No oil pressure...

[caw333]

Need a little help thinking out loud. I've got a 95 Z-28 and a couple of weeks ago I lost oil pressure, no big deal right? ... wrong. Decided this morning I'll go ahead and change out the oil pump and oil sending unit. Well now that I've got all that changed out I still dont have any oil pressure. I can hear the lifters clattering so I no that the guage is accurate when it reads 0 psi. Whats next?

[Morley]

Oil pump drive

[caw333]

Ok ... been doing a little research on this oil pump drive and it looks simple to change if the motor is out of the car ... So my question is has any one ever changed this drive with motor in the car and is this a task thats going to make me loose my sanity. Any ideas or tricks?

[Morley]

Originally Posted by caw333

Ok ... been doing a little research on this oil pump drive and it looks simple to change if the motor is out of the car ... So my question is has any one ever changed this drive with motor in the car and is this a task thats going to make me loose my sanity. Any ideas or tricks?

I really don't know, never delt with LT1's much.

New info. but first some questions. You have the pickup on the pump securely? It is the pickup for the F body LT1 and not corvette? Did the drive rod fall out when changing the pump? did you look at it for damage and reinstall it correctly?
If it is the drive stub shaft that has broken/gone bad, You have to remove the intake to access it. It sits under the intake at the back of the engine where the distributor would sit on a Gen I SBC and meshes with the cam gear, just like the gear on a distributor.

[caw333]

yea when I changed out the oil pump I bought the same one that was in it, The Melling M155HV and the pickup tube that goes with it. I made sure that the pickup tube was good and tight. When I had the pump out I inspected the shaft that goes up into the motor and it looked fine. I replaced the little plastic piece that connects the oil pump shaft with the drive shaft also. When all this started a couple weeks ago the car went from around 50 psi to 0 psi. Its got to be the drive (maybe). I'm going to see what I can figure out today. Oh and thanks for helping.

[Morley]

Got some more input from the Corvette guys.

Pull the intake one bolt and that is it.
BTW a common problem if a high volume pump was used is for the stub shaft plate to break off. More performance used to make a plate to prevent this but they are now out of business.
You can inspect the gear at that time and use a STD oil pump primer tool to see if the motor can build pressure, you can use a flash light to see if the pump shaft has dropped down or not once you pull the drive unit

[caw333]

Thank you Morley for all of your help. On my next set of days off maybe I can get some oil pressure back.