Oil filter bypsss plug: Pros and Cons

69427

The Artist formerly known as Turbo84
Joined
Mar 30, 2008
Messages
2,972
Location
Clinging to my guns and religion in KCMO.
Lately I've been reading too many horror stories about guys wiping out cams due to oiling issues, and the resulting trash that gets thown into the pan and pump (and possibly through the filter bypass and into the oil passages). I have no clue what the pressure level of the bypass spring on my engine is, so I have no idea how often (if ever) that it opens. I've got the GENV/VI design on the oil filter flange setup, if anyone has info on the bypass spring rating.

I like the idea of eliminating a possible short-circuit route for trash into the engine, but what down sides am I looking at? The filter regularly gets changed at less than a thousand mile intervals, so it should never get plugged up. I baby the engine until it's warmed up, and I'm looking into a lower viscosity oil to help the startup lubrication delay and lower the load on the distributor gear and pump.

So, what's your thoughts on plugging the bypass?

thanks,
Mike
 
Last edited:
NO. If you have trash going thru the engine it was either there to begin with or it got there because some parts are failing (could be the cam because of oil issues. Flat tappets will be phased out in the near future)

Oil bypassing the filter is a consequence never a cause. Plugging it in that case could make it blow up, with far more severe consequences.
 
NO. If you have trash going thru the engine it was either there to begin with or it got there because some parts are failing (could be the cam because of oil issues. Flat tappets will be phased out in the near future)

Oil bypassing the filter is a consequence never a cause. Plugging it in that case could make it blow up, with far more severe consequences.

Everything I have ever read, agrees with the above, the guys at GM were correct, leave it alone....

:gurney:
 
This is a controversial subject. Believers one way or the other.
The spin on oil filters with the bypass built in, such as the PH8A and others, has a bypass rating of 7 to 11 psi.
From memory here :banghead:, there were 2 bypasses available for the chevy blocks from GM, one was 15 psi bypass, the other 30psi, and of course the chevy filters have no internal bypass.
With a new standard paper 1 qt filter the pressure differential is 1.5-2 psi and a not too dirty filter 4-5 psi.
The general consensus is that the bypass is usually open during cold startup.
Years ago some expensive diesels had a gauge before and after the filter, to monitor filters.

I recently changed my thoughts on oil, and have gone to 0w40 Mobil1 on everything including a truck with flat lifters used for towing. It uses 2 remote filters only because the adapter was the cheapest and hopefully the bypasses therefore don't open much.
I think the startup lube is a big, big issue.

I also recently bought a 1 owner like new truck from a friend of mine with 180,000 miles on it that had regular oil changes at 5000 miles with 5w30 Mobil1. The ONLY thing that was ever done to it was a pcv valve replacement. Still original spark plugs. That impressed me. I changed the oil and filter with the same oil again and after 4000 miles, it still looks as poured out of the can. Cleanest I've ever seen. Hope the engine guts are as clean.

As far as dist gear load, I had one fail. Dist stopped turning. I had been using heavier oils and coincidentally it failed completely when it was colder down her (45° in S Florida) :nuts:

WornDistGear1.jpg

If you're changing every 1000 miles and primarily track use with proper oil and no less than a 25 micron filter, I would block the bypass.

Perhaps an interesting and/or prudent route, would be to have an oil analysis before and after. The results would be very interesting.
 
Thanks for all the input, guys. I'm just trying to get a feel for how much trash the filter can catch before the pressure delta hits the bypass setpoint. Hopefully there's time (and filter trash-catching capacity) while the filter pressure increases that I could hear some strange new noises and shut the engine off before the bypass opened. I used to run the PF-35 size filter, but with the lower positioned GenV/VI filter boss position, I'm using the shorter PF-25 filter due to clearance issues near the header collector.

Just trying to wrap my mind around this issue.

Thanks again for the input.
 
I believe these newer "fancy" K&N filters, Mobil1 and such advertize to filter smaller particles, think I read 10 microns ??? I would expect those filters to create a higher pressure delta once they trapped a lot of these small particles that would normally go thru a regular oil filter....
The bypass was needed when mineral oil was standard, 15W40 ???? Modern oil, especially synthetics are thin and don't build up sludge like the oil that was used in the 70's
I don't see a need for a bypass with good synthetic oil and 3000 mile oil change interval
 
Here are a couple of other tidbits you may find interesting.
The Fram HP1 filters and others that are considered racing filters use an element in the 60 micron range.
Many new setups including semi, military and marine expensive engines are using a bypass filter system. They usually filter only about 10% of the oil at a time, but do so down to a 2-5 micron level.
Companies like Cummins, Caterpillar and John Deere have done extensive studies of over 100,000 miles and have had results of anywhere from 60 to 80% less wear on engine components.
I'm not suggesting one be installed, but it is proof that good filtration does make a big difference.

BTW Advance has a sale on now for 5 qts of Mobil1 and a Mobil1 filter for 34 bucks. I normally don't buy the expensive Mobil1 filters, but this is a decent deal.
 
BTW Advance has a sale on now for 5 qts of Mobil1 and a Mobil1 filter for 34 bucks. I normally don't buy the expensive Mobil1 filters, but this is a decent deal.

It's not a bad deal but be prepared they might be sold out..... AutoZone does price match and they're often next door to Advance....
 
BTW Advance has a sale on now for 5 qts of Mobil1 and a Mobil1 filter for 34 bucks. I normally don't buy the expensive Mobil1 filters, but this is a decent deal.

It's not a bad deal but be prepared they might be sold out..... AutoZone does price match and they're often next door to Advance....

Thanks.
Got some yesterday
Got 4 of them within a 3 mile radius of me.
 
So, what's your thoughts on plugging the bypass?

thanks,
Mike

I think that's one of the most ill advised dumb stupid things you can do as a mod on an engine. The oil is constantly being filtered. What is the impact of not filtering for a few minutes from time to time. Nothing.

Blocking the bypass and potentially starving the lubrication system will destroy the engine in seconds or minutes.

The bright side is, if you block the bypass, the filter will definitely catch all the material you created by starving bearings for oil
 
Last edited:
So, what's your thoughts on plugging the bypass?

thanks,
Mike

I think that's one of the most ill advised dumb stupid things you can do as a mod on an engine. The oil is constantly being filtered. What is the impact of not filtering for a few minutes from time to time. Nothing.

Blocking the bypass and potentially starving the lubrication system will destroy the engine in seconds or minutes.

The bright side is, if you block the bypass, the filter will definitely catch all the material you created by starving bearings for oil

:rofl::rofl::banghead::ill::gurney:
 
So, what's your thoughts on plugging the bypass?

thanks,
Mike

I think that's one of the most ill advised dumb stupid things you can do as a mod on an engine. The oil is constantly being filtered. Only partially, if the bypass is open. What is the impact of not filtering for a few minutes from time to time. Nothing. Only if it's "clean" oil that's not being filtered. If it's not clean, it's a whole different outcome. Blocking the bypass and potentially starving the lubrication system will destroy the engine in seconds or minutes.
Yeah, but a bunch of trash going through the bypass will destroy the engine too. The bright side is, if you block the bypass, the filter will definitely catch all the material you created by starving bearings for oil

You're missing my point. If the bypass spring rate is only minimally higher than the pressure drop across the filter then it doesn't take much trash to bump up the pressure drop across the filter to the point of opening the bypass, allowing all sorts of debris to contaminate the whole engine. So, a working bypass doesn't save the engine. I'm trying to figure out if I gain any time before the engine is damaged by filtering all the oil before the filter is completely clogged. It should take some finite amount of time longer to plug up the filter completely than it takes to partially plug it up and cause the bypass to open. As I mentioned earlier, I'm trying to figure out if I gain any time (perhaps seconds, just long enough for me to push the clutch in and shut off the ignition) with a plugged bypass. This issue is only of reasonable interest to me because of track day activities. This isn't an issue for normal street driving.
 
If there is enough dirt in there to plug the filter it's likely going to burst, especially with a high pressure pump...
Let's assume your dizzy gear is being chewed up... Eventually this stuff ends up in the filter - with a bypass it gets distributed throughout the engine, without a bypass it cloggs up the filter which then bursts and the stuff is again going thru the engine.... Can't win .... :smash:
 
I eliminate the bypass on my engines and use System 1 burst proof filters. There is no way you can accumulate so much trash that you will clog one up, if you do you have engine troubles that no bypass could ever fix or eliminate. I don't like dirty oil going through my bearings on every cold startup. On a typical SBC spin on adapter the differential pressure to open the bypass is about 10-15 lbs and cold thick oil through a crappy paper filter will easily open that thing. I wouldn't be surprised if some of them open at a lot lower rating. You can easily check it on a small scale and check how much it takes to push it open. I would assume the same range for a BBC

Now think about this, what if the thing is open because of thick oil and some trash gets in there and the bypass sticks open?

Just run a good filter, a wix or something like that..not some el cheapo junk. IF your engine starts making a coil startup noise or a slow oil pressure buildup with the bypass eliminated it's not the bypass that is the problem but your dilter, it's not flowing properly and the bypass was probably open all the time to allow for proper pressure but no filtration. Just say no to unfiltered oil in your engine :D
 
Glen 64 runs a bypass plug with full filtration and has never had an issue.
I have never messed with changing the stock unit, and have never had an issue.
I would suspect the GM engineers had their reasons, so I have left it alone.
 
So, what's your thoughts on plugging the bypass?

thanks,
Mike

I think that's one of the most ill advised dumb stupid things you can do as a mod on an engine. The oil is constantly being filtered. What is the impact of not filtering for a few minutes from time to time. Nothing.

Blocking the bypass and potentially starving the lubrication system will destroy the engine in seconds or minutes.

The bright side is, if you block the bypass, the filter will definitely catch all the material you created by starving bearings for oil

37 years now been building performance engines and I have been plugging the bypasses all these years on all my circle track engines and street and strip engines and so far never starved a bearing of oil by doing this.

Hell my dry sump engines run no bypass and the bearings always look good HMMMM

I have one 2 barrel circle track engine that has been runing 10 years now with out being refreashened and it won another championship this past year and no bearing issues that I know of,

Using HV pumps and heavier oils and junk filters the bypass is pretty much open all the time,

At least once a year I get a call from the track telling me there engine only has appox. 30 pounds of oil pressure HMMM I always say take the orange filter off put a 1061 NAPA gold filter on and call me back and its amazing going to a good filter oil pressure is back to 60 pounds again.

Summary with junk filters that can not support oil flow the bypass is wide open all the time and these engines only have a standard volume pump and junk filters will not support the oil flow

Mike 38 years now and I have not starved a bearing yet!!How long does this take to happen????????????????????????????????????

I have some cranks 18 years old and look like the cam out the box !!!!

I have seen to many engines come in the shop with the bypass not plugged that have had dist. gears fail and cam lobes and lifters fail and all the junk went through the bearings HMMMMMM

Its interesting they sell filter adaptors with no bypass in them HMMMMM
 
Top