Breaking in a Long block Overhaul

[lreppond]

I had Metric rebuild my engine and I picked up my car today.  The mechanic who did the installation is about 30 miles from my home.  I managed to drive the car under 50mph @ 2k rpm.

I AM NOT mechanically inclined. Although I’ve tried reading everything in relationship to breaking in a new engine, I either didn’t understand the terminology or read conflicting info.  The info from Metric was short and sweet but not particularly enlightening for me.  If anyone has gone through this process, I’d appreciate your input. 

Things like:should I warm the engine before taking it out?   On the freeway is driving at a steady speed or varying it desirable? Is breaking in better on highways or city streets, etc.  Metric advises an oil change at 500 miles but I’ve read that some suggest at 50 miles!  I’m so confused and I really want to break this engine in properly.  I know I’m trying to get the rings to bed into the cylinders properly but I’m just not sure how to get there. 

This is a 130.983 engine mated to a four speed manual transmission. 

[Cees Klumper]

What I recall doing, and I think there should be a write-up of the procedure in the Technical Manual someplace, is to use the car as normal (so no warming up before driving off for example), however avoiding very high revs / asking all from the engine for the first maybe 600 miles (1000 km). Above all, I took care of varying the revs, meaning no long stretches at the same/similar speeds. Then changing the oil after those 600 or so miles (I also changed it after the first 10 miles or something similar very short period, I think but now not sure - this is all almost 20 years ago) to swap the break-in oil (part fossile?) with 'normal' (synthetic) oil. I am sure others with more knowledge will chime in soon.

[Mike Hughes]

I had Metric rebuild my engine and I picked up my car today.  The mechanic who did the installation is about 30 miles from my home.  I managed to drive the car under 50mph @ 2k rpm.

I AM NOT mechanically inclined. Although I’ve tried reading everything in relationship to breaking in a new engine, I either didn’t understand the terminology or read conflicting info.  The info from Metric was short and sweet but not particularly enlightening for me.  If anyone has gone through this process, I’d appreciate your input. 

Things like:should I warm the engine before taking it out?   On the freeway is driving at a steady speed or varying it desirable? Is breaking in better on highways or city streets, etc.  Metric advises an oil change at 500 miles but I’ve read that some suggest at 50 miles!  I’m so confused and I really want to break this engine in properly.  I know I’m trying to get the rings to bed into the cylinders properly but I’m just not sure how to get there. 

This is a 130.983 engine mated to a four speed manual transmission. 

To begin with, when you start up the engine, the engine will warm up more quickly if you drive away as soon as you have verified good oil pressure.

For the first 500 miles:  Driving at one constant rpm for extended periods (like on the freeway) should be avoided, varying the speed will help bed in the rings in the cylinders.  Even a 280 engine does not generate a whole lot of torque at low RPMs, so it may be easier on the engine to run it up to 2500 or maybe even 3000 RPM before shifting to the next gear.  If you are lugging at low RPMs you are likely pushing down more on the accelerator to maintain speed or to accelerate.  This may inject extra fuel into the cylinders which may wash the oil on the cylinder walls and cause premature wear.  Avoid hard acceleration.  There is certainly nothing wrong with changing the oil at 50 miles, but if Metric says change oil at 500 miles, trust them and change it at 500 miles.

The engine is not magically fully broken in at 500 miles but driving it normally after the initial 500 miles of break-in is OK.

Opinions about oil are like noses - everybody has one.  Here's mine, based on 40 years of observation in new vehicle sales:  Run regular petroleum-based or part-synthetic oil for the first two oil changes.  THEN switch over to full-synthetic oil if you are inclined to use it.  The rings will be happier in the long run.  Full-synthetic oil is SO slick that it prevents that little bit of extra friction between the new rings and the fresh cylinder walls that helps the rings bed in better.  Customers who would bring their vehicles in to the service department complaining about increased oil consumption at 50-60K miles invariably had switched from the petroleum or part-synthetic oil that was in the engine at delivery to full-synthetic oil right after they bought their cars.  Those who waited an oil change or two before switching to full-synthetic didn't seem to complain about similar oil consumption problems at what is relatively low mileage for modern engines.

[Pawel66]

There were some tips given on the Forum, e.g.: https://www.sl113.org/forums/index.php?topic=27705.msg199169#msg199169

[dirkbalter]

I am about to start my engine for the first time as well. Attached is what metric recommends. He is the one giving you the warranty, why would you question that? Or, if in doubt, why not call him?
As Mike said, opinion are like noses…..

[lreppond]

I’m not questioning what type of oil to use.  I’m following Metric suggestions to the letter.  What I’m questioning is how to drive my car during the break in period.  Driving across the San Mateo bridge, my speed was between 40-50+ mph.  After the bridge, I was on surface roads and tried to switch gears as the tach reached around 2500 to 3000.   Speed was rough 30-40 mph, tach in a similar range to the bridge driving but primarily in 3rd gear not fourth as on the bridge. 

[dirkbalter]

Sorry if I misunderstood you. I was told (metric) to vary the load on the motor. Don’t let it sit in idle for to long. Don’t take it on the freeway at constant speeds for longer periods of time. Basically, drive the car normal but take it a bit easy on high rpm’s during the break in.

[Harry]

I recently completed my 230SL rebuild and would have to agree with Dirk.  I didn't do anything "special" other than avoiding high RPMs, constant RPMs for long periods (like an hour or more), no long term idling, and just "paying attention".  I watched oil pressure and temperature closely - a habit you should have regardless.
I used the same oil that I normally ran in the engine with a high zinc content, and changed the oil after 500 miles or so.  I also used a break-in filter from Mercedes.  But Metric is known to do good work and these engines are solid so you shouldn't be too concerned.  I'd absolutely follow their warranty guidance (as you said) and also be looking at retorquing the head and adjusting the valves at the right intervals.
Mostly - enjoy!

Harry

[lreppond]

Thanks to everyone for the good advice.  Much appreciated. 

[Benz Dr.]

The thing to do, is to not only gradually add RPM and load, but also duration over a period of time. So, start out slowly, throttle up lightly, hold for 10 seconds, and then let your car coast. Keep doing that several times, and then increase the amount of time you hold your engine at one speed. Keep increasing, throttle, time, and load, a bit at a time, until your engine is broke in. You can tell when that happens because your engine will rock backwards slightly when shut down. If the crank stops dead, it's not broke in.

What's actually happening during break in:

As you apply load, the piston rings will bit into the cylinder wall and knock off any high spots. Coasting will help to polish those areas smooth and then you can keep doing that until the cylinders are mated to the rings. Driving around a town on quiet streets is much better than taking it out and driving at one prolonged high speed. It can take longer than you might expect to break in your engine.   

[bracurrie]

I would love to know what the break-in procedure was when these engine's were in production. I know they did some form of testing/break-in for each engine before installation.