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Practical Engine Building: Step 10: Initial Start Up

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Step 10: Initial Start Up

05.15

00:00 - When it comes time to start your engine for the very first time, there are a few steps that should be taken that can help ensure you don't inadvertently cause any damage.
00:10 Before going any further, you're going to need to fill the engine with fresh mineral based engine oil, as well as fitting a new oil filter that's also been primed with oil.
00:20 The oil you choose should be of the same grade as what you intend to run.
00:25 However it's not advisable to use a high quality synthetic oil as this can be too slippery to allow the rings to bed in correctly during the breaking in process.
00:36 Next we can fill the cooling system.
00:38 I recommend for the initial break in period that just plain water is used with no glycol or coolant added.
00:46 Glycol in particular is a lot more prone to leaks forming than plain water when the engine hasn't been run.
00:52 After the break in period the water can be drained and filled with coolant as per the manufacturer's recommendations.
01:00 Once the engine is filled with oil and coolant, we want to disable the fuel and ignition to prevent any chance of the engine starting up inadvertently.
01:09 With EFI this can be achieved by unplugging the ECU or alternatively disconnecting the crank angle sensor.
01:17 With a carburettor we'll need to disable the fuel pump and the ignition system.
01:22 I actually prefer at this stage to also remove the spark plugs from the engine while we're achieving oil pressure for the first time as this will remove the compression load from the piston and reduce the amount of load placed on the big end bearings while there's not actual oil pressure to protect them.
01:40 Now we want to crank the engine over on the starter motor until we can achieve good oil pressure.
01:47 If you don't have an actual oil pressure gauge fitted to the engine I'd suggest temporarily fitting an external gauge during the initial start up and run in process as the oil pressure warning light on the dashboard won't give you enough information about what the oil pressure is actually doing.
02:05 You may find that it takes as long as 30 to 60 seconds of cranking to achieve good oil pressure but it's essential to do this prior to allowing the engine to start for the first time.
02:18 We want a constant supply of pressurised engine oil throughout the engine and cylinder heads to provide protection to the components during initial start up.
02:28 This is even more important with a freshly built engine as the oil galleries will initially be completely dry of oil and this is why it can take so long to build oil pressure this first time.
02:41 Once the oil pressure begins to register on the gauge, we want to continue to crank the engine for another 30 to 60 seconds to ensure the oil is adequately distributed to all of the components.
02:54 At this point we should be seeing somewhere in the range of 20 to perhaps 50 psi depending on the cranking RPM and the grade of oil you're using.
03:04 Particularly if you're barely registering any oil pressure, this may indicate a potential problem.
03:12 Provided you're happy with the oil pressure, you can now refit the spark plugs and enable the fuel and ignition systems ready for startup.
03:20 We can now start the engine.
03:23 During this initial startup the engine may run slightly rough, and you're also likely to find some smoke is evident from the exhaust.
03:31 This is normal and is just the excess lubricating oil that you used during assembly being burned off.
03:37 It should settle down within a few seconds.
03:40 Once the engine's running there are a few checks that are important.
03:45 Firstly we want to take note of the engine sound, and specifically we want to listen for any signs of mechanical issues such as knocking or grinding noises.
03:55 We also want to pay attention to the oil pressure gauge to ensure that the oil pressure is sufficient.
04:01 With the engine cold and idling, at perhaps 1000 to 2000 RPM, it's not uncommon to see pressure in excess of 80 to 100 psi.
04:11 If you're still only registering perhaps 10 to 20 psi at this point, again it may indicate a problem with your lubrication system or oil pump.
04:20 The last check we want to perform is to make sure we have no fluid leaks from the engine.
04:25 This includes oil, water, and fuel.
04:29 With a lot to take note of during this initial startup, it can be beneficial to have a helper who can focus on just one or two tasks, and you can focus on the others.
04:39 If there is a problem, we want to know about it quickly so we can prevent or limit further damage.
04:45 During this initial startup we can also perform any required initial setup activities such as setting the base ignition timing, or base fuel pressure ready to begin the break in process.
04:58 We can also top up or bleed the cooling system as required.