DarkObsession

Another night, another question. I think (hope) I know the answer based on my searching but would like thoughts from the experts.

My 1985 has the stock engine and about 90k miles on the clock. Today I went for a quick drive, stopped and talked to another Corvette owner for about an hour, and got back on the road. When I started going down the street I got the low oil pressure red light when I'd get higher in the revs. The gauge was showing 11 psi, and then 10 psi.

Here's the thing, I don't trust this gauge at all. I replaced the original sending unit a couple of months ago because it was reading 80 psi constantly. When I replaced the sending unit I got different readings, sometimes around 50, sometimes 60, sometimes 35. There never seemed to be any rhyme or reason to the numbers and they also never changed even under acceleration.

Now, having static readings higher up in the range is one thing but it made me nervous to see 10, 11, and have the red light on today. I haven't noticed any other issues, noises, and the oil level spot on so I don't think I'm spraying oil out the engine while I go down the road.

What do you think experts? I think the gauge is just wrong but I'm not sure how to get a reading I really trust other than getting a mechanical gauge and hooking that up. Any thoughts (and hopefully reassurance) would be appreciated.

antfarmer2

I would put a t on it with a mechanical gauge to help figure it out and peace of mind.

PatternDayTrader

The only thing you can do at this point is exactly what antfarmer2 said ..... then decide what to do after that.

Does it sound noisey ? Is it knocking and clattering ??

DarkObsession

No, nothing noisy or unusual at all. I was really surprised when the light came on. Came on about 2200 RPM.

Grr, not looking forward to getting back to that sending unit area again.

PatternDayTrader

Its probably ok if theres no noise, but you better check it with a manual gage.

jv9999

Did you take a good look at the connector when you changed the sensor? Mine was dirty and corroded making the gauge read all over the place.

DarkObsession

Is there an alternate place to hook up a test mechanical gauge? When I replaced the sending unit I had to take out the wiper motor, which was a pain.

DarkObsession

No, I didn't look at that part. I don't know if I can get the wire off without taking everything apart again. I'll have to look.

PatternDayTrader

I want to say there's a plug in the side of the block just above the oil filter, but I cant remember if that's on the small blocks or the big block chev engines.

GRIS

ABSOLUTELY. THIS IS THE FIRST THING TO DO.

cv67

Isnt there a plug above the timing cover just south of the intake to the left some?

Hopefully just your sender

If its still doing it after putting a mech gauge on it (auto chains sell em for under $30) your pickup tube may be coming loose

WW7

With the junk parts they're selling now ,it's not unusual to get bad parts from parts stores...I had to install 3 water pumps in my 89 before I got one that worked.....WW

DarkObsession

I'm picking up the mechanical gauge tomorrow to see what's going on. It looks like the oil temp sensor is above the oil filter from what I've seen online. Hopefully I can quickly check there and see what the problem is. I'll report back. Thanks all.

DarkObsession

Okay, here's the latest. I disconnected what I thought was the oil temperature sensor and hooked up a mechanical gauge for a test. Turned the car on and it immediately went to 40 psi, up to about 55 psi under engine revving. HUZZAH, I have oil pressure!

Here's where things get weird. What is shown in the picture below? I think this is the oil temperature sensor but when I turned the car on I got a ZERO oil pressure reading from the factory gauge (all while the mechanical gauge was showing 40-55psi). Do the two sensors work together somehow? Are maybe the wires crossed up? I wouldn't think the two gauges would be able to show any information if they were switched up but who knows. Any help would be appreciated. I guess now I should go buy a new sensor for what's shown below, whatever it is.

WW7

That is a picture of an oil temp sensor, which by the way cost $100.00 new....... Removing it should in no way affect the oil pressure... Maybe it's just a coincidence that the oil pressure sender stopped working after you started working on the car...Like I said in my post above, what they're selling as parts now days is mostly junk...I bought an AC Delco oil pressure sender after buying 2 of the store brand senders from Advance Auto that didn't work at all.. It seems the ACDelco parts are a little better....WW
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DarkObsession

Yeah, I saw that so I decided not to just go out and pick up another one. I hooked everything back up and the oil pressure gauge still isn't working right. After I ran it for a while it started registering more than zero, but not much.

I guess I need to figure out how to mount that mechanical gauge somewhere in the car. Anyone ever try mounting gauges in the ash tray area?

PatternDayTrader

I guess I'm failing to see why your not replacing the oil pressure sensor ?? It seems to me that you have proven there is in fact the proper amount of oil pressure, and if your gage is not reading properly then you can either test the circuit or throw a new pressure sendor at it. I vote for the latter ....

DarkObsession

Yeah, that's another route. Just don't know that I'll ever trust the gauge again but it's a better idea than having hot oil pumped into the cabin. Any recommendations on a decent sender?

PatternDayTrader

I prefer AC Delco parts. Oil pressure senders are inexpensive too.

No matter what, I wouldn't be messing with a mechanical gage in a street car.

DarkObsession

I know what you mean. There's just that whole trust thing!