Oil pressure nightmares
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Teching In
Joined: Aug 2009
Posts: 26
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From: Green Lake, WI
Oil pressure nightmares I can't for the life of me figure out if I have a real problem or if I just lucked out and got an engine build that for whatever reason has low oil pressure. Here's the story:
2006 GTO, LS2 engine with a mild cam, ported heads, and accompanying bolt ons
Back in 2020 my motor started ticking on the dyno. Limped it home, took it apart. #2 exhaust lifter had spun. Wiped out the cam lobe, so I took the engine apart and had a quality engine builder clean the block, inspect the crank, replace the bearings, upgrade the pistons and con rods and give me back the short block to reassemble.
While I was putting it back together I added an Improved Racing Oil Pan Baffle, Crank Scraper, and Windage Tray. I installed a Melling 10295 oil pump as well. When I got it all put back together, the factory sensor was telling me the engine had low 10s psi oil pressure at idle and only 38 at WOT. At first I thought maybe I used the wrong O-ring. So I dropped the pan and put the thicker oil ring on. No improvement.
The following winter I took it apart again, took the short block to a different shop and we looked at it again. We took the crank out and a couple of the bearings had copper showing, and they had only a few hundred miles on them. I saw when I reinstalled the pickup tube to the pump the last time that the ear had gotten bent. The shop inspected the crank and said the journals were fine. They put new bearings in it. Meanwhile I got a new pickup tube, another new 10295 pump, an Improved Racing barbell and the bracket to hold down the other side of the pickup tube, a new cam retainer plate, and I aligned the pump this time. Got it all back together, ran it up and the pressure still reads low and I'm getting warnings on the dash.
I got myself a mechanical gauge and hooked it up right after the oil filter. On a cold start, it makes 45psi at idle. At operating temp it makes around 20 psi at idle. The electronic sensor consistently reads lower than the mechanical gauge, a good 10-15 psi lower. The most recent thing I tried is replacing all the O-rings in the valley cover because I had never done that before. No improvement.
All that aside, an engine with a 10295 pump, a crank scrapper, a windage tray, a billet barbell, and every gasket and seal in the oil circuit being brand new, does not seem like it should be making only 45psi of pressure at idle when cold and only 20psi when hot. If I wind it up hot, the mechanical gauge shows it will barely make 50 psi of pressure. I used to see 65+psi on the factory pump at WOT. None of this makes sense to me and I feel like if I continue to run the engine as it is I'm going to hurt it.
I'm tired of throwing money at this trying to fix the problem. What am I missing?
2006 GTO, LS2 engine with a mild cam, ported heads, and accompanying bolt ons
Back in 2020 my motor started ticking on the dyno. Limped it home, took it apart. #2 exhaust lifter had spun. Wiped out the cam lobe, so I took the engine apart and had a quality engine builder clean the block, inspect the crank, replace the bearings, upgrade the pistons and con rods and give me back the short block to reassemble.
While I was putting it back together I added an Improved Racing Oil Pan Baffle, Crank Scraper, and Windage Tray. I installed a Melling 10295 oil pump as well. When I got it all put back together, the factory sensor was telling me the engine had low 10s psi oil pressure at idle and only 38 at WOT. At first I thought maybe I used the wrong O-ring. So I dropped the pan and put the thicker oil ring on. No improvement.
The following winter I took it apart again, took the short block to a different shop and we looked at it again. We took the crank out and a couple of the bearings had copper showing, and they had only a few hundred miles on them. I saw when I reinstalled the pickup tube to the pump the last time that the ear had gotten bent. The shop inspected the crank and said the journals were fine. They put new bearings in it. Meanwhile I got a new pickup tube, another new 10295 pump, an Improved Racing barbell and the bracket to hold down the other side of the pickup tube, a new cam retainer plate, and I aligned the pump this time. Got it all back together, ran it up and the pressure still reads low and I'm getting warnings on the dash.
I got myself a mechanical gauge and hooked it up right after the oil filter. On a cold start, it makes 45psi at idle. At operating temp it makes around 20 psi at idle. The electronic sensor consistently reads lower than the mechanical gauge, a good 10-15 psi lower. The most recent thing I tried is replacing all the O-rings in the valley cover because I had never done that before. No improvement.
All that aside, an engine with a 10295 pump, a crank scrapper, a windage tray, a billet barbell, and every gasket and seal in the oil circuit being brand new, does not seem like it should be making only 45psi of pressure at idle when cold and only 20psi when hot. If I wind it up hot, the mechanical gauge shows it will barely make 50 psi of pressure. I used to see 65+psi on the factory pump at WOT. None of this makes sense to me and I feel like if I continue to run the engine as it is I'm going to hurt it.
I'm tired of throwing money at this trying to fix the problem. What am I missing?
Hot oil pressure at 50 psi with rpm, isn’t bad at all. Oil pressure is determined ultimately by your bearing clearances. Do you happen to know where they were set up at? It’s obvious here that your electric gauge on the dash isn’t right…and that’s fairly common.
Agree w/Che70velle. OP, you said a lifter turned. Was the lifter bore damaged? Also, how about the cam bearings? When all comes out of the wash, I still think the most likely thing is the O-ring on the pump, and/or the pickup tube mounting area of the pump intake. Also, it could be the pickup tube has a small crack, and when hot, the crack opens up. One way you could verify is something I did, and it worked for me, and I've also seen others do this with success. First thing to do is take a spin in the car, and warm the motor and oil up to temp. Park the car, and raise the rear of the car, and dump another 3-4 quarts of oil into it. DO NOT REV THE ENGINE!!! THEN check the hot idle oil pressure. If it changes, the O-ring/pump intake/intake tube area has some sort of issue. If it doesn't, then it's an internal issue. Another thought; if it is internal, perhaps the pump bypass spring isn't heat treated properly. When it gets hot, say 210°, maybe it collapses to easily. Just trying to help, and I wish you luck. The OEM gauge, and oil sender, are as reliable as a politicians promises.......
EDIT!!!! DONT FORGET TO DRAIN THE EXTRA OIL!!!!
EDIT!!!! DONT FORGET TO DRAIN THE EXTRA OIL!!!!
Last edited by grinder11; May 26, 2022 at 08:28 AM.
