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Originally posted by Mike:
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Most motors now are run-in on dyno's at the engine assembly plant, primarily for QC purposes and also for emissions. A "green" motor usually burns a lot of oil until the rings seat, and this would quickly destroy O2 sensors and catalytic converters. You would never meet OBD2 emissions and certainly not CA emissions if the thing had visible oil consumption.
GM does not do this, the test the engine using water pressure to be sure of integrity but the first time the engine is ever fired is on the assembly line when the car is born and it goes thru emissions at the end of the assembly line. Been there and seen it done, from the time the engine was born on the line to when it when to the dyno it took about 15 minutes, all the while the car is running, car is fired, systems are checked, driven off line to front end alignment, then off to the dyno for brake and other system checks, here the car is run up to 70mph for a set time and then off to water testing.
This info is from GM...
Weird, I had the opportunity to speak with a GM engineer last summer and he claimed they DO dyno the motors at the assembly plant.
Usually, engine assembly plants are separate from line assembly plants. The motor is mated, fired up, and good to go. Otherwise, even with modern automated engine assembly, you must get the occasional dud motor. So would the entire assembly line grind to a halt while you change out the motor or pull the car off the line??
How on earth could you possibly pass an emissions test with a green motor? The amount of blow-by and oil burning would fail the test. Good bye O2 sensors and catalytic converters.
We have a local Cummins certified engine rebuild shop. When they first start the motor on the dyno, if you're outside you'll see CLOUDS of blue smoke from the stack for about 5 minutes, then it settles down.
After 40 minutes or so, as the load is carefully increased to max, the motor is running as it should be. At the end of the 1-2 hour run, they shut down the motor, change the oil and filters, and mate the motor back to the truck.
I've seen folks in the local car clubs who rebuild motors for Old Iron cars: 50's to early 70's. Same thing, there are CLOUDS of blue smoke for the first few minutes.
In high school I tried to carefully help rebuild a 350 for my friends old truck. Same thing, when we fired up there were CLOUDS of blue smoke for about 5 minutes.
The shop instructor had warned us this would happen so we kept the motor at 2,500 RPM. Twenty minutes later when we shut it off, the oil level was a bit below Low. We changed the oil and it seemed to run ok after that, using about 1 quart every 2,500 miles. Hey, we were on a budget back then.
Even if you don't have a dyno, every engine rebuild book I have ever read ALWAYS recommends running the motor at 2,500 RPM for at LEAST 15-20 minutes just to break-in the cam and start to seat the rings. Otherwise they warn of early failure.
A slow putt-putt drive at under 1,000 RPM from the assembly line to headlight aiming (BTW: my GMC headlights arrived almost crosseyed)then to the transporter isn't even enough time to break in the cam. Or does the dealer take every car off the transporter and run the motor at 2,500 RPM for 20 minutes? You know, just for their customer's well-being.
Again, I don't see how cars could pass stringent new emissions tests, or how they could be factory-filled with a synthetic, if the motor wasn't run-in on a dyno.
