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Discussion Starter #1
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
 

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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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Discussion Starter #3 (Edited)
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
 

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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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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.
 

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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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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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