Too much oil in crankcase; - CEL on solid
1999montana
10-16-2014, 10:01 PM
I changed the oil in our 1999 Montana van (like normal) with a filter change over the weekend last. I might have overfilled the crankcase by about 3/4 of a liter. It registers about a liter too much on the dip stick. First time in 266,000 Kms. Just passed its emissions check in April; - all good. O2 has never been replaced.
On the way home from work tonight the CEL came on solid.
Don't know the code or which sensor is throwing it yet, but I wondered if the excess oil might cause enough blow-by to clog the O2 sensor.
Putting a scanner on it tomorrow morning.
Thoughts, anyone?
On the way home from work tonight the CEL came on solid.
Don't know the code or which sensor is throwing it yet, but I wondered if the excess oil might cause enough blow-by to clog the O2 sensor.
Putting a scanner on it tomorrow morning.
Thoughts, anyone?
1999montana
10-17-2014, 09:14 AM
Random misfire... cause unknown. No other codes. Reset the ECM. Plugs have 60,000 miles on them. Coil packs are original. O2 never replaced. Guess I could install a new one anyway.
Engine was cold when it accelerated onto the highway; - maybe it didn't appreciate it. Still need to drain a liter of oil from the crankcase; - raining today. Weekend I guess.
Hey is it me, or do the text editing features not work?
Engine was cold when it accelerated onto the highway; - maybe it didn't appreciate it. Still need to drain a liter of oil from the crankcase; - raining today. Weekend I guess.
Hey is it me, or do the text editing features not work?
Tech II
10-17-2014, 09:25 PM
Not your O2 sensor......P0300 could be a plug, wire, coil, injector, fuel pressure, etc......
The main problem with overfilling the oil is, the level in the pan rises and it comes in contact with the rotating crank, and will aerate the oil, causing it to foam...this causes lack of lubrication, and improper heat transfer.......too much foam and the pump will cavitate and not circulate enough oil, and pressure will drop...
Most GM engines take 4.5 -5.0 quarts.....0.5 over, should not be a problem.....however, when you get to quarts being overfilled, then you have a problem....
The main problem with overfilling the oil is, the level in the pan rises and it comes in contact with the rotating crank, and will aerate the oil, causing it to foam...this causes lack of lubrication, and improper heat transfer.......too much foam and the pump will cavitate and not circulate enough oil, and pressure will drop...
Most GM engines take 4.5 -5.0 quarts.....0.5 over, should not be a problem.....however, when you get to quarts being overfilled, then you have a problem....
1999montana
10-18-2014, 09:22 PM
Not your O2 sensor......P0300 could be a plug, wire, coil, injector, fuel pressure, etc......
The main problem with overfilling the oil is, the level in the pan rises and it comes in contact with the rotating crank, and will aerate the oil, causing it to foam...this causes lack of lubrication, and improper heat transfer.......too much foam and the pump will cavitate and not circulate enough oil, and pressure will drop...
Most GM engines take 4.5 -5.0 quarts.....0.5 over, should not be a problem.....however, when you get to quarts being overfilled, then you have a problem....
No arguments with your comments. Only point I was making was that the plugs had been replaced 55,000 miles ago along with wires. Coil packs are original. Injectors are original to the vehicle as well. The O2 is original and has never been replaced; - now has over 267,000 Kms on it; - time to change it if only for PM.
I was only theorizing that coincidentally the crankcase got over-filled and shortly after the misfire occurred.
Were they related; - it doesn't sound like it. We did drain about 900 ml of oil out after the shop I go to scanned the ECM found the code and cleared it. There were no other codes. After clearing the ECM the code did not return.
The vehicle is running well except for this one incident, getting on average about 34 miles per Imperial gallon on the highway (Imperial gallon is 4.55 liters vs the 3.78 liters in a US gallon) so if it has issues with injectors or secondary ignition it certainly does not show up in the way the engine normally runs.
I guess because so many sensors combine to affect fuel delivery, spark timing and advance that any one sensor being marginal should show up as a performance issue or low fuel mileage.
Back in the day, (70's) you could put an Allen scope on the engine and view RPM, coil primary and secondary voltage, spark plugs firing under load, dwell, advance curve and vacuum to determine how well the engine was running. Misfires could be identified on the scope. I'm not even sure how the ECM learns that a misfire has occurred on a particular cylinder with today's technology, but it is somewhat amazing that it can.
It's one of the reasons our DOT (called the MTO) switched to reading the OBD port and viewing what the ECM is seeing from the sensor monitors to determine if the engine is running properly. If the monitors show green, then they are operating properly and reporting data to the ECM. In my view the test misses the point though because the entire test takes less than 10 minutes but never sniffs the tailpipe emissions. You could have a perfectly monitored engine with ring or oil consumption issues that never show up in the test unless the person doing the test is surrounded by dense blue smoke. An exaggeration for sure, but it makes the point that as an owner I can no longer tell how well the engine is running because they do not provide a readout of hydro carbons, CO or NOx.
Up until Friday last I had not experienced a misfire or reduced fuel mileage. A short trip of 200 miles today indicates the engine is running very well.
Sounds like a Gremlin, or maybe just my wife's heavy right foot causing a problem.
The main problem with overfilling the oil is, the level in the pan rises and it comes in contact with the rotating crank, and will aerate the oil, causing it to foam...this causes lack of lubrication, and improper heat transfer.......too much foam and the pump will cavitate and not circulate enough oil, and pressure will drop...
Most GM engines take 4.5 -5.0 quarts.....0.5 over, should not be a problem.....however, when you get to quarts being overfilled, then you have a problem....
No arguments with your comments. Only point I was making was that the plugs had been replaced 55,000 miles ago along with wires. Coil packs are original. Injectors are original to the vehicle as well. The O2 is original and has never been replaced; - now has over 267,000 Kms on it; - time to change it if only for PM.
I was only theorizing that coincidentally the crankcase got over-filled and shortly after the misfire occurred.
Were they related; - it doesn't sound like it. We did drain about 900 ml of oil out after the shop I go to scanned the ECM found the code and cleared it. There were no other codes. After clearing the ECM the code did not return.
The vehicle is running well except for this one incident, getting on average about 34 miles per Imperial gallon on the highway (Imperial gallon is 4.55 liters vs the 3.78 liters in a US gallon) so if it has issues with injectors or secondary ignition it certainly does not show up in the way the engine normally runs.
I guess because so many sensors combine to affect fuel delivery, spark timing and advance that any one sensor being marginal should show up as a performance issue or low fuel mileage.
Back in the day, (70's) you could put an Allen scope on the engine and view RPM, coil primary and secondary voltage, spark plugs firing under load, dwell, advance curve and vacuum to determine how well the engine was running. Misfires could be identified on the scope. I'm not even sure how the ECM learns that a misfire has occurred on a particular cylinder with today's technology, but it is somewhat amazing that it can.
It's one of the reasons our DOT (called the MTO) switched to reading the OBD port and viewing what the ECM is seeing from the sensor monitors to determine if the engine is running properly. If the monitors show green, then they are operating properly and reporting data to the ECM. In my view the test misses the point though because the entire test takes less than 10 minutes but never sniffs the tailpipe emissions. You could have a perfectly monitored engine with ring or oil consumption issues that never show up in the test unless the person doing the test is surrounded by dense blue smoke. An exaggeration for sure, but it makes the point that as an owner I can no longer tell how well the engine is running because they do not provide a readout of hydro carbons, CO or NOx.
Up until Friday last I had not experienced a misfire or reduced fuel mileage. A short trip of 200 miles today indicates the engine is running very well.
Sounds like a Gremlin, or maybe just my wife's heavy right foot causing a problem.
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