took the oil pump from the 68 barracuda apart to clean it up and got to wondering about the purpose of the anti drain back valve in the stand pipe.

the anti drain back valve allows oil flow through it,, in the normal installed position that would be from the top down

the anti drain back valve blocks flow from the bottom up,, again in the normal installed position..

so,,, with the engine off,,as oil flows through the oil pump stand pipe, from the top down,, the anti drain back valve does nothing to stop oil from draining from the filter,

so why is the anti drain back there,, this is my guess,, it is an anti drain back,, but what it does is stop oil that is in oil lines higher than the filter,, this would be the lines that feed the rocker arms and the rocker arm shaft itself from draining back through the pump and the filter in a reverse flow and running, again in a reverse flow through the oil pick up tube and into the pan.

so my thought is,,the anti drain back valve in the stand pipe does not keep oil in the filter,, it keeps oil in the rocker arm shaft and lines that are higher than the filter, when the engine is off..
because what it really does is, stop oil from running backwards through the filter.

It blocks flow in the normal direction (top down) unless the engine's running.


Not quite. It's a spring-loaded valve. When the engine's running, pump pressure easily overrides the ADBV's relatively light spring load, opening it and allowing oil to flow. Shut off the engine, no more oil pressure, and the ADBV's spring closes the valve, stopping (or at least slowing) draindown.

There is another ADBV as well, a rubber flap one-way valve at the inlet (ring of circumferential holes) of most oil filters applicable to the slant-6 engine—but not quite all, and the exception is a little surprising! This rubber flap prevents oil draining down in reverse flow through the filter inlet and the pump outlet.
Yeah, it does.
It does that, too, because oil can't flow further backward than the filter, on account of one or both ADBVs.

It's a little more complicated than that, actually. The bulk of the central ADBV's job of keeping the filter full is done not by the valve, but by the standpipe. Given a working outer ADBV, oil in the filter can't drop below the top of the standpipe. The central ADBV adds a slight extra margin of oil retention; the main reason it was added was to address new-car owner complaints (under warranty) that the oil light didn't go out immediately upon startup first thing in the morning. There are two '62 TSBs on the subject; the first one described a filter-to-pump nipple with a standpipe to replace the plain nipple, to quicken the oil light shutoff time on cold start. The second one, issued awhile later, described a filter-to-pump nipple with standpipe and valve.

The thing is, though, that valve isn't all-benefit/no-drawback. The valve plate and its seat ring present some flow restriction even when the valve is open. Obviously it's not enough to ruin the engine; slant-6s started coming with this valve as original equipment in late '62, and if that valve were causing oil starvation the slant-6 wouldn't have its reputation for long life. But if the goal is to maximise flow and minimise restriction, the valve-equipped standpipe probably isn't the best choice (a bored-out plain nipple would be first pick, followed by a no-valve standpipe).

There's a filter with a built-in standpipe—Wix 51805.

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Doing doc's method of touching up the oil passage corners/ radius treatment, I've seen as much as 80 psi on the gauge with the stand pipe(I then pulled the nut I used to shim the oil pump spring fearing the oil pump would cause a gear failure at high rpm)....so I know it isn't really causing much restriction....

51806 is the filter + standpipe, 51515 is the regular filter.

Bit of trivia - the standpipe is a two piece "loose" press fit. If you want to remove the valve - you can situate it in the vice, insert a punch against the plate of the valve, and tap it out. Discard the spring and plate, reassemble tube to base. YMMV, can't say for sure all were made this way.

I'm more partial to the 51806 though instead of using the standpipe in the pump - makes oil changes less messy.

hi pierre and other sages of sl6s- have changed oil hot and cold in many sl6s. every time when i unscrewed the filter much oil dropped out of the filter so i figured oil was properly holding in the filter. this was even true with sl6s that didnt have the standpipe. some in the early 70s did not have the standpipe just a short adapter for the filter to screw on. heres one ill bet only the old fuds here can remember- 1960 sl6s had a paper cartridge inside a canister, not a common spin on filter, which also dropped a load of oil when you unscrewed it.they also had an annoying rubber flat rubber gasket you had to carefully position on the bottom of the canister when you reinstalled the canister. sometimes the old gasket would remain stuck to the plate which would lead to leaking. after that first experience smart slantsixers put an oil drain pan under the filter to catch it or continued using f bombs while they cleaned up the floor. the canister on these ancient models had a nut on the top to unscrew the filter container. i also recall the 60 model sl6s had a carbon pile generator to the left of the water pump,not a right side mounted alternator. any fuds here who can remember these items from my nostalgia trip? regards bob f

BTW, there is nothing to prevent oil drain from anything fed directly by the oil gallery, like the rockers. This oil will slowly drain out via the bearing clearances.

Aftermarket replacement oil pumps have pretty much always come with just the short nipple. The standpipe was factory equipment starting in late '62, without interruption.
Spin-on filter was standard equipment right from the start in '60 in the North American market. Replaceable-element filter was optional equipment for taxi/fleet. This remained the case right on up into the '70s.
That was the first design, used when specified (taxi/fleet) through '65. Lots of gaskets! Bolt-to-lid gasket, lid-to-can gasket, spring-to-element gasket, and element-to-can gasket. Note this type of canister has male threads, so no nipple or standpipe or valve of the type we're discussing is used:





In '66 it was supplanted by this other type of canister where the whole lid unscrews. Gasket count is down to two: an embedded O-ring for the lid-to-can seal, and an almost foolproof rubber ring that seals the stubby outlet pipe of the cartridge to the bottom of the can. There's a dimple/hole stop to prevent overtightening the lid. There's no rubber antidrainback valve in this canister, which is that weird exception I was mentioning above.





This one has female threads like a spin-on filter, so it gets used with an adaptor nipple, a standpipe, or a valve. This type of canister was used on some RHD export slant-6s as early as '62 (such as the Australian S-model Valiant; it was mounted on a bracket above the water pump) as well as on a variety of V8 applications (such as the 273 in the 1965 Australian AP6 Valiants).
The canisters, both types, have a thick rectangular-section O-ring to seal to the mounting pad -- just like a spin-on filter. Sometimes this O-ring comes off the filter and sticks to the mounting pad, whether we're talking about a spin-on filter or a canister type. But there's seldom a reason or need to remove the canister type; that would defeat the whole point of a replaceable-cartridge oil filter canister.

UPDATE The replacement elements for the later-type canister are no longer manufactured. The one for the early canister (Wix 51076, NAPA 1076, Fram CH-236APL, Chrysler 2129023, etc.) has a flat surface on both ends. The one for the later canister (Chrysler 2532752, Baldwin P272, Mopar L128, AC PF370) has a stubby pipe protruding from one end, to fit in a matching receptacle at the bottom of the canister. Here are pics of a (NOS) replacement element of the type needed for that later type of canister:





(Also interesting to note this element comes with a new lid O-ring and a rubber antidrainback flap to be installed between the bottom of the element and the floor of the canister).

It's beyond doubt there are large stashes of these filters on shelf at various old-parts places, but they are no longer a parts store item. Running any of the numbers into the online interchanges comes up zero (Wix, Baldwin, Fleetgard, Fram, etc). But they're no longer a parts store item.
There's nothing such as a carbon pile generator. A carbon pile is a tool used to load-test batteries. The '60 Valiant had an alternator mounted on the manifold side of the engine. All other '60 slant-6s had a DC generator on the manifold side of the engine.

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Right! 51806 (also NAPA Gold 1806). Thanks for the correction. I used to favour those, but my preference these days is Fleetguard LF3487. No internal standpipe, but a very advanced filter medium. If I could get that filtration medium with the standpipe, that'd be best of all, but they don't seem to make it, at least not last time I checked.
It does that!

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hi uncle dan - thanks for chiming in. always learn something new when i hear from you. some comments in response- when i worked in garages many moons ago always heard the dc (black cylindrical shaped)generators referred to by the A mechanics as carbon pile generators. never knew why. most said one reason they preferred the then new alternators is because they would generate current at idle and cruising speed whereas the dc generator wasnt too good at charging current production at idle. the 60 i was referring to was uncle moes and it was a 60 full size dodge seneca which had a black dc generator to the left of the sl6 manifold. remember it b/c i took it out once to install brushes and end bearings. according to what youre saying the 60 (first)valiant was the first to have the new alternaror. did not know those bits about the canister oil filter. the one i saw must have been a used taxi or fleet car. . worked on a few early 70s sl6 dusters which did have that short nipple on the oil pump seat. they were high mileage beaters and must have had their oil pumps replaced by after market parts.still owe you that mint julep if you remember. take care. bob f

Y'don't think I'd forget something like a mint julep, do ya?!

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Some generator systems used a carbon pile regulator , whether the early Mopars ever used this system I have no idea,but it certainly was a type of regulator used in days of old. It basically used a stack of carbon discs and varied the resistance by increasing or decreasing pressure on them.....they worked OK,not a patch on today's systems.but did the job.

Waaaaaaaaaay before the era of the slant-6.

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hi again uncle d- would never think you would forget a mint julep. so sweet you have to drink them slowly like thunderbird or ripple. you probably would forget a gin fizz though. they taste lousy. two questions though. are those cartridge filters for the old sl6s with the canister still available. could you adapt a spin on filter ( per 1) and eliminate the canister by screwing in a standpipe or short nipple. seems to me the fuds told me you could do that. aunt flossie had this 62 dodge dart with the polyhead 318 v8. it had a canister filter like the old one in the sl6 . it sat under the engine upside down. well remember having to carefully set the block to canister gasket(used grease) and replacing the ring gaskets at the tighening nut on the closed end of the can. there was a spring under that nut to hold the cartidge pushed to the base on the block. purolator filters for the 62 318 included all those gaskets and washers. interesting how some of todays newer cars have returned to the canister style oil filter. my 01 saturn L had it. told vw has it too. best regards bob f

I'd probably be drunk off my rear axle after half a one, anyhow—my yearly alcohol consumption rounds down to zero...
...and gin is one of the reasons why. The first time I ever got well and truly drunk was on gin and tonic. It only took about two more times (beer) to put me off for good.
Yes, from all the major filter makers.
Yes. The early-style canister you'd unscrew, install a regular nipple or standpipe/valve, and then a spin-on filter would go. The late-style canister you'd unscrew and directly replace with a spin-on filter.
Ahh, that's a different animal. The pre-'63 A-engines had a shunt-type oil filtration setup with the replaceable-element filter you mention. A change was made in the oiling path for '63 in conjunction with the switch to a spin-on filter—see page 1, page 2.
Nothing new under the sun!

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