Johnny-LT1-runner

iTrader: (15)

I recently took off the intake manifold and cleaned everything up to take care of some leaks, and replaced the oil sending unit while I was at it.
When I am at a stop my oil PSI gauge reads in the red, however it stays around 35-40 during driving. It is more responsive than the old one. Could it be that the new sensor is just more accurate?
I'm running 5w-30 synthetic and know that it has a higher viscosity than ground oil, therefore a slightly lower oil pressure, could that have anything to do with it?

IronOutlaw

iTrader: (4)

Put a mechanical gauge on there and check it. It's ok to be low but not in the red.

95ZR28

How many miles on the motor? Your cam bearings could possibly going bad! Mine is doing the SAME EXACT THING!!!

Johnny-LT1-runner

iTrader: (15)

Before I replaced it oil pressure was always low, not nearly as responsive to throttle, and stayed around the 10-25 range, but it never hit the red. Of course when it hits red the "check gauges" light comes on, but it doesn't seem to be a problem with the way it runs. When I first start it up PSI is above 60. Once it warms up it drops down.

227K, It runs great for what it is.

IronOutlaw

iTrader: (4)

Oh, well it may be time to start saving for a rebuild. Probably just worn bearings.

95ZR28

Mine does the same thing! Still very responsive, Worms up and drops! But NOT THAT LOW!!! With 227k miles IMO you shouldnt run synthetic oil if you are... But I do know if its on synthetic that you shouldnt go back! Try the mechanical gauge and maybe some 10w-40, it might raise like mine did!

Johnny-LT1-runner

iTrader: (15)

Yeah, that'll be down the road, a full rebuild and the LE2 package to top it off. For now it's just hanging on till then.

TheDon619

iTrader: (4)

on that high of a mileage motor its retarded to run 5w-30. 10w-30 or 40 is what id put in it

01ssreda4

iTrader: (96)

I agree, I would try to run a little thicker oil. It should help. However, let me fully explain my theory on sending units. I obviously broke mine When I ran the new Oriellys brand one, I noticed that the gauge is very sluggish to move. Its got a very dull like feeling and mostly hovers around the center span of the reading. I was concerned about this as I replaced it during a motor install. Fearing the worst about a bad motor or pinched o ring, I bought a mechanical gauge. What I saw was beauty before my eyes. It held 32 psi at idle, then gracefully swept as rpms rose, and was extremely repetitive. It did not deviate from its responsiveness in any rpm sweep. Once it rose from 32 psi, pressure directly correlated with rpm, all the way up to the pump's high pressure cut off which I believe was around 70 psi. They whole time as I watched the stock gauge, I noticed it would reach a low of 30 and only got to around 50, but liked to stay in the middle ground of 40 most of the time. The moral of this babbling, a sending unit interprets pressure as it sees fit.

Smoke Em

where did the sending unit come from?? did you put it on with the proper socket? most likely its just the sending unit, i went through 2 of them because i changed it while the intake was off and before i was holding 20 psi at idle and after i was holding 0 psi at idle.

but with that many miles i would def check it with a mechanical gauge to be safe

jaycenk

iTrader: (1)

Check with mechanical. Did a fresh build and mine showed 0 at idle lol. got my blood pressure going. After I put a mechanical on it I found I was at 20 in gear at idel (700rpms) and had up to 65 to 70 closer to 5500. Went through to senders and and both did the same thing. turns out my gage is way off.

Johnny-LT1-runner

iTrader: (15)

O reilleys. The main point of my question is this, if the gauge is now inaccurate, so the oil pressure is really higher than it shows?

fleetmgr

It's ok to run synth, but I'd want more viscosity than 5w-30. Whatever gave you the idea that you shouldn't go back? It's perfectly fine to move back and forth at will, and even mix the two if that's what floats your boat.

DAVE00

iTrader: (10)

Just double check that sending unit you put in. I had the same exact issue with mine back when I broke the sending unit during the manifold reinstall. Replaced it with a brand new unit from the local AP store and after I fired her up the pressure was reading wayyyy low and was freaking me out. Triple checked everything and finally ended up pulling it and replacing it with another new one. This time the pressure read right and had plenty of pressure all along. Just my 2 cents.

jaycenk

iTrader: (1)

Like I said you really need to take the time to put a mechanical gage on it and see where it is at. It may be right on or it may be High or low. Throw a mechanical on it and rout it through the hood and in the window and hold it or lay it somewere you can see it and drive around and test it to see where you are at. Thats what I did so now I know what the pressure really is at all points hot and cold even though my stock gage is showing low. I know where it is really just by looking at the wrong readings on the stocker. I took the mechanical back off and hooked the stocker back up.