Best way to run in an engine

[obi_waynne]

If you were getting a new car or rebuilt engine how would you run it in?

There are quite a few schools of thought here.

I note that demonstrators from new are driven quite hard from day one and don't seem to suffer as a result.

Most manufacturers insist on 2000 miles of lower RPM driving. Mini for example don't even specify an oil change until the first service is due (at least a year from new! ) This makes no sense to me whatsoever?

Can an engine be run in on a rolling road effectively?

I prescribe to the high load low RPM driving to get everything bedded in, lots of steep hills and stop start driving.

 

[stamford]

Interesting thread. Years ago when I built engines I used to take it easy for around 1500 miles, low revs etc and then another 1500 miles opening it up gradually and then progessive use. During that time I would carry out frequent oil changes to remove any crap from the initial build that may still be in the block after the machining, generally the first change within 100 miles to make sure. Then again these were not your normal small production engines but tuned ones. I remember when I rebuilt my HSX Chevette engine it was so hard to drive that at low revs and slow for so long! I even remember being at Castle Combe watching my mates racing around and them asking why I wasn't out on track. I used that day to run some more miles on it, but not on track.

When I was racing the Audi GT we never rebuilt our engines using new shells, we always purchased engines with at least 80k miles on them as that was found to be the best run-in period! We would strip and rebuild them using the original bearings. Never lost an engine in that time doing it this way. We built a few new ones and even after a run-in period they siezed on track as they were still too tight. Even an expensive ABT turbo engine built and ready to run seized after 4 miles around Goodwood, bent the crank! Supposed to have been bedded in.

When I bought a new Picasso I can recall that having a run-in period of around 1500 miles of 'soft' use before opening it up gradually.

I guess these days I would still follow the old principles of staged run-in periods and frequent oil changes and do this with normal driving with varying loads and conditions. I don't think a rolling road run-in would be ideal but having never done it that way I can't really comment.

 

[turbonutter69]

The run in for my Focus was 1000 miles. And it didn't have an oil change until first service which was 12500 miles.

 

[Yugguy]

When I got my new Clio 172 which I paid for I followed the grannying-in route and then got an oil change straight after the running-in period.

When I got my Vectra 2.6GSI company car, from new, I just drove it.

If I ever had a new car again which is unlikely I think I'd just do what I do anyway, which is let it warm up and then drive normally, with high revs sometimes.

 

[HDi fun]

Just drive it normally really. Don't go mad with revs first 500 or so miles and try to drive at differing loads and engine speeds. So if you're on a M/way at 70mph, drop to 3rd for 20 minutes or so to vary the engine speed.

Avoid heavy load (full throttle) operation.

Oil should be left alone if this is what the manufacturer states. Many cars bed in on mineral or semi and only get a synthetic fill at the first service.

 

[thexav]

Whatever the manufacturer tells me I'd get an oil and filter change done at 200-500 miles if I had a new car or new engine.

The key I think is to vary the load, some motorway some town with a bit of stop start. It is very important to warm the engine up, lots of short journeys on a cold engine would surely kill the whole point of a run in period.

 

[Big Fat Fatty]

lol, when I saw the title of this thread at a glance I thought it said "what's the best way to ruin an engine?"

My answer would be to give it to me for a week!

 

[HDi fun]

I think this was discussed here 4 or 5 years ago. There is a school of thought which says hard and fast, although I think the author of the site was referring to motorcycle engines in that context.

I'm not sure that the early oil change is good. You need some metallic swarf to hone up the bores in the early stages of running in. Hence the no oil change for 12,000 or more miles in some cases.

 

[obi_waynne]

I've heard that the fast run in method can lead to blown oil seals on car engines. I think it has something to do with "blow by" round the piston before it beds in but I'd be curious to know if anyone can shed any light on this.

 

[HDi fun]

I'm inclined to agree. The fast break-in is a radical concept. The more orthodox method is probably safer and it's certainly proven to work.

The worst thing is apparently steady [engine] speed and steady load. It's better to vary both in my opinion.

 

[Richard1]

Stop and think about what is happening during the break-in period. If we are Porsche, with a perfectly clean environment, perfectly calibrated equipment, all new parts, etc. the bearing areas are round, no turbulence. The rings are a perfect fit, etc.

In the real world, how many of us replace the bearing cap bolts on every rebuild, or stretch them to the exact microns required to get a perfect circle? How many of us have perfectly calibrated torque wrenches? How many of us have dust free clean rooms for assembly?

If we tighten down bolts with dust in the surfaces, old bolts, torque wrenches that do not apply the right amount, we cannot expect a perfect circle in the bearings. We need to let them wear slightly to create the perfect hydrodynamic cushion of oil without turbulence or cavitation. We probably have cylinders that are not perfectly honed and need the rings to seat against them. The soft lead on the top surface of the bearing is meant to wear to the point of making the cavity as round and smooth as possible so the oil can form its cushion.

I'd rather have all that happening with little extreme pressure, and change out the oil at 50 km and 800 or so at least.

If you push hard and don't have a perfect circle in the bearings, you don't have a complete hydrodynamic cushion. So you have extra wear on the top and bottom of the bearing surfaces..... the amount depends on the additives in the oil.

And if you are replacing the cam, you want it to run in smoothly against the lifters. A hard run-in is dangerous.

 

[HDi fun]

So this thing about leaving the swarf in there for 30,000 miles 'til the first service is a myth which the makers use to make the TCO attractive to fleet buyers. Which it is. And not so clever for the buyer of a 3 yr old car which has perhaps only been serviced once, maybe not at all in the case of low annual mileage.

Well, I'd never have believed that, would I now? Surely the mass market manufacturers would never be so cynical. Oh dear, how naive I must be. :blink: :blink: