Oil light staying on, urgent help needed

[flyingtele]

hi there, my car has recently had its head gasket replaced. Went to fire the car up and it started fine, but I noticed that the oil light did not go out. So i have low oil pressure, but I dont know why, but I have a few ideas.
Bits of metal/debris/muck could have fallen down the oil galleys, but before I started the car, I flushed out the whole oil system with fresh oil and then filled with more fresh oil.

After I re-filled it with oil, I noticed that on the dipstick the oil level was about 2 cm above the Full marking, so it was obviously way overfilled. What I think has happened is the crankshaft churned and aerated the oil making the pump unable to pump oil.

I cannot think of anything else apart from a faulty pressure sender, but it was working fine before the head gasket job.

If anyone has any help, that would be greatly appreciated as I don't want to drive it until that problem is fixed. Car is ST185 with 3sgte motor

[flyingtele]

Update: I decided to start it and remove the oil cap. Instead of seeing oil flowing around, there was just lots of pulses of air coming out of the oil filler cap. So the only conclusion I can come to is that the oil pump is being starved of oil and is pumping air, which I find very strange after having checked the oil level at the full mark. Any suggestions?

[Doctor J]

Disable ignition and remove oil pressure switch.
Using starter, crank the engine for 3 seconds
If at the end of this time the oil will not come out of the hole ln a strong jet, the oil system needs repair [oil filter, oil pick-up screen oil pressure relief valve in the pump

[hatchy_gt-s]

look to see whats coming out of the exhaust because the oil light sensor checks pressure not oil as you already stated and it could be (hopefully) that its not picking up oil but the other prob. might be that you have low compression. what you want to check for is at start up does it blow blue smoke, after that rev. it up if it continues to smoke blue its going to be piston rings, if its only at start up it going to be your valve seals
if i would have to make a guess it will most likely be the valve seals being as you had it removed
Q.Q. did you have the head machined?

[flyingtele]

yes, head has been faced. the head and the block mating surfaces are perfectly flat. head gasket is multi layer steel type. I do not want to start it and rev it because there is no oil flowing to the top of the engine! It will be burning oil for quite a while, as I changed the cat for a downpipe oil would have found its way into the exhaust. and also i cleaned out the inside of the exhaust manifold and that will burn off. Also the insides of the cylinders were coated in oil to prevent rust so will be smoking for a while.
Previous head gasket wasnt blown, but I wanted it changed before it did blow.

[new echo owner]

Just disable the ignition system and hook up an oil pressure gauge, crank it over, it will tell you if the oil pump is working or not, and some idea of what the pressure is. Don't have to guess!

N.E.O.