I have VW bora that the transmission had been rebuild with a new oil pump ,but now the oil pressure is only reading 75 PSI at 2000 RPM what can be the cause

I looked at info for 1500--5.7L engine.
6 psi @ 1000 rpms
18 psi@2000 rpms
24 psi @ 4000 rpms

Sometimes, you can use analog gage in place of oil pressure sending unit and double check oil pressure that way. If oil pressure is actually low, if high mileage engine, I doubt replacing oil pump will help. I just wanted to add, check oil pressure engine warmed up.

Are you sure the gauge is reading correct? You also didn't mention how many miles the vehicle has. If it's less than 150k I would doubt the motor it worn out, (excessive bearing clearance would cause poor oil pressure even with high volume pump). Chevy's have a lot of issues in the dash with the motors that make the individual gauges work. I would check the oil pressure with a manual gauge. If you don't have the skills to do this yourself, a qualified shop wouldn't charge much to do it. If you find that the gauge is incorrect, there is a guy in MN that rebuilds the instrument cluster for $65 with all new stepper motors (the motors that work the gauges) and replacement of all the bulbs, plus gives it a lifetime guarantee. www.speedometerrepairguy.com.

Oil pressure always changes with rpm.
At idle you should have around 10 psi, and it should max out at high rpm around 50 psi or so.
You not only can't have as much pressure at idle, but you don't need it either.

Normal oil pressure should be between 40 and 60 psi. A cold engine will normally have higher pressure. If you're seeing 75 psi on a warm engine I would recommend having the pressure checked with a manual gauge to verify the gauge in the Jeep is working correctly. If the gauge is correct oil viscosity may be too high (oil too thick) or there may be a problem with the oil pump pressure relief valve. If the gauge is not correct the sending unit may be at fault.

What year and model is it ?

I know this happens to many VW family engines due to low oil pressure.

When oil heats up it thins out. The 'second oil pressure switch' sees a low pressure above 2300rpm and turns on warning. ....the one on the cylinder head.

At idle, the 'first oil pressure switch' is monitored....the one on the oil filter housing.

This is called a 'Dynamic Oil Pressure Monitor System'.

If the engine is cool, the light stays out, yes ?

The oil pick up becomes partially blocked and not enough oil pressure is developed turning on the warning. Dropping the oil pan and cleaning the pick up cures this problem.

If this is not the case, then the engine is worn internally and oil pressure is being lost from the bearings.....like a lot of little leaks..

Other than the 1.8t engine, the pump will max' out at 120 psi cold at 3000 rpm and run 45 to 80 psi down the road warmed up = Good engine.

The 1.8t however must never see oil pressure above 90 psi or things get damaged. Valves and valve gear. Expensive..think $3500.00

It is possible the switches themselves are bad. If so, always buy from VW as the aftermarket switches stink !

The electronic monitoring system it's self seems very durable, so that would be last thing to check. It's just an electronic relay on the relay board under the dash. On the Vanagon it is under the instrument cluster head.

Now, you could try thicker oil or add a bottle of LUCAS BREAK IN OIL from the parts store. $14.00.

This will help with lubrication...something new oils lack.....( 'Google' ZDDP for info' on that problem ).....and thicken up the oil in the engine.

Only sure way to tell what problem you have is to use a 'master oil pressure gauge' screwed in to both oil filter housing and cylinder head and monitor oil pressure . Warm at idle should be 15 to 25 psi. At 2000 rpm should be above 20 psi up to 80psi.

If pressure falls to near zero at high rpm at the cylinder head when fully warmed up, this indicates internal wear. Time for another engine or rebuild.

Often just replacing the rod and main bearings will give you another 80,000 miles ...subject to what engine you have.

Measure your oil at normal operating temp, without the engine running of course. This will give you a more accurate reading once the oil has circulated in the system.

The system works like this:

• With the ignition on, the oil pressure indicator light on the dash should come on and flash. Once the engine is started, the light should go out and stay out as long as the engine is running.
• If the oil pressure drops below approximately 0.3 bar or 5 psi when the engine is running below 2000 rpm, the light will flash.
• If the oil pressure drops below approximately 1.8 bar or 27 psi when the engine is running above 2000 rpm for more than 3 seconds, the indicator light will flash and the buzzer will sound.

If either this two warnings occur:

• The engine should be switched off immediately and the oil level should be checked.
  

At 2000 RPM a new GM engine should be close to 45 psi for oil pressure. It'll drop to mid or high 30's at idle. Hope this helps.

I would suspect that you have a weak or failing oil pump, however before condemning the pump I would do a physical oil pressure check with a gauge. Oil pumps are not easy to replace so lets make sure it is the problem before replacing it. For reference yours can be done with the motor in the vehicle.

Physical Pressure Test:

This may require you to tuck a oil pressure gauge under the driver side wiper arm and go for a short drive to make the situation replicate. Depending on how you hook up the gauge (in place of oil pressure switch) the light will be on full time during the testing and this is ok. If you can replicate this symptom that you are reporting in the drive way in gear it is desirable as you can better read the gauge.

The oil pressure should be:

3.0L = Oil pressure should be 6 PSI at idle and 35-75 psi at 3,000 rpm with engine at normal operating temperature.

3.3L = Oil pressure should be 5 psi at idle and 30-80 psi at 3,000 rpm with engine at normal operating temperature.

You see that there is a large "in spec" region for the 3,000 rpm range as listed. I would look for the pressure to be at the higher end of the scale and the idle pressure to be right in spec. If any of these pressures are low I would suggest changing the oil pump.

If your motor is one that I have not listed here please comment back and I will provide the appropriate spec per the motor in your van.

The oil pressure specification for your engine is 13 PSI at idle hot, 37 to 75 PSI at engine RPM higher than 1600. I suspect your oil pressure gauge sender unit or gauge is inaccurate. I would have a known accurate mechanical oil pressure gauge temporarily screwed into the present oil sender unit to verify actual pressure.

If you have the correct pressure I would replace the sending unit first.

Yes I believe there is!! I can't think of it right off hand.I will look it up and get back to you. Also have you checked to see if your spark plug seals are worn. I am replacing mine now.I had an issue with the engine light coming on at certain revs!!!

I’m happy to help further over the phone at https://www.6ya.com/expert/phillip_293d34ebcf028794