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Oil pressure drops when engine is hot

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Old 05-28-2015 | 08:30 PM
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Default Oil pressure drops when engine is hot

I get the fact that oils gets hot and thin and oil pressures drop, but just took car to track for first time and saw that my oil pressure drops dramatically when hot and under hard acceleration at high RPMs. I was seeing 2PSI on my electric gauge. After the car sat for a bit, I would get about 12 at idle and it would not increase much when I increased RPMs. I'm not sure if I have a problem, or the electric gauge is having heat saturation issues. I have the gauge sender located in the stock LS location. I plan on adding a Y connection on the block for my electrical gauge and adding a mechanical wet gauge to compare. Engine has a new melling high volume oil pump and should be just fine. Any thoughts?
Old 05-29-2015 | 08:45 AM
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Not sure on the LS engines, but a Motorcraft oil filter is the ONLY oil filter to use on a Ford. Aftermarket oil filters are junk. I can't tell you how many hundreds of cars that I have solved all of their oil pressure problems with a simple filter change. If you are not using an AC/Delco filter, I would suggest that you start there. It is the least expensive (& most overlooked) starting point.
Old 05-29-2015 | 09:30 AM
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Not sure what kind of oil pressure you are running, but the electric sender has a diaphragm that moves a coil that varies the voltage output. If you put a mechanical gauge on it and it reads OK, you probably have a leaking or ruptured sensor diaphragm.

I will also second tbone's comments on oil filters. I will only use OE replacement filters, generally Motorcraft. Its worth 10 minutes and 6 bucks to find out.
Old 05-29-2015 | 12:29 PM
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The ls2 ecm reads oil pressure. You can use an obd-ii app (like Torque) to verify your readings. I haven't gotten to track temps yet but get down to about 27 psi at idle and ~220F temp.
Old 05-29-2015 | 12:54 PM
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What kind of oil are you running and are you a quart over full?

Mine is a stock 60,000 mile LS1 oil pump and it fluctuates between 70 and 80 PSI under the same conditions. The oil pressure is the top gauge on the right and 50 psi is straight up on it.

Note this is a mechanical gauge feeding off the oil filter housing and only NAPA gold and 10-30 Mobil 1 for me. I run 8 quarts in a 7 quart pan and with the remote filter that puts it a good 1/2 inch over full on the dipstick.
Attached Thumbnails Oil pressure drops when engine is hot-12_zpsmg5akwbe.jpg  

Last edited by charchri4; 05-29-2015 at 01:16 PM.
Old 05-31-2015 | 09:46 AM
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I've learned from my first 302 build, if your going to do something, do it right.

I just ordered an oil filter relocation kit and oil cooler kit. The oil cooler sandwich plate has 2 additional ports for sensors. Also ordered mechanical oil PSI gauge and oil temp gauge. They will be installed in a custom pod centered up on top of the dash.

When all this comes in, I'll get to work. I'll start by inspecting current oil and cutting open current oil filter to ensure everything is good. I'll plumb everything and pre-fill the oil cooler before installing. I'll start with 6qts of Mobile 1 and work from there. After everything is circulated, I'll probably add another quart to compensate for all the new oil lines.

I'll now be able to monitor oil temp and pressure on both a mechanical and electrical gauge. If everything is good, then yeah! If not, I'll have to start in pan to make sure PO installed windage tray properly. I'll post results when I get them.
Old 05-31-2015 | 12:00 PM
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A lot of track folks run LS1s a quart high too. I always did autocrossing my donor Camaro and run a good 1/2" up the stick in the Miata too. It's won't help low oil pressure of course but less likely to pump the pan dry in a long left turn. If you didn't know LS1s tend to go dry with more than a few seconds of high RPMs with left G force on them.
Old 06-01-2015 | 10:03 PM
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It's a start to monitoring the issue. Bought a t adapter from JEGS. Have both a mechanical and electrical gauge now.
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Old 06-02-2015 | 12:18 AM
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What the heck is that a boss frog subframe? There is no way under the sun I could ever get at my sender much less see it enough to take a picture of it!
Old 06-02-2015 | 07:57 AM
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Nope, just a V8R subframe. The motor is an LS2 out of a 2006 GTO. Don't know if there is any design difference in other LS2s?
Old 06-03-2015 | 07:38 PM
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Is it possible its a forward mount subframe when they still made those? Can you see if the tunnel is modified?
Old 06-04-2015 | 01:47 AM
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More likely my trans mount is too low! When we talked to Shandell at Mitty he said they offered the option for a while but after a year of nobody wanting it they dropped it. He said they only made 1 forward frame as a mule. So it's possible but not likely it's a forward mount framer.
Old 06-04-2015 | 08:07 AM
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I just had time to change the filter. Oil pressure seems good now and stays good while driving and getting engine hot. Seems like that filter was bad/clogged. Clogged with what you may ask? I will cut it open in a few days when it fully drains. This was the first filter after engine was disassembled and inspected, so it could just be from that (hopefully). I will also follow thru with my cooler and relocation kit install. Using a Wix and Mobile 1 now. Engine sounds good and seems healthy. Only time will show if any real damage was done when the pressure dropped to near zero at high RPMs.
Old 06-05-2015 | 03:58 PM
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You sure the gauge was reading right before? I would think you would hear some noise coming out of her at 0 oil pressure. Seems to me oil filters are suppose to have a valve in them to bypass if that happens. Sure hope everything is OK with it.

I only run WIX or NAPA Gold (Same filter made by WIX) on mine. The wackos that cut them apart on youtube say they are the best.
Old 06-05-2015 | 08:10 PM
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Originally Posted by charchri4
.

I only run WIX or NAPA Gold (Same filter made by WIX) on mine. The wackos that cut them apart on youtube say they are the best.
I have heard good things about them, too.

I always run whatever is installed on whatever engine that it is from the factory. A Ford gets a Motorcraft. A GM gets a Delco, A Toyota gets a Toyota, ect. Working at the dealership, I have seen way too many warranty claim disputes over failed engines equipped with non-factory oil filters. The Fram filters seem to be among the worst. Have you ever noticed the weight difference between the factory filters & some of the aftermarket stuff?
Old 06-06-2015 | 12:28 AM
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+1 ^^ I do that too till the warranty is up at least. I still run a good old Delco PF52 on my 260,000 mile Caviler. I've seen a couple of engines toasted by the oil filter and that is no place to save a few bucks.

The most memorable melt down I ever saw in the dealer was a car came in with 35,000 miles on it and the factory oil filter. What was memorable was how mad the customer was that we wouldn't warranty it...
Old 06-21-2015 | 05:58 PM
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Quick update. I am currently in the Field with the Army, but my wife informs me all my "boxes of stuff" have arrived. I should have an oil cooler, oil filter relocation kit, oil temp gauge, EGT gauge, and gauge pod ready to go. I may have time over July 4th weekend to do something with it all.

I still have not cut open the old filter, but it is sitting waiting for me. After the filter change, pressure seemed good and engine is not making any noise that indicates spun bearing. Plan is another FULL oil change with filter when I add the cooler and relocation kit.
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