Low Oil Pres Cutoff Switch

[PC Rat]

I was thinking about wiring in this low oil pressure cutoff switch on my Daytona. I don't want to wire it into my ignition, because that could create a dangerous situation. Wiring it to cut off the electric fuel pumps might be a little dangerous also. I have a retard box for the nitrous and was thinking of wiring it to the 11 deg retard chips in the box. So if the oil pressure went below 7 psi it would activate the retard and I could feel that something was wrong, but the engine would continue to run.
Any other thoughts or ideas?
Brian

[flat broke]

A shiftlite? A loud ass buzzer like on the Mercruiser dealios? A vibrator in your shorts? :D
Chris

[Old Guy]

What danger? I've been running a pressure switch that cuts the ignition off if oil pressure drops below 20 psi for the past 4 years. At WOT, my engine will self destruct with less than 20 psi oil pressure.
Of course, that makes it impossible to start the engine without bypassing the pressure switch. I use an ignition switch of the type used to start outboard motors. The kind that turning the key cranks the engine and pushing the key in closes the choke. The part of the ignition switch that is normally used to close the choke is used to bypass my oil pressure switch. As soon as the engine starts, there is enough oil pressure to keep it running.
I also have a pressure switch on my fuel line before the carb. That switch doesn't shut anything down. If the fuel pressure drops below 6 psi, a small, very bright red light on the instrument panel gets my attention. This tells me when I need a new fuel filter.
These switches are made by Hobbs. They are sold at NAPA stores, however you probably need to call Hobbs to find out what NAPA part number is on the switch you want.
It's not obvious from reading the web page, but the Hobbs pressure switches are adjustable.
http://content.honeywell.com/sensing/hss/hobbsparts/products/pressureSwitches.asp

[Oldsquirt]

What danger?
At high speeds, a sudden engine shutdown can produce very undesirable results, not the least of which would be a lack of steering.
I vote for a bright warning light........or maybe some sort of electroshock device hooked to the steering wheel. :) Even simpler would be to glance at the gauges from time to time.

[Cs19]

What danger?
WTF? Thats pretty lame Old Guy.
PCrat, I bought this MSD mini LED shift light from Jegs for my launch controller,its just there to let me know when its armed,but this sucker is bright, like if you look directly into it, its like blinding,it would work perfect for that.
Hows that thing coming along anyways?

[Captain no fun]

I'm on board with no cut-off. That can kill you, or someone else. I have a N/C switch that opens on a rise. 30 PSI, wired in series with my high water alarm, and my accusump switch/ valve. In the event of low oil pressure, the alarm sounds, and it's LOUD, my accusump will supply about 5 seconds of pressure. Enouigh time to shut down safely, a quick glance at the oil pressure gauge tells me if it's an oil pressure, or high water problem. My switch is on the filtered side of my Oberg 600 filter. The filter has a 600 micron screen, and they have been known to plug, so knowledge is power. That's my .02.

[Aluminum Squirt]

I understand the shut off could create a dangerous situation with no power/steering etc, but wouldn't oil pressure that low create a dangerous problem at WOT pretty quickly when your motor seized up anyway? I think I would rather have a dangerous situation and a saveable motor, than a dangerous situation and a definete rebuild. A ratchet or pop-off would make it a little safer I guess. I'm not sure I totally understand captain no fun's system, but it looks to make sense with an accusump giving you enough time to at least make an informed decision to kill it, run it, or at least point it in the right direction. I think its a good idea, but I'm not running any sort of speeds that will kill me, and my boat settles down pretty good when the power gets cut. I've also got a roll cage if I put it on the shore and there are no PWC's where I boat. Just my $.02-Aluminum Squirt

[JayBee]

I ended up with my boat after the previous owner blew the engine in it. He had gotten the boat with a trashed 455 and had somebody swap in a 396. They left the stock automotive oil pan on it, and had the pickup tight against the bottom of the pan. They wired up the fuel pump through an oil pressure switch so the pump only runs when you have oil pressure (seems like it's got to have at least 20psi).
The previous owner was not too bright. When I bought the boat from him with the "new" engine blown, told me it never had low oil pressure because he safety switch never shut the engine off. He seemed to think that as soon as your fuel pump shuts off the engine will quit - had no concept of those little reservoirs on the carb called float bowls...
When I got the boat the engine still ran great, but sounded like there was a rod with no piston on it flailing around in one of the cylinders. When I tore it down I found the #1 rod bearing was completely gone, and several more had spun. The amazing part is this thing still had 65psi oil pressure at idle!
Personally, I think it would be hard to miss one of those very bright racing warning lights. I think that would be my choice...

[V-DRIVES RULE]

YOUR GOING TO KNOW ANYWAY WHEN YOU HAVE LOW OIL PRESS. BECAUSE THERES ALREADY BEEN A MAJOR FAILER ! YOU DONT NEED A SWITCH OR LIGHT TO TELL YOU! :eek: :eek:

[Captain no fun]

Yes V-drive, you know soon enough, but we're talking about gradual declines, like when you've been spankin' the b'jesus out of it for 20 minutes wide open, and your viscosity if faling due to exsessive oil temps.. It's just meant to save a motor, in that case. I'm barely in the 70 MPH range now, so not real fast, but fast enough that when you're heading for a wall of rock, it's nice to have a chance to reverse it. Hard failures are not a recoverable event under any circumstance, those things seize in a tenth of a second and it's all over.

[PC Rat]

YOUR GOING TO KNOW ANYWAY WHEN YOU HAVE LOW OIL PRESS. BECAUSE THERES ALREADY BEEN A MAJOR FAILER ! YOU DONT NEED A SWITCH OR LIGHT TO TELL YOU! :eek: :eek:
Easy there big guy! What if an oil cooler line blows?
Brian

[PC Rat]

WTF? Thats pretty lame Old Guy.
PCrat, I bought this MSD mini LED shift light from Jegs for my launch controller,its just there to let me know when its armed,but this sucker is bright, like if you look directly into it, its like blinding,it would work perfect for that.
Hows that thing coming along anyways?
Did you have to drill a new hole and mount it in your dash?
I've been spending a lot of time working on it. Engine still isn't done yet. I fixed the stringers, made new seat mounts, installed new gauges, slightly re rigged the back end, working on a new transom adapter, I'm almost done rewiring the whole thing.
Brian

[Sleek26]

I think I'd rather have a really loud horn blow rather than an LED. You could mount it where it wouldn't be seen and you couldn't possibly miss it.

[maxwedge]

I usually just listen for the sound of connecting rods impacting the sides of the engine block, and my wife screaming something about an engine fire. Worked pretty well last time.

[Captain no fun]

In bright sun, wearing sunglasses, going 50+ looking ahead instead of down, you won't see the light, no matter how bright, but you'll hear the horn. Get a horn for an automotive type alarm they've got that high frequency pitch that cuts through all the lower frequency engine noises. Like all agree on, if you lose an oil cooler line, or run out of oil, break a drive shaft, it's all over. But mine goes off after a long run, and I start idling around. After a couple of beers it's just kinda nice to have a reminder to shut it off and let it cool down. I'm just trying to make my boat idiot proof, because of the owner!

[MAXIMUS]

Ok... this is what I have & what it has done for me so far... I am running a low psi mercury buzzer & a oil accumilator which has a check valve in it & does not allow the low oil sensor to see it. What this all means is when I broke my oil drive a couple of years ago I heard the buzzer go off due to no oil psi & still had plenty of time to shut down the engine with out killing it! The accusump gives about 10 seconds of oil psi before it runs out! With out this system I would have trashed a very expensive piece! I would highly reccomend this set up to everyone & if anybody needs more detail let me know & I can draw a schematic! :smile:

[Captain no fun]

Maximus, that's a good way of doing it. I've got a sender for the gauge in the dash, off of the side tap BBC. The low alarm is on the filtered side of my O'berg filter, so if my filter gets plugged, I'll know. It's a servicable filter. Mine is also wired in with the high water alarm (Stringer height mounted Rule switch) So, it requires a quick check to the gauge to verify oil pressure VS High water. Either one you don't want in a freeboard challenged boat like mine.

[PC Rat]

Ok... this is what I have & what it has done for me so far... I am running a low psi mercury buzzer & a oil accumilator which has a check valve in it & does not allow the low oil sensor to see it. What this all means is when I broke my oil drive a couple of years ago I heard the buzzer go off due to no oil psi & still had plenty of time to shut down the engine with out killing it! The accusump gives about 10 seconds of oil psi before it runs out! With out this system I would have trashed a very expensive piece! I would highly reccomend this set up to everyone & if anybody needs more detail let me know & I can draw a schematic! :smile:
Yes, I would like to see the schematic. How do you keep the buzzer from going off when you turn on the ignition, but have not started the engine yet? I bought a Masterlube oil accumulator, but haven't installed it yet. I'm not sure if it has the check valve and low oil sensor in it.
Thanks,
Brian

[Captain no fun]

It gets complicated, but the enable switch for my low oil pressure is a rule Auto/manual switch plate. The manual side of the switch opens the accusump for pre-lube. With the ignition on, when the oil pressure gauge says pressure, you start. After start, you restore the oil into the accusump, close the solenoid by switching to "Auto" The automatic side is the permissive for the low oil alarm, passing power to the low pressure switch. In the event of low pressure, the sender closes, passing power to the horn. The auto also enables my mid- 2000 gph/ auto switch under the floor board, in case I get a side splash of significance, that pump will evacuate the passenger compartment. Through all of this talk of permissives, and hearing others, I think I'll parallel in a switch on the acusump that will horn when pressure drops below 60 PSI. Right now, the accusump is automatic, but the sender is after filteration, so I am only relying on that sender. If you are aware of accusump pressure, you would know it was draining. Remember, every electrical circuit has a source of power (Battery) a path, (Wiring) a switch, a load (Horn) and a path back to the source.(Ground wire) I've got about 45 wires in my boat, kind of a lot, but they all are there for a reason.

[MAXIMUS]

I am running a remote mount rex marine oil filter mount & dan olsen oil cooler. My dash guage is tied into the front side plug on the bbc. My buzzer is mounted in the oil filter adaptor which is upstream from the check valve & tee where the accumilator ties into just before the oil reenters the block. When the oil drive broke my buzzer sensor lost oil psi & alerted me. My oil guage on the dash showed me actual oil psi from the accusump which let me know that I was still ok. When the ignition key is turned on then yes the buzzer goes, but i can unplug it in the garage when I am working on it!

[Captain no fun]

You sound worse than me. LOL :D I try to anticipate all bad things, too many late night brainstorms...but..but what if..

[PC Rat]

The switch I bought is the Summit Low Pressure Cutoff Switch; it doesn't actually say in the instructions, but the provided wiring diagrams look like it's a normally open switch.
Captain No Fun, it sounds like you have a normally closed switch. Where could I get one?
Maximus, where could I get the check valve?
Thanks,
Brian

[SUI-CY-COLE DIMARCO]

use a gauge..best thing out there..cut out seems to not work all the time in a boat..to many sudden stops and well..in a v-drive very sudden starts,,j/k

[Captain no fun]

Any oil pressure sending switch, that activates a light, like the light on most cars in the dash. They're normally closed, (passing power), and open on a rise in pressure,( oil pressure). I got mine @ NAPA, and you can get them adjustable, or set. If you go set, just tell the parts guy where you want the opening to be. probably between 20 & 30 PSI. You may have to get a grey haired guy to help you, they've seen more!

[MAXIMUS]

I used a 3/4" brass female pipe swing check that would be found in a plumbing supply house or maybe home depot. If you can't find one then pm me & I'll send you one.