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Discussion Starter · #1 ·
I have seen postings claiming that we do not have an oil filter bypass in our stock filtration setup. I have also seen postings saying the filters themselves have the bypass valving in them.

If you believe that stuff then I have some very nice oceanfront property in Missouri to sell to you that I got cheap from RickDLance! :D

Any "expert" that is telling you this......well........:hail: if you just feel you have to, or better yet find out for yourself whats correct, then wonder after that if you are ever getting the right info or not :confused: from said "expert".

So anyone have info to the contrary?

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TX :
At one time the delco filters did have a bi-metalic spring that pushed the filter media up against the top of the cartridge .
And you ask how I know. Well I dropped one on the floor and it landed perfectlly on end , (not the threaded end ) and the filter media was then loose , so I proceeded to get another to install . Later I cut it open to find this bi-metalic spring that sits on the bottom that had a very obvious kink in it. I was later told that was used to allow oil bypass on cold strartups.


:)
 

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Discussion Starter · #4 ·
TX :
At one time the delco filters did have a bi-metalic spring that pushed the filter media up against the top of the cartridge .
And you ask how I know. Well I dropped one on the floor and it landed perfectlly on end , (not the threaded end ) and the filter media was then loose , so I proceeded to get another to install . Later I cut it open to find this bi-metalic spring that sits on the bottom that had a very obvious kink in it. I was later told that was used to allow oil bypass on cold strartups.


:)
I am with you, but thats used to enforce the EXISTING built in oil filter bypass, the actual factory one like every vehicle comes with.

Agree?

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Well, I've got to get home and check my lubrication flowpath illustration and service manual - but since almost every engine lube oil pump is a positive-displacement gear-type, almost every engine has a relief valve built into the pump output, which often serves dual duty as the oil pressure controller. The difference is that the pump relief will not "bypass" but instead dump back to the oil pan and not supply unfiltered oil to the lubrication galleys. The filter cartridge internal bypass will in fact bypass the filter media and allow unfiltered oil to flow to galleys, bearings and parts.
 

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if your filter doesnt have a bypass you need to change to another brand because if your filter gets clogged no oil for your engine aand that is no good you need a bypass because dirty oil is better than no oil
 

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I have a scan of the lubrication flow schematic *SOMEWHERE!* but I can't locate it now, dangit! But, in lieu of that, from the Service Manual, 6-1128 Engine Mechanical - 6.6L (Engine Repair) - Lubrication Description: "Engine lubrication is supplied by a gear type pump assembly. The pump is mounted on the front of the engine block and driven by the oil pump drive gear on the crankshaft. The pump gears rotate and draw oil from the oil pan sump through a pick-up screen and pipe. The oil is pressurized as it passes through the pump and is sent through the engine block oil galleries. Contained within the oil pump assembly is safety relief valve that eliminates overpressurization. Pressurized oil is directed through the sub oil gallery (5) to the full flow oil filter where harmful contaminants are removed. Two bypass valves are incorporated into the oil cooler assembly which will permit oil flow in the event the filter or the oil cooler become resticted. The oil is directed to the main oil gallery (4), and from the main oil gallery it flows to the piston cooling channel left bank (3), and the sub oil gallery (6) on the right bank. The sub oil gallery on the right bank supplies oil to the right bank piston cooling channel (1). Located in the front cover at the sub oil gallery (6) is an oil pressure relief valve which regulates oil pressure within operating range. Oil flows from the main gallery (4) to the vertical crankshaft/camshaft bearing galleries (2). From the crankshaft/camshaft bearing galleries (2), the oil flows to both the camshaft bearings and the crankcase main bearings. Oil flows from the crankshaft main bearings to the connecting rod big end. Oil flows from the crankshaft/camshaft bearing galleries (2) to the number 1 camshaft bearing (7), where it splash lubricates the fuel injection pump gear. Oil flows from the crankshaft/camshaft bearing galleries (2) to the number 2 and 5 camshaft bearings (8). Oil flows from the crankshaft/camshaft bearing galleries (2) to the number 3 camshaft bearing (9), where it exits to both cylinder heads and enters the hollow rocker arm shafts. Oil flows through the rocker arm shafts and rocker arms where it lubricates the upper valve train components. Oil also flows through the rocker arms, through the passage in the valve adjusting screw and into the hollow pushrods where it is directed to the valve lifters. Oil flows from the crankshaft/camshaft bearing galleries (2) to the number 4 camshaft bearing (4) where it exits into the turbocharger supply line to lubricate the turbocharger. Oil exiting the turbocharger is routed through the turbocharger oil return pipe and into the flywheel housing."

(My emphasis added)
 

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I thought the purpose of the bypass valve in filters was to let oil bypass if the filter became overly clogged so the engine wouldn't starve for oil. Different than the pump bypass which dumps oil back to the crankcase to keep pressure under control.
 

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I thought the purpose of the bypass valve in filters was to let oil bypass if the filter became overly clogged so the engine wouldn't starve for oil. Different than the pump bypass which dumps oil back to the crankcase to keep pressure under control.
:exactly: Back in 01 when I got my first Duramax it was explained clearly in the diesel supplement that a by pass filter was a must. Other wise if the filter became clogged the engine would starve for oil. Most engines do have a by pass for the filter built in near the filter mount so oil can by pass the filter if it becomes clogged. The duramax does not. It does have a by pass for the oil coller should it become clogged.
 

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Discussion Starter · #11 · (Edited)
Not exactly Dave, your information is "not" exactly, we have 3 bypasses built into the engine. If you took your filter and filled it with epoxy then drilled and tapped the center post and screwed it on you would still have flow. It would be reduced flow, but you would still have flow.

If you had the oil cooler assembly in your hands you would see 2 of the bypasses, the 3rd is an internal pump bypass. I should have taken pictures of it. Fingers posted some in the PUSU (results) thread.

The Dmax of course has a built in oil filter bypass.

What does "My emphasis added" mean? :)

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Not certain what you are getting at tx,
:help2:
 

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Discussion Starter · #14 ·
Just education versus mis-information spread about our trucks. Especially when the mis-information is being portrayed as an "expert" view.

Amazing we can't settle if we have a factory filter bypass. A hardware bypass, not the filter itself.

We do, I assure you.

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Not exactly Dave, your information is "not" exactly, we have 3 bypasses built into the engine. If you took your filter and filled it with epoxy then drilled and tapped the center post and screwed it on you would still have flow. It would be reduced flow, but you would still have flow.

If you had the oil cooler assembly in your hands you would see 2 of the bypasses, the 3rd is an internal pump bypass. I should have taken pictures of it. Fingers posted some in the PUSU (results) thread.

The Dmax of course has a built in oil filter bypass.

What does "My emphasis added" mean? :)

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I will agree with that. Which leads me to a question will the third pump by pass allow oil flow with a totally pluged oil filter if the oil filter does not have a by pass?

Every thing I have ever read, GM literature and manuals, Amsoil info and other filter companies info clearly state the Duramax must have a by pass filter or sever engine damage could occure.
 

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Discussion Starter · #17 ·
The two bypasses built into the oil filter/cooler assembly are there to handle filter bypass, such as if you get a plugged filter as you suggest. One is capable of bypassing the filter alone, and the other is capable of bypassing the filter and the cooler. Tonight when I get home I will post pictures of the bypasses and indicate where they go from and to.

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I can assure you that the oil pump has a bypass, because if it didn't when it gets zero out it would over pressure everything and do some big time damage to weaker components.

Greg
 

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Discussion Starter · #19 ·
what he said is right
Then what is the purpose of the 2 oil filter bypasses built into the truck filter/cooler assembly? Do you know they exist, or are you passing along what you heard from someone else?

Don't take that question as rude or anything, because thats not the intent. The intent is to get the correct understanding out there and not further hear-say.

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I expect the one built into the filter mount/cooler has a higher setting than the one in the filter. I see no need for both.
 
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