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billybobbooth

oil pressure and flow gpm

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does anyone have any idea what psi before pump relieve valve a national or rn 2 cylinder runs at? I know its over or around 80-100psi

 

also anyone know how much oil the pump flows roughly? in gpm? the sump holds 10-15L so 2.2 - 3.2 gallons. I'm guessing around 0.5-1gpm maybe?

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The National book says set to 12-15psi if I remember rightly. .Your 80 to 100 is way too much- do you have problems with oil leaks? I have yet to find an old diesel of any make that uses much above 40 psi and old Kelvins don't have  or need  any oil pressure!

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On 31/12/2018 at 17:04, billh said:

The National book says set to 12-15psi if I remember rightly. .Your 80 to 100 is way too much- do you have problems with oil leaks? I have yet to find an old diesel of any make that uses much above 40 psi and old Kelvins don't have  or need  any oil pressure!

my oil pressure is about 35 but i use to have very poor oil pressure due to ever gap blocked, by mistake once I didn't realise the oil relief valve was in the original filter and when took this off it was over 80psi but I'm more worried about the if the valve fails the paper filters will give up and get into the oil ways so I'm going onto spin on filter but wasn't sure what these pumps can put out oil flow wise. I know the pressure comes from the bearings but didn't know what these pumps can handle as im planning on getting a filter with safety valve fitted.

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The filter or the filter head contains a bypass valve not an oil pressure relieve valve, they are different.

This opens in the event of the filter becoming so blocked that it will not pass oil, very rare. Only occurs if the oil is incredibly dirty.

So it cannot blow the filter material into the oil ways.

 

Oil pressure relief valve is in the main oil gallery feed and prevents the pump from over pressurising the oil filter case.

 

We had Ford Transits blowing up their oil canisters due to the pressure relief valve in the oil pump sticking closed. Its the only instance of this that I have ever known.

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If its a Vokes filter ,the design allows the element to lift against spring pressure if the paper blocks............with modern detergent oil ,the chance of the element blocking is low,but cold oil also lifts the fllter until the oil warms up..............i had a Mack truck once had over 100lb pressure cold,oil would force out between the head and block from the rocker oilways......Mack cured the problem by changing the filter design to include an extra relief valve..........most automotive pumps will pump 300psi easily,without mechanical failure.

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Is this a replaceable pleated paper element in a removable can with a spring and large washer in the base?

If so the spring is the bypass (blocked filter) valve, the excessive pressure across the filter forces it down against the spring till the top of the element comes away from the filter head.

Canister filters have the same arrangement built in.  This illustration has the oil flow in the wrong direction!

 

129_1202_10+filter_fodder+filter_cutaway.jpg

Edited by Boater Sam
added more

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I don't think references to Ford Transits and Mack trucks are relevant to  the circa 80 year old National engine fitted  in Towy. Talk of canister oil filters is over complicating matters. In my opinion what BB  needs to do is to is dismantle and clean all the  original lubrication system, fresh sae30's oil in, adjust the pressure  on the gauge to the figure I quoted and go and worry about something else on his nice  old wooden boat.

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Its still oil is it not? Since when on here has a post to be completely relevant?

I was only explaining.

Another ignored.

  • Greenie 1

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4 hours ago, Boater Sam said:

Its still oil is it not? Since when on here has a post to be completely relevant?

I was only explaining.

Another ignored.

BB also said in one of his posts that he intends to switch to a cartridge filter, so entirely relevant. 

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my current set up has oil pump - filter - relief / bypass valve (excess pressure goes back to sump)

 

the filter is currently a paper filter in a old purolator canister. I'm looking into changing this to a spin on filter with no built in valve but the the housing to have a valve it. it will also have a back pressure warning so if the filter gets too blocked it will indicate a filter change required as it will be a 7 micron filter not a typical 10 or 25 micron. I would rather change the filter regually than not + it gets grease in the oil due to some of the lubricating points.

 

my problem is a I don't know what my oil pump can put out gpm or lpm. I also don't know what pressure the pump can handle if the relief / bypass after the filter fails this would cause there to be atleast 80+ psi in the line yes meaning 0 for the oil is being bypassed back into the sump. what I don't want to happen if this fails is for the filter to crush or give up and leak and then 0 oil gets to the engine I would rather all oil got to engine at higher psi than none. so I wanna put in a filter and housing and pipes that can deal with this but not have to spend £££ on a 1500 bar system as it will never get that high.

 

most people don't worry but at £18k for a new replacement engine of same type or close to that to put in an appropriate engine I would rather be over engineered that cause catastrophic damage. the worst over oil pressure will do is cause oil leaks or pos wear a bearing more due to the rampage not score and destroy everything.

 

I have a 0 compression leaver so a runaway is easy to solve by killing compression unlike some engines that only lower it.

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You cant stop some engines from doing bigends.......I rebuilt a E6 Russel Newberry, several times........Last time the engine was fitted with every kind of alarm,  failsafe ,shutdown,extra filter,you name name it,and still one of the big bronze bigends smashed off the side plate....and each time it went ,a freezer full of prawns was lost.......................however,back to the canal............I would suggest you fit a custom made adaptor to take a Perkins 2654407 spin on .....these have the very common 3/4"x16tpi mount that is fairly standard in the industry...used by Perkins,Ford ,Toyota ,etc......chances of a relief valve sticking shut are remote with the use of series 3 detergent oils..............all you need is a low oil pressure shutdown/alarm.,,,,,,,,,,,,,,if you want to run the motor hours on end unattended,then a shutdown is essential......a combined fuel shutoff with low oil pressure,,high coolant temp,and maybe coolant level too ................finally ,if the oil does tend to get dirty quickly,I would suspect a coolant leak.

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If you want a simple way of fitting a filter,look into a Fleetguard LF 670 adaptor kit..............there are dozens of kits to fit this filter to just about anything,...............if you want to go the full belt and braces ,also fit a bypass filter as well ,like the Fleetguard LF750.

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well I fitted my new bit of kit, took a while to get lined up but got it on in the end pumped oil round, fired up well 2nd attempt 1st was a pitafull attempt. and intresting ive got between 3-4.5bar of back pressure on the system 3 at idle and 4.5 on higher rpm this was same after 5-10 mins of running so oil didn't get warm this is also with a 7 micron filter as i want to get rid of as many bits as pos before I do my oil change ill then run another 7 micron for a few months on my run up to the port and then will go to a 10 or 25 micron filter.

 

intresting though is on idle even after 10 mins my oil pressure gauge for the engine was still around 20 ish psi and on higher rpm was around 35-40psi and not bouncing so my old oil filter was clearly too big a causing problems.

 

my only fear is the back pressure at the filter as the change filter pressure is 1.5 bar and I'm at 3-4.5 but hopefully this is just down to filter micron choice. but all in all my main oil pressure is up and far more stable...

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please bare in mind this was done with old oil reason I would rather throw away a £5-£10 filter in testing as i need to remove they system again fully fitting in place once happy there are no leaks or problems ill replace filter, clean sump and gearbox and replace oil. + I don't want new oil sitting in engine over winter as this is when it gets a coldest but b wettest in the engine room so gets more water mix than in summer.

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The backpressure due to cold oil cant be avoided..............you should consider that the internal relief valve in the filter is lifted and bypassing a large portion of the oil.................so the finer the element the more oil will bypass the element altogether..................no filtration of maybe 70% of the flow........................heavy ,low powered engines with large oil capacity take a long time to heat up,and until the oil is around 70C,the filter isnt effective..............This is one reason most old engines used a strainer and a bypass filter........

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Apologies for delayed response. My National starts with a high pressure (maybe 40) and has been adjusted to gradually drop back to 12-15 psi when running.  In very hot weather when idling (e.g. in locks or going past moored boats) it sometimes drops a bit below that but I was told by a retired boatman that providing a National has 'some' oil pressure there is nothing to worry about!

 

Regards

 

David L

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Again Ive been absent for a few weeks, but having discussed with several well known RN engineers and dave at the "factory"...  when cold getting 60-80 il/sq in is norm but as it warms it drops to the 15psi (give or take)   and runs like that when warm all day...

 

As important is too use a good sae 30 oil,,  and check the oil level every morning before starting ad top up sump if required...

most weeks when on trips, i spend a couple of mimutes checking oil pipes are all tight and secure..

 

 

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1 hour ago, Strads said:

Again Ive been absent for a few weeks, but having discussed with several well known RN engineers and dave at the "factory"...  when cold getting 60-80 il/sq in is norm but as it warms it drops to the 15psi (give or take)   and runs like that when warm all day...

 

As important is too use a good sae 30 oil,,  and check the oil level every morning before starting ad top up sump if required...

most weeks when on trips, i spend a couple of mimutes checking oil pipes are all tight and secure..

 

 

this is fine then as is about what I'm running after all the work ive done it sits between 10 -15 psi closer to 15psi, yes oil checked reg but sence ive stopped oil the oil leaks and got rid of the breather I no longer loose oil and the little I do burn gets put back in by the rockers

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