Oil Filter Adapter Bypass Spring Pressure? - Team Camaro Tech
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post #1 of 10 (permalink) Old Aug 31st, 02, 03:52 PM Thread Starter
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I am currently reassembling my 400 small block. I was checking out the oil filter adapter and I noticed that the bypass spring was very weak. I can use my pinky to easily depress the spring. Is this normal? It seems to me that this would allow alot of oil to bypass the filter when oil pressure is above 10 psi or so.
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post #2 of 10 (permalink) Old Aug 31st, 02, 05:42 PM
David Pozzi
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it operates on pressure differential. When the oil is cold and thick, it may bypass more. When the oil is hot, it probably doesn't bypass much, but who knows?
I plugged mine and it hasn't caused any problems. You have to change filters regularly, or they might get damaged with a plugged bypass.

I guess a stiffer spring would be a better deal.

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post #3 of 10 (permalink) Old Aug 31st, 02, 06:13 PM Thread Starter
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Yeah, after I posted that question, I got to thinking about that and I realized that there is pressure on both sides of the valve. If there is enough pressure drop after the oil passes throught the filter media, the the bypass valve will open. It doesn't seem like that there would have to be much pressure drop in order for the bypass valve to open though.

How do you plug it off?
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post #4 of 10 (permalink) Old Sep 1st, 02, 04:38 AM
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I always put a pipe plug in the hole on any engine I build to prevent unfiltered oil from running through the engine. This feature is for people that never change their oil filter as it is designed to open when the filter is clogged from way too much crud but it can open at other times and that is definately not desireable. The original idea was dirty unfiltered oil is better than no oil or blowing out the oil from the engine. Since we change our oil once in a while, this feature is not needed and can cause unfiltered oil to circulate at times so we should remove it.

You need a 1/4"-18 NPT tap (PIPE THREAD) from your local hardware store and a matching pipe plug. I like the ones that use an allen wrench to install them. There are also square drive plugs available. Pop out the washer, spring and valve with a screwdriver and you are ready to go. I do not advise you use any teflon tape on this plug as pieces could come loose and cause problems. Do not thread the tap in very far or the plug will not fit right and just run right through. There is not much metal to tap so go easy, test fit the plug and tap a little further if needed. Screw the plug in and re-install the filter adapter and that is it.


[This message has been edited by stingr69 (edited 09-01-2002).]
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post #5 of 10 (permalink) Old Sep 1st, 02, 02:46 PM
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moroso has a plug just for this reason easy to install, been in my 400 for a year no problem an if you use the pre screeen you wont have to change filters so often. screen is jegs#710-23845 plug is 771-14845
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post #6 of 10 (permalink) Old Sep 1st, 02, 06:26 PM
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Just remember to keep an eye on the oil pressure. If it starts to fall change the filter. Also take it easy untill the engine warms up.

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post #7 of 10 (permalink) Old Sep 2nd, 02, 12:11 PM Thread Starter
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I used stingr69's pipe plug method. It seemed to work fine.

About how long do you all get before you notice your oil filter beginning to clog up?
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post #8 of 10 (permalink) Old Sep 2nd, 02, 02:49 PM
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I would like to mention a couple of things.

First of all, there are probably 10 bazillion Chevy motors runing around with the bypass still working and no damage to the motor.

I know of 2 engines that were pretty well destroyed due to an oil filter coming apart internally and the filter material ending up in the main oil feed to the motor. Both these engines had the bypass blocked.

Moral to the story...I personally would not block the bypass on anything but an all out, race only, engine. If you still decide to keep it blocked, make certain that you run only the very best HP type oil filters...either Fram HP series or Moroso. And always warm the engine up completely to operating temp before any type of rpm's are attempted.
In my opinion, its not worth the possible damage to an engine. Most of us change our oil before it even gets dirty anyway, so who cares ???

Bill Koustenis
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post #9 of 10 (permalink) Old Sep 3rd, 02, 07:52 AM
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I absolutely agree with Bill.

During a cold engine start with no bypass valve there is a high pressure drop across the filter. this can lead to filter rupture. hence the filter failures noted.

During normal operation the the valve is closed. If you change the filter regularly the valve will not be normally open and engine wear will not suffer.


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post #10 of 10 (permalink) Old Sep 3rd, 02, 09:01 AM Thread Starter
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Maybe I should rethink plugging off the bypass. I think that I will plug leave the adapter that is plugged off for the first hour or so of running. That should make sure that all of the dirt that gets in the engine during assembly gets filtered out. After that, I think that I will go back to the adapter with the bypass spring.
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