🚀 go-pugleaf

In article <TWq09.102$El3.78159@sapphire.mtt.net>, levy_jeff@hotmail.com 
says...
>
>
>"John Harvey" <no_one@home.au> wrote in message
>news:pq44kuoa602ltm81ujh262avl7l6og4phd@4ax.com...
>> DaveC wrote:
>>
>> >Would like to have in my car a high coolant temperature alert and low 
oil
>> >pressure alert combined and automated. Coolant monitor input should have
>> >calibration ability for custom adjustment for each vehicle. Pressure can
>be
>> >simple zero volt input trigger (I think most oil pressure crises are the
>> >result of loss of pressure, not simply the lowering of this). Output
>could be
>> >either an audible alert or relay contacts to break ignition supply (or
>reduce
>> >the supply voltage so as to get your attention) or sound an alarm.
>> >
>> >Does such a thing exist?
>>
>> Yep, called Murphy Gauges.  Not available as temp/ pressure combined
>> AFAIK, but they're certainly available separately.
>>
>> They're gauges with adjustable switches which can be used to either
>> switch an alarm or shut down the engine at predetermined settings.
>> Commonly used on industrial engines, especially gen sets etc. which
>> operate unattended.
>
>Shutting down an automotive engine from a drop in oil pressure is very
>dangerous. Say you were going around a corner and you were low on oil, the
>oil pump sucks a glup of air, and you end up stuck in the middle of a huge
>interesction with a dead engine.

Right on. Besides, if the threshold for shutting down the engine was hitting 
zero oil pressure, as the OP wanted, damage has already been done. So there 
is no particular rush to kill the engine.

In fact, there are only 2 reasons for the oil pressure to hit zero. The 
first is if the oil pump shaft somehow breaks (basically impossible), and 
the second is if you are so low in  oil, that it momentarily sloshes away 
from the pump inlet. The latter is better addressed by paying attention to 
basic car maintenence, and keeping the oil level where it should be, rather 
than attempting to throw technology at the problem.

Otherwise, no amount of wear on the oil pump, or any other similar scenario, 
will result in a total loss of oil pressure.

Bob.