Member Since: 21 Oct 2016
Location: wiltshire
Posts: 38
Help - no oil pressure new pump
Hi everyone,
Having just finished my engine swap (came from an S Type jag)
I have no oil pressure. I've swapped the sumps over and I fitted a new oil pick up pipe, gaskets, seals,new oil pump from Citroen, Water pump, glow plugs, gates cambelt kit. I've used castrol oil, fram oil filter.
Now while cranking the oil light didn't go out. Repeated this a few times without the engine starting. Concerned but realising the oil has a way travel and voids to fill I allowed the engine to start for a couple of seconds, still the oil pressure light didn't go out.
I've removed the filter (bone dry) and the pressure switch and cranked it over. Briefly started and I switched it off. No oil at all!
Now, what should I do?
I can't remember if the new oil pump had blanking plugs in it, thus not picking the oil up. Surely I'd of saw it?
Do I need to prime it somehow?
Any ideas are welcome!
Thanks
12th Jan 2017 9:26 pm
Disco_Mikey
Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20727
It takes a good 7-8 seconds of running for the pressure light to go out after a new pump/engine replacement
The OEM pumps do not come with any blanking plugs in the ports, so this can be ruled out
Nothing to say you dont have a faulty pump, but I have had no issues with the OEM pumps...My D3 Build Thread
Member Since: 21 Oct 2016
Location: wiltshire
Posts: 38
That's reassuring to hear Mikey!
Tomorrow I'll let it start and idle for maybe 10 seconds max? Then if no oil pressure still I'll have to investigate further?
Someone mentioned before about removing the Allen key in the top of the pump to fill it with oil?
12th Jan 2017 9:46 pm
Biffysun
Member Since: 09 Jul 2011
Location: Central
Posts: 1787
If you can it wouldn't do any harm to get a 'lick' of oil on a new pump and help prime it
12th Jan 2017 9:48 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Worth remembering that the oil pump does not produce oil pressure - it provides a flow of oil to counteract gravity. Oil pressure is produced by the engine internals and the tight clearances between components.Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20727
The_Bay wrote:
That's reassuring to hear Mikey!
Tomorrow I'll let it start and idle for maybe 10 seconds max? Then if no oil pressure still I'll have to investigate further?
Someone mentioned before about removing the Allen key in the top of the pump to fill it with oil?
They are threadlocked in, and can be ridiculously tight
I'd start it and let it run for 10 secs. It should go out sooner than that though My D3 Build Thread
Member Since: 15 Jan 2016
Location: GL
Posts: 10360
Yeah took mine about 10 seconds.
You just have to be really brave unless it's making a bad noise.
Keep starting and stopping it really don't help!
12th Jan 2017 9:59 pm
The_Bay
Member Since: 21 Oct 2016
Location: wiltshire
Posts: 38
Thanks guys! I'll give it another go after work tomorrow night. I'll let you know how I get on.
12th Jan 2017 10:49 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8069
If you oiled the crank bearings and cam shafts when assembling, it will not do any harm, can be a bit nerving waiting for the light to go out, do not be tempted to unplug the injectors and crank the engine over It can when others can't,
It will when others won't,
It goes where others don't.
12th Jan 2017 11:01 pm
The_Bay
Member Since: 21 Oct 2016
Location: wiltshire
Posts: 38
Good and bad news!
After 6 long seconds of tapping the oil light extinguished.
Great runs lovely!
Bad news is the front crank oil seal is leaking. I must of caught us putting it in. It is a genuine seal.
I've read there's a tool for installing them. Where can I get one and how much is it?
Thanks, Barney
13th Jan 2017 7:58 pm
rrhool
Member Since: 28 Aug 2014
Location: Norfolk
Posts: 4399
Robbie wrote:
Worth remembering that the oil pump does not produce oil pressure - it provides a flow of oil to counteract gravity. Oil pressure is produced by the engine internals and the tight clearances between components.
I'm not sure that's correct Robbie. The pump does produce pressure, and it is regulated by the pressure relief valve within the pump.
Richard
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13th Jan 2017 8:15 pm
Disco_Mikey
Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20727
Any pump only creates flow. Pressure is created by resistance to flow. If the pressure increases too much, a pressure relief valve opens My D3 Build Thread
Member Since: 23 Aug 2015
Location: nairobi
Posts: 286
only by pure physics, how can you create flow without pressure? these two things are happening together and one is relative to the other, as in any pump.
pumps move a liquid (or a gas)...
the actual pressure is created by a resistance or inability of flow....the greater the resistance the greater the pressure - Marine Engineers term this "back pressure"...
if the pump is operated with a flooded suction (it doesn't have to lift the fluid) & discharges to the same reservoir a pressure gauge in the discharge or out port of the pump will register zero or a very small value.
Couple the pump to an engines oil system this is the restriction or resistance will increase the pressure which will also vary with the viscosity of the oil or fluid (which in itself varies with temperature)
So a worn engine will have a lower pressure...
Pumps also come in various types basically these can be spilt into two types positive displacement & centrifugal.....vehicle oil pumps are positive displacement they have the ability given restriction of an engines oil system to generate a pressure that ensure the oil lubricant gets to all the places it should.
A centrifugal pump (used for other duties) wouldn't do that, it would generate a pressure even if the discharge was closed off, these are used for circulating fluids (e.g. the engine coolant pump in a vehicle)
Most pumps need to be "primed" (have some oil fed in on assembly or connection) some can draw a liquid from the reservoir to the pump suction by them selves...these are positive displacement pumps....aka an engines oil pump
A worn positive displacement pump (like in an engine) won't (& can't) deliver the same output pressure, but it will take a (longer) number of engine / pump revolutions to establish a suction, prime itself & then deliver a positive pressure. The situation is the same every time the engine is started.....new engine / new pump & not new engine not new pump...the latter is different as the pump has residual oil in there from the last use...it establishes a flow & a pressure far more readily (dependant or the type / condition / temperature of the oil & the condition (wear / clearances) of the engine & pump.
An oil pressure relief valve limits & therefore controls the pressure when it gets to a value - it wouldn't & shouldn't affect the pressure being established - unless it was stuck or held open (highly unlikely). No way of checking this.
Pump technology has been (one of many) features of my working life - hydraulic systems when I was lad as an apprentice in machine tool building - right through being a marine engineer (all the types & sizes of pump you can get) right up to now working on industrial machinery ..... its handy to know & appreciate the pumps concept & technology (which is basic physics) to make & keep machinery operational. Not witch craft or black magic.
Vehicle engine oil pumps, quite simple positive displacement pumps, they do wear, do take a very short while to deliver on first use, do deliver a varying pressure.
The oil pressure ensures the oil gets to all the places it has to, in sufficient volume to keep the engines bearings healthy & unworn.
Cars used to be fitted with oil pressure gauges (& ammeters, & vacuum gauges & voltmeters)...here you could see the situation of establishing & varying pressures.....a simple on / off light doesn't give you the benefit of that data.....many vehicle users today just would look or appreciate a gauge - they live in the boolean world of on or off...good or not so good.BREXIT - done properly.
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14th Jan 2017 8:56 am
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
To add the automotive angle to the 'closed-circuit-pump-produces-no-pressure' description above, first consider what we are trying to do with that oil - namely keeping moving metal parts apart.
We can avoid delving too deep into hydrodynamic action if we think of the humble crankpin. The diameter of the bit of the connecting rod which connects to the crank is slightly larger than the diameter of the crankpin. As our goal is to keep the metal parts apart during the explosive action from above we introduce oil into the space.
Given a sufficiently powerful high-pressure oil system it would be possible to force the 2 metal surfaces apart throughout the cycle. But this would be inefficient as you would be working one powerful system against another whilst adding weight and mechanical complexity (other systems do use this method).
The other option - hydrodynamic action, uses the geometry and relative motion of the 2 parts to create a wedge-shaped void that is filled with oil, before being squeezed and compressed to the point of forcing the 2 metal surfaces apart. This is oil pressure in action in your engine.
Of course the downside of using geometry and mechanical action to produce oil pressure is that an increase in the relative clearances through wear will reduce the oil pressure and, ultimately, parts of the cycle will have metal-to-metal contact as the pressure will not be sufficient to keep the parts apart. This in-turn increases wear, reducing oil pressure further and the death-spiral begins.
The upside is that measuring oil pressure is arguably the best method of analysing engine health.
So let's hear your support for the often-overlooked oil pressure gauge. A cheap tool that can be screwed into your engine at every oil change to measure your engine health.
Land Rover - Turning Drivers into Mechanics Since 1948
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