Running in the Engine - Engineering explained.

But not by me .........


Ok, Gen 4 manual says:

*The future performance and reliability of the engine depends on the care and restraint exercised during its early life. It is especially important to observe the following precautions during its first 600 miles.

* After starting, do not race the engine, wait until warmed up

* Avoid prolonged vehicle operations at a constant speed . Moving parts will break in better if you are vary your speed.

* Start off from a stop slowly, avoid full throttle starts.

* Avoid hard breaking, especially during the first 200 miles.

* Do not drive slowly in a high gear.

*Drive the vehicle at moderate engine speeds.

* Do not tow a trailer fopr the foirst 600 miles.


So, some of these are obvious, like brakes being worn in, and waiting for the engine to warm. However.....

I would love to know whats actually happening during the first 600 miles. Or not happening if the engine is stressed. Anyone wanna make this super clear and preferably detailed for monkey boys like myself.

It has preoccupied a lot of my driving time, wondering what is going on under that hood with the engine and transmission. And at what point do we start incrementally increasing revs etc, and by how much etc etc...... ?


Super - mega detail welcomed. Guess work will also be happily tolerated


Andy.

All the different parts of the engine will differ in size by a tiny amount from car to car, due to the limitations of the manufacturing process. When the engine is new, all those parts have to be worn slightly so that they fit perfectly together. There will be microscopic bits of metal being worn off the inside of the engine as pistons and camshaft and valves all do their complicated stuff.

If you just rag a brand new engine, there's a chance that a couple of those bits might decide not to play nicely and jam or knock bigger chunks off each other, so it's better to take things easy to allow for gradual wear.

It's not such a big deal these days are manufacturing tolerances are far tighter, but still well worth it.

Nice1 Gadget, that's interesting stuff.

So, when would you start introducing higher revs then mate? After say 600 miles or...? and finally (sorry, i ask far too many questions) at what point will you hammer it

The longer you are able to be gentle with it the better, to a point. Dreadnaught had 18k of oap miles under her belt when I took her on and it showed. She was unable to rev cleanly and was generally very tight. But equally everything was nicely bedded in when the abuse started. I personally think that the first year or service which ever is first is a good length of time for being at least vaguely careful. After that crack on.

Had a conversation with a test engineer for a performance brand about this a few years back. His opinion was that babying a vehicle can do just as much damage as thrashing it. He swore that vehicles he'd driven hard but respectfully* from new had measurably better performance in later life.

*Respectfully means letting everything get up to temperature.

With any 4x4 vehicle, the worst thing you can do is drive at a constant speed on the motorway for ages. That creates an uneven wear pattern in the ring & pinion sets. Varying your speed avoids this.

Everything that has been said is the way to do it,,plus the need for an early oil/filter change at 500/600 miles to be sure that all the initial running in rubbish is removed and you have a clean engine to progressively bed in.