spin through the Sierra Nevada's (that's probably a 9-10K load) or go unloaded and just lug it in 5th with constant variation of RPM - probably vary the speed between 55 - 80 as well?

Also - why without coolant? any risk of warping/damage without coolant? To me, heat would transfer way too fast or unevenly with the jackets empty??
You're running the truck with load, your definition will be different than mine. Without a trailer load to me is hills/throttle/boost, with a trailer I put another truck on my gooseneck and went for a drive and will continue to do so for my own motors. The easiest way to define a load is either throttle/boost or weight which I have done. You want RPM to vary. To me that usually means in/out of 5th with varying load (light throttle/low boost) to moderate load (moderate throttle/high boost).


As for without coolant, you're running the truck for 30-45 seconds. You're not going to warp anything or overheat anything in that amount of time. EGT at idle is ~400f-500f if you're lucky so the heat transfer to the cylinder wall isn't all that high and you also still have oil spraying on the walls/onto and into the pistons to cool them. If 30-45 seconds worries you then you probably shouldn't own a Cummins haha. I've seen various shops telling customers to let them idle without coolant for ~10-20min to just make sure everything is set then to do a hot retorque on the head fasteners. Firepunk goes over this procedure in some of their videos which really struck me as odd but if it works for them I expect them to keep on doing it.
 
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PureHybrid

Isuzu Shakes IT
Feb 15, 2012
2,755
46
48
Central OH
I've never ran an engine without coolant for more than a min like Brad said.

You don't really need to load the engine to it's max potential to get things settled in. Even an empty trailer with some hills would be great
 

NevadaLLY

Adam B
Feb 24, 2019
305
27
28
Reno, NV
I've never ran an engine without coolant for more than a min like Brad said.

You don't really need to load the engine to it's max potential to get things settled in. Even an empty trailer with some hills would be great
I was really only thinking trailer w/ truck so if there's a major issue, just switch trucks. Loaded to me is 20K+, not 10K. Now I understand on the coolant side - so you don't have to pull any hoses if there is a fuel/oil leak after the system is pressurized, but not really running. I have also always been under the old rule of thumb that its really hard on the engine to start up for just a few seconds. I thought that would be especially bad on a new build.
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,431
42
48
Boise, ID, USA
I broke my engine in like James. First start no coolant, found I left an oil gallery plug out. Made oil pressure anyway, but a couple seconds of idling and there was oil freaking everywhere. Fixed/cleaned that up, added coolant, idled it for a couple minutes to make sure everything seemed good. Took it on a 1 hour drive through the mountains the next morning to vary the RPMs and make sure the tune was vaguely correct. Brought it home, cooled it off, and then towed a tractor up and down a 6% grade for an hour.

Almost 50k miles on the build now, and everything still seems happy.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
18,206
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Phoenix Az
I only ran no coolant because usually I have the engine hooked up just enough to start and idle (no front clip). Should there be a leak in a difficult place, easy to yank the engine and fix it. No ones perfect so I prepare for the worse.
 
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sneaky98gt

Member
Nov 5, 2013
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In every motor I've ever built, I'll run it for just a brief time at first to check for leaks or any problems (usually less than a few minutes). The "no coolant" option discussed above is not one I've ever done, but doesn't sounds like a bad idea in case there are any oil leaks.

After that, go drive it moderately hard and through a wide variety of loading situations. Not "doing-burnouts-in-the-parking-lot" hard, just some solid 50-75% throttle pulls through lots of rpm range and loading situations (a.k.a. not highway cruising for long stretches). Do this for a good hour or two, let it completely cool, check it again for leaks and problems. If all looks good, drive it like you stole it from there.

The "wait-some-arbritrary-period-of-miles-before-towing-or-driving-hard" advice is ill-advised at best. I used to work as a mechanical engineer for a very-well-known heavy diesel equipment manufacturer. Their break-in on brand spanking new diesel engines was very similar to what I described above, although in a much more controlled manner and with a lot more real-time data feedback. Their "drive it like you stole it" stage was significantly more strenuous than we could ever replicate in the real world.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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Mid Michigan
Prime oiling system just before engine install.
Fill with coolant on install.
Check for leaks on initial startup and repair any found.
First oil change at 500 miles, then as per normal.
Drive it like you normally would from the get go.
Do not "baby" it.
 

Doms

New member
Apr 23, 2020
25
1
3
Saskatchewan
What is the best method for priming the system? I see Melling makes a product that uses air to pressurize the oil system. Is something like this worth it?
 

NevadaLLY

Adam B
Feb 24, 2019
305
27
28
Reno, NV
Ok - so consensus is generally the following:
1) Install motor without front clip - turn over and run for less than 1 min - allow oil system to pressurize. Turn off - inspect for any leaks/misses. Pull if necessary - otherwise, complete reassembly.
2) Finish install - fill coolant/fluids.
3) Startup - do quick inspection for any leaks. <1Min
4) Go for drive - 1hr at minimum (50-100mi). Vary RPM/Load through entire range - not WOT - 50-75%. I am going to elect to tow a flat bed with truck on board. First, for loading purposes, second for spare truck purposes if I have a major issue in that first test. I might OPT to just tow the 3K flatbed empty and just have a friend come get me should the need arise.
5) Change Oil - inspect filter for major metal or issues. Inspect all clamps, mounts, hoses.
6) Let cool for a full cycle.
7) next drive - tow through mountains with trailer and truck. 100-300mi. full RPM range - throttle 100% on a few sections.
8) Change Oil - inspect filter - should have no major metal contaminants.
9) Let cool for a full cycle. - Should be good to go as per usual use.
 

clrussell

pro-procrastinator
Sep 23, 2013
5,657
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Hard to imagine you guys have never ran an engine for a short period with no coolant.

shit I can’t remember the last time I put coolant in something before I started it.
 

rcr1978

Member
Apr 1, 2007
771
11
18
Spring Creek, NV
For priming I put "some" (not a lot) white lithium grease in the oil pump when I had it apart for inspection to help create a good suction. Left the glow plugs out, disabled the fuel system, and spun it over with the starter until it got oil pressure. Mine got oil pressure pretty fast.
 

NevadaLLY

Adam B
Feb 24, 2019
305
27
28
Reno, NV
Should I be concerned with cylinder washing with 100’s in the first warm up cycle at idle? I’ll be loading a new tune for all the upgrades and it’s a Dsp5 so I’ll be on tune 1
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
18,206
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Phoenix Az
Should I be concerned with cylinder washing with 100’s in the first warm up cycle at idle? I’ll be loading a new tune for all the upgrades and it’s a Dsp5 so I’ll be on tune 1
no, if the tune is quality. you'd need a pretty jacked up tune to be worried. i wouldnt even worry if it was a 100% stock tune on 100% overs at idle.
 
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