Well, after reading several posts about oil pressure problems in the early LS1 motors, I finally get my chance to experience my own problem and after reading so many issues, I can’t see to find on that is consistent with mine. I have a 1999 Pontiac Firebird Trans Am vert, LS1 with an M6, 72,000 original miles. Yesterday, after letting the car warm up of course, I decided to goose it and run out through 1st and 2nd gear, never running it above 5,000 rpms. Immediately following, I pulled into the gas station to fuel up and shut the car down after letting it idle for a about 30 seconds. I fuel up the car, fire it back up and look down to find that the “CHECK GAUGES” light was on. I scanned my gauges and saw that I had “0” oil pressure, that would be about the time that my heart skipped a few beats. I thought to myself that the OPSU must have went because the engine sounds fine, no weird tapping of ticking or anything. I then shut the car down and checked the oil and looked around for any puddles underneath the car….nothing and the oil was good, clean and within its safe limits. At this point, I decide that the sending unit must have went and decided to drive it home (a few blocks away) keeping in mind the oil pump problems that I have read about in the past. I keep everything calm and quiet and I make it about a half a block then I start hearing some light ticking coming from the engine. I then hit the brakes kind of hard and pull into a side street and prepare to shut down. At that point, I look down and discover that I have full oil pressure (where it normally is, 40 at idle and 60-65 at acceleration). I listen and discover that the mild ticking I was hearing went completely away. So now I drive home very cautiously, listening and monitoring the OP all the way. Pull in the driveway, still normal. I shut the car off to restart it, NO OIL PRESSURE again. Now I know that something going wrong, I decide to quickly turn the car around and back it into the garage to prepare it for service and as soon and I start to back up, oil pressure is back and normal. I finish turning the car around and back it into the garage and shut it down. Start it back up, NO OIL PRESSURE AGAIN! Now I am very confused thinking of what could be wrong and what could be causing the problem, o-ring, pick up tube, pressure relief valve, oil filter. I decide to change the oil filter first, thinking that maybe it collapsed and is now causing oil pressure problems. Change the oil filter, fire it up, and boom, perfect oil pressure. Let it run a minute to confirm that it stays up and no engine noise, I think I may have figured out the problem. Shut the car down, let it sit for 5 minutes, fire it back up and you guessed it, NO OIL PRESSURE, let it run for a few to see if it is going to come up and I start hearing the mild tapping again. I am done messing with it for the night other than cutting apart my oil filter to check for anything suspicious. Cut the oil filter, nothing but clean oil inside, no particles, and the filter was intact. What a day….

I go to sleep and of course I can’t because I am thinking about my toy and what can be wrong with it. The only thing I keep thinking that it has something to do with me surging the oil to the front of the oil pan, remember I hit the brakes to pull off of the road and pressure came back, and I backed up causing the oil to surge to the front of the pan, both of which brought my oil pressure back.

I now wonder where to start. I haven’t hooked up a secondary oil pressure gauge to confirm no oil pressure but I am pretty certain that the ticking was lack of oil getting to the top end. I know my engine and I know the sound it makes normally and that was not one of them. I have discovered that the 98-00 oil pumps fail, most likely the pressure relief valve getting stuck open, causing no oil pressure. I am going to pick up a SLP HV Oil Pump and change it out, also changing the timing chain while I am in there. I wish I could do the H/C/I I’ve been planning to do while I am in there but I don’t have the loot for that yet.

So does anybody have any ideas what is going on with my Oil pressure?

Opinions about the SLP HV Oil Pump?

And last but not least, I have been told that the LS2 are the best option for the LS1 motors over the LS1/LS6 timing chains. Is the LS2 timing chain a direct replacement? I have heard that there is too much play in the LS2 chains without guides installed which are not in the LS1 motors.

I have searched and searched but nothing that matches my symptoms, close but not exactly.

BTW, I am running Mobil 1 10-30 full synthetic,and I have 1000 miles on this oil.

 

Ls2 chain is much stronger and whoever says you NEED to run a guide is full of ****...on the oil pressure I would check it with a manual gauge and go from there...and in my a high volume oil pump isn't a good idea unless you increase your oil pan size, you will drain the pan quicker with a high volume and that's bad news...get a stock ls6 or melling 295 pump if you need to change it and call it a day...but if I were you I would park the car and wait til you can afford a cam because its only an extra $300 (other than tune) and changing out an oil pump and timing chain only sucks because for all that work you get no extra power! If you are going to crack the motor, do everything at once and have something to look forward to when doing the work, makes it a whole lot funner of a job if you ask me...but check that oil pressure manually because you don't wanna ruin that motor bc that's big $..the way it sounds to me is you have a bad sending unit that's going intermittently bad in you...anyway good luck hope you get her sorted out..

 

I want to do the cam but I want to match up a set of heads with it when I do it. I am going to hook up a manual gauge just to confirm prior to tearing into it but I feel confident that I am loosing oil pressure and I DON'T want to ruin my motor. If I end up inside the front cover, I will be changing the timing chain. Thanks for the input bud!

 

Maybe somethin to do with pickup tube?

 

If you change can don't forget about all the stuff that goes with it stronger valve spring/harden pushrods and you might as well do the intake and heads can job is not cheap can and springs and pushrods alone are 799.00 plus tax then if you add heads depending on which ones and intake as well your looking at 2000-3500

 

While Your there replace oil pick up tube trust me!
My issue was this..
Its a 98 z28 ls1 runns great no smokds no oil burnt.. had great pressure only when u floor it oil pressure would drop an start knocking ..
I thought tonmu self oilpump is probly bad..i replaced oil pump to the tsp ported ls6 oil pump along with heads cam Supporting mods.got her back an guess what it did it again..(my heads did have alot of sludge in them the old heads.i can inagibe how its down there ) soo im leanig toward oil pick up tube cloged up..it could be that..im still waiting to get car back from shop once again..praying to god everything works out well

 

UPDATE: On Thursday, July 18th (my B-day), I tore into the T/A to change out the oil pump knowing that it had to be bad. I didn't even need to hook u a mechanical gauge to confirm no oil pressure, I just dug into it. I got the old pump out and began my investigation. I found that the pressure relief valve spring was in pretty rough shape, it looked like it had seen better days. It also appeared that the tiny piston did not slide very smoothly in and out of the relief cylinder. I ruled it as a pressure relief valve malfunction, stuck open causing little or no oil pressure. Put the engine back together and fire it up, perfect oil pressure! 60psi at cold start, 70+ on higher RPMS. After warm up, the OP never dropped below 50psi. It appears that the problem has been fixed! The best news is that my engine sounds great, no knocking, tapping, or any other strange noises. I was a little worried about how long the engine ran with no oil pressure.

 

Please let me know your findings! I am curious to know what was going on!

 

Glad you got it sorted. What oil pump did you end up using?

 

Melling M295.

 

I need help also with oil pressure. I out the o-ring in the freeze plug, barbell in and the rest of the.plugs but still no oil pressure what could it be? Its an ls2 with a 408 stroker with a tsp can and ls3 heads.