Question about drawback and bypass valves

[stangguy]

Mainly what I am interested in is a combination anti drainback/bypass valve considered an ok thing to have in a filter? I guess I am mostly interested in the type of combo valve used in at least some of the super tech brand of oil filters. I have always been a little leery of the combo valves. I really like the general construction of the filters, but wondering about the combo valve. I have used a lot of the OCOD frams, but I think I would switch to the ST brand if the combo valves are OK.

 

[ZeeOSix]

I don't like combo valves because at very cold temperatures I have doubts they would work as well as a filter having a separate ADBV and bypass valve. Especially since the combo valves I've seen all seem to be made of nitrile rubber, not silicone rubber.

 

[stangguy]

That makes sense, luckily the vehicles I would use these filters on literally never get started at below 40 degrees F. so doubt if that would be a problem. Even so, I would prefer they were silicone.

 

[BravoDosCero]

ADB and bypass valves have a different function.

The ADB is a soft valve which works with no pressure in the oil circuit. Uses the fluid weight to be closed and opens as soon as the engine is started and the oil pressure is greater than the fluid weight. It is placed at the inlet of the filter.

The bypass valve is harder than the ADB, should work only when the engine is running and the oil pressure reaches a certain value (filter is clogged) to prevent oil starvation. It is placed at the opposite side of the ADB, at the bottom of the filter.

Now think about the oil flowing through the filter. First, the pressure opens the ADB valve. Oil fills the dirty chamber and the shell forces it to go through the filtering media. At the bottom of the filter, the bypass valve opens when reached the clogged filter pressure and the oil enters the clean chamber.

Let's think now about the combo valve. Should be placed at the inlet to work as a regular ADB. So the oil opens the ADB valve and when the filter is clogged should surround it to enter the clean chamber. The energy needed to force the fluid to do such a close turn (almost a 360º) is higher.

The difference between the combo valve and the regular bypass is that when the filter is clogged, the combo valve requires more energy to force the oil through the combo valve. Therefore the fuel consumption is higher when you have a clogged filter.

 

[ZeeOSix]

^^^ The combo ADB/bypass valve is still designed to open at a specified delta-p across the filter media, so it won't need any more energy to force it open than an old fashioned spring loaded ADBV set to open at the same delta-p. I trust metal springs (that aren't effected by temperature) to open at the right setting, and more consistently than a rubber bypass valve that's functionality could be effected by it's temperature (ie, elasticity).

 

[BravoDosCero]

^^^ The combo ADB/bypass valve is still designed to open at a specified delta-p across the filter media, so it won't need any more energy to force it open than an old fashioned spring loaded ADBV set to open at the same delta-p. I trust metal springs (that aren't effected by temperature) to open at the right setting, and more consistently than a rubber bypass valve that's functionality could be effected by it's temperature (ie, elasticity).

Sure, ZeeOSix: it is possible that the functionality of a rubber bypass valve is affected either by the temperature or the oil quality, although the problem shouldn't arise unless the oil changing period is longer than recommended. Springs have also drawbacks, but I prefer them.

That's what I mean: the oil path when the filter is clogged (assuming the ADB/bypass and the COMBO valves are already open) consumes more energy with the combo valve than with the ADB/bypass due to the winding path. Rough scheme:

 

[zrxkawboy]

Therefore the fuel consumption is higher when you have a clogged filter.

I can’t imagine a measurable difference in fuel consumption, or even anywhere close.

 

[ZeeOSix]

Sure, ZeeOSix: it is possible that the functionality of a rubber bypass valve is affected either by the temperature or the oil quality, although the problem shouldn't arise unless the oil changing period is longer than recommended. Springs have also drawbacks, but I prefer them.

That's what I mean: the oil path when the filter is clogged (assuming the ADB/bypass and the COMBO valves are already open) consumes more energy with the combo valve than with the ADB/bypass due to the winding path. Rough scheme:

View attachment 39627

Hydraulic oil pump HP required to push X gpm at Y PSI only depends on the flow and pressure the pump it putting out. The PD oil pump will be doing the same amount of work regardless if the filter bypass valve that is set to same exact PSI setting is located at the base end or dome end.

The oil pump doesn't care where the bypass valve is located, only what the total flow resistance of the oiling system is, which is equal to the filter flow resistance (delta-p) added to the oiling system resistance (delta-p). If the filter's delta-p increases to the point of the bypass valve setting due to clogging, then that is added flow resistance the pump must overcome, but the location of the bypass valve won't matter, only the total delta-p across the oil filter.

If there was any added flow resistance going on inside the oil filter because of the bypass valve location, it would be so small (like 0.001 PSI) that no instrument in the world could accurately measure the difference. And it surely wouldn't make any difference in what gas mileage (fuel consumption mention in post #4) a vehicle gets.

 

[Bettez88]

Would a filter with a combo valve be fine for use on a lawn mower since it doesn’t see low temps?

 

[Sayjac]

For reliability of bypass function, I much prefer an OF with a traditional separate metal spring bypass (dome or base end) over a nitrile combo valve.

Something to think about, when GM asked Champ Labs to make their ACDelco ecore filters for their vehicles with no block bypass, they said NO to combo valves. All ACD for GM vehicles have used and continue to use separate dome bypass. This while the combo valve was still being used in other Champ Labs made for ecores like Super Tech and ACDelco for non GM applications. Draw your own conclusion.

Not all ST series filters use a combo valve, in fact the applications that do now are getting less. And the newer WM MP series OF with silicone adbv all have separate metal coil spring bypass. Especially if equivalent ST uses combo valve, imo makes the MP worth the price difference.

All that said, 'generally speaking' combo valves 'likely' ok for 3-5k mi ocis. However, with all the standard bypass options available for a similar price or not much more, no need for me to use one.