Audiable Oil Pressure Alarm

Hi Ross, yes that's correct its the oil switch which is connected to the dash light. A audible alarm will be better than a light although when the low oil pressure light comes on it probably is too late to avoid some damage. Doesn't seem to be much in the way of sophisticated oil pressure protection systems around other than the one by Murphy which looks at engine revs and alarms after recognising engine speed, that is it realises at idle oil pressure will be low and has a alarm point for idle and another for working speed.

The sender wire on my TDI 4.2 is short and not easy to work on although not impossible but sourcing the wire behind the dash is a attractive option but working out which wire is the issue.

Cheers Peter

Just a thought ,maybe there is another port on the motor that could be used for another simple oil light switch and then conncet this to my alarm ?

I would still be interested in what other options are available in regard to oil pressure alarms ?

THanks Peter

Peter,
the murphy gauge looks at anything you set it to. It is a very simple system where you can adjust the trigger needle to your requirements.

I set mine for 20psi as the low end pressure hot and idling was 25psi.

I had it set to set off both a piezo alarm and flashing led.

Also had a murphy temp alarm set to warn at 100c.

Here are the gauges set in the aux fuel pod.

Hi, I assume you must get a oil alarm on start up until the oil pressure comes up each time. What is your oil pressure when running at 100kph ?, I was thinking 0 to 80 psi guage would be suitable..............Peter

Peter,
that is correct the alarm runs until you have pressure. It could annoy some but it never worried me as it is about 8 seconds from glowing the engine to pressure. After that about 2 seconds with no glow. You could put a small spring return push button switch in stop the alarm until you have reached pressure.

All engines are different and my 6.5l chev engine would get to 65 psi cold until the pressure relief valve cut in. The 1 HZ engines go higher than that though and I don't know about Nissan engine oil pressure. That info should be in a workshop manual I would think.

To complete the question 45psi hot at 100kph.

Thanks, looks like the Nissan 4.2 is roughly the same. The book says morethan 78 kpa at idle and between 318 and 424 Kpa at 3000rpm. Seems you are taking good care of the 6.5 Chev.

I am keen to avoid any needless repairs like engine rebuild and I think coolant and oil pressure alarm gives a reasonable degree of engine protection.

Peter,
probably the most important one to add is a low water alarm. If you lose coolant quickly you will lose your engine before you realise what has happened.

We lost 4 cruiser engines at work through the loss of water and none since low water alarms have been fitted. All the new Rangers they are using have been fitted with low water alarms.

I used a Muirhead 1739 low level coolant alarm and tapped the sensor into the plastic tank on my radiator. They can also be placed into the top radiator hose. Muirhead link

Her are some photos of my low water alarm.



If you mount the sensor in the radiator you may have to place it lower in the radiator. I knew before hand that mine would be fine mounted in the top of the radiator tank.

Pic of ports???? [gif]75278[/gif]

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Hope it works, can't preview the post.........

Hi John, Yes thats it! The one forward, the 1/4" bsp is the return to sump! I use both of these for my by-pass filter! Use a good quality allen key, it is tight but it will come out. It has some sealing gunk on it. regards Michael

Thanks Michael, that sounds like a good idea, I will check that out. I appreciate you replying. A lot of people buy the Watchdog alarm but I get the impression not to many connect up the oil pressure switch to it. Perhaps because the alarm will sound until oil pressure is up/
Cheers Peter

Peter, you may be right about the lack of hookup on the oil sender, it would be a bit annoying if the alarm is loud. I use those two ports behind the alternator for my bypass filter!! Michael