Summary

What's the proper way to break in a freshly built engine and what type of oil should be used for that period? Again this is an area where there's a huge amount of confusion and a huge amount of misinformation. For this reason we actually have included a module in both our practical and our fundamentals course on engine break in.

00:00 - Naden has asked, what's the proper way to break in a freshly built engine and what type of oil should be used for that period? Again this is an area where there's a huge amount of confusion and a huge amount of misinformation.
00:12 For this reason we actually have included a module in both our practical and our fundamentals course on engine break in.
00:20 And it's a process that I've sort of gone through and developed in my own career.
00:25 I've got a process that works exceptionally well and as with most engine builders I tend to be a little bit superstitious, once I've found something that works, I stick to it, and I don't vary.
00:36 The important part about engine break in first and foremost is understanding what we're actually trying to do.
00:43 And this is where a lot of the misinformation comes from.
00:45 A lot of people think that we are trying to bed in the bearings or the crankshaft, and that's just not the case.
00:52 If we ever end up with metal to metal contact between the bearings in the crankshaft journals, we're going to end up instantly causing damage, and once that occurs, no amount of gently running is going to help the situation.
01:05 We're going to end up with damage that needs to be fixed.
01:07 The main area that we are trying to deal with during engine break in, is to bed the rings against our freshly honed bores.
01:16 And we have a relatively narrow window in order to do this.
01:19 So what we're trying to do is bed those rings so that they achieve a correct seal against our cylinder walls.
01:27 And if we achieve this we're going to end up with an engine that produces good power, low blow by, and has low oil consumption.
01:34 So what we're trying to do there is use the rough surface of that hone pattern to abrade the rings and make them seat.
01:43 And we only have a narrow window as I've said before that hone pattern will be broken down.
01:48 So the worst thing we can do when we're breaking in an engine is to baby it or to allow it to idle for extended periods particularly when it's hot.
01:58 This will place almost no load on the rings and it will allow that hone pattern to be broken down without it actually performing its job.
02:05 So what we want to do is use moderate amounts of load and moderate amounts of RPM.
02:10 Then what happens is when we use moderate amounts of load, combustion pressure gets in behind the rings and it forces them out against that fresh hone pattern.
02:19 So this forces the rings against the wall and helps the bedding in process.
02:22 Of course because that hone pattern is a little rough to start with it also causes a lot of friction and hence a lot of heat.
02:30 So we need to be careful, we don't wanna go straight to wide open throttle and 8500 RPM.
02:35 That's going to cause the rings to overheat.
02:37 So we want to vary between periods of moderate load and then periods of low load and that'll allow the rings to cool back down.
02:45 The bedding in process is normally completed within about the first 100 or 200 kilometres of use.
02:52 So those people who have heard engine builders requiring 1000 or even 5000 kilometres of running in, it's absolute rubbish, it's simply not necessary.
03:01 After the first couple of 100 kilometres of use, your rings, your engine is as bedded in as it's every going to be and after that, it's all downhill so you may as well get out and start enjoying your engine.
03:12 The other thing just talking about there, you've mentioned oil.
03:15 There are some specific running in oils.
03:18 I've used those myself but now I've tended to go away from them.
03:22 The reason for this is the running in grade of oil tends to be incredibly thin.
03:27 It's almost a little bit like water.
03:28 And the idea here is we're providing an oil that's going to allow the rings to bed in correctly.
03:34 So for example, it's common in performance engines to use high quality full synthetic oils.
03:40 Those are actually so slippery that they make it harder for the rings to bed in, so we clearly don't want to be using a full synthetic oil during break in and that's where these running in oils come in.
03:53 More recently what I've done is gone away from running in oils and I actually use a good quality mineral based oil.
03:59 That's still going to provide the protection I need, because even during break in, these engines are still producing reasonably high power levels, we want to protect all of those components with a good quality oil.
04:10 But the mineral based oil is not so slippery that it will prevent the rings from bedding.
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