Oil Pressure Drops with Throttle: Insight?
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Teching In
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Oil Pressure Drops with Throttle: Insight? I am writing this post to see if anyone has some opinions on troubleshooting a potential oiling issue on my newly built motor.
2001 C5 Z06 - L96 Gen4 6.0 swap
Got the new motor on a base tune to drive around to put a few hundred miles on it before a WOT tune. I noticed when I give it gas while driving the oil pressure would show a drop of 2-4 PSI and when I release the throttle the oil pressure would jump back up 2-4 PSI. Melling 10295 high pressure stock volume oil pump, the motor has great oil pressure. 50+PSI on cold start, ~32 PSI when oil temps hit ~200F, ~26 PSI when oil temps hit ~220F. I am using 5w-30 Mobil 1 for my normal break in miles. The "pressure drop" does not replicate on my gauge when revving at a stand still under no load. Cruising at 2k RPM with oil temp 200F+ oil pressure is at 40PSI, if i give some throttle to accelerate oil pressure drops from 40 to 38 and when I let off it jumps back to 40. If I continue with acceleration the oil pressure rises normally and still has a 2PSI jump at the end; for example im driving at 2k RPM with 40PSi, give gas and it drops to 38 and rises to 43 once I hit 3k RPM, then i let off at 3k RPM and it jumps from 43 to 45 PSI. I have verified this condition with a mechanical oil pressure gauge located above the oil filter at the block off plate. My gauge reading to the dash is located behind the intake like the gen 3 motors. I have not done a WOT pull, the most RPM ive done is 5k. I check the dipstick multiple times for signs of foaming/bubbles if there is a windage issue, no foaming noticeable.
To my understanding there should not be any drop in oil pressure with acceleration, it should always increase. I spent a lot of time and money building this motor so I want to make sure everything is healthy and I am not damaging anything.
Currently I am leaning towards a potential issue with the oil pump pressure relief spring valve, that it cant handle the change in load, but unfortunately there is no way to test that without tearing apart the motor. And I am not sure why it would be such a small fluctuation only with load.
Or am I crazy suspecting this to be an issue at all? I am not loosing a significant amount of pressure, but I still think I shouldn't be loosing any pressure.
If the pickup tube oring is pinched, wouldn't there be worse symptoms happening all the time? I was very cautious installing the pickup tube, I am confident it is not pinched. I also added the bracket to use both bolt holes for the pickup.
This is my first time using a crank scraper instead of windage tray, but windage symptoms do not correlate to my condition to my understanding.
Any insight here would be greatly appreciated
Brief overview of the build: The previous LS6 cracked a piston when the spark plug porcelain broke and dropped down into the chamber. The new motor is a L96 block with 273 heads. Took the block to machine shop to be pressure tested, decked, bored .030 over, align honed with arp main studs, new cam bearings installed, rotating assembly balanced and rods resized with arp rod bolts. The oil pump was reused from the previous motor, it has less than 2k miles on it. LS6 crank polished and reused, cam was reused. Cloyes 4x billet gears and katech chain. DOD delete valley cover using o-rings. New oil barbell. Johnson linkbar axle oiling lifters 2116. Diamond Forged Pistons. Gen4 rods. New front cover for cam sensor hole. Custom measured Manton pushrods. plasti gauge was used to double check clearances measured by machine shop. both mains and rods checked at .0020-.0025 like they said. Stock sized bearings from king. crank thrust was checked and measured at .004 with dial indicator. I decided to use a crank scraper from Improved racing which replaces the factory windage tray per instructions. I also added oil pan baffles from improved racing for the batwing style pan, installed per the instructions. Pickup tube is set to factory specs. I used the thicker red o-ring for the pickup tube, this is not my first time installing a pickup, there is no reason for me to believe it is pinched. PCV is vented to atmosphere with catch can for now. I used Driven break in oil with zinc on the first start up. I built this motor myself while I was working at a mechanics shop so I know everything about it if there is information missing here.
2001 C5 Z06 - L96 Gen4 6.0 swap
Got the new motor on a base tune to drive around to put a few hundred miles on it before a WOT tune. I noticed when I give it gas while driving the oil pressure would show a drop of 2-4 PSI and when I release the throttle the oil pressure would jump back up 2-4 PSI. Melling 10295 high pressure stock volume oil pump, the motor has great oil pressure. 50+PSI on cold start, ~32 PSI when oil temps hit ~200F, ~26 PSI when oil temps hit ~220F. I am using 5w-30 Mobil 1 for my normal break in miles. The "pressure drop" does not replicate on my gauge when revving at a stand still under no load. Cruising at 2k RPM with oil temp 200F+ oil pressure is at 40PSI, if i give some throttle to accelerate oil pressure drops from 40 to 38 and when I let off it jumps back to 40. If I continue with acceleration the oil pressure rises normally and still has a 2PSI jump at the end; for example im driving at 2k RPM with 40PSi, give gas and it drops to 38 and rises to 43 once I hit 3k RPM, then i let off at 3k RPM and it jumps from 43 to 45 PSI. I have verified this condition with a mechanical oil pressure gauge located above the oil filter at the block off plate. My gauge reading to the dash is located behind the intake like the gen 3 motors. I have not done a WOT pull, the most RPM ive done is 5k. I check the dipstick multiple times for signs of foaming/bubbles if there is a windage issue, no foaming noticeable.
To my understanding there should not be any drop in oil pressure with acceleration, it should always increase. I spent a lot of time and money building this motor so I want to make sure everything is healthy and I am not damaging anything.
Currently I am leaning towards a potential issue with the oil pump pressure relief spring valve, that it cant handle the change in load, but unfortunately there is no way to test that without tearing apart the motor. And I am not sure why it would be such a small fluctuation only with load.
Or am I crazy suspecting this to be an issue at all? I am not loosing a significant amount of pressure, but I still think I shouldn't be loosing any pressure.
If the pickup tube oring is pinched, wouldn't there be worse symptoms happening all the time? I was very cautious installing the pickup tube, I am confident it is not pinched. I also added the bracket to use both bolt holes for the pickup.
This is my first time using a crank scraper instead of windage tray, but windage symptoms do not correlate to my condition to my understanding.
Any insight here would be greatly appreciated
Brief overview of the build: The previous LS6 cracked a piston when the spark plug porcelain broke and dropped down into the chamber. The new motor is a L96 block with 273 heads. Took the block to machine shop to be pressure tested, decked, bored .030 over, align honed with arp main studs, new cam bearings installed, rotating assembly balanced and rods resized with arp rod bolts. The oil pump was reused from the previous motor, it has less than 2k miles on it. LS6 crank polished and reused, cam was reused. Cloyes 4x billet gears and katech chain. DOD delete valley cover using o-rings. New oil barbell. Johnson linkbar axle oiling lifters 2116. Diamond Forged Pistons. Gen4 rods. New front cover for cam sensor hole. Custom measured Manton pushrods. plasti gauge was used to double check clearances measured by machine shop. both mains and rods checked at .0020-.0025 like they said. Stock sized bearings from king. crank thrust was checked and measured at .004 with dial indicator. I decided to use a crank scraper from Improved racing which replaces the factory windage tray per instructions. I also added oil pan baffles from improved racing for the batwing style pan, installed per the instructions. Pickup tube is set to factory specs. I used the thicker red o-ring for the pickup tube, this is not my first time installing a pickup, there is no reason for me to believe it is pinched. PCV is vented to atmosphere with catch can for now. I used Driven break in oil with zinc on the first start up. I built this motor myself while I was working at a mechanics shop so I know everything about it if there is information missing here.
I have to question why you’d even consider reusing the oil pump from the hurt engine, regardless of the low miles. At a minimum you needed to completely disassemble the pump and wash everything. And if you did this, $200 for a new pump, compared to what you spent on this investment is pennies on the dollar, plus peace of mind.
You definitely have something going on, as an increase in rpm should increase oil pressure. Did you clean the pickup screen properly? They come apart with some work. How did your oil filter media look after first oil change?
You definitely have something going on, as an increase in rpm should increase oil pressure. Did you clean the pickup screen properly? They come apart with some work. How did your oil filter media look after first oil change?
Agreed, If you didn't open that pump and inspect it, I would question it after a motor failed. Personally, I wouldn't even waste my time after an engine failure. The lifters alone are far too expensive to save $150
Remember, The pump get's directly fed by whatever is in the oil pan, Then it goes to the filter...
Remember, The pump get's directly fed by whatever is in the oil pan, Then it goes to the filter...
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Teching In
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Thanks for the replies.
I agree, I should have replaced it.
I have the filter from the first change, I just need to get a tool to cut it open properly.
My initial reasoning for not replacing the oil pump is that there was no indication of any metal contamination in the oil from the previous motor. A pilot ground got dropped in the intake, it made its way into cylinder 5 and tore up the piston and head and broke the spark plug. The piston cracked between the ringlands and the alum block cracked behind the sleeve, which was surprising because the sleeve barely looked scratched. I was super bummed when I tore it down because the motor looked perfect and would have been very healthy for a long time. So I originally thought there should be no damage to the oil pump because there was never any metal that went through it to damage it. I regret that now after thinking about it.
I did not take it all the way apart to clean it. I used compressed air and a lot of brake clean while also spinning they key multiple times. Same with the pickup tube and I boroscoped it after.
Its funny because I refused to reuse the intake after that mess but never thought twice about the oil pump.
The lifters are also reused from that motor, but those are a little too expensive to replace
I agree, I should have replaced it.
I have the filter from the first change, I just need to get a tool to cut it open properly.
My initial reasoning for not replacing the oil pump is that there was no indication of any metal contamination in the oil from the previous motor. A pilot ground got dropped in the intake, it made its way into cylinder 5 and tore up the piston and head and broke the spark plug. The piston cracked between the ringlands and the alum block cracked behind the sleeve, which was surprising because the sleeve barely looked scratched. I was super bummed when I tore it down because the motor looked perfect and would have been very healthy for a long time. So I originally thought there should be no damage to the oil pump because there was never any metal that went through it to damage it. I regret that now after thinking about it.
I did not take it all the way apart to clean it. I used compressed air and a lot of brake clean while also spinning they key multiple times. Same with the pickup tube and I boroscoped it after.
Its funny because I refused to reuse the intake after that mess but never thought twice about the oil pump.
The lifters are also reused from that motor, but those are a little too expensive to replace
Thanks for the replies.
I agree, I should have replaced it.
I have the filter from the first change, I just need to get a tool to cut it open properly.
My initial reasoning for not replacing the oil pump is that there was no indication of any metal contamination in the oil from the previous motor. A pilot ground got dropped in the intake, it made its way into cylinder 5 and tore up the piston and head and broke the spark plug. The piston cracked between the ringlands and the alum block cracked behind the sleeve, which was surprising because the sleeve barely looked scratched. I was super bummed when I tore it down because the motor looked perfect and would have been very healthy for a long time. So I originally thought there should be no damage to the oil pump because there was never any metal that went through it to damage it. I regret that now after thinking about it.
I did not take it all the way apart to clean it. I used compressed air and a lot of brake clean while also spinning they key multiple times. Same with the pickup tube and I boroscoped it after.
Its funny because I refused to reuse the intake after that mess but never thought twice about the oil pump.
The lifters are also reused from that motor, but those are a little too expensive to replace
I agree, I should have replaced it.
I have the filter from the first change, I just need to get a tool to cut it open properly.
My initial reasoning for not replacing the oil pump is that there was no indication of any metal contamination in the oil from the previous motor. A pilot ground got dropped in the intake, it made its way into cylinder 5 and tore up the piston and head and broke the spark plug. The piston cracked between the ringlands and the alum block cracked behind the sleeve, which was surprising because the sleeve barely looked scratched. I was super bummed when I tore it down because the motor looked perfect and would have been very healthy for a long time. So I originally thought there should be no damage to the oil pump because there was never any metal that went through it to damage it. I regret that now after thinking about it.
I did not take it all the way apart to clean it. I used compressed air and a lot of brake clean while also spinning they key multiple times. Same with the pickup tube and I boroscoped it after.
Its funny because I refused to reuse the intake after that mess but never thought twice about the oil pump.
The lifters are also reused from that motor, but those are a little too expensive to replace
As FastBrick said, the pump/lifters/bearings saw whatever was in the pan, and it all happened very forcefully and very fast.
At least the lifters are after the filter... That doesn't mean the small stuff can't still get by. Just because you didn't see any metal doesn't mean there weren't small particles on the micron level.
As Che70velle said I/ We would have at least had them apart. I believe Johnson will inspect and clean them for you for a small fee.
We are not trying to scare you or spend your money Un-Necessarily. We want to see you and others be successful.
I feel like you need to at least open that pump up and inspect it.
As Che70velle said I/ We would have at least had them apart. I believe Johnson will inspect and clean them for you for a small fee.
We are not trying to scare you or spend your money Un-Necessarily. We want to see you and others be successful.
I feel like you need to at least open that pump up and inspect it.
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Teching In
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So that all happened when I got the new lifters and installed them, that metal piece got dropped in the intake when I was working on it. I started the motor and there was an awful noise, double checked things and started it again and the noise was gone. Had a misfire and that's when I pulled the plug and found a catastrophe. So that motor had less than an hour of run time and the same goes for the new lifters before I tore it down. In that time a tiny chunk of piston would need to pass the pickup screen, oil pump, and then the filter to get to the lifter, that is where my skepticism comes from.
The motor has been running strong for 600 miles so far, besides this oil pressure fluctuation. Logically, the filter would have prevented anything from damaging the lifters, can't say the same for the pump.
I was looking over the oil pressure logs again and something else seemed odd. I never brought the engine past 4k rpm and in the log I am building up to 50-55 psi of pressure. Unfortunately I cant see exactly what RPM, but that seems like too much pressure to me to be in the 50s at 3k rpm.
Again leading to the theory of something wrong with the oil pump or pressure relief spring.
I will get the first filter and the current one cut open to look for anything abnormal.
The motor has been running strong for 600 miles so far, besides this oil pressure fluctuation. Logically, the filter would have prevented anything from damaging the lifters, can't say the same for the pump.
I was looking over the oil pressure logs again and something else seemed odd. I never brought the engine past 4k rpm and in the log I am building up to 50-55 psi of pressure. Unfortunately I cant see exactly what RPM, but that seems like too much pressure to me to be in the 50s at 3k rpm.
Again leading to the theory of something wrong with the oil pump or pressure relief spring.
I will get the first filter and the current one cut open to look for anything abnormal.
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I am writing this post to see if anyone has some opinions on troubleshooting a potential oiling issue on my newly built motor.
2001 C5 Z06 - L96 Gen4 6.0 swap
Got the new motor on a base tune to drive around to put a few hundred miles on it before a WOT tune. I noticed when I give it gas while driving the oil pressure would show a drop of 2-4 PSI and when I release the throttle the oil pressure would jump back up 2-4 PSI. Melling 10295 high pressure stock volume oil pump, the motor has great oil pressure. 50+PSI on cold start, ~32 PSI when oil temps hit ~200F, ~26 PSI when oil temps hit ~220F. I am using 5w-30 Mobil 1 for my normal break in miles. The "pressure drop" does not replicate on my gauge when revving at a stand still under no load. Cruising at 2k RPM with oil temp 200F+ oil pressure is at 40PSI, if i give some throttle to accelerate oil pressure drops from 40 to 38 and when I let off it jumps back to 40. If I continue with acceleration the oil pressure rises normally and still has a 2PSI jump at the end; for example im driving at 2k RPM with 40PSi, give gas and it drops to 38 and rises to 43 once I hit 3k RPM, then i let off at 3k RPM and it jumps from 43 to 45 PSI. I have verified this condition with a mechanical oil pressure gauge located above the oil filter at the block off plate. My gauge reading to the dash is located behind the intake like the gen 3 motors. I have not done a WOT pull, the most RPM ive done is 5k. I check the dipstick multiple times for signs of foaming/bubbles if there is a windage issue, no foaming noticeable.
To my understanding there should not be any drop in oil pressure with acceleration, it should always increase. I spent a lot of time and money building this motor so I want to make sure everything is healthy and I am not damaging anything.
Currently I am leaning towards a potential issue with the oil pump pressure relief spring valve, that it cant handle the change in load, but unfortunately there is no way to test that without tearing apart the motor. And I am not sure why it would be such a small fluctuation only with load.
Or am I crazy suspecting this to be an issue at all? I am not loosing a significant amount of pressure, but I still think I shouldn't be loosing any pressure.
If the pickup tube oring is pinched, wouldn't there be worse symptoms happening all the time? I was very cautious installing the pickup tube, I am confident it is not pinched. I also added the bracket to use both bolt holes for the pickup.
This is my first time using a crank scraper instead of windage tray, but windage symptoms do not correlate to my condition to my understanding.
Any insight here would be greatly appreciated
Brief overview of the build: The previous LS6 cracked a piston when the spark plug porcelain broke and dropped down into the chamber. The new motor is a L96 block with 273 heads. Took the block to machine shop to be pressure tested, decked, bored .030 over, align honed with arp main studs, new cam bearings installed, rotating assembly balanced and rods resized with arp rod bolts. The oil pump was reused from the previous motor, it has less than 2k miles on it. LS6 crank polished and reused, cam was reused. Cloyes 4x billet gears and katech chain. DOD delete valley cover using o-rings. New oil barbell. Johnson linkbar axle oiling lifters 2116. Diamond Forged Pistons. Gen4 rods. New front cover for cam sensor hole. Custom measured Manton pushrods. plasti gauge was used to double check clearances measured by machine shop. both mains and rods checked at .0020-.0025 like they said. Stock sized bearings from king. crank thrust was checked and measured at .004 with dial indicator. I decided to use a crank scraper from Improved racing which replaces the factory windage tray per instructions. I also added oil pan baffles from improved racing for the batwing style pan, installed per the instructions. Pickup tube is set to factory specs. I used the thicker red o-ring for the pickup tube, this is not my first time installing a pickup, there is no reason for me to believe it is pinched. PCV is vented to atmosphere with catch can for now. I used Driven break in oil with zinc on the first start up. I built this motor myself while I was working at a mechanics shop so I know everything about it if there is information missing here.
2001 C5 Z06 - L96 Gen4 6.0 swap
Got the new motor on a base tune to drive around to put a few hundred miles on it before a WOT tune. I noticed when I give it gas while driving the oil pressure would show a drop of 2-4 PSI and when I release the throttle the oil pressure would jump back up 2-4 PSI. Melling 10295 high pressure stock volume oil pump, the motor has great oil pressure. 50+PSI on cold start, ~32 PSI when oil temps hit ~200F, ~26 PSI when oil temps hit ~220F. I am using 5w-30 Mobil 1 for my normal break in miles. The "pressure drop" does not replicate on my gauge when revving at a stand still under no load. Cruising at 2k RPM with oil temp 200F+ oil pressure is at 40PSI, if i give some throttle to accelerate oil pressure drops from 40 to 38 and when I let off it jumps back to 40. If I continue with acceleration the oil pressure rises normally and still has a 2PSI jump at the end; for example im driving at 2k RPM with 40PSi, give gas and it drops to 38 and rises to 43 once I hit 3k RPM, then i let off at 3k RPM and it jumps from 43 to 45 PSI. I have verified this condition with a mechanical oil pressure gauge located above the oil filter at the block off plate. My gauge reading to the dash is located behind the intake like the gen 3 motors. I have not done a WOT pull, the most RPM ive done is 5k. I check the dipstick multiple times for signs of foaming/bubbles if there is a windage issue, no foaming noticeable.
To my understanding there should not be any drop in oil pressure with acceleration, it should always increase. I spent a lot of time and money building this motor so I want to make sure everything is healthy and I am not damaging anything.
Currently I am leaning towards a potential issue with the oil pump pressure relief spring valve, that it cant handle the change in load, but unfortunately there is no way to test that without tearing apart the motor. And I am not sure why it would be such a small fluctuation only with load.
Or am I crazy suspecting this to be an issue at all? I am not loosing a significant amount of pressure, but I still think I shouldn't be loosing any pressure.
If the pickup tube oring is pinched, wouldn't there be worse symptoms happening all the time? I was very cautious installing the pickup tube, I am confident it is not pinched. I also added the bracket to use both bolt holes for the pickup.
This is my first time using a crank scraper instead of windage tray, but windage symptoms do not correlate to my condition to my understanding.
Any insight here would be greatly appreciated
Brief overview of the build: The previous LS6 cracked a piston when the spark plug porcelain broke and dropped down into the chamber. The new motor is a L96 block with 273 heads. Took the block to machine shop to be pressure tested, decked, bored .030 over, align honed with arp main studs, new cam bearings installed, rotating assembly balanced and rods resized with arp rod bolts. The oil pump was reused from the previous motor, it has less than 2k miles on it. LS6 crank polished and reused, cam was reused. Cloyes 4x billet gears and katech chain. DOD delete valley cover using o-rings. New oil barbell. Johnson linkbar axle oiling lifters 2116. Diamond Forged Pistons. Gen4 rods. New front cover for cam sensor hole. Custom measured Manton pushrods. plasti gauge was used to double check clearances measured by machine shop. both mains and rods checked at .0020-.0025 like they said. Stock sized bearings from king. crank thrust was checked and measured at .004 with dial indicator. I decided to use a crank scraper from Improved racing which replaces the factory windage tray per instructions. I also added oil pan baffles from improved racing for the batwing style pan, installed per the instructions. Pickup tube is set to factory specs. I used the thicker red o-ring for the pickup tube, this is not my first time installing a pickup, there is no reason for me to believe it is pinched. PCV is vented to atmosphere with catch can for now. I used Driven break in oil with zinc on the first start up. I built this motor myself while I was working at a mechanics shop so I know everything about it if there is information missing here.
At least the lifters are after the filter... That doesn't mean the small stuff can't still get by. Just because you didn't see any metal doesn't mean there weren't small particles on the micron level.
As Che70velle said I/ We would have at least had them apart. I believe Johnson will inspect and clean them for you for a small fee.
We are not trying to scare you or spend your money Un-Necessarily. We want to see you and others be successful.
I feel like you need to at least open that pump up and inspect it.
As Che70velle said I/ We would have at least had them apart. I believe Johnson will inspect and clean them for you for a small fee.
We are not trying to scare you or spend your money Un-Necessarily. We want to see you and others be successful.
I feel like you need to at least open that pump up and inspect it.
Have you checked OP with a mechanical gauge and it reports this1-2 psi drop? I'm with Grinder just enjoy the car but keep an eye on it. Could the oil be extremely aireated causing this momentary drop in pressure? Have you considered trying different oil filters to see if the issue remains. Just some thoughts to throw out there.
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I’m having the same issue but with new pump, L96 my truck looses 4-6 psi on throttle and has horrible hot oil pressure in gear. My “melling” pump was unfortunately purchased from Michigan motorsports and I think it’s a counterfeit, melling told me it most likely was. I believe mine is a relief valve issue too. Truck won’t make more than 60 psi cold and 50 hot at any rpm’s above 3000. 30-38 idle in gear and around 40 out of gear heat soaked.
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Update Since my last post, I cut the oil filters open and did not see anything to be concerned about. I did notice the oil that drained out was very contaminated with fuel and had a green tint. My assumption is that it's from left over assembly lube and the hack job tuner that had my AFR set to 13.6 and ran my tune wayyy too rich. After putting fresh oil in, the oil pressure dip seemed to improve... maybe placebo.
Since then I purchased HP tuners to tune it myself and so I am able to log my oil pressure along with throttle position. So far I haven't noticed any sudden or large 4psi drops with throttle yet. I took a break on tuning over winter to focus on body work. I will continue logging my oil pressure when I resume tuning this spring.
I agree with Grinder and others, I will keep and eye on the pressure and look at my logs. Every oil change cut the filter and inspect. If nothing changes then it's perfectly fine to me.
Since then I purchased HP tuners to tune it myself and so I am able to log my oil pressure along with throttle position. So far I haven't noticed any sudden or large 4psi drops with throttle yet. I took a break on tuning over winter to focus on body work. I will continue logging my oil pressure when I resume tuning this spring.
I agree with Grinder and others, I will keep and eye on the pressure and look at my logs. Every oil change cut the filter and inspect. If nothing changes then it's perfectly fine to me.
