Running in period

[SimonR]

I got a booklet with my new engine about how to fit it and a few dos and donts when running it in (first 500 miles).

The advice was:
Don't take it above 3,000 rpm
Avoid short journeys
Avoid long periods of idling

The explanation for that last item was that it caused glazing on the cylinder bore.

My questions are:
What is glazing and why would that happen only on a new engine?
What are the problems caused by glazing?
Why avoid short journeys - is it something to do with heating/cooling too many times in the run-in period?

Just a few little questions to make a friday afternoon go a little faster!

Have a good weekend :cool:

PS I have done my first 100 miles!

[F690OTF(RIP)]

On short journeys (less than 5 or 10 miles), the engine doesn't properly warm up. The most obvious effect of this which I can think of is that the oil doesn't become thin enough to get into all the places it needs to get. If you do lots of short journeys, some parts of the engine may go essentially un-lubricated. In fact this is sound advice all the time, not just for the first 500 miles.
This problem is exacerbated by the fact that petrol will condense on the cold walls of the cylinders, which has the effect of washing the oil off them. Again, if the engine is not allowed to warm up properly then this will be happening for a greater proportion of the time, promoting engine wear.
In the old days of leaded petrol, I guess a new engine would have worn much more quickly in the event of poor lubrication than an older engine with lead deposits in place. I don't know whether there's a modern equivalent to this.

Those are my ideas, anyway. I'm sure others will have much more definite answers.

[Katana550]

Just to add a bit here,

The exact requirements for running an engine in vary across makes/types/specifications but are similar (and for the same reason) for all internal combustion engines: cars/bikes/tractors!

When an engine is assembled (whether a new engine or a 'proper' rebuild) the barrels within the cylinder block are 'honed' this, essentially, scratches a criss-cross pattern over the complete internal surface.

When the engine is assembled - hopefully with new piston rings - the action of the rings against the cylinder bores actually wears both of them into a tight fit that will ensure oil-tightness (that was some excellent English!) and a correct compression figure.

The requirement to not over-rev the engine excessively stops the bores 'glazing' (a smooth non-matched interface) with the piston rings. This effect is also produced by constantly running the engine at a steady speed (idling).

It is usually a good move, during the run-in period, to vary the engine speed as much as possible and, occasionally, to actually exceed the maximum RPM/engine speed for short periods of time.

Hope this helps


Tim

[Mat_C]

Glazing is often due to running in on fully-synthetic oil. The rings don't bed into the bore causing it to burn oil amoungst other things.

Use a normal, mineral based or special running in oil during this period. Then change the oil filter and put in some decent oil.

It is always safer to slightly exceed 3000rpm than allow the engine to labour. After about 500 miles, increase the rpm limit gradually!

[Simon]

I carefully followed the running in instructions with my new engine and, nearly 50,000 miles later it is a top performer that uses very little oil indeed. I have a 25 mile trip to work then back again every day which is mixed conditions, ideal for running in the car. Remember to change the oil and filter after the first 1000 miles.

[hornmeister2000]

I had a reconditioned about 2000 miles ago and the advice I was given was:

For 500 miles:
Don't over-rev
Don't potter around below 50 (ie push it occasionally)
Allow to warm up slightly before driving

For 1000 miles:
Still take it a bit easy

It went back to the garage at 500 miles to have the head re-torqued, oil and filter changed. I was also advised to us mineral oil for the first 6000 miles to allow it to bed in properly, then use a high quality synthetic after that.

Incidentally, what do people recommend as a good oil. I always used Magnatec 15W40 but am open to suggestions of a good oil to use. Now with recon engine, I'll hopefully be able to go down to 10W40 without it all coming out through the exahust!

[E_T_V]

Uh ohh not this thread again!(there was some discussion a while ago on this and the old noticeboard.)

However for my 2p I use semi synthetic 10w40 in everything I own with no additives as they're rubbish. Oil consumption isn;t a problem on my A series with 15k on it.

[SimonR]

Re. oils, check else where on the forum as this has often been debated. To let you into a (not very closely guarded) secret, the oil that I would totally recommend (Unipart Silver part synthetic) is on very special offer - instead of £23 it's £7.75 at my local Rover dealership: Marshalls, Cambridge.

I've bought 15 litres of it and will be using the first lot in about 220 miles.