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Hi all,

I have recently read through the article on proper break-in procedure here http://www.myturbodiesel.com/1000q/enginebreakin.htm.

There is something I would like to clarify though.

Under the sub-topic "Proper new engine break in procedure (can really apply to any modern water cooled passenger car engine)", the writer mentioned this term "% power or throttle" several times.

For example,

On a brand new engine (rebuilt or replaced engine), let it idle for 20 seconds to let the oil circulate. You should also be checking coolant levels and other things on a new engine. Then drive it with normal load below about 50-60% power until the engine is warm.
After you've put some miles on it, once the engine is warm, rev it at varying throttle up to 75% with both medium load while driving in stop and go conditions. You want to avoid low rpm/high load power settings (like lugging the engine) so don't be afraid to downshift. Do not go to redline, try to avoid going above 80% power, and avoid steady rpm driving (like highway) and excessive idling. The best thing you can do is to drive up to 75% power and then coast down in gear under engine braking (foot completely off the accelerator pedal).
Between about 500-1000 miles, drive more normally and try to not exceed 80% throttle/load. A brief, smooth, rpm cycling to 95% power is fine after 1000 miles.

For all the above phrase in bold, what does it refer to actually? Does it refer to the rpm (i.e., 75% power means 75% of the redline rpm)?

OR

Does it refer to how you press the accelerator pedal (i.e., 100% power or throttle means you totally floor the accelerator pedal)?
 

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It refers more to how you press the accelerator pedal and a combination of load and RPM. I try to avoid stating RPMs because RPM is not a good indicator of load on the engine. For example, you can rev the engine high in neutral gear and there's no load on the engine. And if you put the car in 5th gear at 20 miles per hour, there's excess load on the engine. Lugging the engine with high load and insufficient RPM is bad for an engine.

So I wrote % throttle/load/power. Here are a few more examples. If you are going downhill in 3rd gear at 40 miles per hour, the engine has little load but higher rpm. This is an example of low % power. But going back up the same hill in 3rd gear at 40 miles per hour, the engine has the same rpm but higher load. Both these situations have different accelerator pedal positions since a different amount of power is requested.

But the overall point of the article is this: a little more or little less during engine break in isn't going to significantly change long term engine health, power, or mileage. All engines have build variation. Don't thrash the engine when it's new and keep rpm and load varying.

Long term engine life depends more on long term maintenance. You can break in an engine fine but if you thrash on it when the engine is still cold, you're going to have more engine wear. I recently talked with someone who said their car's previous owner probably didn't break in the car well, yet their car made more power than most people with the same amount of modifications. Build variation.

I will add some more notes to clarify this in the article.
 

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Yes, they pretty much say the same thing. A little more or a little less isn't as important as long term maintenance on the long term health of the engine. Letting a 3 year old have a soda won't contribute to obesity but giving them 2 liters of soda every day for life will.

The difference is that I am not so strict about exact RPM for the reasons stated above. RPM is only a partial indicator of what's happening - load is also important and rpm and load depend on the situation. As a general rule during break in, medium rpm with higher load is better than higher rpm with low load since this loads the rings and engine without overloading them.

And automatic transmissions can't control the engine rpm and load as easily as a manual transmission - does this mean that all autos are broken in incorrectly?
 

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There are several schools of thought but I'm a follower of "break it in hard". Please note that you should always properly warm up an engine (especially diesels since they have a lot of blow by when cold). Light engine loading, relatively low RPM's, short shift it, don't touch the throttle when starting (that applies to any modern fuel injected motor), etc. Once all fluids (not just the water temp gauge but oil and transmission fluid as well) are up to normal operating temps then drive it like you mean it. You're not trying to redline it but acceleration and, more importantly, deceleration via engine braking across a wide RPM range is critical. No cruise control. Several WOT runs to 2/3 max RPM then allow it to coast back to lower RPM's is perfect. If you google it you'll find several specific recommendations for this process.

Above poster is absolutely correct as well. Proper service intervals for all fluids, filters, etc. is mandatory. Following my own advice has given me 2 previous Honda Accords. First one ('79 with a blistering 79 bhp) went 8 years with me, 175,000 miles or so. Second one ('87 LXi) made it 11 years and 250K miles. Current Accord #3 ('04 V6) is just getting to the sweet spot at 67K miles and sings like a champ at redline, pulls hard and clean all the way there.
 

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No cruise control. Several WOT runs to 2/3 max RPM then allow it to coast back to lower RPM's is perfect.
I feel no cruise control, varying RPM up and down is important. However, I feel that medium load is better on a fresh engine than WOT at 2/3 RPM. As long as you don't beat on it (most people never beat on their car as long as they own it anyways - how many people take the car to redline more than twice ever? ) on a new car.
 

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Yes, they pretty much say the same thing. A little more or a little less isn't as important as long term maintenance on the long term health of the engine. Letting a 3 year old have a soda won't contribute to obesity but giving them 2 liters of soda every day for life will.

The difference is that I am not so strict about exact RPM for the reasons stated above. RPM is only a partial indicator of what's happening - load is also important and rpm and load depend on the situation. As a general rule during break in, medium rpm with higher load is better than higher rpm with low load since this loads the rings and engine without overloading them.

And automatic transmissions can't control the engine rpm and load as easily as a manual transmission - does this mean that all autos are broken in incorrectly?
This is another thread talking about break-in procedure: http://forums.tdiclub.com/showthread.php?p=464223. It is a very long thread (49 pages). Here and there, people did ask the break-in procedure for automatic transmission.

For automatic transmission, I think Drivbiwire (the person who wrote the other break-in procedure) suggested to just drive it with varying load without having to worry too much on the RPM. Since it is pretty difficult to upshift or downshift at a specific rpm in automatic, except maybe tiptronic.
 

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This is another thread talking about break-in procedure: http://forums.tdiclub.com/showthread.php?p=464223. It is a very long thread (49 pages). Here and there, people did ask the break-in procedure for automatic transmission.

For automatic transmission, I think Drivbiwire (the person who wrote the other break-in procedure) suggested to just drive it with varying load without having to worry too much on the RPM. Since it is pretty difficult to upshift or downshift at a specific rpm in automatic, except maybe tiptronic.
So in other words it doesn't make a big difference.....:panic: LOL...
 

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What do you mean by "it doesn't make a big difference"?

From what I have understood, the most important thing to do in breaking-in an engine is to vary the load on the engine. In other words, babying the engine (most probably with an intention to get better mileage) is a BIG NO. In fact, a properly broken-in engine will potentially achieve better mileage than if you just baby it from the beginning.

All those info are based on what I have been reading these past few days. I have never practiced the procedure myself since I don't even own a TDI. So, I am basically trying to gather as much knowledge as possible before I actually drive my own TDI.
 

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I meant being so strict on RPM. I don't think break in overrides driver pedal control when it comes to good mileage and if you read Drivbiwire's posts you learn to cut through his puffing. Don't worry, you will still get good mileage even if don't have a perfect break in. According to his post, break is still happening up to 60,000 miles, and everyone who doesn't follow his exact procedure up to 60,000 miles is down on fuel economy.
 
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