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| Engine Break In | |
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| Tweet Topic Started: Dec 13 2011, 03:55 PM (2,360 Views) | |
| musquoni | Dec 13 2011, 03:55 PM Post #1 |
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Hey everyone. I tried searching for engine break in on this forum and I'm getting something other than that. Im reading other places to do an easy break in or a hard break in. I asked my machinist what he does when he breaks in an engine and he told me to go with the hard break in. warm up at about 2,000 rpm for 20 minutes change oil, drive it hard fluctuating between 2nd and 4th gear for about 50 miles then change the oil again. So my question is: What is the proper "Break In" method for a fresh rebuild? |
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| Scoobs | Dec 13 2011, 04:00 PM Post #2 |
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there are many opinions, ive been told both, drive it like you stole it, but give it a break after doing that, let it cool completely then start up and drive home, ive heard baby it. When we first ran my car Gercedez, me and GeoGlenn drove it like we stole it, runnning it up to high rpms, you can see the video on my project page of it if your wondering, click the Gercedez Menz link in my sig and browse |
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| Coche Blanco | Dec 13 2011, 04:04 PM Post #3 |
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Troll Certified
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Do whatever you think is right. I started my car, made sure it was running good. Shut it off after about 5 miles (15 minutes or so run time) of testing. I drained the oil ( I left the "old" oil in from before I started rebuilding it). Then I filled it with 5w30 and drove it for 300 or so miles. The first ~50 miles were super hard driving, never keeping the same speed and always revving way up and leaving it in gear to slow down. Then I just drove it "hard" for the other 250 miles. Then I changed the oil again. |
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| idmetro | Dec 13 2011, 04:16 PM Post #4 |
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Lots of opinions on this one. Personally I did the rebuild, put in fresh oil drove 100 miles with near constant variation in speed, changed oil then drove 500 miles reasonably gently not keeping speed the same for more than a couple of minutes, changed oil, drove 3000 miles "normally" and started into my routine 5k oil change intervals. At 25k miles I switched to synthetic oil (you can certainly do it sooner but you will want to make sure the rings are well seated first). So far I am at 30k miles use a very minimal amount of oil between oil changes (based on the light coating in the engine compartment I have a very small leak somewhere that I haven't yet tracked down) and average 45-50 mpg depending on the time of year with an 80 mile per day commute. I'm happy... |
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| Tofuball | Dec 13 2011, 04:30 PM Post #5 |
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Strange Mechanic
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Whatever you do to break it in is probably fine, just don't use synthetic oil unless the rings specifically call for it. I've heard to avoid constant RPM for long periods, as it might 'glaze' the cyl walls and not allow the rings to break in properly. I don't have any science to back that up. I've always just driven the car normal, avoided long idling, and kept it out of boost during break in. |
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| musquoni | Dec 14 2011, 12:03 PM Post #6 |
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Does it matter what oil or oil filter I use during break in? Is there any preferred weight or brand of either oil or filter? |
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| clarkdw | Dec 14 2011, 02:34 PM Post #7 |
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Non-synthetic 5w-30 and whatever is your favorite filter. Fram is a bad word on this forum. |
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| rmcelwee | Dec 14 2011, 07:10 PM Post #8 |
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I'm no expert (I've only rebuilt / broke in one engine and used the method below) but my experts say: Keep in mind that there really shouldn’t be any metal to metal contact happening within your engine, other than the rings to the cylinder walls. The rings are the ONLY things we are interested in breaking in or seating. What seats rings is cylinder pressure. Rings and pistons are designed so that cylinder pressure sneaks behind the compression rings and forces them out against the newly honed cylinder wall. Why do I mention this? Because I want you to take your warmed up car out on the road, find a nice straight stretch and do a couple of heavy throttle runs in third or fourth gear from about 2500-5500 rpm. Each time you hit 5500-6000 rpm, snap your foot off the gas and let the car coast down to 2500 rpm while in gear, to pull high vacuum in the cylinders. Repeat this step about five times and you should have a nicely mated set of rings and cylinders. NOTE: When I say “heavy throttle”, I am referring to a normally aspirated engine. For a turbo or supercharged car, modulate the throttle to achieve about zero on your boost gauge, rather than full throttle. This would be roughly equivalent to full throttle in a normally aspirated car. |
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| nwgeo | Dec 14 2011, 09:36 PM Post #9 |
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Yep, I have done exactly what your machinest said with both small and large(460) engines and by small I mean 1.0 metro. In fact the professional engine houses in my town will void thier engine rebuild warrentees if you do not follow a procedure similar to what your machinist suggested. Only difference is they speacified 2500 RPM for 30 mins. and then just normal run.
Edited by nwgeo, Dec 14 2011, 09:36 PM.
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