Would like some comments on this idea. I want to use some low oil pressure switches, preferably auto for cost reasons, on my engine cooling and manifold cooling system and hook it up to the existing oil pressure and water temp alarms. Might even include one on fuel pressure.

Any thoughts? Do you think it would work?

Are these switches listed somewhere as to there pipe size and switch setting? You know the guys in the auto parts stores, "duh, what car is it", no help there.

A switch is a switch.
Get one for a model car that has only an idiot light no gages(ie.1985 Buick Electra)actually any GM motor, from a junk yard(cheap) and tee it in. I'm assuming you have GM big block motors. Most oil pressure switches are for 1/4 pipe thread. Most of the cost will probable be for fittings to plumb it in.
Your theory should work. My guess is the alarm will come on too fast after shutdown for your likings. Let us know.
I don't know what kind of cooling system you have. Closed or raw, or what kind of pressures are involved with either system.
Either way it makes sence to me to find out I have poor water pressure before the motor gets hot.
After selecting the pressure switch use a gage to find out at what pressures the switch makes contact and what pressures it breaks contact. so you know what your operating parameters are

Where I run its usually pretty busy or rough and watching gauges just doesnt happen. Have had 2 bad weekends lately because something stupid happened and the stock alarm didnt pick it up so Im thinking of alarming as much as I can. Even nuisanse alarms would get me to look at the gauge and be better than hurting engines. I might need some kind of delay timer to cover the out of water events that are normal in rougher water. They are Raw water cooled Mark 4's

Thanks for the reply.

Go for it. I know what you mean about busy and no time to be constantly checking gages.
Bikinis are hard to watch when you're worried about $$$$$$$$$$$ MOTORS

Haha I wish it was bikinis, more like blowboaters everywhere. I hope it doesnt snow tonight.

form,
I hope you were kidding about an oil pressure switch for the cooling system??? You really meant a auto temp switch ,right?
The alarms work by a ground just like an idiot light in a car ,so actually you could use a "idiot" switch almost anywhere for temperature. Come to think of it you COULD put a pressure switch in the cooling system. Just check the specs on the pressure they operate on. Most quality (not Pep Boys) auto supplies should have the specs in their parts books. The last time I bought parts from Pep Boys I had to F%&* with them. I asked for a specific spark plug , but NO they had to have what type of engine . So I told them 540 Ford...well they couldn't find it . Then they asked "what year" , so again I told them 73 which the block was. Had them looking for the longest time . At that point I figured I may have well add insult to injury and went somewhere else to buy them

Yup I hear that, And I am talking about a pressure Switch for the cooling systemto activate the alarm. One on the block, one on each discharge to the elbows and maybe one on each manifold if I can figure out the thermostat issues. The damn temp switches dont do much if theres no water there to get hot and by the time they go off its too late.

I think that you are looking for a "Hobbs" switch .I know that TAE on Monroe in Toledo Has them in different pressure settings I think that no. and nc .are available.They are usually 1/8" npt.

Rob
http://www.hobbs-corp.com/family.asp

By the time you get to the manifolds or elbows the pressure may be too low since it's near the exit. A lot of oil pressure switches operate near 5lbs and may not have 5 lbs. left that far form the pumps and that close to the exit. Although if my memory serves me correctly (and it doesn't always) I think VW Beetles(the originals) had a switch that operated around 2 lbs.

MOPOWER I think you are right on the VW's also the thread is 1/8 npt, but it looks darn near 1/4 inch.
I have the same problem with the jet ski's cutting me off when going into the marina's.
We call them "lake flies" You know irritating as hell and no real direction of flight to them.