Automatic Low Oil Pressure engine shutdown - SailNet Community
 
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post #1 of Old 05-15-2009 Thread Starter
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Automatic Low Oil Pressure engine shutdown

Hi everyone

This is a circuit I´ve came up with as a possible retrofit to all 4 stroke engines and wich I designed to a friend who asked me for an automatic shutdown circuit in case of an oil pressure drop.

Opinions on improvements are, of course, welcome




Regards

Pedro

Portugal


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post #2 of Old 05-15-2009
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I am not a fan of such things because a circuit problem such as pressure switch failure could prevent you from running the engine even if it's fine. And Murphy's Law says this will happen at the worst time. Automobile engines don't have such circuits. How many auto engines do you know of that have been destroyed by a sudden loss of oil pressure?
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post #3 of Old 05-15-2009 Thread Starter
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Quote:
Originally Posted by JimsCAL View Post
I am not a fan of such things because a circuit problem such as pressure switch failure could prevent you from running the engine even if it's fine. And Murphy's Law says this will happen at the worst time. Automobile engines don't have such circuits. How many auto engines do you know of that have been destroyed by a sudden loss of oil pressure?
1st- It wouldn´t prevent you from running the engine at all: It has a bypass switch...

2nd- How many fellow sailors do you know who had to use an epirp? or a life raft? that doesn´t mean you shouldn´t have one

Besides that, autos don´t come equipped with such a feature because of three things in my opinion:

-Cost saving (some cars don´t even have a temperature gauge. isnt´this one usefull either?)

-While one is driving the dashboard and the respective low press warning light is always in front of your eyes. In a boat that seldom happens..

-A crippled engine in a car is never potentially as dangerous as in a boat...

Anyway, thanks for the comments...

Regards

Pedro

Pedro

Portugal


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Last edited by pedcab; 05-15-2009 at 10:29 AM.
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post #4 of Old 05-15-2009
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Pedcab's point about the engine being a bit more critical in a sailboat than it is in a car is a fairly valid one... with a car, if the engine dies, you don't go anywhere.. so you're relatively safe, provided no one runs into you. That is not the case with a boat. Then again, an anchor is an important, but often overlooked, piece of safety gear.

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post #5 of Old 05-16-2009
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Quote:
Originally Posted by pedcab View Post
Hi everyone

This is a circuit I´ve came up with as a possible retrofit to all 4 stroke engines and wich I designed to a friend who asked me for an automatic shutdown circuit in case of an oil pressure drop.

Opinions on improvements are, of course, welcome


[snip]

Regards
I like it.

I would probably change U1 out for a small PIC processor to give more control over behavior (maybe not just length of delay but also watch the start signal), but then I'd have to amp up the PIC's output pin to power the relay coil which is another component.

What are you pretending not to know ?

Please support my
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Last edited by wind_magic; 05-16-2009 at 01:07 AM. Reason: sp
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post #6 of Old 03-23-2011
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I have a full "watch dog" shut down system on my 53 hp diesel.
It has a bypass switch you use to start the engine. This ensures that the bypass is tested every time you use the engine.
The watch dog will pull the injector solonoid to off if the engine tempreture is too high or the oil pressure drops.
An engine stopping is a very good indicator !! It takes a split second to flick the bypass and restart in an absolute emergency.
In practice this situation is not going to happen very often.
Safe drifting or anchoring until you sort the problem, get help, or go to plan B !!
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post #7 of Old 03-23-2011
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ummmm thats federally mandated for all gasoline powered cars and trucks with electric fuel pumps and EFI systems, etc. in the USA and has been so since the late ~70s or early 80s.
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