Yesterday was a pretty warm day, the car was warm and as I drove it and came to a stop, the oil pressure would go down to nothing, it was also low when I was driving. Checked the oil and theres enough, what could it be?

 

Bad oil pressure sending unit or bad oil pump or worn out bearings.

Install a mechanical pressure gage (at least temporarily) to be sure what the oil pressure really is.

 

If your oil pressure was really at 0 psi your engine would die. You have a fuel pressure cut off switch (oil pressure safety switch) that will cut your fuel pump off if the oil pressure goes down to low.

I would install a manual oil pressure gauge to make sure. I would not drive the car until I knew for sure.

 

not at idle, and even then, not instantly. sure, its not good for it, and you're wearing it out quick, but it wont instantly freeze the second it has no oil.
in some cases, the engine will continue to run with no oil, at RPM until it gets to low RPM or shuts off... THEN it freezes. lol.


i know its suppost to have one, but does anyone know what they're set to from teh factory?

yup, me too.

 

what will new parts cost to fix this thanks

 

Wrong. The switch is not designed as an engine- safety switch. It is designed to keep the car running if the primary relay for the fuel pump fails. If the primary relay was not operational, low oil pressure would shut down the motor. You know the primary relay has failed when the fuel pump doesn't energize at key on, and the car takes 30 seconds to start.

 

It's not an engine-safety switch, it's a crash safety switch.

The timed relay is for starting only. It's intended to shut off after a few seconds. By that time, it's assumed fuel pressure and/or oil pressure is up so the car will start.

The oil pressure switch is intended to shut off the fuel pump in the case of a crash where the engine stops and the fuel line is compromised. You don't want the in-tank fuel pump dumping gasoline on a crash scene.

As for cost, the sender is only a few bucks. The other things are a lot more expensive.

 

My bad...I have been owned.

I've been away from fuel injection to long.

 

if the sender is fairly inexpensive, how much would the other parts cost?

 

What other parts do you have in mind?

The gauge sending unit is about $15. Have you tried it yet? www.partsamerica.com www.autozone.com etc

 

Well, when it happened to me... I think it was about $2500 or there abouts. My oil pump failed and I ended up having to replace the engine. I have been oversensitive to oil pressure ever since.

 

How many miles are on the engine? You might have worn lower end bearings that are bleeding oil pressure. Very expensive to fix. You might also have a worn out oil pump. Not as expensive, but a major hassle to remove and replace. Both can be nursed along with thicker oil. What weight of oil are you using?

Yes, could be pressure sender, guage, or bad ground. But this usually means the gauge suddenly reads zero. You can pull a valve cover and fire up the car. If you get oil flow in a few seconds and it's splattering everywhere, your pressure is fine. If it just drools along, it's a bit low, try thicker oil. If nothing flows or very little after a few seconds, you have serious problems.

Troy
So Cal

 

owned,
Do you think that relay could be the cause of my long cranking issue? It takes like 3-4 seconds before engine fires intially, but after at OT, it starts fine. Well, actually, occassionally I get a nice cloud of smoke just after start up. I was first thinking leaky injetor(s), or maybe rings. Any ideas?

 

mine has smoked ever since i got the car 5 years ago when i start it, the car has 90,000 miles. When i start the car cold in 70 degree weather the pressure is at about 35, when it idles and the temp around 170, the oil pressure is at about 17, when i accelerate the pressure wont go over 30-35? Is this bad? I do recall before accelerating the pressure would increase more than it does now. Ocaasionaly when the car is warmed up I've noticed for the past couple monthes when I idle my oil pressure bounces up and down by about 5.

 

Is the mechanical pressure gauge and a gauge sending unit the same? If so, after I buy it, what do with the part to check the oil pressure? Thanks alot.

 

Im not sure if I'm usinf 5w-30 or 10w-30, would it help if I put in 10w-40 or 10w-50?

 

By "mechanical gage", I meant going to the parts store and buying an oil pressure gage kit that includes the gage and tubing. Install it on the engine, the fitting in the front above the timing cover will do for this purpose, and compare what it reads to what your dash gage reads.

The gage sending unit is mounted on the back of the engine and converts the pressure in the engine oiling system to an electrical voltage that the dash gage converts to a pressure reading. It might be less expensive and less hassle to go to the parts store and ask for an oil pressure gage sending unit for your year, model, and engine size vehicle (which you have not yet said what it is), and replace your existing sending unit. If the pressure is really as low as you say your gage says it is, you should have been hearing valve lifter tapping (perhaps not, though). The symptoms you describe could very well be the sending unit, not an actual low pressure situation.

The smoke at start-up is the typical problem with small block Chevy valve stem seals getting hard and allowing oil down past the guides into the combustion chamber. A little annoying, can be fixed without completely tearing down the engine, but it certainly is not related (directly) to the low oil pressure situation.

 

can someone post a pic of where the manual oil pressure gauge is supposed to go, I have a 91 L98

 

From what I hear the switch/sender is above the oil filter.

 

I opened up the oil cap today while the car was running and there was no splashing, just moving parts and oil. How bad is this?

 

Does it make a difference if i start the car then take off the oil cap or should i take off the oil cap first then start the car? Thanks, I also noticed when idling if I have the hood open im getting a farting sound near the throttle body on the passanger side, when im driving i hear the farting from the driver side, could this be related to my pressure problem? Thanks

 

Meaningless.

The factory gauge system is notorious for failing. When it does, it's almost always a bad sending unit. Did you ever replace the gauge sending unit, or hook up a mechanical gauge?

There's only so much diagnosis that can be done over the Internet without some actual information. Without real information, guessing is just wasted bandwidth.