Plug filter bypass?
 

Everyone agree? Should I remove the filter bypass in the remote adaptor (Mark 4, 7.4) and plug it? Nows the time.

For sure !!

What he said

But, if for some reason your filter becomes plugged, motor will not get any oil. And while on this subject, will a filter alone flow enough cold oil until oil is warmed up? I gotta believe that GM and Merc have alot more testing involved and at stake on this item.
enlighten me.

I am running mine just the way it was from Merc. My crazy theory is that Merc knew what they were doing and a good flowing 10w40 oil will easily make it through the filter and cooler with minimal pressure drop if the lines are sized properly. Most boat guys change their oil and filter long before it is plugged with dirt. If you plan on running straight 50 wt. it may be a good idea to plug the bypass.

US1
If the oil bypass pressure is reached the engine will still get oil, but the filter and oil cooler will be bypassed. The bypass is to protect you from blowing the filter if it gets plugged. I believe it is set at around 15 PSI and from my hydraulics engineering days I am here to tell you that 15 PSI would be a pretty dirty filter and/or way to many 90 degree fittings. Bottom line is I really don't think you will ever notice a difference either way. Just my 02.

Not sure I am the one to enlighten you as you have a very good point. GM and Merc have to worry about idiots tha refuse to warm up there motors and warranty though. I have been running plugged by-pass for many years. YOU MUST GET SOME HEAT in the oil before runniing hard if you plug the by-pass. You should anyway! I have never had an oil related problem. I like ALL my oil filtered. There are others on the board with way more expertise than I have but that is just my opinion. :)

What would you gain by doing this?

Heres a quote form Merc's Manual 90-14499-1 887. Page 3B-68
"IMPORTANT. Production-performance engines do not use an oil filter by-pass valve. On these engines, by-pass valve is removed from the adaptor and oil by-pass hole is welded shut. Do not install an adaptor with a by-pass valve incorporated as inadequate oil filtration will result."

No don't plug it...
 

There is a big misconception about the oil filter bypass. Most people believe that it opens at 15 pounds of pressure. It doesn't, it opens when the pressure difference is 15 pounds. In other words, when there is 15 pounds of restriction in the filter.

If the engine has 50 pounds of oil pressure going into the filter, the bypass wouldn't open until the pressure coming out of the filter dropped to less than 35 pounds. The bypass seldom opens and bypasses the filter.

I wouldn't trust Mercruisers expertise on this matter, every Merc HP engine I have ever worked on has the oil filter bypass, I don't care what the manual says! (plenty of errors in those manuals!)

Leave it in there!
Sincerely
Dennis Moore

I hear ya, but, with the thermostat, oil cooler, hoses to the remote filter, and the filter, I wouldnt be surprised if there is a 15lb drop through all that stuff, especially when the oil is cold. Lets rephrase that question. Assuming I change oil filters frequently, which I do, would there be any downside to plugging the relief valve. Especially considering the pump has its own relief valve.

You should use a high pressure filter that has extra capacity if you plug it. I know K & N makes one. I have always left the stock Merc set up as is with no problems. It is really whatever you want to do.;)

The conscern as I see it, is not relieveing access pressure, which is what you are stating above. The thing is, that if you plug the bypass valve and then by some wild chance have a filter get plugged, you now have a motor with no oil flow. My guess is that is a bad thing. :) Sure, your pump is still pumping away, but not moving any oil. It has no where to go. Just spinning it's tires.



My HP motor had the bypass valve. So wouldn't put to much merit in the Merc brochures. Many errors in them.


Recall GregP's oil filter troubles?.............. where a small amount of water got into his oil and swelled the filter elements shut, starved the motors of oil. Not only 1 time, but more.

The Question is:
Do you have more to gain, or more to loose by eliminating the valve? It's there for a reason.

Keep in mind, you are working with a marine motor. Not many of these are operated in dusty conditions, so why the thinking that all the oil needs to be filtered?


You mentioned this is a 7.4 , I'm assuming not some 800 hp motor. Why change a proven thing?

It's your dime.
Don't you hate it when you ask a question in hopes of getting an answer, only to have it create more questions? ;)

hehe yea, its not a 7.4 any more, just the adaptor. oh well, Im gonna plug it for break in and then put the relief back in after 20 hrs or so, I figure thats the best of both worlds. I filter out all the breakin crap and any left over garbage from the rebuild and then back to the relief for safety.

I had a problem with high oil temps. We assumed that the oil was taking the least restrictive passage, which was through the bypass and not going throught the remote oil filter, oil cooler, and oil thermostat. I was kinda of second guessing the idea of doing away with the bypass, so I called and talked to tyler crockett and he said on most of his motor's he build's, they plug the bypass and run high burst filters. So I welded up the bypass in my stock merc unit and run a fram HP4 filter now.. My oil temps are alot better now, plus the engine will never get unfiltered oil now.. Plus I change oil every 15 hrs, So a plugged filter is a think of the past. If anybody gets a plugged filter in this short of time, you have alot more to worry about then oil pressure. I know if the filter plugs up it will not get any oil pressure, just gotta watch the gauges and keep on top of things.

Just my experience but ... I had a rash of oil filter problems due to the condensation moisture causing the filters to stop flowing completely. I would have 75 psi going into the filter housing and 0 psi coming out (since I have no pypass). ALL paper element filts that I tried did the same thing.

I personally am certain that almost all marine motor oil filters stop filtering long before you would ever expect and run all your oil through the bypass, as with the very low engine op temps you do get condensation buildup which kills the filters very quickly (my record minimum time on a filter before failure was was 10 minutes at idle on the first start of the season).

There are two known solutions to this problem. One is run only synthetic media filters, ie Wix Racing. The other, which I use, is run cleanable filters (I am using System 1 units).

Prior to switching to the System 1 filters I had filter shut-downs with AC filters, FRAM filters and K&N filters. Since switching to the System1 filters I have had no problems, have seen not signs of moisture in the filters when cleaned (although I still see some condensation evidence if the motors aren't run hard enough and long enough to get the oil temp over 200* for at least 10 minutes).

The system 1 filters do have an internal bypass, but my assessment from checking the media and feeling the pressure needed to open the bypass (which is much more than a stock GM filter adapter bypass) is that the filters have porobably never used their internal bypass.

And I have not had one suddden, total loss of oil pressure on the "out" side gauge since.

my $0.02 - Greg

GregP,
If a majority of the filters stop filtering before they are changed and are operating in bypass, wouldn't the oil temps increase? I have my temp sender in the pan and have never seen an oil temp increase even right before a oil and filter change. As a matter of fact I randomly check the oil cooler for heat and it is located after my filter in the flow path and it is always warm from the passing oil. Running properly sized lines and fittings makes a huge difference with flow capacity. Also this is another reason to stay away from 50 WT oil. There aren't to many on the board from my experience who need more than 10W30 or 10W40 wt. oil.
The filter I run is a Fram PH8A and Amsoil 10W40 Synthetic, all -10 oil lines with no sharp 90 degree fittings. Something else to ponder is that some filters have a built in bypass. Right??

Alot of good thought here from travis ect. ,,, please think about
just looseing a lifter roller !! once something this small happens the bypass will stop the filter from working and their goes your bearings ect. ,,,unless the bypass is pluged then your safer ,tons safer .
Everyone I know uses a super good oil filter so that or not changing oil should not be a problem as we all take care of our motors,if not we would not be worried about the bypass !!!!!!

But just to take care of your motor WARM THAT OIL ,and block the bypass !!!!!:D :D :D
THIS IS REAL WORLD ;) ;)

My coolers are in the bellhousing so I can't check them for heat. I do have gauges on both inlet (mechanical for checking pressure while in the engine bay) and outlet (electric for the dash reaout) side of the filters so I could easily see where the pressure went away and flow stopped. In normal use there is a 10-15 psi drop across the papers filters (when not stopped completely that is), the System 1 filters show 5-10 psi drop across the filter housing. The amount of water required to stop the filter element from passing oil was low enough that even cutting the elements open you could not "see" any moisture, let alone any "milk".

As to filters with an internal bypass, "GM" application filters usually don't, many "Ford" application filters do. Don't know where Mopar apps are.

-Greg

Ah Geez, do you think just once I could ask a question that had a clear cut answer? I suppose then I wouldnt be asking huh?

I've had alot of experance with this in racing and I would block or not use it at all on anything I care about

I dug this up out of the ancient history archieves. Am at the same point you were Formula31 with to plug or not to plug. How did you make out? I have oil temp problems in both engines with the only thing not being changed is this bypass. I've even changes engines and still have oil temp problems. I am planning to tap in a 1/4" pipe plug before reinstalling the current engine that lost its main bearings. My automotive machinist says plug the valve. What is the prefered way of plugging this valve off?

BT :cool:

Please plug it ,it will save the motor in the long run
p.m.me I will tell you how if needed

Seems if you leave it alone and had a blockage that would cause it to bypass you would see it in the oil temps. and shut it down when YOU are ready and find the problem but you would still be able to have the use of the motor and if you were in a bad real world spot like a real bad storm or lets say you are right in the way of a real big ship and the filter lets go because it does not have a bypass you my friend are now at the mercy of the sea.Ok lets say that the bypass is blocked off and you make sure that the filter you are running has a bypass in it and it goes into bypass you might not know because the oil temps won't change and there might not be much of an oil pressure change on your gage so now you are running unfiltered oil and you don't know it and if you don't know it it seem like you could be running that way till your next oil and filter change and good by motor for sure. What Dennis Moore says leave it :cool:

Have to vote with Bobby on this one guys. I have ran boat motors with by-pass plugged for many years now. Never had a problem blowing or plugging a filter. I always use a quality filter and like everyone here change it often. I would be more worried about by-passing when not needed then something plugging up. Just my .02. :)

I run a pluged adapter on my Burb with no problems. My only sugjestion is use a filter with LOTS of volume. The bigger the better I like the AC-Delco 2 quart jobie on the Burb. Rag's