OEM Initial engine break-in procedure.

[Retracnic]

Greetings,

I would like to know the initial engine break-in procedure used by major automobile manufacturers or their suppliers.

I am intimately aware of the procedures employed by race and performance engine builders. What I am looking for is what do the big guys (Toyota, GM, Honda etc) do to break-in an engine before it leaves the factory.

Any help would be appreciated in this matter

Regards,

Bryan Carter

PS – I know what the owner's manual says...

 

[Hydroformer]

I am by no means an authority on this but in my experience I've seen that: at the engine plant, engines are fired up with a natural gas / propane fuel hood brought down on the manifold. Run time is only a few seconds (just to verify start-up). At the build plant: cars are driven off the line and frequently a lap around a test track (0.5-1.5miles), mostly to capture BSR-NVH issues.

These short start-up runs don't even come close to qualifying as a 'break-in' period. So far as I know (atleast with N.A. cars) the break-in is left to the end user. AKA- the customer.

*Without data, you're just another person with an opinion.*

Hydroformer

 

[GregLocock]

It varies. These days most will get a couple of minutes idling before being driven onto the wheel alignment and dyno and into the lot. The next time they are driven is for shipping, full throttle, wheels spinning.

As hydroformer says, it isn't really a break-in.


Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Retracnic]

Thanks for the responses.

This is on par with what I expected. I had hoped for something a little more comprehensive on the part of the factory. Oh well.

Regards

 

[GregLocock]

No.

When Rover first started to commit technical suicide by going into partnership with Honda, they sent us over some prototypes.

We phoned them up, asking what the running-in procedure was. Hasty conference at the other end of the phone, and the result was "Oh, we just let them idle for a minute before loading them up".

With the exception of scuffing the cylinder liners it's a bit hard to see what running-in really accomplishes, and I would have thought that scuffing was best accomplished at variable loads and speeds.

That being said, where I work, we run every engine on the dyno before it goes into the car. I'm not sure for how much longer we'll do that.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[ivymike]

idling a bit before you load the engine the first time helps to keep the pin joints from seizing.

seems like a few diesel oems do a "hot check" where they run the engines up to thermostat temp and check for leaks, odd noises, etc, then confirm/set the power output.

at least one major automotive oem in the US "cold checks" engines by motoring them and measures friction as a way of telling whether everything got put in the right holes.

 

[kenre]

Interesting topic as in im the process of building a nice street 350 chev. I have rebuilt many many engines.
Normal practice is to start engine, confirm oil pressure and rev to 2000 for 1/2 an hour to break in the camshaft and lifters. Then drive with varying load and revs. This is what i was taught years ago. The new engine is LPG only, so i asked around and most answered load it up straight away to seat the rings!!

What has myself confused is, whats the difference with a factory built engine that doesnt need the cam run in, and an aftermarket cam needing to be run in????

Ken

 

[patprimmer]

Aftermarket cams might have higher valve acceleration rates and higher spring pressures.

Regards

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[ivymike]

They *might* have a different surface finish spec'd after grinding as well. If you do need to "wear in" a cam, then I'd expect to see that the surface is initially very "peaky" when profiled, and that bearing area increases rapidly as the peaks are worn down (just going by what some liners look like, as some have probably recognized).

 

[evelrod]

I'll have to agree with Greg on the wheel spin deal. Having worked at a couple of the Big 3 outfits and on the docks at Long Beach...One special case...a really pretty bright red Ferrari at full chat, tires smoking, haulin' a** down the dock!!!

Rod

 

[franzh]

When OEM's measure profits on pennies or less per item, spending 1/2 hour on a break in dyno just doesn’t happen (on the mass production automotive side). One of the primary reasons for a break in is to allow friction items (mostly the rings, piston skirt, and cylinders and the cam surfaces) to mate. With today’s precision machining and rolling friction surfaces (cam followers) there is little need for a strict break in procedure. A simple light load or fast idle the first minute or so followed by moderate driving the first hundred miles is generally sufficient.

An initial dyno and motoring dyno is performed at the OEM stage, but this generally lasts no more than a couple of minutes at most. At a major US OEM engine assembly plant in the early 70’s, I saw a carousel dyno, where 8 engines are worked at once, run on a dry gas (this one used natural gas) while oil leaks, oil pressure, and initial run in were performed. As each engine was completed, it was removed and another installed.

Oil leaks can be checked by vacuum/pressure drop with 5 psig air pressure, oil pressure can be checked statically too. Originally, with manually adjustable ignition timing, that was performed at this stage, along with engine balance.

If the engine is built right and the human factor removed (the dreaded “Monday morning, and Friday afternoon” engine scenario) there is no reason the engine should be almost ready the moment it is installed. A site visit with a major piston ring manufacturer will show the research being done to allow rings to seal almost immediately, providing the proper cylinder wall finish is provided.

As a real life example: In the 60’s, where each engine was assembled by hand, with individual build up stations, and 60’s metallurgy, it was expected for an engine to last less than 100,000 miles, frequently with at least one valve refresher during that period. When emission restrictions became enforceable, the engine manufacturers had to tighten up the production processes and refine the build procedures. With today’s emission mileage warranty requirements, it is rare to see an engine ready for the scrap heap in less than 100,000 miles, with 200,000 not uncommon. Imagine the warranty costs if an OEM had to rebuild engines routinely at 60,000 miles. We still see smokers at less mileage than that, but a simple check of the required routine service shows that little attention has been paid. By simple observation, it appears that one manufacturer in particular seems to have a problem with smoker engines in vehicles approaching 5 years in age (I would guess about 75,000 miles).

Franz

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[dgallup]

When I worked for a major diesel truck engine manufacturer more than 20 years ago, they dyno tested every engine. The engine ran for about 30 seconds to bring the oil pressure up then it went to "high idle" to check the govenor setting then it went to rated power speed to verify the power rating. Total time was under 90 seconds.

About the aftermarket cams, I suspect they are not micro finished like the better OE cams thus the need for extended breakin. My experience with aftermarket producers is they do not have the same level of engineering, QA or production technology as OE. I know that is a gross over-generalization and there are exceptions but the general poor quality in the aftermarket is astounding.

 

[evelrod]

I don't know about all that cam finishing stuff. In my experience many of the aftermarket and performance camshafts are made on the same machines by the same mfgrs as the OE cams. From what I have seen the finish is equal...perhaps breakin specs have more to do with product liability/warranty and convention than actual wear rate.

Rod

 

[patprimmer]

If the OEM cam has say 0.380"lift and 60# on the seat pressure spring pressure, and the aftermarket cam has say 0.650"lift and 120# on the seat, the need for extra precaution during break seems obvious to me.

Regards

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[DOHCPower]

I have always been under the presumption that idling at a solid speed, IE, 2000rpm, while great for breaking in camshafts, is absolutely HORRIBLE for piston ring seal.

 

[kenre]

Patprimmer,

i think you hit the nail on the head with the higher spring pressures and more aggressive lifts!. now what is the best way to seat the rings? OEM dont seem to worry about this, so my guess is modern manufacturing is precise enough that a good seal is almost instant.

Ken

 

[ivymike]

well, what exactly do you suppose is happening when you "seat the rings?"

 

[DOHCPower]

No scarring,scuffing and a good ring to cylinder wall relationship begins...

 

[kenre]

seat the rings... ? im sure that is where all the high spots are worn down on the cylinder wall to enable a good seal.

 

[icrman]

2K Rpm ? Why? Funny a nice old engine like a D342 Cat that hits rated HP at somewhere around 1300 rpms. Can't reach that supposed magical 2K cam break in rpm. And besides at that rpm the cam is only spinning at 1K. I can't see any thing special happening at 1K rpm at those lobes that doesn't happen at 5 to 600 rpms.?????