I'm having trouble understanding some of the fundamentals of sandwich adapters. Some have written that if a sandwich adapter is used for a bypass filter the filter will drain at shutdown. I would like to ask the group where this drainage ends up - in the oil pan - or does it drain into the engine? Also the sandwich adapter diverts a small bit of oil flow to the BP filter - where does the clean oil travel into?
flow question and sandwich adapters
- Thread starter mjo
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mjo ..let's see if I can say this right..
Okay ..the filter will drain like any other bypass filter. It's hooked up to the pre-fullflow part of the filter (you've installed a intermeidate divider that has a direct route to the ff filter and a "bypass" to the full flow filter. It's behind the ADBV ..at least on its feed side.
Whether it drains forward or drains backward ..it ends up on the pan. If it drains back ..naturally it goes to the pan. If it drains forward, it pushes oil out of the filter ..and that oil pushes oil out somewhere else (leaks down somewhere) and it ends up on the pan. Any cached oil ..will also be displaced due to added volume (if you see what I mean).
Here's the flow engine ..it then splits to the outlet port/bypass filter - inlet port AND the relief port. The flow splits on one side of the "wall" in the sandwich ..and converges on the other side of the wall before it goes into the full flow filter.
Now if you're talking JUST a pressure tap sandwich adapter (basically a spacer with a tap/port on it) then there's a small flow that goes to a bypass filter and then is returned to some non-pressurized location. It can be the pan ..the valve cover ..whatever.
Again, in either installation, the filter can drain forward and backward ..or both.
btw- unless you install some check valve ..or hang it very low ..every installation will drain/siphon. I can't think of any way that it wouldn't. Even if you tap into a remote mount, those lines will either drain forward or drain backward too. The excess oil in the bypass filter will force oil out of the fullflow filter, moving it "forward".
Okay ..the filter will drain like any other bypass filter. It's hooked up to the pre-fullflow part of the filter (you've installed a intermeidate divider that has a direct route to the ff filter and a "bypass" to the full flow filter. It's behind the ADBV ..at least on its feed side.
Whether it drains forward or drains backward ..it ends up on the pan. If it drains back ..naturally it goes to the pan. If it drains forward, it pushes oil out of the filter ..and that oil pushes oil out somewhere else (leaks down somewhere) and it ends up on the pan. Any cached oil ..will also be displaced due to added volume (if you see what I mean).
Here's the flow engine ..it then splits to the outlet port/bypass filter - inlet port AND the relief port. The flow splits on one side of the "wall" in the sandwich ..and converges on the other side of the wall before it goes into the full flow filter.
Now if you're talking JUST a pressure tap sandwich adapter (basically a spacer with a tap/port on it) then there's a small flow that goes to a bypass filter and then is returned to some non-pressurized location. It can be the pan ..the valve cover ..whatever.
Again, in either installation, the filter can drain forward and backward ..or both.
btw- unless you install some check valve ..or hang it very low ..every installation will drain/siphon. I can't think of any way that it wouldn't. Even if you tap into a remote mount, those lines will either drain forward or drain backward too. The excess oil in the bypass filter will force oil out of the fullflow filter, moving it "forward".
OK, Gary. So, you're saying that the filtered oil from the BP filter flows back into the engine. But, the oil flowing into the inlet of the BP filter came from the oil pickup tube? Or did the inlet oil come from the oil pump itself? Maybe this depends on the engine?
Draining the BP filter is a good thing if you need to service the BP element. However, would a sandwich adapter introduce the risk of air injection into the oil pump?
Draining the BP filter is a good thing if you need to service the BP element. However, would a sandwich adapter introduce the risk of air injection into the oil pump?
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Well, oil pumps don't hold oil back. Otherwise, no one would ever have startup noise. So ..the oil pump is typically void of oil and has to reprime itself. Sure, it's lubed plenty ..but it's never a perfect seal.
So, I wouldn't worry about air in the oil pump. ...except maybe when it was first assembled (depending on the pump type).
So, I wouldn't worry about air in the oil pump. ...except maybe when it was first assembled (depending on the pump type).
I made a one way oil flow valve. I used 2 brass barb ends with a brass coupler in between. I used a steel ball (bearing) and it fits and mates inside next to one of the holes in the barb. I put in a spring to put pressure against the ball bearing. Viola, oil passes one way fairly easily, but it won't flow in the reverse direction.
Vern
Vern
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Vern, keep in mind that even with your check valve, if the bypass is mounted high enough, the drain line will ..naturally, drain and the air bubble may reach the filter. If too long a time elapses before restarting the engine, the filter may empty anyway.
Now putting one of your setups before and after the bypass filter would probably work out well.
Now putting one of your setups before and after the bypass filter would probably work out well.
When Frantz was big back in the 60's they were the king of adapters. They had a one port plate that eliminated the full flow filter. They had a one port sandwich adapter and a two port sandwich adapter. They had a two port adapter that eliminated the full flow filter. I still have a few of them. With the Frantz two port sandwich adapter some of the oil could bypass the full flow filter. With the Perma-Cool adapter all of the oil must go thru the full flow filter to get to the engine. The trouble I had with the Frantz two port adapters is they depended on flow to create a pressure to feed the Frantz or Motor Guard. On some very small engines you didn't have enough oil flow to create enough pressure to the bypass filter. The Perma-Cool adapters depend on the spring in the relief valve. I always like for the bypass filter to drain at shut down. My Camry drains good with the sandwich adapter, the full flow filter also does because the threads are down. My Subaru won't drain because the air can't get up into the filter like it could returning the oil to the oil pan. I loosen the tee handle when the filter is still hot to let in air. As the air enters the filter the oil drains out. The Subaru also has a sandwich adapter. I got spoiled in the early 80's with the Frantz two port sandwich adapters. The Perma-Cool adapters I like better. Frantz didn't put an orifice in the filters used with the two port sandwich adapters. because you were not taking oil off the system. I don't think it makes any difference.
Ralph
Ralph
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