Audiable Oil Pressure Alarm

Submitted: Friday, Mar 08, 2013 at 21:13
ThreadID: 100978 Views:2250 Replies:3 FollowUps:13
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The Watchdog TM2 has a orange wire which can be connected to the oil switch to give a audible alarm when the oil light comes on. I have a 2005 TDI 4.2 Patrol. Is there another point to tap into other than the oil switch. I have a 150mm lead from a harness to the oil pressure switch which is not easy to work on. It is covered in solid conduit so I would have to cut that off. I thought there may be a better place in the circuit to splice into so perhaps you could share how you wired yours up or what you have done about a audible oil pressure alarm.
I have the coolant alarm wired up and this works great and I would like the same protection for oil pressure failure
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Reply By: Ross M - Friday, Mar 08, 2013 at 22:55

Friday, Mar 08, 2013 at 22:55
kwk56pt
If your vehicle has an oil pressure switch which earths a light on the dash, then it may be possible to ID the wire which runs from the light and to the switch.
I can't help with the colour but it should be possible to splice into the loom somewhere under the dash where the wires go to the back of the dash cluster.

Someone with a wiring diagram for Nissans may have the loom/position and wire colour to make it easier for you.
I still like the idea of connecting at the switch though, if possible.

We are talking about an oil pressure switch and not confusing it with an oil pressure sender for a gauge I hope!

Ross M
AnswerID: 506372

Follow Up By: Member - kwk56pt - Friday, Mar 08, 2013 at 23:37

Friday, Mar 08, 2013 at 23:37
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
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Follow Up By: Member - kwk56pt - Friday, Mar 08, 2013 at 23:43

Friday, Mar 08, 2013 at 23:43
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
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FollowupID: 783312

Follow Up By: Rockape - Saturday, Mar 09, 2013 at 07:14

Saturday, Mar 09, 2013 at 07:14
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.

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FollowupID: 783317

Follow Up By: Member - kwk56pt - Saturday, Mar 09, 2013 at 22:01

Saturday, Mar 09, 2013 at 22:01
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
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FollowupID: 783366

Follow Up By: Rockape - Sunday, Mar 10, 2013 at 06:11

Sunday, Mar 10, 2013 at 06:11
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.

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Follow Up By: Rockape - Sunday, Mar 10, 2013 at 06:12

Sunday, Mar 10, 2013 at 06:12
To complete the question 45psi hot at 100kph.
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Follow Up By: Member - kwk56pt - Sunday, Mar 10, 2013 at 15:28

Sunday, Mar 10, 2013 at 15:28
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.
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FollowupID: 783439

Follow Up By: Rockape - Sunday, Mar 10, 2013 at 15:54

Sunday, Mar 10, 2013 at 15:54
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.

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Reply By: Michael ( Moss Vale NSW) - Sunday, Mar 10, 2013 at 07:49

Sunday, Mar 10, 2013 at 07:49
The 4.2 has extra pressure ports on the block. There are 2 ports behind the alternator only a few centimeters apart. One is 1/8bsp and the other is 1/4 bsp(British standard pipe thread). The smaller is the pressure port. You can buy any old 1/8 BSP oil pressure sender for about $10 and screw it in and it saves mucking around with the original one. The pressure range doesnt matter because you only need to see the zero pressure if the oil pressure fails. You will need a set of Allen keys to get the plug out and they are pretty tight. Quality keys are advisable . Hope this helps. Michael
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Follow Up By: Member - John - Saturday, Apr 06, 2013 at 15:37

Saturday, Apr 06, 2013 at 15:37
Pic of ports???? [gif]75278[/gif]
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Follow Up By: Member - John - Saturday, Apr 06, 2013 at 15:38

Saturday, Apr 06, 2013 at 15:38
That didn't work...............

Hope it works, can't preview the post.........
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Follow Up By: Michael ( Moss Vale NSW) - Saturday, Apr 06, 2013 at 18:20

Saturday, Apr 06, 2013 at 18:20
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
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Reply By: Michael ( Moss Vale NSW) - Sunday, Mar 10, 2013 at 07:49

Sunday, Mar 10, 2013 at 07:49
The 4.2 has extra pressure ports on the block. There are 2 ports behind the alternator only a few centimeters apart. One is 1/8bsp and the other is 1/4 bsp(British standard pipe thread). The smaller is the pressure port. You can buy any old 1/8 BSP oil pressure sender for about $10 and screw it in and it saves mucking around with the original one. The pressure range doesnt matter because you only need to see the zero pressure if the oil pressure fails. You will need a set of Allen keys to get the plug out and they are pretty tight. Quality keys are advisable . Hope this helps. Michael
Patrol 4.2TDi 2003

Retired 2016 and now Out and About!

There's time to rest when you're dead,
Get out and do something instead!

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AnswerID: 506454

Follow Up By: Member - kwk56pt - Sunday, Mar 10, 2013 at 15:11

Sunday, Mar 10, 2013 at 15:11
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
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Follow Up By: Michael ( Moss Vale NSW) - Sunday, Mar 10, 2013 at 17:49

Sunday, Mar 10, 2013 at 17:49
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
Patrol 4.2TDi 2003

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There's time to rest when you're dead,
Get out and do something instead!

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