I've checked the oil level after a recent dealer oil and filter change several times. All readings were high whether checked hot (as recommended on the oil stick) or cold. My son and I pulled the oil filter after sitting overnight and before running the car and found only a relatively dry filter and no reservoir oil.

This would seem to indicate that there is no anti-drain back valve and that the dirty non-filtered oil (possibly including any gunk on that side of the filter) is draining back into the engine. So far, I've been unable to find any info detailing what is actually happening.

Is there an anti drain-back valve with the oil pump or elsewhere? I'd appreciate an explanation should someone have knowledge of the mechanical setup. Thanks, John

 

What year? The 3.6 has a completely different filter design then the 3.8 and 3.3.

 

Usually the anti-drain valve is in the filter housing. It is activated when the filter is tightened and deactivated when the filter is loosened. This allows oil to drain out of the housing back to the engine when you change the filter (before draining the sump). With the new filter installed the anti-drain valve is activated again and the filter housing maintains a full oil level from the oil pumped through it.

You can check this by watching how long the oil pressure warning light stays on after a start. Immediately after an oil and filter change the engine will take several seconds to fill the filter housing and turn off the oil pressure warning light. Thereafter, any restart of the engine should turn off the oil pressure warning light after just a moment.

Good luck

 

I may not have made my question clear.

The vehicle in question is a 2013 GC SE with the Pentastar 3.6 L V-6. The cartridge type filter is located on top of the engine and is no longer a spin on filter.

Examining the filter after cooling overnight, the filter housing is empty and the filter cartridge in a near dry condition (apparently for easy non-messy removal at time of oil change). This would indicate that there is no longer an anti-drain back valve in the housing and that the non-filtered oil from the input side of the cartridge has drained back into the sump along with any contaminants not retained by the filtering media on that side of the cartridge.

My question is whether there is an anti-drain back valve between the filter housing and the sump or is the contaminated oil draining directly into the sump? Or, does the oil pump itself, when not running, act as the anti-drain to prohibit the non-filtered residual oil from re-entering the sump?

 

seems you misunderstood his answer. The anti-drain back valve is the stem in the middle that the filter goes over. When you loosen the cap, it allows oil to drain back into the sump, which is why you are supposed to take the filter cap off before draining the oil.

 

I've worked with cars and filters back to the late 1950 and earlier models without filters and then on to the full flows most of you are familiar with.

I thought what I had written was clear but won't be understood unless you've actually changed the cartridge on the Pentastar V-6. On opening the cartridge housing on an overnight cold engine you'll find it empty with the exception of the very small amount retained by the filter media. All the oil including the contaminated oil and some residue (and that's my problem with this) from the input side of the filter has been returned to the sump (possibly stopped and held by the oil pump). The valve that fits into the center of the cartridge appears to be only the by-pass.

The intent appears to be that little oil will be retained by the cartridge thus making it a much less messy job to change at the expense of poorer quality filtering. That's why my Q was directed to the actual mechanical setup on the Pentastar. And, hence what exactly is that?

 

Most all filter assemblies have an anti-drain valve to keep the filter flooded with oil that is activated by the assembly being tight. When the filter or filter housing is loosened the retained oil is allowed to drain. This is obvious with the upright filter housing.

Most all filter assemblies have an oil by-pass valve that is quite separate from the anti-drain valve. The purpose is to allow oil to reach the bearings (and the rest of the engine) in the event that the filter gets plugged.

So, if you do not loosen the filter housing the anti-drain valve keeps the filter housing filled with oil. This allows an immediate oil pressure reading when the engine is started since the filter housing does not have to fill with oil after every stop. When you change your oil and filter you will notice the oil light stay on for a while with the engine running until the filter is full and oil can be distributed to the rest of the engine.

Engines do not need another anti-drain valve to operate correctly to minimize wear. The oil returned to the sump is no more contaminated than the oil already in the sump. If you are thinking back to when engines were fitted with a filter housing and replaceable fibrous filter and you needed to clean out the housing of sediment - don't. Modern filters don't work that way.

Good luck.