Ok for awhile now the oil pressure on my 88 SC lo3 is been real low and the guage acts real funny. It rarely goes about 30 except on a cold start then it will be around 40. well at idle the guage will read 30 steadily then suddently drop to 10 then jump back up...i replaced the sending unit on the back of the intake that controls the guage but it still does it..i have machanical guage im getting ready to put on...was going to do it yesterday but i got the wrong T fitting. anyways has anyone esle had this problem with there guage? I really think my wire coming off the oil pressure sending unit is bad...its kinked and doesnt look quiet right...

 

The oil pressure sending unit is actually down by the oil filter adapter. I think you changed the wrong thing.

 

the sensor for the guage should be just above the oil filter (and is a PITA to get to). A new one is about $30. Older blocks also had one for the idiot light at the back of the intake manifold.

 

Mine doesnt have the light but when the oil pressure switch (what i replaced) was disconnected the guage went straight up. I just assumed this was what controlled my guage. Obiously it did. I think I know where the oil pressure sending unit is...ive seen it when changing oil. Also when I put the machanical gauge in should i put it on a t fitting behind the manifold?