Crankcase capacity
This is taken from Louis LaPointe (http://www.lubedev.com/smartgas/quickies.htm):
"MYTH: Overfilling your crankcase with oil can cause engine damage.
HINT: It is perfectly okay to overfill your engine by one quart of oil. Your engine will love you for it. Especially at higher RPM. The oil level is not level when the engine is running. Plus the "level" keeps getting lower and lower as you rev the engine at high speeds. If fact if you drive fast enough, the engine will suck air instead of oil. Your engine will blow its guts all over the pavement because the oil at high speed hangs in the rocker covers and does not easily return to the oil pan."
What happens to the engine when a crankcase IS overfilled? How does an engine behave if it's been overfilled?
Criminy
Comments
Re: Crankcase capacity
[quote="Criminy"] What happens to the engine when a crankcase IS overfilled? How does an engine behave if it's been overfilled?
Criminy[/quote]
I've seen dyno tests where power was picked up by running low, so fuel consumption should be reduced when driven under normal conditions, or so the theory goes. I don't know that I'd run crankcase low as I figure its a tradeoff between longevity and mileage/power. On the other hand I'd be just as concerned of running it too full. If the level raises up high enough the crankshaft will beat its way through the oil and froth everything up into a foam which has little lubricating and cooling benifits. I've been told if you get carried away you can blow the main seals. The only time I know that has truly happened was someone at the local "Jiffy Lube" went in for service and it got filled twice. At what point it is that overfull I do not know, but speculate it would vary with the individual engine/vehicle. Most of my vehicle run extra oil, but in the way of oil coolers and bigger/remote oil filters while keeping the level in the pan the same.
Crankcase capacity
A windage tray will help.
I believe one issue would be the amount of oil in suspension in the air around the crank will increase when over filled robbing more power.
Crankcase capacity
Hmm. Well. Hondas do not take kindly to being overfilled.
Crankcase already had 3.6qts of oil per the manual and 0.5qt of GM EOS when added to this 0.5qt of motor oil carrying boric acid (probably more). Civic really, REALLY didn't like it.
Engine was hot when BA went in, couldn't start the engine without stepping on the gas, and engine would only keep running rev'd way up - it'd die if it came down to idle with hard restart.
Left the engine to cool off, checked the dipstick half an hour later - if the full mark was 1inch from the end, it showed more than 2inches. It started and ran like a champ until it warmed up and came back down to idle.
Best I can figure, the crank was taking a swim at low rpms, but not at higher as the pump was drawing more oil out of the case. Drained it, mixed BA into the new oil bottle, and filled it to 3.6qts - she runs and idles just fine...
Crankcase capacity
If it's overfilled a little, the crank will getinto the engine oil robbing power. If's a lot you could hydrolock the engine in the bottom end.
Oil is a LOT thicker than air, costs a lot of power to spin the crank through it...
Crankcase capacity
Funny story... A friend of mine, bless his heart, didn't know what a dipstick was for (honest!).
He "checked the oil" on his parent's '83 diesel Jetta by peering into the filler, and decided that he had better top it up.
Result: Smoke. Lots of smoke.
After some tlc in the shop (I beleive all they did was drain the oil), the car ran fine. When they sold it many years later, it had over 400000K on it, still running great.
Cheers, Stinky
Crankcase capacity
Mercedes specifically warns NOT to overfill. Can cause damage to the cat converter.
My 111. 2 litre engine uses 8 litres of oil in the crankcase - which is almost double that of the Japanese 2.5 litre engine on my Nissan.
Then again, the Merc engine seems to do away with a PCV valve altogether?
Re: Crankcase capacity
I agree the mercedes are actually announce this after the they are struct with reports that this can affect lots of benz parts