Running In My Rebuilt Engine

[driversdomainuk 8]

Hi

 

I am currently getting my engine rebuilt - reground crank, new piston rings - possibly new liners and pistons and other bottom end bit and bobs....

 

Working on the basis that the garage will have done their bit after the rebuild, how best should I run the engine in when it comes to driving it..?

 

How many miles should I safely run in before I give it a good hard drive (i.e track day etc), and what sort of driving/speed should I do - I am planning to do a few 250 mile drives at 60mph down the motorway, but some have said I should not be too soft on it, and just try and drive it as normal...?

 

Any help would be great as I want to make sure it gets the best chance to run in properly.

 

thanks,

[Dream Weaver 2]

First of all, don't use the motorway to run it in, keeping sustained revs at say 70mph will do more harm than good.

 

I just ran mine hard, didn't bother with any soft running. Just let the oil get fully warm on each journey and drive as normal.

[driversdomainuk 8]

First of all, don't use the motorway to run it in, keeping sustained revs at say 70mph will do more harm than good.

 

I just ran mine hard, didn't bother with any soft running. Just let the oil get fully warm on each journey and drive as normal.

 

thanks for that - so why out of interest would that do more damage than good..?

 

I take it the engien will feel tight and not as quick for a while also

[Dream Weaver 2]

You need to be varying the load and revs so that the rings have time to bed in properly and dont glaze the bores. By keeping a constant speed/load they don't do the rings any good.

 

Vary your speed, vary the load and drive at about 8/10ths.

 

I kept mine to 6,500rpm for 500 miles, then let rip. Do plenty of full throttle runs, lots of slowing down in gear, and a few low rev runs as well.

[dazEmad 0]

I ran my new engine (not rebuilt) in upto about 4000 rpm for the 1st 450 miles it was very tight. It was used just on normal roads with hard accelerating to bed everything in and then gave it some welly after 450. I feel its been a great running in method with no problems after its running in, engine sounds very sweet, oil pressure to the max bar and goes like a good un.

[ALEX 98 1 Cars]

First of all, don't use the motorway to run it in, keeping sustained revs at say 70mph will do more harm than good.

 

I just ran mine hard, didn't bother with any soft running. Just let the oil get fully warm on each journey and drive as normal.

 

I vote for that too.

Others will dissagree.

 

Plus it lets you enjoy the fruits of your hard labour sooner!

Edited October 10, 2006 by ALEX

[niklas 1]

Also agree with the above.

Let everything get warm and step on it. A lot of full throttle acceleration all the way in each gear etc.. Just like we usually run our cars

[Dream Weaver 2]

And to add to the running hard opinion:

 

1. When I had the 205 MOT'd I asked my mechanic about running in, and he said modern oils are so good that cars don't need running in nowadays.

 

2. When we had a brand new BMW engine in the Beemer last month, I asked them the same question for that and he said just take it easy for 100 miles

 

It's entirely up to the engine owner though

[Edd-XS 0]

There are soo many different methods of running an engine in... when people buy new cars, are they told to 'run them in' or are the engines pre run? Does it really make that much difference aswell? Ive just had my engine re-built and obviously want to do the best thing, but If i dont cain it too hard to start with and always let it get up to temperature, Am i going to notice a difference? Sorry for the slight hi-jack but its on the same theme

Edd

[Guest rick03054]

I've been reading a lot about this recently, but I don't actually have any first hand experience other than a mate who got a brand new imprezza and thrashed it when warm from new and it was fine.

 

Most of what I've read talks about running it in gently and all that but doesn't back it up with any engineering. The stuff backed up with engineering suggests hard acceleration, lots of variation in engine speed (obviously not really high revs though) and plenty of engine braking, which pushes the rings out into the bores to allow them to bed in properly, and not overheat or just rub, which would cause glazing and an inferior seal.

 

That's my take on it anyway.