New Engine Start Up

[Marty Rogan]

So I guess putting a completely rebuilt L28 (fresh everything) running it to the local drag strip (50 miles) and running several mid 13's isnt recomended then:stupid:

In a word ... NO!!!!

[ChrisA]

Well just for curiosity I googled "how to break in a new engine" and I got some surprises.

One guy said "drive it hard" but he was the minority (claims he's done over 300 engines this way). I dont think I can follow this guy's advice.

Here's a good one I found that I liked.

"Piston rings, which separate the air from the combustion chamber with the oil/air from the crankcase, need to settle, and are unlikely to do so if the car is driven spiritedly. Even after 300 or 500 miles you'd be surprised how much filth is in your oil - tiny metal particles mostly - which needs to be replaced."

1. Change oil at 300 miles.

2. Change oil again at 1000.

3. Change oil at at the scheduled interval (typically 3000/3500 miles.)

4. Drive very gently the first 1000 miles. No racing, no crazy downshifting, no hard braking, no dumping the clutch.

5. Drive normally until your first scheduled oil change (3000/3500 miles), but still refrain from spirited driving.

6. Drive normally from then on.

Sounds like reasonable, logical advice.

Now, when we rebuilt the engine in my Dad's Cutlass (350 Rocket bored oversize with hotter cam), we we're told to drive it normally but refrain from long durations at a sustained RPM. Like, no driving down the interstate at a steady 75 MPH. Normal around town driving which varies the RPM constantly is what was recommended to us.

FWIW,

Chris A.

[jmortensen]

The run the engine for 30 minutes at 2000 rpm has to do with mating lifters to the cam. I've never done this on an L engine, and none of the people I know who have built L's have ever done it either. It's a V8 thing. The procedure is outlined in the How to Rebuild book. I've never actually read all the way to the end before and really just used it for a reference but I was pretty surprised to see it in there. I don't see following this procedure for 30 minutes hurting anything, but extended running with no load can definitely cause ring seating problems. For instance, some people will let a car run at x rpm for 3 hours, or put it on stands and have it driving the wheels with no load for 3 hours. Running an engine for a long time at a steady state is a bad idea. The whole idea is to accelerate and decelerate a lot when you're breaking the motor in. That's what breaks in the rings.

[Virto]

Here is an exact wording of the run-in from How to Repair/Rebuild your Nissan/Datsun OHC Engine, by Tom Monroe:

Once the engine is fired, it must be kept running at NO LESS THAN 1500 RPM and must be well lubricated and cooled. Lubrication is particularly important to the camshaft and rocker arms.

This is why the engine should not be slow idled under any circumstances during initial run-in. If the engine won' maintain 1500RPM, SHUT IT OFF!

This was taken word for word from Tom's book, so I was incorrect in stating 2000 RPM was the target. Before this of course, make certain you have good oil pressure. The main problem with poor oiling or a slow run-in is damage to the camshaft lobes, which isn't exactly cheap, and requires some disassembly.

Sorry for misquoting the book, but hopefully this helps clear things up.

Jmortensen: You're right, long term constant speed running is not so great for an engine, but the book states no LESS than 1500 RPM. If pressure is good, there's no reason not to increase the RPMs to a higher level and then drop back to the 1500RPM minimum. This is certainly easier with the car on stands or in neutral, but could be done on the street (if you have a mighty control of clutch and throtte), and some around the block action would certainly keep the RPM varied...although I wouldn't leave the garage to be honest. You're right in mentioning that bedding in the rings requires accel and decel, and this is possible in the garage without going below 1500. Tom Monroe mentions that as you run the engine, you'll see the RPM increase as the engine "loosens up" and things are mating together as they should.

Marty: It should be noted that during this initial run-in the engine temp will be higher than normal, as the engine is "tighter" and tolerances are lower. As the engine breaks in, the temp will decrease. You should make sure you have a helper to watch the radiator and top it off as is required. Blowing a big ol' fan at it probably wouldn't hurt either. If the engine starts to overheat, stop it ASAP, since you don't want to warp anything.

[jmortensen]

You're right in mentioning that bedding in the rings requires accel and decel, and this is possible in the garage without going below 1500. Tom Monroe mentions that as you run the engine, you'll see the RPM increase as the engine "loosens up" and things are mating together as they should.

I really have to disagree. When you put a real load on the engine the rings really have to work hard. When you're just revving the motor the engine doesn't have any load, so it doesn't do any work, so it doesn't load the rings (much). This is why we need a dyno to measure output. Because it doesn't make much of any output freewheeling in neutral.

Short story. My ex-roommate gets a call from a guy who is frantic. He's just rebuilt his engine in his Ford something or other, and it's smoking like crazy. He describes his break in method: "I let the car idle for 5 or 6 hours to 'seat the rings'". My friend asks to see it. The guy drives it over, and complains it's making NO power and the smoke was self-evident. He tells the guy he wants to take the car for a day and see if he can fix it. After several hours of driving it like he stole it he was able to as he put it "break the glaze" on the cylinders. The thing suddenly stopped smoking and was making a lot more power. He returned it to the guy who built the motor but didn't tell him what he did, because the guy was one of these "you have to be super careful for the first 10,000 miles" kind of guys.

But again, I don't think the 30 minutes is going to hurt anything, I just don't think it's necessary and like I said I don't know anyone who has rebuilt an L engine that has done that run in procedure at all.

[Virto]

I really have to disagree. When you put a real load on the engine the rings really have to work hard. When you're just revving the motor the engine doesn't have any load, so it doesn't do any work, so it doesn't load the rings (much). This is why we need a dyno to measure output. Because it doesn't make much of any output freewheeling in neutral.

Short story. My ex-roommate gets a call from a guy who is frantic. He's just rebuilt his engine in his Ford something or other, and it's smoking like crazy. He describes his break in method: "I let the car idle for 5 or 6 hours to 'seat the rings'". My friend asks to see it. The guy drives it over, and complains it's making NO power and the smoke was self-evident. He tells the guy he wants to take the car for a day and see if he can fix it. After several hours of driving it like he stole it he was able to as he put it "break the glaze" on the cylinders. The thing suddenly stopped smoking and was making a lot more power. He returned it to the guy who built the motor but didn't tell him what he did, because the guy was one of these "you have to be super careful for the first 10,000 miles" kind of guys.

But again, I don't think the 30 minutes is going to hurt anything, I just don't think it's necessary and like I said I don't know anyone who has rebuilt an L engine that has done that run in procedure at all.

And it's entirely possible that this is just an extra step that's not required...but at the same time, what if there's a problem with one in one-hundred rebuilds? SOMEONE is gonna be unhappy, and frankly a half hour isn't long enough out of my day to justify having to rebuild your rebuild.

It certainly can't hurt anything, so it might as well be done. If I rebuilt my engine tomorrow (unlikely, since I'd somehow manage to set the iron on fire, what with my mechanical skills) I wouldn't skip this step.

And you mentioned the Ford guy idled his engine. Right there is the problem. We're not talking about idling an L series, I mean 1500 is almost double normal idle speed, and since you mention "driving it like he stole it" this indicates that it's probably a good idea to run MORE that 1500 RPM, as I said was probably in the engines best interest before.

I know that in rebuilding various Mopars that we would always run the engine at about 2000 RPM for 45 minutes or so. Over the course of rebuilding 3 340ci engines, we never once had a failure, excessive smoking or a lack of power without using a dyno or the street.

I'm certainly not looking for a fight, because I personally haven't done this, I'm just quoting a book on the specific subject of rebuilding an L series. God knows I'm not the best mechanic, or the most knowledgable, so take my advice with a grain of salt.

Marty, it's YOUR engine and you can do whatever YOU want with it. Apparently this isn't a required proceedure. I was just trying to help...not create confusion or problems. :stupid:

[SteveK]

In a word ... NO!!!!

Why

Give specific empiric engineering information, not just a NO!!

On several occasions I have re shelled/re ringed and even done a complete rebuild using fresh components and then driven straight to a drag meet.

I am in no way comparing my set up to a race set up but if its a bad thing, how are race engines broken in, do you see top fuel dragsters running around the local Kwik Mart car park with a sign on the back saying "running in please pass"

Yeah-ok race engines are designed to be disposable and stripped down after every meet. So what we are talking about is an effect on longevity of the engine, but lets try and dispel the old wives tales and think science here

Anyone got any hard cold data to say one-way or the other

Plus, It is not unknown to "pamper" an engine and glaze bores or burnishes bearings

As far as I am concerned as soon as the cam has bedded in (few minutes) its fair game.

If it breaks then you got something else wrong

[Marty Rogan]

Why

Give specific empiric engineering information, not just a NO!!

On several occasions I have re shelled/re ringed and even done a complete rebuild using fresh components and then driven straight to a drag meet.

I am in no way comparing my set up to a race set up but if its a bad thing, how are race engines broken in, do you see top fuel dragsters running around the local Kwik Mart car park with a sign on the back saying "running in please pass"

Yeah-ok race engines are designed to be disposable and stripped down after every meet. So what we are talking about is an effect on longevity of the engine, but lets try and dispel the old wives tales and think science here

Anyone got any hard cold data to say one-way or the other

Plus, It is not unknown to "pamper" an engine and glaze bores or burnishes bearings

As far as I am concerned as soon as the cam has bedded in (few minutes) its fair game.

If it breaks then you got something else wrong

I thought you were trying to be funny and I was trying to be funny back. I am not an automotive engineer, don't have emperic data and certainly don't think I know it all, or I would not have asked the question in the first place.

I did a search on this site and researched other places. They all seemed to say the same thing. Smooth accelleration not to exceed 4500 RPM for the first several hundred miles. Smooth accelleration, but don't beat on it.

Like someone said, it's your car do what you want. If you want to take a fresh engine to the drag strip, go for it. Personally, I want my year to run strong for years and years. Ihave no intention of tearing it down again any time soon.

Marty

[Marty Rogan]

And again, I really appreciate the people that took the time to respond with good advice. I will be using it.

Marty

[Carl Beck]

Hi Marty:

Fill the block with water first.. don't put anti-freeze/coolant in until after you've brought the engine up to full operating temp.s. to check for leaks... If you find anything leaking it's better to deal with just water anyway.

Anti-freeze/coolants will leak where plain water won't.. but I've found that if you start with plain water - you're less likely to find leaks when you do put anti-freeze/coolant in. A few thermo cycles on the engine will help assure it's sealed up as well. Watch the freeze plugs...

good luck,

Carl B.

Clearwater, FL USA

http://ZHome.com

[xxjoeyxxeb]

When my friend and his father first got his frame off restoration 71 MGB started up they ran it on stands at about 2000RPM for about 20 minutes, then varied the rpm at different intervals. They did tons of work on that small 4 cyl, and the thing it a beast.

[Zedrally]

Hi all,

I've been following this thread with interest, everyone appears to have similar ideas, not all the same but similar, however no-one has given the factory break-in procedure, does anyone know what or how the engines where run in fresh from the factory?