An oil accumulator (Moroso or Accusump both are well known brands is racing) is a hydro-pnuematic cylinder. Ok, so what does that mean? These accumulators are sealed aluminum tubes with an o-ring sealed piston inside. On one side of the piston is a pressurized air chamber, on the other oil. The oil compartment is connected to the engine through one hose. During initial startup additional oil is added into the system with the accumulator valve open, the oiling system pressuizes and fills the accumulator's oil chamber, the piston forces the air in the air chamber to condense, thusly pressurizing the for mentioned air chamber. Now, if the engine's oiling system looses pressure, resistance on the accumulator piston falls, which now allows the pressurized air chamber to push the piston thusly pushing the oil from the accumulator into the engine's oiling system. When the oil pick-up in the pan is once again submerged in enough oil to maintain pressure in the system, the oiling system pressure over comes the air-pressure resistance in the accumulator and this whole process begins again.
I hope this clarifies the funtion. The accumulator system is dynamic, fluctuating pressures result in a constant exchange of oil in and out of the accumulator (to some degree).
One thing to remember is to always shut the valve before turning off the car.
Getting oil out (say for an oil change) is easy, you just open the valve with the motor off; no positive pressure on the accumulator results in pressure coming out of the accumulator.
As for the equal distribution through the oil galley, this is my Theory. Assume oil-pump pressure drops, accumulator oil begins to enter the system, however since there are no check balls in the galleys, this oil will travel any direction it can. However, since the pump is still spinning, oil can only back feed as far as the pump, because the pump is still working to pump oil the correct direction. However, oil is not being fed out of the pump, but it also can not travel backward through the pump so, this path is neutral. Therefore, oil can only flow through the galleys the proper direction, because only the proper flow direction allows for flow, and if the oil is flowing in it's proper direction, the oil will distribute itself exactally as it would if the pump were supplying. Once again this is only MY Theory on how the accumulator maintains proper flow and protection when attached to an oil galley
*Note* When using the spacer block thingy that the BAT Accusump can be equiped with (for non oil-cooler cars), the oil flow is directional due to the inclusion of one-way check-balls.
It is always wise to check the accumulator's air pressure, the same as it is wise to check your oil level. Things being ideal, neither your oil level or accumulator pressure will need a top-up, but this is the real world, so keep tabs on it; it should easily hold it's pressure from one oil change to the next.
I'm not going to say that it is not possible to fit an accumulator by the coolant resvoir, BUT there is no way mine would fit there. 1.5 qt Moroso accumulator = 10" long 4.5" in diameter, PLUS there is ~2.5" of additional space needed at one end for the air chamber pressure gauge and valve stem, and another 3-4" on the other end for the oil control valve (on/off). You could remove the gauge to save an inch of length, and the valve does not need to be mounted directly to the accumulator, it can be remote and connected by hoses.
Honestly, I found 3 places that my accumulator fits up front: 1. the battery tray (if you want your battery in your trunk) 2. Mounted to the under-side of the right inner fender (this is where the washer resevoir is mounted, so using this location would require removing the washer resevoir and sprayer pump) 3. Under the cowl panel where the cabin filter is. This requires removing the cabin filter assembly, 2 bolts, it comes out easy. This is where mine is, I care less about having a cabin filter than a clean windshield, besides the filter needed to be replaced and I didn't feel like it.
Last edited by Pope; 02/15/05 09:57 AM.
