Oil filter bypass delete, is it harmful?

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Hey, first post, hi guys I own a 1990 Nissan 300zx of which has oil relief valves located in the block, I removed them because I was told they can be highly problematic on this car's engine, and that if I simply make sure to change my oil and filter regularly I won't have any issues, however recently I've been noticing that my oil pressure isn't as high as it used to be, when first starting the car sometimes there is lifter chatter for about 1-2 seconds and then it goes away, making me think that because I'm not running pressure relief valves, that my OEM oil filter might have gotten an issue and is causing a lower than normal oil pressure situation.

Also something to note is that the oil pressure doesn't go higher than 60 no matter what, whereas about a month ago it would go as high as 90 when revving the engine, looking at the gauge it's like something is restricting flow when the engine wants to start building more pressure, I'm running SuperTech 20w-50 which according to my owners manual is suitable to my summertime climate here in Texas

I've looked at the oil pan and don't see any dents or anything that could restrict flow to the oil pump, nothing has changed visibly other than my oil pressure gauge is reading lower than normal pressure for highway RPMs, but listening to the engine it sounds fine, except for that occasional lifter noise on startup

Could not running pressure relief valves have messed up my oil filter? That combined with running a heavy weight oil and such, could it have done anything to the inside of the filter?
 
The oil relief valve you took off is allowing oil to be dumped back into the pan rather then keep
higher pressure on the oil system leading to bearings and lifters!

If the oil relief valves are known to fail, then have spares, if they fail closed pressure climbs, if it fails
open, oil pressure drops to where you are now.

The oil filter isn't damaged either way, they can handle 250-350 PSI, a level you won't reach.

If you want to do something that makes a difference in oil and engine life, then use FilterMags
on your spin-on oil filter, I've been using a pair for the last 3 yrs or so, clean oil way longer!
Check out the pics in this PDF:

" FILTERMAG vs HOMEBREW "
https://app.box.com/s/uxvu8dmscf5wcgftutdm0ejqwgn86tw7
 
I took of the oil relief valve and simply plugged the holes in the block, so if all is according to what you said, and I also believe this to be true, then I should have higher oil pressure, which I did for awhile.

I've read a few threads on here where by some people lost oil pressure due to a faulty filter, so that's kind of what got me thinking

The relief valves fail, but sometimes it can end badly, I've seen some people have them get sucked up through the oil pump and cause major damage. A mechanic who specializes in these cars told me when he sees one with bearing issues, at least half of them have issue with the pressure relief valves

That filter mag looks interesting. I run a magnetic drain plug so I'm assuming that is similar?
 
Wow I can't believe anyone would do something this terrible to their own car. Your oem fitler doesn't have a bypass built in and you removed the one in the block. If your oil pressure surges you will end up with a blow out in your filter media. The filter can can handle a couple hundred psi but not the media.
 
I know it sounds like a terrible idea, but this was recommended to me by really good Z mechanic, and I've seen on these particular engines the by-pass valves have issues and lead to an engine dying. I figured worst case scenario I can install a filter with the bypass feature if it's an issue

So maybe I could have blown out the filter media and this could cause lower than normal oil pressure? I was running at many times 90psi of oil pressure before even hitting 5k RPM, but I figured my oil pump would make it so that I wouldn't run oil pressures that are dangerous to my filter

I'm going to change my filter, I have a new oem one in the trunk, guess I'll see what happens, because like I said everything else looks fine, if the oil pressure goes up, I guess I'll start looking for a filter with the bypass feature?
 
For the filter media to burst/tear you need a very dirty engine and oil that plugs the filter!

That's actually hard to do with any car /truck built in the last 10 yrs!
In the 70s, 80s, and 90s, I drove various junkers hi miles with hi blow-by
gases into the crankcase, with lots of blowby foam on the oil, but never plugged a filter!

IMHO it's a 1 in a million problem, unless you have a cup of sand in the engine! LOL
smile.gif


The sample pics posted here lately of torn filter media all looked like manufacturing defects that got out.
 
Well I should add that running 20w-50 and having a thermostat (has since been replaced) that wasn't allowing the car to reach operating temp is something that was going on, with the engine cold it was very easy to go from 70psi-90 with a quick rev
 
UPDATE: So I changed the filter and oil pressure is acting normal again, looks like the filter got messed up by not running bypass valves, time to find an oil filter that has them in the filter I guess, also time to get a new thermostat, if the oil doesn't get to operating temp then it will just have even more pressure than it really should
 
Concerning your oil pressure,these cars are legendary for having the oil pressure sending unit going bad. Mine usually is 100% accurate and then sometimes it'll gradually go to zero then jumping back up again. My Z31 turbo's gauge always sat on 0.
 
Yeah, that's why I wasn't sure whether to believe oil pressure was an issue, but the gauge combined with lifter tick made me go "hmmm"

also I took a look in the old filter, sure enough the filter media is wrecked, looks horrible, like someone crunched it.
 
I'm confused here, because I don't know the details of how that engine is set up.


Typically there are two BP relief valves in an engine.
1) in the filter (or in the block right next to the filter mount). This protects the media from ruptures, and also assures flow should the media blind off
2) in the engine near the pump, to protect the pump from damage due to positive displacement volume concerns. This assures the entire system does not "over pressurize"
(I supposed there could be some amalgamation of the two concepts into one device; not seen that before but conceptually it's possible ...)

So when you removed the "relief valve", was it the one in the block near the filter? That is likely the one to protect the filter. The easy way around that, if that is indeed what you changed out, is to pick a filter similar to OEM specs, but with a BP valve in the filter, that would mimic the OEM feature you removed from the block.

I am not a fan of ever removing any relief valve; they are there for a reason. I would need to understand the specific failure mode of the OEM valves, and why it's become a "thing" to remove them in that niche market.

Do you have any pictures of what you removed? That would help us understand.



NOTE: I'm moving this to the filter forum; it's not "bypass filter" related. I think you confused the BP device topic with BP filtration and put your thread in the wrong area. You'll get more discussion here.
 
Last edited:
Originally Posted By: Donatello
Well I should add that running 20w-50 and having a thermostat (has since been replaced) that wasn't allowing the car to reach operating temp is something that was going on, with the engine cold it was very easy to go from 70psi-90 with a quick rev

Originally Posted By: Donatello
Also I took a look in the old filter, sure enough the filter media is wrecked, looks horrible, like someone crunched it.

Cold 20W-50 oil, cold thermostat, high revs and no oil filter bypass valve equals lots of delta-p across the filter, resulting in crushed media like you discovered.

Yes, find a filter that has a bypass valve that fits before you smoke your engine.
 
Donatello, take a look at TG3682 FRAM TOUGH GUARD® OIL FILTER spec at Fram.com
It is spec for your car and many other Nissan and Subaru. "By-Pass Valve Setting NONE"
There is no by-pass valve in the filter.
I was going to use these filter for my Camry Honda since they were on clearance at Walmart but decided not to.
 
Last edited:
Originally Posted By: Tundragod
Donatello, take a look at TG3682 FRAM TOUGH GUARD® OIL FILTER spec at Fram.com
It is spec for your car and many other Nissan and Subaru. "By-Pass Valve Setting NONE"
There is no by-pass valve in the filter.

Thats why he ran into issues (collapsed filter guts resulting in less oil flow & pressure) when the bypass valve was removed from the engine block and ran a filter that has no bypass valve of its own.
 
Originally Posted By: dnewton3
I'm confused here, because I don't know the details of how that engine is set up.


Typically there are two BP relief valves in an engine.
1) in the filter (or in the block right next to the filter mount). This protects the media from ruptures, and also assures flow should the media blind off
2) in the engine near the pump, to protect the pump from damage due to positive displacement volume concerns. This assures the entire system does not "over pressurize"
(I supposed there could be some amalgamation of the two concepts into one device; not seen that before but conceptually it's possible ...)

So when you removed the "relief valve", was it the one in the block near the filter? That is likely the one to protect the filter. The easy way around that, if that is indeed what you changed out, is to pick a filter similar to OEM specs, but with a BP valve in the filter, that would mimic the OEM feature you removed from the block.

I am not a fan of ever removing any relief valve; they are there for a reason. I would need to understand the specific failure mode of the OEM valves, and why it's become a "thing" to remove them in that niche market.

Do you have any pictures of what you removed? That would help us understand.



NOTE: I'm moving this to the filter forum; it's not "bypass filter" related. I think you confused the BP device topic with BP filtration and put your thread in the wrong area. You'll get more discussion here.


I removed the bypass valves in the block, they are right in the area of the oil filter tree and oil filter. I have no idea what the OEM bypass valves open at however, so would it matter if the filter I buy was a different setting?

These are where they are supposed to be, however mine looks exactly like this with the metal plates blocking the holes
rebuild_25_thumb.jpg


This is what would be in the place of those blocked ports if I had done nothing
main.jpg
 
Originally Posted By: ZeeOSix
Originally Posted By: Tundragod
Donatello, take a look at TG3682 FRAM TOUGH GUARD® OIL FILTER spec at Fram.com
It is spec for your car and many other Nissan and Subaru. "By-Pass Valve Setting NONE"
There is no by-pass valve in the filter.

Thats why he ran into issues (collapsed filter guts resulting in less oil flow & pressure) when the bypass valve was removed from the engine block and ran a filter that has no bypass valve of its own.


exactly

I'll try to get pics of the carnage, not sure I want to post that embarrassing stuff though lol

also not too sure I have anything to open the old filter with
 
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