Oil Pressure Gauge or light?

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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Re: Oil Pressure Gauge or light?

Postby sunnybob » Sun Jan 21, 2018 6:28 pm

leswaller wrote:No, the principles of any pump rely on creating a lower pressure on the inlet side caused either by piston suction or gear rotation


I see but I presume there is a pressure of the oil moving. I'm going to add a pressure switch in the line. The inlet oil sucked by the pump is able to create a pressure detected by the switch or should I put it on the return?

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Re: Oil Pressure Gauge or light?

Postby shifter » Sun Jan 21, 2018 6:56 pm

My 500 twin wet sumps a bit over the winter lay up all I do is drain the crankcase of oil usually just over a pint check there is still a bit oil in the tank start the bike have a little run then top the tank to its level job done and no tap to forget about.
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Re: Oil Pressure Gauge or light?

Postby SPRIDDLER » Sun Jan 21, 2018 7:21 pm

Interesting! But to my non-physicist mind, since the oil tank is open to the atmosphere the pressure in the feed line will be largely atmospheric and governed by the 'head' of oil above the pump.
Surely, pressure is only created within the pump................?
If there was oil in the feed line at a greater pressure than atmospheric then the oil within it would be forced back up to the tank?
I poke badgers with spoons.

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Re: Oil Pressure Gauge or light?

Postby g80csp11 » Sun Jan 21, 2018 7:51 pm

most automotive oil pressure switches operate at about 3 -5 PSI, there is only a depression on the inlet to a oil pump when running and a vey small pressure from the head of oil
all switches if used would be in the pressure side and only work once pressure is developed , typically 30 - 60 PSI depending on oil type , speed of engine and temperature)

an engine in need of a rebuild could easily flicker the oil switch when idling

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Re: Oil Pressure Gauge or light?

Postby Mick D » Sun Jan 21, 2018 7:57 pm

Hi

The pressure will be higher in the return line, although only very marginally, not sure if it would be high enough to reliably trigger a switch.

Regards Mick

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Re: Oil Pressure Gauge or light?

Postby sunnybob » Sun Jan 21, 2018 8:05 pm

g80csp11 wrote:most automotive oil pressure switches operate at about 3 -5 PSI, there is only a depression on the inlet to a oil pump when running and a vey small pressure from the head of oil
all switches if used would be in the pressure side and only work once pressure is developed , typically 30 - 60 PSI depending on oil type , speed of engine and temperature)

an engine in need of a rebuild could easily flicker the oil switch when idling


You are saying the 30-60 PSI is only on the outlet pipe?

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Re: Oil Pressure Gauge or light?

Postby g80csp11 » Sun Jan 21, 2018 8:10 pm

pressure at oil filter from the pump to engine , return pressure much lower as its essentially a open pipe
think of the return like a garden hose , only any pressure when restricted

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Re: Oil Pressure Gauge or light?

Postby JEAN-NOEL » Tue Jan 23, 2018 5:08 pm

Hello,
On my G12 CSR I have fitted succesfully a Morgo Kit, with 100 PSI pressure gauge. But it is a late engine with discharge valve integrated in oïl pumps body. Perhaps not suitable for a G9 (some haven't discharge valve, and oïl pressure can reach 350 PSI with straight oïl 50). I use Castrol 20/50. At idle, cold, the pressure gauge reaches 80 PSI, and when hot about 50 PSI @ 3000 RPM. I can post a picture.
Cheers.
J.N.

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Re: Oil Pressure Gauge or light?

Postby sunnybob » Tue Jan 23, 2018 5:23 pm

Thank you for your replies and it seems there is no enough pressure on pipes from oil tank to engine and the other way around for a switch... :-(
Plan B is an electric switch on tap, but need to be home made as nobody sell it....
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Roberto

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Re: Oil Pressure Gauge or light?

Postby JEAN-NOEL » Tue Jan 23, 2018 8:29 pm

Hello Roberto,
"Anti sumping tap fitted with ignition cut out for AMC singles and twins" from Andew Dove. He advertises in Jampot Journal.
Personally I like oil pressure gauges, because in 50 years they allowed me to avoid the breakage of engines on: Alfa Romeo Giulietta Sprint 1300 1961, Porsche 911 E 1971, PIPER PA 28 161 "Warrior" 1978 ...
Kind regards. J.N.

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