New/rebuilt engine break-in
I know at this point, this topic is just like driving a plutonium-fueled Delorean up to 88mph without first checking the destination date on the time circuits and verifying that the flux capacitor is.... fluxing. In other words, beating a dead horse.
For hours, I've searched and read several threads here about it. My apologies for a lengthy post and if you're already rolling your eyes.
The engine is the original 12 valve Cummins out of my 1990 Dodge. Everything done to it is as follows.
I was referred to a machine shop by Craig at Big Power Diesel. The shortblock was rebuilt using a Mahle rebuild kit with Victor Reinz seals/gaskets. The cylinders were in great shape but I was told that a .020" bore was a standard practice for a rebuild in order to start with a good bore and taper. I do recall the pistons being somewhat loose in the cylinders. New pistons have very little movement. In went new .020" over pistons, wrist pins, wrist pin bushings, cam bushing, cam thrust plate, standard upper and lower main and rod bearings and billet oil squirters. The original crank and connecting rods were inspected, said to be in great shape and reused. I opted for new rod cap bolts and paid extra to have the piston and rod assemblies balanced. A Hamilton 182-214 cam with a set of their 1.45" tappets, HD push rods and a gear retainer. New billet freeze plugs installed by me. All other expansion plugs replaced. JB Weld epoxy applied along their perimeters by me.
The cylinder head and work was sourced via Eric at The Hungry Diesel. A reman'd unit from Cummins. It was machined true and had .062" diameter o-rings installed with a protrusion of about .012", new Hamilton 165lbs springs, retainers and collets, 3-angle valve job (valve heads back-cut) and a port and polish and clamped down with a set of ARP Custom Age 625+ studs.
I built a custom coolant bypass kit using a Keating Machine billet rear freeze plug and a Watts 530C PRV which dumps into the upper radiator hose via a thermostat housing (with a threaded vent port) from a p-pump motor.
It seems like the general consensus is to, within reason, drive it like you stole it for the first 500 miles or less. I've even seen mention of distances as short as 20 miles. All for the purpose of getting the rings to wear down the peaks in the crosshatch in the walls and ultimately seat. Others have elaborated and suggested dragging around a somewhat heavy trailer; around 8000lbs. I certainly don't disagree with this. During my time in diesel tech. classes, the only way I had ever been taught to break-in an engine is to bolt it to a dyno and give it 100% load for a few minutes. I was lucky enough to have been able to do that with a couple engines I had rebuilt. Both ran excellent and easily achieved their advertised power ratings.
I'm excited to hear my engine come to life very soon. Yet at the same time I'm nervous. I've always had the mindset of, "What if?" Which could either be a blessing or curse. With the amount of time, money and care I've put into this engine, I want to ensure that I treat it the right way in order to prevent issues and so that it will run damn near forever. I've done my absolute best to make sure everything was and is done right. If I ever doubted anything, I researched it until my brain was numb to get some answers. At times, researching it all over again because I second guessed everything I read the first time.
I'm aware of the recommendation to retorque head studs after each heat cycle, a few times. I believe I've also seen mention of doing so until the the nuts don't turn any further beyond their previous position at the final torque value? Between the retorques and prior to the first, I can push the engine within reason in order to seat the rings, can't I? Even with o-rings in the head, I'm not thinking the head gasket it going to leak immediately after the first start-up but just wanting to have confidence in the fact that it'll handle some slight abuse for the first heat cycle.
Can a break-in be done properly without dragging a heavy trailer around? I'd assume it may take a bit longer than it would with that much of a load. I'm only asking in the case that I can't locate a trailer heavy enough. I suppose I could strap my 4000lbs Passat TDI to a car hauler. Adding the trailer weight, it might only be about 6000lbs though. Would that be sufficient?
Also, I have an NV5600 transmission with a South Bend Con-OFE clutch kit. I had the flywheel surfaced prior to reinstallation. No changes to the clutch disc or pressure plate. Is that enough to think of it as a rebuilt or new clutch and therefore, need a break-in before towing anything?
I think I've covered it all. I'm not quite 100% confident as of yet so I'm hoping for some votes of confidence and words of wisdom and advice to get me there. If you have any questions or concerns, ask away.
1990 Dodge D350
Giles' 12mm VE - Airdog II 165 - THD 370s @ 75lpm - BW S362fmw/68/12 - Hammy 182/214 - '01 NV5600
2013 VW Passat TDI
AFE exh. - AFE Stage 2 intake
Last edited by jimbo486; 07-24-2016 at 03:05 PM.