And it has been (disastrous) for many engines. I just got mail today
from a guy with an Alpine that smoked all of the bearings in his engine
because something lodged in his bypass valve, which dumps to the pan. I
had a 68 Jeep Wagoneer that did the same thing for the same Reason.
Find an old PH8A and rip it apart. There is no valve in the filter,
other than a rubber disk flap for anti siphoning. I've ripped the cans
off of several over the years when they were put on way too tight!!
The relief valve is designed to regulate the MAXIMUM pressure the
system will see. When the filter plugs, the pressure climbs, and the
bypass valve would open just enough to relieve that extra pressure by
venting it into the pan (by design), there by maintaining the regulated
maximum pressure for the engine. When something gets lodged in the
bypass and keeps it open, the oil will always take the path of least
resistance.....right out the open hole into the pan !! This is why the
oil pump pickups have screens on them, too keep out anything that could
cause this.
In my previous post, I made it sound like some engines do not do this.
They all do ! As long as the bypass is not lodged by debris or is
malfunctioning, the bypass regulates the max pressure because the bypass
has a piston or plunger backed by a fairly strong spring. The strength
of this spring is what regulates the maximum pressure. Too much
pressure can damage babbit bearing and can blow the can part of the oil
filter off of its screw on base (seen this many times). Too much
pressure is also difficult for the pump to generate. If a bypass valve
has too stiff a spring or is stuck shut, it is not uncommon to snap oil
pump shafts, or shear off the shear pin on the gear on the shaft. And
we all can guess what too low of oil pressure can do to the longevity of
an engine.
The oil pressure bypass valve is a commonly overlooked critical part of
any engine rebuild, or major maintenance. If your engine seems to have
very low oil pressure, and changing a thicker grade of oil does NOT
change the pressure, then the Bypass valve Should be looked as soon as
possible, and probably the pump as well, if debris is found in the
bypass valve.
Rich.
>----------
>From: marrone@wco.com[SMTP:marrone@wco.com]
>Sent: Thursday, October 24, 1996 7:26 AM
>To: Richard Atherton (Entex); tigers@autox.team.net
>Subject: RE: Renault Spin on Filter
>
>You may be right Rich, but according to a 1966 Ford shop manual the 260/289
>does indeed have a relief IN THE FILTER element which "If the pressure
>between the valve faces is great enough...the valve will open. Oil then
>bypasses the element, maintaining an emergency supply of oil to the engine",
>that is a quote from the manual. There is also a relief in the pump, the
>discharge from this relief is routed back to the pump intake.
>
>In any case, higher restrictions in the filter is not the best of ideas. If
>it works how rich suggested (which it very well may for some makes) it is
>not only a bad idea but could potentially be a catastrophy!!
>
>
>
>> The filter itself does not contain a bypass, although most contain anti
>>siphoning valve (rubber disk on the inside that lays against the ring of
>>holes on the bottom of the filter). The actual bypass valve is in the
>>oil pump or in the block where the filter is attached.
>> Your assesment of the operation of the bypass valve is correct! A
>>smaller filter WILL be more restrictive to the flow at higher rates, and
>>thus the preasure will be higher at the filter base. When this preasure
>>begins to exceed the preasure of the relief spring, the bypass valve
>>will open. Depending on the engine, the oil going through the bypass
>>valve will still be pumped through the engine. On others, it will be
>>dumped back into the pan.
>> I believe the Alpine 1592 engine dumps back into the pan, because when
>>I had a plugged filter along time ago, my oil preasue gauge would bounce
>>between 5 and 15 lbs at idle when warm, and wouldn't go above 20...Ever.
>> When I changed the filter and the oil (same weight and brand) the
>>presure at idle was 20, and would climb to as high as 50, with no
>>bounce. The bounce was caused from the oscilating of the bypass valve
>>at idle.
>>
>>Rich
>>
>>
>>
>>
>>>----------
>>>From: marrone@wco.com[SMTP:marrone@wco.com]
>>>Sent: Wednesday, October 23, 1996 10:26 PM
>>>To: Rick Fedorchak; tigers@autox.team.net
>>>Subject: Re: Renault Spin on Filter
>>>
>>>What I have heard is the smaller the filter the "sooner" the bypass becomes
>>>activated. Even largish (PH8A) filters have their bypass open at higher
>>>RPM
>>>(and viscocity) but smaller filters bypass sooner and you end up spending
>>>more time without the filter in the circuit.
>>>
>>>
>>>>
>>>> I've seen one of these critters installed on the Ford
>>>>motor........and it's pretty tiny. Makes me wonder what the intended
>>>>filtering capacity is versus what the Ford motor needs.
>>>>
>>>>Can anyone provide any feedback on how these small filters worked on their
>>>>cars. Any problems encountered by using them ??
>>>>
>>>>
>>>>
>>>Frank Marrone MK I Tiger B9471116
>>>marrone@wco.com 1966 LTD
>>> Series I Alpine (2.3L powered by Ford)
>>> Yamaha Seca 900
>>>
>>>
>>
>>
>Frank Marrone MK I Tiger B9471116
>marrone@wco.com 1966 LTD
> Series I Alpine (2.3L powered by Ford)
> Yamaha Seca 900
>
>
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