jmmullin

Alright a friend from work and I got done with the heads and cam swap today. I have 5.3L heads, torquer v.2 cam, 92 mm FAST intake and 92 mm throttle body with pacesetter longtubes. No exhaust yet, but that will go on tomorrow at a shop in town. (Didn't think I would love the open headers like i did ) Anyway, its a pretty rough ride, but better than we both had expected.

The car starts right up and starts to idle, just a little high, then fluctuates a few hundred rpm up and down around the 1100 mark. This I believe is normal, but the oil pressure is lower than I expected. There's a million and one threads that i've searched and all the scenarios seem different, but here's mine...

At first start up, pressure was in the 30 psi range and stayed pretty constant, fluctuating up/down a little with the idle. At cruising, pressure is around 40, which I believe again is pretty normal. The Check Gages light came on three times on the way home, because of low pressure. Each time was at a stoplight just getting started rolling again. The rpms didn't go below 600 or so, which I know is low but the engine isn't tuned yet and its my first time so it wasn't normal driving, but the oil pressure is really stumping me. Oil hasn't been changed yet, and I've seen a few people say that once the oil has been changed and filter replaced, pressure returns to normal. (because of graphite and whatnot from the original gaskets getting into the oil) I got the h/c package from TSP, along with a double roller timing chain, unnecessary but i don't know my future plans for it yet, as well as a ported pump. Does this stuff seem alright to everyone? Has anyone had similar issues?

Thanks

ls698ta

No it doesn't seem normal. When I put in my ported pump at start up it was 75psi then at hot idle its at 45 to 50psi. while crusing its at about 60 to 70psi. I must say and hope you didn't pinch the O ring. If you did then its possible that your oil pressure will just get worse until it hits 0.

ls698ta

oh forgot to ask did you change your oil sending unit? They seems to get old and stop reading the correct psi.

jmmullin

I don't believe we changed out the oil sending unit. I'll ask him tomorrow if the car keeps acting up. He's done this job several times before, including his own car and he did not anticipate anything going wrong, so I doubt he did anything incorrectly like pinch an o-ring, but obviously something is acting up from the driving today... Thanks for the reply and I'll do a little more research and run the car a little longer, change the oil, and see what happens. It is ok to drive the car as long as there is good pressure, i.e. I can drive it an hour to home on the highway with the good 40 psi and not worry about anything right?

ls698ta

honestly I wouldn't drive it anymore until you figure out what is wrong. I won't even drive my car if I have a check engine light on...but thats just me.

PortMasters

30-40 PSI isn't horrible, but if it got low enough to turn on the check gauges light there is something wrong. Generally the problem with something like that has to do with the O ring on the pick up tube not being sealed all the way. I know thats a pain in the *** to redo, but it might be the problem. before the heads and cam swap, what was your general oil pressure? Also did you install a new o ring on the pick up tube?

Port Masters

jmmullin

What all has to be done to get the o-ring problem fixed? Please refresh my memory.. All I did in the process involving the oil pump was take it off, he put the pump back on, along with the timing chain. The old oil pressure was around 40 at idle and 50 cruising...it never really fluctuated at either point.

Forgot to mention the oil was Mobil-1 synthetic 5w30

AL SS590 M6

You have to pull the WP and front cover to get to the pump.
I agree with everyone else on this. Get in there and replace the O-ring on the pick-up tube.

jmmullin

I'll mention that to the guy that helped me out and we'll see what we can do with it. I did replace the oil pressure sender unit...that thing in the back on the driver side, because it broke off when we were tearing it all down. He told me to just tighten that piece up well, but it didn't have to be torqued down to anything specific, so I used that special socket for it and just tightened it up...don't think that is the problem. O-ring is next! Is there a part number for that?

Kraest

Replace the O-ring.

That's not normal.

jmmullin

The part number for the pick up is 12558251... will I need the whole thing? If not then is there a specific part number for the o-ring or should I just go pick one up that looks like it. I assume there's a p/n somewhere but all i could find on the search was the pickup number. Thanks

EDIT: Also...my gauge goes from 0-40-80 psi ranges, but on the v6 it goes up to 120. Are there different versions on the Z28's, like does anyone's Z28 have the same gauge readings as my V6? Or am I going crazy.

PortMasters

Here is a link to thunder Racing..they keep them in stock for $5.00 http://www.thunderracing.com/catalog...vid=3&pcid=227
Thunder Racing - Gaskets & Seals for your 1998-2002 LS1 F-Body

jmmullin

booya. bueno. thank you very much

what is everyone's oil pressure gauge ranges? As in what are the marks on the gauge in the dash? 0 - 40 - 80 psi?

PortMasters

Haha no problem. My 2000' z28 reads the same 0-40-80 psi, all of them used the same layout it's just 1998 didnt have the oil life meter "change oil" light. At idle though you should have at least 40 PSI when the motor is at full temp and 50+ at idle when the engine is cold for a first start up. Good luck and I hope that fixes the problem, also a good quick check would be when you get the pump off the car, take the front pump cover apart and check to make sure the dot's on the gears are facing upwards! I have gotten a few pumps from some vendors before where they installed the gears upside down, luckily I have always pulled them apart and blueprinted the pumps before I stick them in a motor. So give that a check as well.

jmmullin

gosh see thats the thing, most of the time, the pressure is up there around 40 or 50, but at idle it drops down anywhere between 15 and 40, the more i research the more it sounds like that o-ring at the pickup...seems like when the engine is turning faster, the pump gets more vaccuum in it to draw oil in/up/whereever than when its just idling, especially since it hasn't been tuned and idle is bouncing anywhere from 400-1200 rpm haha

hopefully tonight we'll have it all disassembled to see how it looks. thanks everyone