I have searched and read a fair amount about lsx oil pressure sending units but nothing matches what happened to mine. The car didn't run for about 7 months while it was down for the turbo setup. Since it has been running again the oil pressure gauge on the dash has been reading lower and lower until one night it got so low, around 10psi at idle, around 200 degree oil temps at the time. I double checked the oil pressure a the factory temp sensor port with a mechanical gauge and this verified that the motor was seeing about 35psi at idle and it quickly came up to 60 with a rev to 4500 rpm or so. The gauge on the dash won't ever read above 20ish psi under any circumstance, rpm or oil temp doesn't matter. I replaced the sending unit with one from the parts store but it behaved identically. I was told there was a screen under the sending unit that sometimes got clogged and could cause a restriction to the sending unit, I went to pull mine out but it had already been removed. I checked the voltage at the harness with the sensor unplugged, key on, engine off, it reads 5v. I have read that it could be a worn bearing but the motor doesn't make any odd noises and like I said before the mechanical gauge reads fine. Is it possible that it could be seeing pressure down at the temp sensor port but not that the pressure sending unit up top? I have driven the car quite a bit, well over 100 miles after verification of oil pressure and it behaves just fine. The oil pressure on the dash reads very low, getting lower as the temps come up, reads around 16psi on cold start. I checked to see what hptuners logs but it is the same as what the dash reads obviously. If anyone has any suggestions it would be greatly appreciated. I would just throw a mechanical gauge on the A pillar but the check gauges idiot light keeps dinging at me and I feel like this issue could be resolved I just need to know what else to look for.

 

These vehicles are known ( ls1's ) weak oil pumps . If the aftermarket unit you have is reading those are normal signs of the operating pressure of a stock unit . I would just remember to "Breath " : nod: Its ok pressure anything under 7 psi is low on these units . Upon full throttle i have seen my motor has gone to 8 psi upon pulling uphill while my buddie was using hp tuners "vs" an 2013 M3 . Perfectly normal for super Heatsoaked "upill" pulls .

 

This would indicate that there's nothing wrong with the engine's bearings or oil pump.

You are not telling us exactly what vehicle this is but as you've posted in the GenIII section and have "99" in your sig, I'll assume you have a LS1.

These engines do not have a screen in the oil port for the sensor.

Purchase and use a GM oil pressure sending unit. For an F-body LS1, 19244505 was the original part number which may have changed to 12562267 which is the same as ACDelco D1818A.

Don't bother with the after market non-GM sending units.

 

Seems like you need an oil pressure sensor to me. That's the first thing I would try. Oil pressure looks bad in the cluster + oil pressure looks good on mechanical gauge = new oil pressure sensor or wiring problem to said oil pressure sensor.

 

The OP did that already but not with a GM or ACDelco unit.

 

OP, please confirm for us what vehicle this is for.

https://ls1tech.com/forums/generatio...g-threads.html

 

Must have missed that. Too much for me tonight while I wait for my SSHT to show up from Comp Cams

 

I'm wide awake buddy, running things while in Vietnam.

Where's my beerskies??

 

It's a '99 C5 guys. Sorry for the lack of detail.

 

I put the mechanical gauge back on the filter housing to make sure I wasn't imagining things last night. It reads on average 10psi higher than the cluster. I let the oil get up to operating temp, around 200 degrees. It was only seeing around 18psi on the mechanical gauge, I revved it to around 4k rpm or so and it came up to 40psi. All of my lsx vehicles have always carried around 40psi at operating temp at idle and come to 75psi at high rpm. This is the first motor I've had a cooler on but not the first turbo motor. This motor was rebuilt around 20k miles ago, before I bought the car. It never had this issue when I pulled it in for the turbo setup about 7 months ago. I drove the car for 2 years before going turbo. Trying to give all of the details, sorry for another long winded post. Thank you guys for all of the input.

 

Yes, your pressure seems a bit low but it's in the range of "acceptable" according to the service guides.

Personally, I'd like to see higher numbers.

Your car calls for a different OPSU, I don't know the difference. ACDelco D1846A (12573107, 12614969, 12616646)