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it says in my new car handbook that i am to avoid driving for a long period/distance at a constant speed for the first 1000 miles, my question is how long is a long period/distance and how much should i vary my speed by?
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All answered in HJ's FAQ's (located in red menu bar to the left of screen)
www.honestjohn.co.uk/faq/faq.htm?id=12
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An educated guess would be, err, 1000 miles as you yourself pointed out.
I've had my Xsara 1.9TD for six months now and have never pushed it past 100MPH. I'm terrified of breaking something.
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David:
It is always good to read a post thoroughly before posting a sarcastic reply.
Andy
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Joe:
I'm in the process of running-in a new car too. As I remember HJ recommends varying speed by 5-10 mph every 5-10 minutes. On the UK roads I have driven so far in the car, for 800 miles, I have noticed that there have been very few times when I could possibly have broken the advice, enen if I had tried.
For what it's worth, I set myself a nominal rev limit of 4000-4500rpm for the first 500 miles and have gradually been increasing it since. Don't labour the engine and, most important of all, don't rev it or drive hard until it is thoroughly warm.
Andy
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You don't mention whether the car is petrol or diesel.
Even with today's tolerances, diesels take considerably longer to
fully run-in, Ford's 90bhp lump is reckoned not to be run-in until >15k miles!
It's not rev's, it's loading - going up to 6000k in 2nd or 3rd is fine providing you're not using full throttle and you aren't climbing a 1 in 3.
I'd consider changing the oil and filter earlier than the recommended service, for what it costs it's not worth not doing.
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So would taking a 1.4 petrol Fiesta with under 10K on the clock, up to just over 6,000 rpm in second gear with the foot flat to the floor whilst accelerating up a motorwat be bad?
I thought that whilst it's a bit noisy, it doesn't actually harm the car? Hmm, that might explain the oil use :-)
Blue
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So would taking a 1.4 petrol Fiesta with under 10K on the clock, up to just over 6,000 rpm in second gear with the foot flat to the floor whilst accelerating up a motorwat be bad? I thought that whilst it's a bit noisy, it doesn't actually harm the car? Hmm, that might explain the oil use :-) Blue
No, it shouldn't cause any long-term (or short term!) damage.
Infact, it does them good to stretch and engines legs once in a while.
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groups.msn.com/honestjohn/problems.msnw?Page=1 - Pictures say a thousand words.....
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"So would taking a 1.4 petrol Fiesta with under 10K onthe clock, up to just over 6,000 rpm in second gear with the foot flat to the floor whilst accelerating up a motorwat be bad?"
I do it frequently with my 1.6 with 10k miles: nice noise, no oil usage:-)
madf
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Second time someone has to be reminded to read the full message in the same thread!
"It's not rev's, it's loading - going up to 6000k in 2nd or 3rd is fine providing you're not using full throttle and you aren't climbing a 1 in 3."
Thanks DL - spot on
If you don't stretch the engine every so often you'll end up with a bore ridge that only shows itself when the engine is fully
stretched which isn't the best time!
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Malcolm - i'm curious - what's a 'bore ridge'?
Mike
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Bora - what Bora ?
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Borasport,
IIRC correctly, it's a minute ridge which is caused by normal piston ring wear in the bore.
If you ran the car in like Jezza, this would be at the limit of the piston travel - no problem (apart from the oil-burning.
If you ran the car in like Miss Marple, the piston travel would never be fully extended, expansion co-efficients and all that.
The engine would develop a bore ridge lower than that of a fully
extended engine, if the engine subsequently got thrashed there would be a possibility of damage caused by the piston rings hitting the ridge.
If I've got this tits up - I'm someone will put me straight.
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Malcolm - I though that what what you were going to say, and it had already created the next question ->
surely, no matter what speed the engine is spinning at, there are no 'elastic' parts, and the piston travels the same distance every cycle ?
or is there something i'm missing ?
Mike
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Bora - what Bora ?
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I lifted this from Puma racing to whom I'm extremely grateful,
think of the G-force on a piston that has just accelerated up the bore and is now reversing direction - enough to create a degree of elasticity?
From: pumaracing@aol.com (Dave Baker)
Newsgroups: rec.autos.tech
Subject: Re: Broken Rings
Date: 06 Apr 2000 13:26:08 GMT
Pulling apart a 308 V8 the other day, the top ring of 5 of the 8
pistons were broken. One entire bank, and one on the other bank. Now why would they break, I'm told it's unheard of on new engines, so why do old one's break 'em.
Most likely cause is that the engine was high mileage and had usually been driven gently. A wear ridge develops at the top of the bore in a specific place dependent on rpm. The higher the engine revs, the higher the piston rises due to rod stretch, thermal expansion, crank flex etc. At 3000 rpm the stretch will
only be a few thou but on a high rpm race engine you can need 30 thou or more piston to head clearance to avoid contact.
So it only needs one high rpm thrash on an old engine that has trundled about all its life to whack the top rings into the bore ridge and break them.
Using the full rev range every now and then throughout an engine's life is actually a good thing to help even out the wear at the top of the bore. Drive at low rpm for too long and that's as high as you'll ever be able to run the thing without risking a broken ring. Most engines that have been driven normally i.e. a good thrash every now and then, have a sort of graduated wear
ridge spaced out over 15 to 20 thou. An engine that has never been past a certain rpm can end up with a very defined, sharp edged ridge at exactly the same height in each bore.
Dave Baker at Puma Race Engines (London - England) - specialist cylinder headwork, flow development and engine blueprinting.
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Malcolm - thanks for that. Being a lurker in uk.r.c.m, i'm not going to argue with such an authority as Dave Baker !
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Bora - what Bora ?
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I'd consider changing the oil and filter earlier than the recommended service, for what it costs it's not worth not doing.
Would have precisely the opposite effect.
If you change the oil earlier on the first couple of changes you will increase the running-in period. Running-in is all about setting the tolerance of your engine, something that wont be acheived if you constantly replace the lubricant. The swarf in the older oil plays a significant part in the process.
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"The swarf in the older oil plays a significant part in the process" ??????
I thought the purpose of filters was to remove swarf....
madf
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Oh the filters will pick it up, but not at the first pass for every little piece of debris. Some will continue to circulate for a while before getting trapped in the filter.
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If the oil filter doesn`t pick up on first pass it will need replacing.That is the purpose of the filter any debris left floating around the engine is bad news.Will cause engine wear faster.
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But during the running in period, that's the whole point of not changing the filter early, to promote some wear so that the engine beds in. Of course after that it will be every 5K for me. It's only £20 at RapidFit.
Blue
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I remember articles in the past with exagerated zoom-ins of pistons moving in bores explaining that running-in involved gradually smoothing off the humpy bits, but not too fast or under too much load because that caused localised heating and damage.
As all engines now have full-flow filters I don't see how swarf debris can play any part in this process. Old engines sometimes had oil circulation systems that only filtered a proportion of the oil flowing around - I don't know why. This explanation sounds a bit dodgy to me.
I also remember reading ages ago that running-in was actually obsolete anyway. Whereas old engines could only be made tight, and relied on gradually running in to loosen them, modern methods meant they could be made to the correct tolerances straight off.
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I believe by-pass filters are even now widely used, on HGVs and on TDIs run by the obsessed on Freds:) Nothing to prevent you also having both of course: the benefit of the by-pass type being that the filtration is much more stringent.
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I agree totally that the engine must be run-in, even modern engines with their very accurate tolerances.
However, once the engine is run-in, I'm just not happy running a new engine on the extended oil service periods that are currently in vogue.
If the engine is fully run-in at 5k, why leave all the carp floating round the system for another 10k or more in some cases?
So the oil and filter are manufactured to a specification which theoretically allows for the carp - I still believe the cost
of a DIY oil and filter change is totally insignificant given the TCO of the car.
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Won`t dissagree there.but given the tolerence on new engine`s will be less swarf to clear.so the interval for oil change will increase.I do dissagree with the idea that after 5k.it needs replacing ie oil filter oil/there won`t be the amount of swarf there so will not need replacing.As old unit`s
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