Why does over-filling with oil damage an engine?
Discussion
Chaps,
I serviced the Golf on Saturday. And put in about a litre too much oil. Took it for a quick round-the-block test run (~3 miles) and realised it smelled of hot oil, got home, drained out the offending surplus and all was well.
So, two questions. One: What is the problem with putting in too much oil? I can see that having the bottom of the crank throws dragging through the stuff is not good. But is there potential for damage as well?
Secondly, am I likely to have done a nasty to my beloved Golf by driving about 3 (brisk) miles with about a litre too much oil in it? (I suspect not.)
Oli.
I serviced the Golf on Saturday. And put in about a litre too much oil. Took it for a quick round-the-block test run (~3 miles) and realised it smelled of hot oil, got home, drained out the offending surplus and all was well.
So, two questions. One: What is the problem with putting in too much oil? I can see that having the bottom of the crank throws dragging through the stuff is not good. But is there potential for damage as well?
Secondly, am I likely to have done a nasty to my beloved Golf by driving about 3 (brisk) miles with about a litre too much oil in it? (I suspect not.)
Oli.
I don't think there is much to be concerned about.
The biggest effect of over filling , as you've correctly said, is beating the oil in the sump (which is probably now above the centreline of the crank) to a froth- very bad for power. You'll also get more oil than usual splashing it's way past the oil control rings into the combustion chambers. This will mean there will be lots of oil in the entire breather system and probably in extreme cases oily deposits within the combustion chamber, valves, fouling the plugs etc. The amount you over filled by and the amount you drove- I don't think you have much to worry about.
The biggest effect of over filling , as you've correctly said, is beating the oil in the sump (which is probably now above the centreline of the crank) to a froth- very bad for power. You'll also get more oil than usual splashing it's way past the oil control rings into the combustion chambers. This will mean there will be lots of oil in the entire breather system and probably in extreme cases oily deposits within the combustion chamber, valves, fouling the plugs etc. The amount you over filled by and the amount you drove- I don't think you have much to worry about.
I have over filled a car before, just to see what happens. It was 5 Quid fiesta, and the test oil cost more than the car was worth !
Basically, if you thrash the engine, the oil froths up, forces its way past the pistons, which results in piston ring damage and great clouds of smoke coming out from behind the car, and the car not running right untill you replace the rings.
Basically, if you thrash the engine, the oil froths up, forces its way past the pistons, which results in piston ring damage and great clouds of smoke coming out from behind the car, and the car not running right untill you replace the rings.
I have over filled a car before, just to see what happens. It was 5 Quid fiesta, and the test oil cost more than the car was worth !
Basically, if you thrash the engine, the oil froths up, forces its way past the pistons, which results in piston ring damage and great clouds of smoke coming out from behind the car, and the car not running right untill you replace the rings.
Basically, if you thrash the engine, the oil froths up, forces its way past the pistons, which results in piston ring damage and great clouds of smoke coming out from behind the car, and the car not running right untill you replace the rings.
zcacogp said:
I presume you did this twice, Mr Hopkins? Was the first test not conclusive enough for you? 
How much thrashing resulted in the damage? (I saw no clouds of smoke, just a smell of hot oil, so I think I am OK.)
And did you bother to replace the rings?
Oli.
when I did it it soaked the air filter (thats where the overflow goes to).
Pete
Normal the oil breather puts out a lot of blow-by gasses and a small amount of oil mist, the oil is mostly collected by the oil trap and drains back to the sump. The remaining gas from the breather is normally routed back to the inlet manifold where it is burnt in the engine.
If your sump is massively over-filled to the extent that it spills over the top of the baffle, it can get whipped up by the crank. This takes a lot of power from the engine and transfers it to the oil as heat. Depending where the breather is, the oil froth can get blown out of the breather along with the blow-by gasses. This means you have potentially quite large lumps of oil being blown into the inlet manifold. If you're lucky it will just get burnt and put out a lot of blue smoke. If you're unlucky it will raise the compression level to the point that the engine starts detonating, or even hydraulically locks. Either of these can wreck the engine in the blink of an eye.
If your sump is massively over-filled to the extent that it spills over the top of the baffle, it can get whipped up by the crank. This takes a lot of power from the engine and transfers it to the oil as heat. Depending where the breather is, the oil froth can get blown out of the breather along with the blow-by gasses. This means you have potentially quite large lumps of oil being blown into the inlet manifold. If you're lucky it will just get burnt and put out a lot of blue smoke. If you're unlucky it will raise the compression level to the point that the engine starts detonating, or even hydraulically locks. Either of these can wreck the engine in the blink of an eye.
I managed to overfill my beta once - lesson, dont fill oil in the dark! It was only about a litre over but when it was revved the oil was forced up the breather, into the air intake. Fortunately it didnt get any further than that as italian electrics failed at the same point.
Made a mess of the airbox + filter though.
Made a mess of the airbox + filter though.
Hello, I got this project car 2007 bmw 320i e93 with the fault diagnose PCV valve fail. What whas happening was that when the engine warms up a bit it starts smoking and shaking. I replaced the valve cover as the PCV valve of this car is built in the cover. I've checked the car oil level through the menue on the cluster and it showed that the oil level is at max (this car have NO dip stick!!! omg) so I assumed that the oil is okay. I took the car for a test drive and after about 10 min of driving the car started to smoke, I though its the oil in the exhause from the faulty pcv valve from before and I pushed the car to about 6k rpm to clear it out, but it got way worst and I got massive cloud of white smoke behind ther car, and I stopped on the side of the road and the car stall and I couldn't start it again so I had to tow it home. On the next day I decided to drain the oil to check for shavings or broken chain guides and I was shocked! There was 11 liters of oil inside the engine and the capacity is only 4.3L of oil + oil filter!
I bought new oil and poored in the right amount but when I started the car after few minutes starts to smoke badly... I think that I could have damaged the piston rings. When I meaured the compression I'm getting 14 bars on each cylinder, so is it possible only the oil rings to be gone or they'll all go if that was the reason for smoking? Thanks
I bought new oil and poored in the right amount but when I started the car after few minutes starts to smoke badly... I think that I could have damaged the piston rings. When I meaured the compression I'm getting 14 bars on each cylinder, so is it possible only the oil rings to be gone or they'll all go if that was the reason for smoking? Thanks
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