New Engine Break-in

Tech about stuff that doesn't fit in the above categories
Post Reply
Site Admin
Posts: 863
Joined: Wed Feb 25, 2004 2:17 pm
Location: Stevensville, ON

New Engine Break-in

Post by Frank » Fri Mar 13, 2009 8:29 am

While reading through some of the topics on the BITOG forum, I came across a discussion about engine break-in that I thought would be useful to share with you: 2005 Corvette. This would be a follow-up to an earlier discussion here (Dyno Engine Break-in on LPG).
Barkerman wrote:You guys are making this all too complicated. In the first 30 minutes or so of an engine's life, it should be run with no load at about twenty five hundred rpm. This gets everything that depends on splash oiling handled and makes sure that eveything else is turning and sliding ok. After that have at it. Any time at idle or over 2.5k or with much of a load is extra wear and contributes nothing to a good start in life for the engine. If you are buying a new car, do what you can, if you are building an engine you've got control of the process and you can do this kind of start up. Other than that you just take what you get. An early oil change, under 1k miles is a good way to see what's going on. By 1k miles you don't need any break-in anything, in the oil or in the driving. Your new car got its rings seated driving off the transporter in onto the dealer's lot, if they were not seated on the first start up. The old days of pouring Bon-Ami down the carb to seat the rings is history. DThumper, congrats on the purchase of your new Corvette, and use the Mobil 1, don't invent a problem. The only thing I would do is be sure to run the Mobil 1 oil filter, it is a very good filter and worth the extra few buck. Just make sure you wave when you blow past me on the freeway. I really like that car.
followed up by:
bbobynski wrote:Possibly good advice for an older engine with flat tappets that relied on splash oiling for the cam lobes to live. The LS1 style engine in the Corvette has roller followers, no distributor drive gear and roller rocker arms. Nothing to "splash lube" so spending time idling above 2500 is time wasted. Absolutely nothing to gain, there.

There is some fallicy in the ring breakin advice. I agree that the ring breakin to the cylinder walls happens very rapidly and your comment about the time to the haulaway truck is pretty accurate. The main thing that needs to breakin with the rings is the SIDE of the rings to the SIDE OF RING LANDS. That mating surface is critical for good sealing and the ring motion against the side walls and gas pressure loads against the side walls is what breaks in the rings to the ring lands. This is especially critical in todays engines that have the top ring closer to the top of the piston and that have hard anodized top ring lands for poundout and wear prevention. Hard anodizing of the ring lands leaves a "pebbly" surface when viewed under and SEM. That surface must be burnished smooth for good ring seal and the hard anodized surface is tough to burnish down. It takes load. To really break in the rings against the side of the piston ring lands it is helpful to apply full load for brief intervals and then allow heavy engine braking to load the rings the other way and cause them to move around on the piston so as to burnish the sides of the ring lands.

I often recommend a procedure that can be done on the expressway by putting the trans in a manually selected lower gear so that the car is about 4500 RPM at 45-55 MPH. Full throttle up too 5500-6000 and then lift and allow engine braking back to 4500. Do this 10 times and then drive normally to cool things off. Repeat. Do this several times on several consequtive days. This is excellent for braking in the rings or exercising the rings on an older engine that might have carbon deposits restricting ring motion causing poor oil economy.

User avatar
Posts: 1482
Joined: Fri Feb 02, 2007 8:32 pm
Location: JAFA , New Zealand

Re: New Engine Break-in

Post by Steptoe » Fri Mar 13, 2009 4:05 pm

Cams break in within the 1st few seconds/minutes as mentioned above, fire up and take rpms up no load for a couple minutes...this also beds the rings, generally one will hear the rings bed with a slight increase in rpms a a distinct change in tone.
Ring beding is dependant on the correct patten and hone grade of the final hone on the bores.
In the production factory this is automated, if done by hand in a machine shop, usually and experianced operator does this job when sizing to each piston.
An engine that doesnt bed the rings may smoke a little and use oil...usually they will bed over the next 500 to 1000 miles...if still doesnt bed in...take to a remote car park and start burning rubber off the rearwheels.

New cars out of the factory, for many yrs, are 'run in' at the factory and bedding is checked as part of the QC so it is a non issue.
An early oil change, under 1k miles is a good way to see what's going on.
worth doing even on a new car, for a rebuilt engine within 10 miles or even after breaking in and tune...this flushes any debis or gasket sealer that maybe floating around, the oil and filter is inpected for anything that maybe a miss

Also, when rebuilding an engine
never reuse an oil pump..replace no matter how old
never reuse a water pump, unless near new
never reuse water hoses, espec the bottom radiator hose unless new new
Never reuse the radiator unless the headers are pulled and cores MANUALLY cleaned and then presure tested, no matter how new.
Older radiators where over built, newer model cars have far less tollerance...a flush is not effective enough to clear all blocked cores or partly bloked ones, any gasket sealant breaking off can block up partly flowing cores A common issue in engine failure.
My Spelling is Not Incorrect...It's 'Creative'

Post Reply