armycopter

I've done an advanced search and there are lots of low oil pressure threads but I can't find one that matches my exact problem. I"m hoping the experts here can help me.

Here is the background info:

-2001 C5 coupe with 49,000 miles. Car has been cammed, etc.

-I've owned the car for about a year (got it last sept). I've put about 3000 miles on it since then and I did an oil change last sept when I first took delivery. It had Amsoil synthetic 10w30 in it.

-The car has always had a little bit of what I think is valve train noise. I"ve done exhausting thread searches on this forum and it appears to be fairly common, especially with headers and all the other engine upgrades I've got.

-Car almost always idles at about 38 psi on the oil pressure and will move up to about 55-60 at WOT. No problems, ever.

Ok here is the problem:

- My wife and I decided to do an overnighter in Hartford, CT yesterday. I filled up the car with gas and as we were about to go, I got a low oil level indication on the DIC. I didn't have any Amsoil so I bought a quart of Mobil 1 synthetic and poured it in. Brought the level on the dipstick up to normal range. I am unsure why my oil was low in the first place. The car does not leak anything, but that's another issue I'll have to look into.

-Drove the car to CT (about 200 miles) and everything was fine. We drove back home this morning and I stopped for gas at about 1/2 hour out from my house. When I started the car back up, I got a low oil pressure on the DIC and noticed the oil pressure idling at 9psi.

-Since it wasn't zero and I couldn't hear any additional valve train noise, I decided to start driving but I watched and listened very carefully. As I accelerated, the PSI moved up to about 40 and stayed there in 5th gear (about 2200 rpm), but would drop down to about 23 if I shifted into 6th gear (about 1400 rpm). I kept it in 5th gear for the ride home. Everything sounded fine.

-After we got home, I let the car sit for about 2 hours and went out and started it again. This time the PSI was at 0! I let it run for a few minutes, increasing and decreasing the revs to see if the PSI changed but it did not. It stayed at 0. Then I started hearing major valve train clatter (well, relatively major... I would say NOTICABLE valve train clatter and definitely more than the normal.)

-Just as I was about to shut it down, it jumped up to 8 psi, then 10, then leveled out at 40 psi idle. I could immediately hear the valve clatter subside and go back to normal. I took it for a drive and it performed absolutely normal. Just like nothing had ever been wrong.

-I am now very nervous and do not want to drive it for fear of getting stranded somewhere or ruining my motor.

If anyone can offer any insight, I would greatly appreciate it.

Thank you,
Mark

DangerBrian

I also have a 2001 with approx 65K miles - no mods. I had this exact scenario happen to me recently in my driveway. I went to move the car and got the "Low Oil Pressure" warning and the gauge said "0". I immediately shut it down and checked the oil level and all was fine. I restarted the car and all was back to normal. The next day I went out and again "Low Oil Pressure"/gauge at "0". At this point I started searching threads here on the forum and found everything from bad oil pumps to the known issue of the OPS; although those usually fail high with PSI of 130. I ordered the OPS relocation kit from DPE Corvettes and installed it. It contains a mechanical gauge before the OPS so you always know if you have oil pressure. Since installing it, I have not had any issues, but I am keeping my eye on it very close. I at least can know with certainty if it is the OPS or wiring or some other issue b/c I have a manual gauge now. My oil pressures were right in line with what you stated and also seemed to have (also what I read as normal) some valve train noise until motor is warmed up. I know all I am doing is confirming some of your findings, but in my case it seems the OPS was the issue. I will be following the thread to see what some more versed guys have to say about it as I am too a little cautious still; but both mechanical and dash gauge are working and displaying the same oil pressures so I hope my issue is resolved

armycopter

Thank you for the feedback Danger. The only reason I would rule out the OPS is that I definitely heard valve clatter (or something like that, I am no expert on engines) right up until the oil pressure started climbing from zero back to normal. Now it sounds fine.

chaase

The oil pressure sensor failing is common, but extra noises coming from the engine is an indicator of restricted flow. I wouldn't drive it except to get it fixed.

It could be your pump dieing or something caught/clogged in the filter or pick up. That could choke off the flow. After running the clog cleared and pressure is back to normal. I would take it in or if you are the handy type pull the pan and filter to see if anything is out of the ordinary.

I am not sure where the oil pump is on the LSx engines, and if they are mechanical or not, but on many small blocks mechanical pumps are pretty easy to replace.

Edit: Here is a how to on replacing the oil pump...not super easy.
http://www.ls1howto.com/index.php?article=4

DangerBrian

Yeah, my motor never sounded any different than normal. That is why I had my suspicions about the OPS, but -0- oil pressure will get your attention! Hopefully you get some good feedback for a direction. This forum has been invaluable to me thus-far

Eric D

Mark,

It maybe time to replace the oil pump. What you had happen is a stuck pressure releif valve, located on the oil pump. It doesn't happen too often but can. A lot of folks will replace the stock oil pump while doing a cam install, so you may have something other than the stock pump in place. If it were mine, I would drive it for a while with a close eye on the oil pressure. It might not happen again, but there is no way of knowing for sure. All it takes is a small partical to cause the relief to stick.

lucky131969

For anyone reading............the above is wrong in every way. If you get a 0 psi oil pressure reading, shut the engine off immediately....do not continue to rev the engine.

ipuig

The oil pressure has already dropped to 0 once. What additional indications are you looking before deciding to at the very least remove the oil pump and inspect or replace it.

I recommend you replace the oil filter, cut open the one you removed and inspect it for metal particles. If there are any present, run a magnet over them. Non-magnetic metallic particles typically come from bearing surfaces.

Blue Angel

This same wierd oil pressure fluctuation was happening with my car as well. What I noticed was after a high RPM sprint the oil pressure at idle would drop below normal, sometimes below 20psi. Driving around at low RPM would bring the pressure back up a bit but it would drop again at idle. Basically the oil pressure would vary proportional to the engine speed.

This type of behaviour, as Eric D has pointed out above, is a stuck pressure relief valve. To get my engine to return to normal pressures I would have to rev it up over 5k RPM, then the relief valve would move and return to it's proper position and idle pressure stabilized at ~35psi just like before.

I'm putting in a Melling High Volume 10296 pump with the low pressure spring next week. I hope the pressure relief valve in this new pump works a lot smoother than the one in my car right now! Unfortunately this is a big job to replace, but I've known about this issue for quite some time and have to tear into the motor to replace a bad cam and lifters anyway, so in goes the new pump!

ZZ06

IF your car is stock why not replace with a stock? OR just buy an LS6 oil pump.

dgrant3830

Absolutely correct!

Eric D

Man, Lucky…you are correct and I should have had that in my response as well. My bad!

However, the engine will shutdown off all by itself if you run it long enough with “0” pressure…..sad thing in most cases, never to start again!

DangerBrian

For anyone interested, I in doing some research on this Pressure relief valve found these 2 resources. The fist link is to another forum where an engineer did a nice write up of oil pressures and shimming the oil pressure relief valve spring; the other is a short youtube video showing the actual pump torn down and being ported/rebuilt. They helped me b/c I had been unable to put a picture with what people were saying. Maybe they'll help you too. I like pictures

http://ls1tech.com/forums/advanced-e...ief-study.html

http://www.youtube.com/watch?v=lMqBV7cNQL8

lucky131969

I guess I must be from a different planet, because it has happened to me (on a different vehicle). My heart immediately went into my stomach, and I almost broke my fingers trying to shut off the ignition

dgrant3830

GF's son has a Scion which has had a bad oil leak for some time. He's been putting off the repair. Well, turns out he thought the oil light on the dash was the oil level sensor, so he would stop somewhere to buy more oil when he got a chance. Light came on one too many times and the engine smoked itself to a dead stop. He's having to spend for a new engine now along with the newly acquired knowledge that low oil pressure is a really bad thing.

armycopter

Well, thanks everyone for all the great responses. It appears I am an idiot by keeping my engine running with zero psi for a few minutes. Live and learn I guess. Hopefully I didn't do any major damage.

I started the car last night and all was well. Pressures were all normal and the car sounded fine.

I am, however, seriously considering replacing the oil pump. I was hoping to find a thread on here that outlined the procedure but no such luck. I am "fairly" mechanically inclined and have replaced cyclinders, pistons, etc on motorcycles (not a car yet) so I think I should be able to remove the front portion of the engine and replace the pump. God only knows why the pump has to be located in that area. I thought most pumps were behind the oil pan. Oh well.

The first thing I am going to do is change the oil and take the oil filter apart to see if there is any metal inside. Then go from there.

chaase

I linked you a full write up on how to replace the oil pump with pictures in my post above.

armycopter

Not sure how I missed that! Thanks chaase!

armycopter

Chaase, after reviewing that link I think I'm going to start calling around and get a quote. It may be a bit more work than I had anticpated!

chaase

I took a look at it and I would pass too 8-)