How to verify crankcase oil level?

[tornik550]

I recently rebuilt my engine. I have the engine on a test stand. I have the oil tank mounted at approximately the same level as it would be in the car. I am questioning the actual oil level in my crankcase.

I put 12qts in the tank. I cranked the engine without ignition to get the oil pressure up. The dipstick doesn't show any oil so I put a couple more quarts in and it doesn't show on the dipstick. I suspect there is actually too much oil because I can see a little bit of standing oil in the cylinders with a scope. It is not oil from assembly cause it was a different color.

Normally I would just wonder if my dipstick was just not correct however since the setup is on a test stand, I wonder if something else is going on and I would like to verify the oil level in the case before starting the engine. How can I do that?

[DRACO A5OG]

What year is the engine?

Wow 14 quarts, that just seems way too much.

I put 12 ( that's with a front Carrera oil cooler ) when I reinstall the engine after a valve adjust and hand turn before start.

But on a rebuild, I read you need to disconnect the fuel pump, ignition and crank the engine to help build up pressure and move the oil where it needs to be, maybe a minimum of 6 times then connect the pump and ignition and start the engine.

[tornik550]

Originally Posted by DRACO A5OG

What year is the engine?

Wow 14 quarts, that just seems way too much.

I put 12 ( that's with a front Carrera oil cooler ) when I reinstall the engine after a valve adjust and hand turn before start.

But on a rebuild, I read you need to disconnect the fuel pump, ignition and crank the engine to help build up pressure and move the oil where it needs to be, maybe a minimum of 6 times then connect the pump and ignition and start the engine.

It's a 2.7l. I was able to get decent oil pressure- approx 23psi when cranking the engine with the starter and no spark plugs installed (fuel and ignition not hooked up). It definitely does seem like too much oil to me.

I suspect the issue has something to do with my tank. I purchased the tank as an extra so I wouldn't have to remove the one installed on my car. i don't know what kind of engine the tank came from. The dipstick pn starts with 930. I really wish there was also a dipstick on the crankcase.

[tornik550]

Does anyone know how much oil typically comes out if you remove the oil drain plug from the engine and not the tank?

[Trackrash]

The oil level in both the tank and crankcase vary, depending on RPM. But usually the level of the tank is lower when being driven and higher when idling.

A fresh motor will take a couple of extra quarts on it's first fill up. A couple of quarts always stay in the motor and oil lines when you change the oil.

I guess your choices are, assuming your oil lines are hooked up correctly and are clear, is to drain the crank case and start over. Or just start the motor and monitor the level in the tank.

[chris_seven]

When the engine is running there should be little or no oil in the crankcase - assuming that the scavenge section of the pump is not damaged or badly worn.

The level of oil in the crankcase on a stationary engine will vary depending on the viscosity of the oil and clearance in the pressure section of the pump and of course, time.

If you have mounted the tank in a higher position than in the car then clearly the 'head' of oil sitting above the pump will be greater so you will have more oil in the crankcase than when it is in the car.

If it is lower you will have less.

I don't think that that the amount of oil in the case when the engine is stationary is particularly relevant other than to provide a very approximate guide to pump condition.

As we check oil level with the engine running, normally at idle, I think that the scavenge section removes virtually all of the oil from the crankcase regardless of engine speed.

At higher speeds more of a vacuum is created as the pump will shift air as well as oil.

By cranking the engine slowly it is likely you have pumped all of the oil from the tank into the case and the scavenge pump hasn't run for long enough to return all of the oil as it isn't running quickly enough to generate enough lift.

I would drain the oil and then re-fill the tank. If it drains immediately into the engine, without cranking, I would worry as a good pump should hold up most of the oil for at least a few hours.

If you add 10 litres then the engine should be safe to start and once running you can adjust the oil level as needed.

If you don't have a dyno I wouldn't run the engine for too long on this test set up as you may affect the manner in which the rings bed in as at zero load the BMEP produced will be on the low side and may not bed the rings in correctly.