Phantom Posted December 16, 2011 Share Posted December 16, 2011 (edited) Did a search and all I found was a short thread on low oil pressure in an LS2. I have an LS1 out of a '98 Camaro Z28 with only 36,000 miles on it. It has been in the car 7 years now and has had what I consider excellent oil pressure. The oil pressure gauge needle generally runs straight up to just right of straight up at all RPM's from idle up. I am running 5W-30 Mobil 1 and have since i put the engine in the car. Just before I put the car up for the winter I got a real shock. I was running down the highway in 6th so the engine was turning 1,500 RPM at 60 MPH and my oil pressure gauge read '0'. Yikes! After much experimenting I've found that my oil pressure gauge reads in the "normal" range as long as the engine is turning 1,900 RPM or higher. If it drops below that it starts dropping off quickly to 0 at anything 1,500 RPM or below. Any ideas of what could be causing this? Is it possible that there is an issue with the oil pickup in the sump that is overcome with slightly higher oil pump speeds? Any one who has experienced this please weigh in. Thanks. Hmm - now that I think about it - I suppose my oil filter could be mostly plugged which a higher RPM pump speed would also over come - either by pushing more oil through the filter or through its bypass. Any other possibilites? Edited December 16, 2011 by Phantom Quote Link to comment Share on other sites More sharing options...
Bigdeezs Posted December 17, 2011 Share Posted December 17, 2011 possibly a spun or damaged bearing(s) bleeding off pressure at low oil pump speed...but overcomes the loss at higher speeds? Hopefully not . Also I would try a mechanical pressure gauge to rule out the gauge, sender or wiring isn't having any issues. Quote Link to comment Share on other sites More sharing options...
Phantom Posted December 18, 2011 Author Share Posted December 18, 2011 With the engine having only 36K miles on it I certainly hope it's not a spun/damaged bearing. Also, the problem came on rather suddenly which made me initially think it was a sender or gauge problem until I realized that it is not random but totally repeatable at specific RPM's. I am keeping that in the back of my mind, though. I think I'll do an oil and filter change to see if it's the filter and save some of the oil to get it analyzed for metal. That could verify or rule out the bearing issue. I also have a spare gauge from my son's 240Z that now has Autometer gauges that I could swap out and test the gauge itself. The sender will be fun as I don't remember where it's installed and I'll have to hunt it down. Quote Link to comment Share on other sites More sharing options...
rsicard Posted December 18, 2011 Share Posted December 18, 2011 Horsepower TV had an issue with Low Oil Pressure on a LSx engine. What was found was an Oil Pickup tube that was not mating correctly and letting in air in the pumping path. The pickup tube was reoriented and the issue eliminated for what it is worth. If that is the problem it may be wise to replace the oil pump. Quote Link to comment Share on other sites More sharing options...
Bigdeezs Posted December 18, 2011 Share Posted December 18, 2011 I've personally had issues with the pickup tube o-ring not seating correctly causing issues like this but it didnt go from working normally to this. It was immediately after installation. Quote Link to comment Share on other sites More sharing options...
ColtGT4g63 Posted December 24, 2011 Share Posted December 24, 2011 I have fought with oil pressure issues in my "old car" in the past as well. Here's what I would do, in this order. 1 - try a different gauge 2 - try a thicker oil / new filter 3 - You can try a different oil pick up O-ring, but like Bigdeez said, its usually a problem that is found immediately after assembly and not something developed. 4 - Remove the pan and inspect the rods / mains, If they're worn out they will cause the vehicle to loose oil pressure once warmed up. So on my car, one night I was at the track and everything was fine with the oil pressure. Then the next time I went to get in line to race I noticed the oil pressure was a little bit lower then normal while sitting there. But I just went and did the run anyway then went home afterwards. Next time I go drive the car, cold start the pressure is good. But as I continue to drive it, the pressure would drop big time. On my car I had a TH350 with no over drive, so when I was on the freeway the engine would be spinning 3k rpm at 60mph. I would normally have 50 - 60 psi of oil pressure at this rpm, But after the engine got hot the pressure would drop as low as 25psi on the freeway. And around town its gotten as low as 5 psi before. I ended up damaging the engine even more, and destroyed one of my turbo's. So I wouldn't drive it around while the problem is present. I had tried different gauge, oil, filter, new O-ring, and problem was still there. Once I pulled the pan and looked at the main journals, I knew what the problem was immediately. Swapped in a new (used) 4.8L, and oil pressure was back to normal. Quote Link to comment Share on other sites More sharing options...
(goldfish) Posted December 30, 2011 Share Posted December 30, 2011 My Subaru just had a similar issue. As it warmed up, the oil pressure light would come on at ever higher rpms. 1000 then 1500 all the way up to 2500. The sender acquired a leak, letting pressure bleed off from the switch causing it to trigger. It was a tiny crack and didn't affect the real oil pressure, only lost 2 drops of oil out of it. Sure made me nervous. Quote Link to comment Share on other sites More sharing options...
RPMS Posted June 24, 2019 Share Posted June 24, 2019 Phantom, I know this is an ancient thread, but what was the resolution to your low oil pressure issue? (my guess is a bad sending unit.) Quote Link to comment Share on other sites More sharing options...
Phantom Posted July 16, 2019 Author Share Posted July 16, 2019 (edited) Yeah - it was the sending unit. Replaced it and all was fine until a year later when it failed too. Got another one and it's been good since then. Edited July 17, 2019 by Phantom Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.