oil pressure sending unit

i've got a 78 trans am and am having problems with the oil pressure. i just got the engine rebuilt and the pressure has slowly gotten closer to zero. i've put in, what i thought was a oil pressure sending unit, but the recipt says its a switch. i'm not sure if i have the right part because the book wire diagram calls it a "oil pressure switch" not a sending unit or sensor. after hooking up the new switch and starting the engine the oil pressure gets pegged. we grounded the wire to the engine and it dropped straight to zero. its acting like a switch and i don't know if that's the part i need or want to fix it.

any suggestions???
anything will help!!
thanks


:biggrin:

my brother's 86 trans am done this
same thing and it locked up day before
yesterday. we kept thinking it was probaly
a sensor or the guage, i guess we were
wrong. be careful and get that checked out.

check the sending unit, when you put the oil pump in did you set up the oil pick up right??

I second the pickup tube. but try hooking an oil pressure gauge in place of the sender plug to see if indeed you have low pressure.

i've got a 78 trans am and am having problems with the oil pressure. i just got the engine rebuilt and the pressure has slowly gotten closer to zero. i've put in, what i thought was a oil pressure sending unit, but the recipt says its a switch. i'm not sure if i have the right part because the book wire diagram calls it a "oil pressure switch" not a sending unit or sensor. after hooking up the new switch and starting the engine the oil pressure gets pegged. we grounded the wire to the engine and it dropped straight to zero. its acting like a switch and i don't know if that's the part i need or want to fix it.

any suggestions???
anything will help!!
thanks


:biggrin:

Autozone says:
On your 1978 PONTIAC TRANS AM, the OIL SENDING UNIT is:

UNDER HOOD, DRIVER SIDE, LOWER ENGINE AREA, ABOVE OIL FILTER, MOUNTED IN ENGINE BLOCK

But it says the same about the oil pressure switch so maybe they are close together. Or even one and the same?

You would have a switch unit or a pressure unit, depending on how the auto is equipped. The pressure unit would be for cars that have oil pressure guages and the switch is for cars with idiot lights. I think all TA's would have oil pressure guages. My feeling from your description is that you have installed the switch. If you have guages, call a GM dealer, tell them you have an oil guage equipped '78 TA and ask for the oil pressure sending unit part number for that car. Then either get it from them or take the number to a parts dealer.

As others have said though, make sure you have oil pressure before driving your car again.