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Proper break-in procedure for V8?

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So my V8 is being rebuilt now (see my thread on the "rod rattle"), and I am wondering what the proper break-in procedure is for these engines once they have had a full rebuild? It is getting rod bearings, crankshaft machined, liners re-sealed, maybe new valves, etc.

I have read conflicting things, some saying to go easy on it for 500 miles, others saying to go for high revs. At what point can I drive it "normally" (i.e. occasionally "spirited" but not abused)?

The "break-in oil" in another thread also sounds interesting. Is this widely recommended?

My first rebuild - so any thoughts are welcomed. Thanks!

- Kent

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Upgrade today to remove Google ads and support TLF.

no'break in oil' used ..moreover, just driven in 'cruise mode' the first week. But, as the *factory-frolic* tour of the Berlin gang suggested later on, the time of slow and short driving was over soon. That's what I can say.based on own impressions

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Good luck on getting a straight answer on this one, Kent. There are more theories on this topic than blow flies on fresh road kill. The "traditional" method seems to favor the avoidance of revs over 3000 RPM for the first 1500 miles or so, but more than a few folks subscribe to several bursts (but not necessarily at WOT) to 4000 with coastdowns to idle while in gear, for the first 20 miles---those first 20 deemed the most critical (to seat the rings) on a new (or rebuilt) motor. Those same folks also say that it should be done using straight 30 weight oil (supposedly dissolves assembly lubes better), with an immediate oil and filter change following those initial 20 miles, then going to a good multiweight oil to the 1500 mile mark, then switching to synthetic (and another new filter) for the "normal" intervals to follow. Seems like a lot of effort for hard to define payback. Unless you did a teardown, how would you know?

A great deal of controversy (if that's the right word) has to do with build "tolerances," and what is an "older motor" versus a "modern" motor. What year would the "cutoff" be? It's a rather subjective call IMO. The theory here is that the more modern motor, built to higher tolerance standards, is less needy of achieving "break in" wear patterns---they're already close to ideal spec upon completion of the factory build.

I've never seen what Lotus recommended for the V8's break in, as I was not the first owner. But I'm sure that someone on the forum will have run across it, and will contribute that information shortly.

Cheers,

John

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Check with the engine builder! Based on what tolerances he set up and the type of rings/bearings installed he should tell you the best break in proceedure. If you trusted the engine builer to build the engine, then trust his judgement on break in.

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All good answers. I will definitely go with what the engine builder recommends, but wanted a little background info first. This helps.

Thanks!

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on my turbo engine I'll go for the "hard way" no high rpm but midrange and mod.boost (not w.o.t.) so the rings bed in well because of the gas pressure behind them and they are forced against the cylinder wall. and lots of variation on the rpm's BUT again avoid high rpm(up to 4000) plus don't forget engine braking as well(and no motorways, lots of b roads remember the variations in rpm) .no semi or full synth.oil for the first 1000km (mineral oil is better for transporting particles) new oil/filter after 30mls/150mls/300mls/600mls. (cheap oil and cheap filter) after 600mls I'll go for fully synth.oil (this is on a cast iron engine with forced pistons)

google "bedding in the hard way" but as said, lots of people, lots of ideas....

Edited by lotus-62

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Thanks!

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BTW this "mineral oil is better for transporting particles" was told to me by my engine builder/machine shop. maybe it is true maybe it is BS (I think they were fed up with me asking them all these question LOL) but fact is It's better to use mineral oil for running in. they where also explaining me about the bedding in (the hard way) and I came across an article on the nissan turbo owner club explaining the same thing.....apparently the extra pressure pushes the piston rings harder against the cylinder wall

my engine is not ready yet so please try and if it does not work just tell me :D lol

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I was going to say the same in reverse! ;)

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Do what you will on the break-in as it's your car but I can tell you I tried using "Motoman's break-in secrets" on one of the 4 cyl 910 engines I rebuilt and I'll never do it again. I followed the instructions to a "T" and had significant problems with the rings not seating properly and getting blow-by and burning large amounts of oil. Eventually after a couple of thousand miles evidently the rings finally seated and the problems subsided. It still burned more oil than it should but at least I wasn't getting the huge blue smoke screen anymore.

What I have done since for the first 500 miles or so is use dino oil for break-in and change at 500 miles, always make sure the engine is completely up to operating temp, vary the rpms (as in don't run a constant speed for significant periods), push the engine a little but not full throttle. This has worked well on the last three engines I've rebuilt with good compression readings, performance and minimal oil usage.

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I see that the Motoman method is to ride the engine hard. Thanks for the tip.

I'll see what the mechanic suggests, but my own instinct is to do what you are recommending - push it a little but not all out.

Is "Dino" oil the same as break-in oil?

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I still have the original run in procedure stuck to my windscreen.

3,500rpm max for 500 miles then 4000rpm max for the next 1000 miles is what it says.

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"Dino" oil is just regular petroleum oil as in from dinosaurs. :D I've never used actual break-in oil but don't see where it would hurt anything.

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thats why I like this forum, the "hard way" makes sence to me but if it ruined your engine who am I to do it again with mine

thanks for telling!

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oneshot,

So that's the original factory break-in procedure from 1985 that the first owner would have had to follow?

It will be painful to drive 1500 miles that carefully, but I'll do it if that's what it takes! I wonder if the 1999 V8s would be different for any reason.

- Kent

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Just been to double check:

3000rpm for first 500 miles and then 4500rpm (not 4000 as I said previously) for next 1000 miles.

It also says to avoid excessive throttle and long periods of idling.

Note this is from a 2000 Sport 350 and is a sticker on the windscreen presumably aimed at the first owner. It is somewhat difficult to remove so I guess that's why it is still there!

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Sorry, I think I looked at the wrong tag. Good to know it is from a Sport 350 V8. Thanks!

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