Accusump, overfilling, etc.

I did a motor build for a guy who had put an accusump on th car prior to me getting involved. I kept it just cause, though I don't 100% get the operation. His doesn't have a valve - it's just connected straight to the oil pressure port. If the oil pump is putting out more than the bladder pressure, it fills. If the pressure drops, it emptys. When the engine isn't running, the accusump emptys all the way and the engine is a quart or so overfilled.

The new problem is that it's spitting a lot of oil out of the breather. On these engines, that is symptomatic of overfilling. Which this one is, but it has to be because of the accusump. So, what is the answer to an engine that wants to be run on the low side to avoid breather oil, but has to be run high because of the accusump? I could remove the accusump, but that doesn't seem like the right answer, and I like the insurance it provides.

Sounds like the Accusump is emptying while the engine is running, meaning: it's actually necessary.

is the Accusump where the driver can get to it ? if so, why not a hand operated valve that could be shut off prior to engine shut down ?

AFAIK, Accusump is always installed with a valve for that reason, to keep all the oil from draining out when the motor is off.

http://www.accusump.com/accusump.pdf/instructions.pdf

With the manual valve, you have to remember to turn it on/off.
With the electric valve (hooked to ignition), only opens when motor is running.

Is it a racecar or a streetcar?

Either way, sounds like a valve purchase is coming.

Carter

Maybe you have too much pressure in the accusump? You set how much pressure goes in the thing, and that sets the point that it starts dumping oil back in. That's why they put a pressure gauge on top of the things.

Dr. Hess wrote: Maybe you have too much pressure in the accusump? You set how much pressure goes in the thing, and that sets the point that it starts dumping oil back in. That's why they put a pressure gauge on top of the things.

Perhaps. This one doesn't have a gauge but it does have a shrader valve. I suppose you would set the bladder pressure to the pressure you want it to reverse flow?

Also - no valve on this one. Just straight piped from the engine to the accusump. Whichever has less pressure gets the oil.

EDIT - Here's a few pics:

The bottom of the accusump fas an AN tee fitting. I tapped the 3rd leg of the tee out for the oil pressure sender. A braided line goes from the original sender location to the bottom leg of the tee

A valve could easily be installed inbetween the T and the accumulator. I've never used an accusump, but the schrader valve is probably there for fine tuning the pressure, which might be hard to do with no gauge. You want the pressure to be set so that it only discharges when the engine pressure drops to the minimum safe running pressure.

It needs a valve.

He needs a solenoid valve wired in to the ign side of the electrics so when key is in RUN the oil can flow. then the pan should never be over full or only slightly if it is from slosh.

What is the diameter of the pipe to the accusump? I have one in the Porsche and my line from the accusump to the motor is 1/2 inch I'd. From the photos the lines look really small. This could be hindering the filling if the accusump with rapid increases in rpm. This would cause the oil no to fill fast enough in to the accusump. With a new motor I amuse the oil pressure is really good and responds very rapidly to changes in rpm. My car does not have a valve I run two quarts over full. Another reason to run a pre charge on the accusump is to force the oil through the motor in start up. With out it oil is filling the a ccusump.first then going to the motor. This causes extended period of time St start up that the bearings are running dry or with very low oil pressure.

In other words the pre charge pressure you set in that accusump is not the pressure that it expels oil it is the pressure that it starts to take oil in. I have mine set at fifteen lbs. No oil goes in to the accusump untill the oiling system reaches this pressure. If it helps it is kind of like a wast gate on a turbo. Like the wast gate the accusump will not let oil in to it until you reach the per set psi of the pre charge. Just like a wastgste will not open until the boost pressure overcomes the preset pressure of the spring. The spring in the wast gate is acting like the precharge in an accusump.

Make cence?

But if you put a valve in Dean you'll eliminate any dry start up as the valve will open right before the motor cranks over. so you don't have dry starts and your never the full sump capasity overfull. Now if your on a turbo no valve maybe a good idea as it would be a post luber as it spools down.

exactly.. if I had an accusump, I would definatly want it to prepressurize the system before starting

I agree that a valve is better but he is working with out one at the moment. They are nice but not a necessity. Furthermore I suspect that even with a valve he will have the same problem.

When the motor was rebuilt was the oil pump replaced? And was it with a high volume one? I suspect that the problem is with the sizing of the tube running to the accusump. As RPM changes oil flows in an out of the accusump with the changes in oil pressure. If the tube to the accusump is restrictive the motor will whip up the oil in the pan into the accusump fills.

On a related note my accusump is installed due to the 944's having the motor played over at a 45 deg angle and the sides of the pan are angles to the passenger side of the car. Thus when you take long sweeping left turns the oil climes up the side of the pan and the system sucks air. Before I owned my car the Previous owner lost two motors due to this and finally installed the accusump and it solved the problem.

I have always wondered if it would be better to have a system that you precharge at start up. Get the motor warm and then rev the motor to fill the accusump with the most oil you can and then "set" it. By setting it I mean that you would close a valve that is electronically tied in to an oil pressure switch that would monitor the oil pressure and only open if oil pressure got below a specified preset level and then close again once oil pressure is re established. I can see a myriad of issues with this including that you could eventually run out of oil in the accusump and that you could end up with the motor running over full. I guess this could be corrected by the driver if he "reset" the accusump on a strait by opening the valve and letting it refill and then flipping it to automatic. You could monitor the pressure in the accusump with a gauge and have it have its own warning light so the driver knows when to recharge it. In theory is seems like a good system but in reality it adds a lot of complexity to what the driver is doing. I think it would be a good system for autocross or cars used in spring racing where the races are short so the recharge would probably not be necessary in race. For endurance racing it would become something that would drive the drivers nuts.

Valve and a gauge. Until then, remove the additional quart(s?)

What you have in the picture is not an Accusump. The Accusump has a divider piston and a charging space and does need a valve to function correctly. What you have there is a Moroso (or similar) open accumulator. It does not have a valve and is not pressurized prior to use. It does not provide pre-oiling like an Accusump unless you add a solenoid valve, as recommended. It's designed to provide reserve pressure for fluctuations while running. The shrader valve on top is for purging it when changing oil.

Here are the instructions; http://www.moroso.com/catalog/images/23930_inst.pdf

Geez guys, would somebody please read the Accusump installation guide (I posted the link above).
It gives a full description of how it works, along with pictures, diagrams, etc.
This is not rocket scence.

Edit: I see from post above that it's not an Accusump. As the linked Moroso document clearly states, an additional 1-1/2 quarts of oil is required in the crankcase.
It also specifically says 'do not pre-charge'.

Maybe a windage tray/oil scraper would help? (paging Kevin Johnson)

Carter

djsilver wrote: What you have in the picture is not an Accusump.

Good call I did not even notice. I was fixated on the plumbing of the unit.

Totally off topic: That's a beautifully clean engine bay!