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HELP PLEASE!!! Oil Pressure Problems!!!

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  1. #1
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    HELP PLEASE!!! Oil Pressure Problems!!!

    Well, after reading several post 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 and fired it back up and looked 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 and 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.

    BTW, I am running Mobil 1 10w-30 and I have 1000 mile on this oil.

  2. #2
    Spaz is My Mentor SMWS6TA's Avatar
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    First things first. Random oil pressure. The cheapest fix would be to replace the OPSU. Remember it's old and even new ones can crap out.

    Oil pump - My preference is melling 10295 or 10296 pumps. The later is high volume/high pressure, for stock & mild bolt ons use the 10295.

    LS2 timing chain. It's a 50/50 on the chain slap discussion. I've heard both sides. IIRC it really effects high rpm, beefed up blocks. I have a LS2 chain going into my engine build. I haven't decided yet on guides.



    What ever you do, make sure you keep an eye on the pressure. I'd go as far as getting an aftermarket gauge to double check the oem one.

    Keep us posted.

  3. #3
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    I am in the process of buying the dual aeroforce interceptor gauges with the additional sensor for oil pressure. I am almost 100 percent sure I am looking for some type of op problem. It's not worth it to tear my motor up. I'd rather find the source of the problem even if it is the opsu than take a chance on frying it. I am very cautious because I don't want to mess shit up... I feel like I lucked out because I caught it as soon as it happened, not several miles down the road with no op.
    Last edited by a91sportyc; 07-16-2013 at 12:45 AM. Reason: type-o

  4. #4
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    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.

  5. #5
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    Good save. Do you have any pics of the old pump and pressure relief spring you can post?

  6. #6
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    I still have the old pump. I can post some pics later this evening.

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