RyanSws6

iTrader: (72)

Thought I'd post this up, my 98 LS1 runs great, leaks oil but fine. Issue is oil PSI is about 40 in gear on the HWY say 1700 rpm and say I go 3000rpm it stays the same BUT if I let off the throttle PSI will jump to 45 which is about normal. I have a new build on the stand now but I'd rather not have to force the build before I throw a rod.

I assume the cam or mains are worn but with 120k I didn't think it needed a rebuild, I've seen LSs going easy going 180+ and run strong. I didn't put the setup together and don't know if its a O ring issue.

Thoughts, theories...

O2Form

One of my mine did the same thing and i never had any trouble. You could check the crank end play, thats about the only thing that could change the oil pressure off and on the throttle. I never hooked up a mechanical gauge to see if it was a electrical glitch or actual oil pressure reading. Maybe you should if you really want to know.

mean_greenZ

iTrader: (1)

Both my cars do that. My 2011 Chevy work van 4.8 does it too. Just what it does.

91sonomast

My 91 Sonoma with the 2.8 did that for 100k+ miles, did it until I retired the truck at 350k miles. I put a new oil pressure sensor in it at one point and it didn't do it for about a year then one day started doing it again, not sure if it was the engine or just the sensor acting funny.

RyanSws6

iTrader: (72)

Thanks for the replies, thought I'd mention this is with Castrol 20W50 and I did replace the sensor and did the same readings...Just in case though, I baby it, nothing over 3k...

I've owned 9 4th gen Fbods and NONE have done this. This is why I've got my rebuild on the stand.

Thing is my clutch is going too (grabs high no slip) so I want to do the eng swap and clutch at the same time.

91sonomast

Just baby it until you get your other engine ready then you can beat the **** outta this one til it goes pop or you decide to swap engines.

trans_am7935

iTrader: (15)

mine does that too. i changed out the sensor and the gauge, still does it. mine only goes down about 1-2psi off throttle though. in my opinion it is just cause the pressure system is so sensitive.