Running In A Motor

[camerondownunder88]

Hi,

Just wanting to gather info on what some people prefer to do when run there motor in on a car after a rebuild.

 

As what do you like to do and for how long and shit so post up.

 

Cameron

[Des]

1000 or so km of driving with different situations as in hills, Flat land and changing your speed so it reaches different rpm ranges, But don't rev its ring off obviously.

 

I have also heard that you should use mineral oil ?

[beerhead]

Des is on the money, but not just mineral oil you want to run it on non-viscosity modifed oil for a while, ie 20W not 20W50. Modern bearings don't have the run in time of old ones. Many people with purpose built race motors will start the motor on 20W, run say 5 mins, turn it off. Change the oil and let it get to operation temperature at ide. Drain the oil change the filter and thrash the living hell out of it :jamie: Not recommended for your daily though.

 

Hills in high gears are the ticket, you want to have the engine running in very high vaccum to suck the rings into the bore and bed them in.

Edited February 16, 2007 by beerhead

[BreakDave - GT]

Not entirely too sure bout this one, but i reckon i've heard bout running diesel oil in after a rebuild, or if engines been lying round for a bit coz it has 'cleaning agents' or something in it??

[Trev]

Not entirely too sure bout this one, but i reckon i've heard bout running diesel oil in after a rebuild, or if engines been lying round for a bit coz it has 'cleaning agents' or something in it??

 

Yep diesel oil has more detergents, I run diesel oil in my 4AGE every now and then, Alot of people use diesel oil as an everyday oil in there petrol engines.

[Redwarf]

Drive it like you're going to use it. :jamie:

[NoPsi]

^^^^ Funny I was going to say something along those lines...more like drive it like you stole it.

[SoulSearcher]

heya!

 

When I had my engine re-done my mechanic basically told me to drive it like I usually would and give it a hammer.... *I am a lead foot, and pretty much drive my car like a maniac* :lolcry:

 

He said the reasons for this were to get the rings to seat properly, and by driving in such a matter (although continuing to vary the rev's and if you're going for instance on the freeway, to change from 4th to 5th and chaning the RPMS.

 

There was a thread with a link about running in (with links) some where in the forum....

 

 

Lesley :lolcry:

[flat out]

from the FAQ. this is for a k motor but you didnt say what engine you was running in

 

There are alot of different ways to run in a motor, and it seems to be a bit of a "black art". The basic things to remember are that a cold engine doesn't wear much, and a hot engine doesn't wear much, but an engine between 20c and 80c does about 90% of its entire wear between these two temperatures as it's warming up. At the start, you want the engine to wear a bit, so the rings bed in and seal properly, and everything frees up and becomes happy with its new surroundings. Some things take a long time to bed in, such as the rings, some things don't take as long. For example, the big end bearings and crank bearings will be worn in the first time you start the motor. Here's how I did mine.

 

The first time I started the engine, I let it idle to operating temperature, giving a few revs a couple of times a minute to keep oil pressure up, then turned it off and let it go dead cold. The next time, I drove the car for about 5 minutes, turned it off and let it go dead cold. The time after that was 10 minutes, then 20 minutes, then half an hour, then an hour, then I didn't worry about temperature cycling it so much.

 

I ran running in oil for the first couple of hundred km or so. This is a fairly thin oil with lots of graphite particles in it. The graphite lubricates the tight metal parts as they try to rub against each other while the clearances are still really small. The oil is thin, so you shouldn't rev too hard with it in, as you can squish thin oil out of the bearing gaps, and the oil can wipe away at high component speed, leaving a fairly bare surface with chunks of graphite and metal on metal which will score surfaces which should be lubricated. After that, I changed the filter and swapped to a straight 30W oil, and kept this for a couple of thousand miles, then renewed the oil and filter with the same, and drove it for another couple thousand miles. I then changed the filter and started off with the 5w synthetic oil, but later changed to the 15w semi-synth as described in the oil section.

 

I tried to keep a sensible but gradually increasing rev ceiling. I took it to 6000rpm on the first day I had it, then 7000rpm on the next day, then I couldn't resist an 8000rpm test run the next day. I didn't flog the arse out of it from then on, but I kept it below 7000rpm until I got rid of the running in oil. Once I'd changed to the synth oil, I was pretty confident the motor was going to hold together, so 8000rpm became more of a regular occurrence. I didn't hold it flat and reach the 8500rpm limit of the stock carb until it was run in fully.

 

A K motor is an old design, and uses fairly high tension rings. At the start of the engine's life, you want to put the engine under large vacuum conditions, so the rings "suck out" against the bore walls and wear themselves into the cylinder hone, so they provide a better seal. The way to do this is to get a long section of road with no stops, and drive along at normal town speed, shift into 4th or 5th and put your foot down, letting the revs slowly increase as the engine sucks air in. Hills are really good for this, as you don't end up going too fast and speeding. Do this sort of thing as much as you can during the first 500 miles, as this is when the most ring wear occurs. Don't unnecessarily labour the engine, but don't just cruise with it either. The point is to be constantly changing the vacuum conditions of the engine. Don't take it on a long steady drive, what you want to do is constantly vary your speed and gear, so you have to put your foot down, and that makes the rings suck out and wear in better.

 

After about 1000 miles, I just drove the thing normally, there's not much you can do but wait, and you'll know when the engine is fully run in, it will get alot more powerful for no reason. Mine took 4 or 5000 miles. Run in period over.

 

There's also no point trying to tune a new fuel supply on a fresh engine, its' needs for air and fuel and vacuum are constantly changing, so you'll find yourself changing the tune every week or month, and if you get it to lean out and detonate, or you can't get it started, or you put too much fuel down the sides of the bores, the engine won't seal up as well and you'll have lost power from the word go. I'd say leave the fuel supply stock until it's run in, and you know a tune is going to last longer than the next 1000 miles.

[SoulSearcher]

kewl write up ^^^^