All vitals are great...great oil, no leaks, idles well, etc. 305/TBI/Auto

When I start the car in the morning, the oil pressure reads around 75 while the RPMs are about 700.

When I put the car in drive, everything is A-OK...nothing happens any different even for the first few stop lights... When I drive, the oil pressure is perfect @ ~75....THEN...

After a few mins of driving or if its really hot out and I come to a stop while I'm in gear, the oil pressure falls off the planet (Sub zero)... The engine sounds the same...no knocking,clicks,bangs,screaming, or fires. Maybe the only difference is a slight change in the RPM's As soon as I let off the brake and add some gas, the oil pressure goes back.

Whats the deal? Good news only please (just kidding, I love all comments)

Assuming the oil level is correct, I'd drop the pan and check the pump pickup and screen.

:beers:

I'd change the oil gauge sending unit after checking oil level.
If to no avail, then sub in a mechanical gauge to check pressure.

I'd change the oil gauge sending unit after checking oil level.
If to no avail, then sub in a mechanical gauge to check pressure.
X2 on the sending unit, that's a very common mode of failure for one.

Always verify that the guage is accurat or not by substituting in a manual guage first. This can be as simple as taping it to the windshield.

Id do that before taking the motor apart.


Chris :cool:

Does the gauge have a mark for zero or just start off at 5psi?
You need about 10psi per 1,000 rpm.

Always verify that the guage is accurat or not by substituting in a manual guage first. This can be as simple as taping it to the windshield.

Id do that before taking the motor apart.


Chris :cool:

Can you expand on "taping it to the windshield"?

Update: I purchased a sending unit today....Next is getting under the car with all of 4 inches of clearance! ;-)

Update: I purchased a sending unit today....Next is getting under the car with all of 4 inches of clearance! ;-)You can get 2X10's or 2X12's and build yourself wooden ramps, aka, steps, to roll the car onto.

Be sure to add the block at the end to not roll over the end.

What are we talking about here? Last time I checked the tap for the oil pressure sensor was behind the distributer.

Can you expand on "taping it to the windshield"?


Ive got a "test guage" with a flexible rubber hose that I substitute in place of the factory sender, the guage looks like a vacume guage but reads fluid pressure. I just duct tape this to the windshield above the wipers so I can read it from inside the car and go for a drive.

I used to use a Stewart Warner guage with duct tape on the cowl until I got the other style guage. I also use it to check trans pressures as well...


As far as where the oil pressure sender is located it should be under and behind the dist... No jackstands required...


Chris:cool:

As far as where the oil pressure sender is located it should be under and behind the dist... No jackstands required...Chris:cool:Sending unit is by the oil filter. Fuel pump switch is under the dist.

I had the same problem when I was installing factory gauges this spring. I attached a mechanical gauge at the block and ran it for a while to verify there is good pressure. At that point it's either the gauge inside the car or the line. I swapped the line from copper tubing to stainless steel hose. It made no difference. I sent the factory gauge back to Ground Up for another one, still no difference. I bought an Autometer and it reads fine. I am putting in 4 Autometer gauges this week in the dash.

I will post pics once the work is done.

Sending unit is by the oil filter. Fuel pump switch is under the dist.


10-4 :beers:


Chris:cool: