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Quick and Easy Low Oil Pressure Light

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tvrgeek Avatar
tvrgeek Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
Forgot to mention. Many here do not trust electronics. This idea is only information. Failure does not cause you to break down. So "safe" electronics.



Cogito ergo sum periculoso

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MGB567 Avatar
MGB567 Gold Member Barrie Braxton
Sunshine Coast, Queensland, Australia   AUS
1966 MG MGB MkI "Money Guzzler"
1979 MG MGB GT V8 Conversion "Darkside"
In reply to # 3908896 by jseabolt Once again, hate to dig up old threads but before I asked and sounded like a typical newbie , I was curious what appears to be a low oil pressure switch at the junction tee but no low oil pressure light (that I can find) on my 77 model.

It's not one of the four lights between the speedometer and tach. I don't think it's built into the gauge.

So this switch is an anti-run on switch?

Now I think I understand better when you write "so this switch is an anti-run on switch". You mean on looking at your car you've discovered an anti-run on switch and Joe has replied "yes". You confused me by asking your question under the topic heading you did. I assumed you wanted to fit a low oil pressure warning light. That's what I did by fitting the A-R connector into my oil pressure line and substituting that A-R switch for a low pressure switch. Carry on.



Convertible: CKD 11/66 first registered 8/5/67. Owned since 3/77. 90% original sheet metal. 18GB +40 balanced with almost all new internals. Peter Burgess big valve fast road head. Piper 285. Fidanza FW. Basil's followers and pushrods. TR7clutch. TT exhaust. ARP everywhere. 123 ign. Needham 4synchro c/r box.. Stock rebuilt/replaced suspension. Superpro bushes. New brakes all round including all pipes in SS flex. Interior redone. CAMS approved roll bar and side bars. Lots more. Hybrid of o/e and show/fast road car. Not for sale - it's my toy!

GT: UK car built/sold December '78. Stripped back to bare shell with VW Golf flared guards, flush fit front and rear valances with front guards immovable. Front and rear seams removed,Torana XU1 vents, frenched indicators front & Mk1 rear lights. Powered by 'worked' Rover 5 litre V8 (ex TVR Chimaera) with efi. T5 box. FC IFS. CCE rear attached to Salisbury axle with Quaife. All new interior with MrMikes covers on MX5 seats. Retro4 7x15 rims (zero offset) and 205/55 rubber. Colour: Jaguar Storm. Not for sale - it's my sanity!

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converse212 Avatar
converse212 Eric Morgan
Atlanta, GA, USA   USA
1958 MG MGA
1970 MG MGB "Daily Driver"
1970 MG MGB GT "Rusty"
1971 MG MGB GT    & more
Well it’s been a while since I posted this, I had almost forgotten about it, since the car has gone to the great race track in the sky....

Sure enough, there wasn’t much point in having a switch that went on and off at such a low pressure. I do intend to do it again, but with a 20 psi switch. I think it serves a good purpose. I scan my gauges frequently, along with mirrors, but a nice bright light really gets your attention



Daily driving a '71 MGB

Resurrecting a '58 MGA

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riley1489 Avatar
riley1489 Gold Member Bruce H
Great White North, QC, Canada   CAN
1953 Jaguar XK120
1959 Riley 1.5 "King George"
1973 MG MGB
In reply to # 3909039 by jseabolt 1) BTW, I studied the the anti-run circuit on wiring diagram. I still can't figure out how this system works! How is that supposed to prevent the car from dieseling?

2) Is this one of those simple things that could leave you stranded if it failed? How can it be bypassed? Jumper wire, ground the wire that plugs into the switch?

3) I haven't seen a car run-on since the 1980s.

James,

1) Read the functionality of the anti-run-on valve circuit (below).

2) Your car does not use/need the anti-run-on valve, as you have a Weber downdraught carburetor where the float chamber vents to atmosphere.

3) Yup and all MGB were produced prior to the 80's! winking smiley

B



Check your ego Amigo!



Edited 1 time(s). Last edit at 2019-03-15 12:10 PM by riley1489.


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Wachtmans Avatar
Wachtmans Wouter Strodijk
OVERVEEN, Noord Holland, Netherlands   NLD
1974 MG MGB "The Bee"
1974 MG MGB "The Bee"
1974 MG MGB MkIII "The Bee"
One of those things you really don't need. Oil pressure gauge is enough for me.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
I was tired, driving home late one night 35 years ago... and one of my oil cooler lines blew. I was busy driving, watching out for deer etc. and I didn't notice that the very dimly lit oil pressure gauge was showing zero oil pressure. If a bright amber light had lit up on the dash I'm pretty sure I would have spotted it instantly... and saved the engine a rebuild I couldn't really afford at the time. I'm going to add a zero oil pressure warning light to my car. Cheap insurance for very little cost or effort.

I don't see any need for a 20 pound oil pressure warning... I have a gauge for that.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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57Coupe Avatar
57Coupe Andy Bloom
Grand River, Ohio, USA   USA
1957 MG MGA 1500 Coupe "1957 Coupe"
If you wait for a light to come on a -0- psi your too late. 15-20psi gives you a fighting chance on a street car. 20-25 on a race car is good insurance as things are happening at a higher rate than street driving.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3909315 by 57Coupe If you wait for a light to come on a -0- psi your too late. 15-20psi gives you a fighting chance on a street car. 20-25 on a race car is good insurance as things are happening at a higher rate than street driving.

I was tired, driving home late one night 35 years ago... and one of my oil cooler lines blew. I was busy driving, watching out for deer etc. and I didn't notice that the very dimly lit oil pressure gauge was showing zero oil pressure. If a bright amber light had lit up on the dash I'm pretty sure I would have spotted it instantly... and saved the engine a rebuild I couldn't really afford at the time.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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converse212 Avatar
converse212 Eric Morgan
Atlanta, GA, USA   USA
1958 MG MGA
1970 MG MGB "Daily Driver"
1970 MG MGB GT "Rusty"
1971 MG MGB GT    & more
In reply to # 3909316 by pinkyponk
In reply to # 3909315 by 57Coupe If you wait for a light to come on a -0- psi your too late. 15-20psi gives you a fighting chance on a street car. 20-25 on a race car is good insurance as things are happening at a higher rate than street driving.

I was tired, driving home late one night 35 years ago... and one of my oil cooler lines blew. I was busy driving, watching out for deer etc. and I didn't notice that the very dimly lit oil pressure gauge was showing zero oil pressure. If a bright amber light had lit up on the dash I'm pretty sure I would have spotted it instantly... and saved the engine a rebuild I couldn't really afford at the time.

Adrian

I think the problem with the zero oil pressure light is as Kenny said....if it’s really zero, the engine is gone. The light I had would still be off for say three to five seconds after shutdown. I haven’t been unfortunate enough to experience a catastrophic failure, but I imagine It isn’t an immediate drop to zero. Even your blown oil cooler hose would have allowed some pressure for some time I imagine....I think 20 is a good set point.



Daily driving a '71 MGB

Resurrecting a '58 MGA

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jseabolt Avatar
jseabolt James Seabolt
Mount Carmel, TN, USA   USA
1977 MG MGB
In reply to # 3909212 by riley1489
In reply to # 3909039 by jseabolt 1) BTW, I studied the the anti-run circuit on wiring diagram. I still can't figure out how this system works! How is that supposed to prevent the car from dieseling?

2) Is this one of those simple things that could leave you stranded if it failed? How can it be bypassed? Jumper wire, ground the wire that plugs into the switch?

3) I haven't seen a car run-on since the 1980s.

James,

1) Read the functionality of the anti-run-on valve circuit (below).

2) Your car does not use/need the anti-run-on valve, as you have a Weber downdraught carburetor where the float chamber vents to atmosphere.

3) Yup and all MGB were produced prior to the 80's! winking smiley

B

Thanks. The two switches (or what looks like switches) in the diagram confused me. So the first switch has been removed when mine was converted to a Weber?

I took a look when I got home and there is a single wire going to the oil pressure switch at the oil line junction. I'm going to see what would happen if I unplugged the wire with the engine running to see if the engine stopped running. If it does, I'll use ground the wire and see if it restarts. It if does restart, I'll just ground the wire. If nothing happens, just leave everything alone.



http://s222.photobucket.com/user/turbofiat/library/?sort=2&page=0

1977 MGB
1980 Fiat 124 Spider (turbo)
1987 Yugo (1500 turbo)
1981 Trabant 601
1987 Citroen 2CV
1968 Ford Fairlane 500

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jseabolt Avatar
jseabolt James Seabolt
Mount Carmel, TN, USA   USA
1977 MG MGB
If you are looking for an actual "zero" switch (normally open) here is one that is close enough:

http://www.partdeal.com/stewart-warner-hobbs-pressure-switch-1-psi-normally-open-2-terminal-78628.html

I've used these on my Fiat Spider's fuel injection and ignition system to do various things with the turbo produces 1 PSI. Like break the O2 signal to the ECU and ground the 5th pin on GM HEI module to retard the timing. And kick the AC compressor off.

They only come in NPT so an adapter would be needed.





http://s222.photobucket.com/user/turbofiat/library/?sort=2&page=0

1977 MGB
1980 Fiat 124 Spider (turbo)
1987 Yugo (1500 turbo)
1981 Trabant 601
1987 Citroen 2CV
1968 Ford Fairlane 500

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3909462 by converse212
In reply to # 3909316 by pinkyponk
In reply to # 3909315 by 57Coupe If you wait for a light to come on a -0- psi your too late. 15-20psi gives you a fighting chance on a street car. 20-25 on a race car is good insurance as things are happening at a higher rate than street driving.

I was tired, driving home late one night 35 years ago... and one of my oil cooler lines blew. I was busy driving, watching out for deer etc. and I didn't notice that the very dimly lit oil pressure gauge was showing zero oil pressure. If a bright amber light had lit up on the dash I'm pretty sure I would have spotted it instantly... and saved the engine a rebuild I couldn't really afford at the time.

Adrian

I think the problem with the zero oil pressure light is as Kenny said....if it’s really zero, the engine is gone. The light I had would still be off for say three to five seconds after shutdown. I haven’t been unfortunate enough to experience a catastrophic failure, but I imagine It isn’t an immediate drop to zero. Even your blown oil cooler hose would have allowed some pressure for some time I imagine....I think 20 is a good set point.

I see no harm in having a light come at at 20 psi or just below normal idle oil pressure. It will come on at zero psi too. thumbs up

I will say that if you blow an oil cooler line all the oil will in the sump will be pumped out in about 10 seconds at highway speed. The engine will be fine if you notice the problem quickly. I have no idea how long I drove with zero pressure... but probably longer than ten seconds.

So where can I get a 20psi oil pressure switch?

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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caribougone Avatar
caribougone Ben Nicoll
Quadra Island, BC, Canada   CAN
I wonder if a oil pressure switch for a Mini would fit? They look right, and I would be surprised if it didn't given BMC/BL's love for having similar parts on various cars.

This one from MiniMania is 22psi...
https://www.minimania.com/part/HPS1/Classic-Mini-Switch-22lb-Oil-Pressure

Or they have one adjustable up to 50psi...
https://www.minimania.com/part/C-GPS101/Classic-Mini-Oil-Pressure-Switch-15-50-Psi-Adjustable

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gofastandfalldown Avatar
gofastandfalldown Glen Horne
Edmonton, AB, Canada   CAN
1970 MG MGB MkII "Miss Pandora Moneypit"
Is it OK to drive around with 2 psi??? Then why put in a zero psi switch?

Alarms should always be set just outside the normal operating envelope. If your normal oil pressure range is 50 to 70 psi, then 45 psi switch would be about right. 20 would be the next best thing.

If you're worried about your furnace kicking out in the winter when you're not home, you would set the alarm callout dialer for 60 deg F, not 32 deg. By then it's too late.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3910507 by gofastandfalldown Is it OK to drive around with 2 psi??? Then why put in a zero psi switch?

Alarms should always be set just outside the normal operating envelope. If your normal oil pressure range is 50 to 70 psi, then 45 psi switch would be about right. 20 would be the next best thing.

If you're worried about your furnace kicking out in the winter when you're not home, you would set the alarm callout dialer for 60 deg F, not 32 deg. By then it's too late.

Normal range is 25 to 70. With a 45 psi switch the light would be on during normal operation.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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