Running in an engine

[Anorak_ian]

All the talk of rebores and pistons got me thinking.

What is the best rev range to start running in new rings?
The first 500 miles up to 2000rpm, and the second 500 gradually work up to 3600rpm?
Or use the whole rev range gently from the off?

[Sphere]

I'm gonna break out the popcorn and the fizz and watch the people below me religiously defending their views

[thundercougarfalconbird]

i guess you have to consider how industrial engines are treated, on water pumps and generators they are started and put to work , and in the case of a water pump they have a high load applied from new at 3600 rpm.

the best advise i can give you about break in for any engine is warm it up and the use it , on a bike or car no extended periods of wide open running.

[IgorVigor]

Personally I would say the first 50~100 miles up to 2000 rpm
then 50~100 miles up to 3000rpm.
and then 50 miles not cruising at higher than 3000rpm but rev it to 3600rpm on acceleration...
I presume you stated 3600rpm as that is your max rpm?

The problem when running in, is you need to bed the bore and rings in, so you need to be fairly gentle initially, but once they start bedding in, you need to work them a bit more so you dont glaze the bore...

I have done the above technique on several bikes, and members of my family have done it with cars and never had a problem.
Obviously the rpm changes according to the vehicle and engine fuel type...

Hope that helps, and I hope I wont get moaned at by anyone for doing the "wrong" method :S

Apart from that, thundercougarfalconbird's answer already answered it (more simply though )

[Anorak_ian]

I was thinking about diesels in general, not just my own, which is 3600.

There is a big difference in petrol bike engines running in, i.e. Royal Enfield state 35mph for a few hundred miles, then 45 etc, while other bikes (jap) jump on and just take it easy for a while.
So I thought there must be a difference between petrol and diesel.

The other thing is the length of run in time, I thought it was 2000miles for a new engine and 1000miles for a rebore or new rings, but I have heard different things from different people.

[andrewaust]

From rebuilding diesels I'd suggest to not go lugging the engine for the first 500 Ks, don't sit the engine on one particular speed "even though industrial engines are built for singular speed applications in many situations" remember these engines usually spend there life powering pump, gen-sets etc, but a bike is going to introduce the engine to a different environment.

The running in process is to "polish" journals, bearing surfaces, wearing in rings etc. Adjust tappets etc at end of break in period. Change the oil often = 100, 500, 1000 Klms, halve it for miles.

If you can, watch temps if its liquid cooled, and avoid long idle periods while running in. Most engines we use don't have oil pressure gauges or anything fancy , but keep an eye on the oil level and if possible check oil pressure.

Everyone who rebuilds engines have there own ideas, these are just some I stick to.



A

[John]

Just been studying the technique for running in of a truck diesel in a generic technical manual for same. The engine is not run in on the road, but on a dynamometer. First, the brand new engine is left to idle for no more than 2 minutes, to allow the oil to be pumped up to the camshafts & lifters. Then, the engine is gently taken to half power revs, where it is then left until full working temperature is achieved. Various parameters are then checked to ensure all is well regarding temperature & oil pressure. With full working temperature attained, the engine is then taken to full power revs, & a load applied from the dynamometer until the engine can only just maintain full rated power revs under maximum load. The engine is now working at full power & full rated rpm. It is then left operating in that state for a full 20 minutes! At the end of this feat of endurance, the load is removed from the engine, & it is allowed to idle for a couple of minutes in order that heat is dissipated generally, & especially from local hotspots, especially the turbocharger!!! The engine is then shut down. Running in is now deemed complete, with the rings bedded in under high pressure to the barrels, & no further nursing is required.
Of course, in the case of a big truck diesel, we are talking of a maximum of perhaps 1100 rpm, not 3600. Even so, the main enemy to a new engine is allowing it to lug down under load at unnaturally low revs, when oil pressure may be insufficient to separate the working surfaces, - & allowing the engine to over rev for prolonged periods (in a high speed type) before the tightness in the bores have subsided somewhat. There is no need to be too precious about nursing the engine under light load after the first hundred miles or so, as high cylinder pressures ensure good bedding in of the rings & low oil consumption later.