I've become a very cautious person when it comes to my car and I'm also fairly technical with a slightly above average understanding of electrical wiring and simple electronics, so this is something I can easily do myself if I find it worthwhile.

My last engine (89/90 LO5 Truck engine) was in pretty bad shape and the oil pressure would go to 0 at idle when warm. I always try to keep an eye on the gauges, but sometimes get in traffic and forget to look.

I’m not sure if the original LO3 engine had the oil pressure outlet behind the intake, but I know the 93 LO5 (flat tappet) does because I had to plug it and was wondering about buying an idiot light switch and rigging it up to some kind of buzzer as an added precaution?

Has anyone done this? I’m assuming I will need to apply current in series with a device; fused of course. If I want to get real technical, I can get one of those cheap voice reminders and rig it to say “DANGER – OIL PRESSURE ALERT” and have it go through the main speaker system. Okay, I don’t need to go that far. lol

I've heard horror stories of people driving along and their oil pump goes out, a filter comes loose or blows and causes their engine to fry due to lack of oil. I know I may be a little paranoid, but if I lose oil pressure and happen to be too preoccupied with traffic to notice, I want some kind of warning! Wonder what vehicle and year I would need to buy the switch for? I was looking at different vehicles, but I don't know if my threads are metric compared to an older block. The dang thing originally had metric oil rings!

Another reason for my added concern is because I possibly cracked the nylon guide when I was pre-oiling after the rebuild. I had some problems and it went sideways and jammed with the screwdriver. I wish I had a tool that would reach down to it because I would replace it with a metal sleeve. We had to pull the distributor and the top part of the shaft came out of the nylon guide and was stuck to the distributor. It went back in and the pump works, but I’m still worried about it.

And now to the fuel pump circuit! I've read some threads containing information about the oil pressure sender by the filter not actually being a safety shutoff switch. If for some reason the fuel pump relay circuit was not working, would it then act as one?

The reason I ask is because my car turns over quite a few times before starting when cold and I've replaced the relay, pump and had to recently replace the sender because the old one was accidentally busted when changing engines, although it leaked and needed changed anyway. But now I wonder if there is a contact problem in the relay wiring since all three parts were replaced?

Before the engine swap/rebuild, I could be sitting in traffic when the oil pressure was 0 and the engine would sometimes quit running like I turned the key off. I had to raise the RPMs slightly to keep it from doing that, but it always started right up when it did die.

So I'm assuming if the relay circuit is open somewhere, the sender would then act as a safety switch and could kill it at a zero pressure condition?

Either way I would like my car to start a little sooner and also have added awareness of my oil pressure condition.

Also note that it's done this ever since (and before) mom gave it to me in 99, even with the original LO3 and this is now the third engine. It has a fairly new module, coil and of course new plugs, wires, cap & rotor. I changed the knock sensor once. Come to think of it, almost every sensor, including the TPS has been replaced. The IAC was replaced once and I rebuilt the throttle body this past summer and swapped in a new regulator. It did get slightly better mileage after that, but nothing else changed. That was fun and easier than I thought it would be! The injectors and screens appeared to be clean and in excellent condition, but I still replaced them with the new screens and flushed them with carb cleaner. I rigged up a 6 volt battery using 4 AAA batteries that I soldered together and flushed the hell out of them while open.

I have another computer from an 89 Caprice, (with chip) but there is no change with it. I wonder if the Caprice chip has the speed limiter programmed?

 

Ok well first off at what oil pressure would you want your alarm to go off? Also you should have an oil pressure light it may be easier to just add a buzzer to work in conjunction with your oil pressure light (could also make it work with you temp light as well). Secondly on the oil pressure switch if it acts a as saftey shut off or a fuel pump relay bypass it depends on the cars wiring Ive seen it both ways. What year make and model are we dealing with and is the wiring stock? However you are correct even if it was designed as a bypass if the fuel pump relay were to die it essentially would act like a oil pressure safety switch. Again how its supposed to act though will depend on the wiring but it can be changed around to work however you want it to.

 

12 years I've owned this car and never once did I know there was a warning light. It's an 89 Camaro (TBI) with a 93 5.7 truck block using the original 89 LO3 heads.

I have a computer from a Caprice that works in it, which I should have specified; sorry about that. I was meaning the extended cold crank condition didn't change with the Caprice ECM and chip.

I would like to put a regular pressure switch in the oil pressure outlet behind the intake manifold/Distributor to set off a buzzer (and possibly light) if the oil pressure drops to critical / Zero.

I know I could probably build a sensor circuit with a relay that would work in parallel to the oil pressure gauge to measure the voltage and have a specified trigger point using a simple potentiometer to adjust it where I want, but it would be much easier to just put a switch in the block and rig it to a 12 volt buzzer. That way I can have the best of both worlds! The OEM gauge and a buzzer/beeper to get my attention in case I lose pressure and happen to not be paying attention to the gauge. I would rather hear a buzzing than a knocking.

I'm just wondering what car to get the switch for because I don't know if the threads are metric. It did have a riser elbow when I got the engine, but I don't know what happened to it. I could take that to the parts store and see what will screw in I guess, but I need to find it. I know this sounds crazy, but we were able to plug the hole in the block with a brass lampshade holder my uncle had in a can of bolts. It screwed right in! We could not find any other threads that would work with it because they are super fine.

I believe the fuel pump relay and oil sender wiring are stock. I guess I'm going to have to trace everything down and see if there could be a bad connection somewhere.

It's only an inconvenience, so I can live a little longer with it. I've gone this long, so I'll just wait until spring or summer to trace everything down.

 

You could either T in seperate switch behind the dist or use the oil gallery port above the oil filter so as not to disturb the original wiring.

There are 1/8" NPT pressures switches available that activate at different psi settings so you could install the one of your choice.
Waiting for pressure to drop to zero before buzzer comes on is probably counting danger if you loose oil pressure at high revs so 10psi? might be a better choice
Setting just has to be above your hot idle oil pressure

 

Check out Summit Racing the make gauge kits with warning lights.

 

All your wiring is stock?

 

That is a good idea about getting one that triggers at a lower pressure instead of zero. The car runs at a lower pressure than I'm comfortable with as it is, but it never touches the red. Comes close though. Right to the upper edge.

As far as I know.