Low oil pressure on newly built motor.
06-28-2015, 05:50 PM
#1
Registered User
Thread Starter
Low oil pressure on newly built motor.
Yes i have looked on the forums and havent seen any possible solutions to my issue.
BACK STORY:
About 3 weeks ago i tried installing headers in my car with the engine in it. Many hours later i became so frustrated that i decided to pull the engine to ease the installation. I have had the engine out multiple times so its no big deal. But after seeing my motor out i decided i might as well build it. Forged rods, pistons, all gaskets, stage 2 clutch and chromoly light weight flywheel, headers, catless dual exhaust. Basically just getting ready to re-turbo my car. My past rear mount setup failed after a couple years so im about to buy a front mount kit and would feel better if i had forged internals.
ISSUE:
First start up, 5-30 with lucas additive. She turned over and idled at about 1200 with semi-normal oil pressure. I reset the pedals and monitored the parameters with my Osiris Uprev Cipher. Everthing checked out so i started the first drive to break it in. (after reading multiple threads on break in opinions i read, "do you trust the people that built the car or people on the internet", so ive decided to go with Nissans soft break in). The car drove like new! kept it under 4k and the thing is smooth as heck. except when i stop.. The idle dropped back down to normal at about 800rpm. At 800rpm the dash oil pressure guage was reading about ~5 (barely above 0). when i tap on the gas and get it to about 1000rpm the pressure goes up to 15. at 2k rpm the pressure is about 30 and so forward. I looked up what nissans spec is on the minimum oil pressure at idle and it shows 16. Not sure what these cars are supposed to idle at but i guess its around 800. So yes the oil pressure is a little low. Also i should mention this is only when the engine warms up. On a cold start it jumps to almost 90 and then lowers to 30 when i start to drive then after a short 5 mile drive its warm and the oil pressure will show low and the oil light will usually come on.
I have ordered a new pressure sensor and am hoping that is all the issue is. I replaced the sensor a few weeks prior to the tear down so its not likely though. I need to hook up a external oil pressure sensor to ensure this though. I just wanted to quickly get on the forums to see if i should not be driving this low oil pressure.
Not sure what could be causing it, hopefully not a bearing out of clearance spec. I hit 100 miles today and am probably going to change the oil in the morning. Opinions on 10-30? too thick of oil for a new motor? i have read that this should increase the oil pressure.
Sorry for writing a book, im at work and am getting paid so i figured might as well not leave anything out!
Build thread:
https://my350z.com/forum/engine-and-...gine-swap.html
BACK STORY:
About 3 weeks ago i tried installing headers in my car with the engine in it. Many hours later i became so frustrated that i decided to pull the engine to ease the installation. I have had the engine out multiple times so its no big deal. But after seeing my motor out i decided i might as well build it. Forged rods, pistons, all gaskets, stage 2 clutch and chromoly light weight flywheel, headers, catless dual exhaust. Basically just getting ready to re-turbo my car. My past rear mount setup failed after a couple years so im about to buy a front mount kit and would feel better if i had forged internals.
ISSUE:
First start up, 5-30 with lucas additive. She turned over and idled at about 1200 with semi-normal oil pressure. I reset the pedals and monitored the parameters with my Osiris Uprev Cipher. Everthing checked out so i started the first drive to break it in. (after reading multiple threads on break in opinions i read, "do you trust the people that built the car or people on the internet", so ive decided to go with Nissans soft break in). The car drove like new! kept it under 4k and the thing is smooth as heck. except when i stop.. The idle dropped back down to normal at about 800rpm. At 800rpm the dash oil pressure guage was reading about ~5 (barely above 0). when i tap on the gas and get it to about 1000rpm the pressure goes up to 15. at 2k rpm the pressure is about 30 and so forward. I looked up what nissans spec is on the minimum oil pressure at idle and it shows 16. Not sure what these cars are supposed to idle at but i guess its around 800. So yes the oil pressure is a little low. Also i should mention this is only when the engine warms up. On a cold start it jumps to almost 90 and then lowers to 30 when i start to drive then after a short 5 mile drive its warm and the oil pressure will show low and the oil light will usually come on.
I have ordered a new pressure sensor and am hoping that is all the issue is. I replaced the sensor a few weeks prior to the tear down so its not likely though. I need to hook up a external oil pressure sensor to ensure this though. I just wanted to quickly get on the forums to see if i should not be driving this low oil pressure.
Not sure what could be causing it, hopefully not a bearing out of clearance spec. I hit 100 miles today and am probably going to change the oil in the morning. Opinions on 10-30? too thick of oil for a new motor? i have read that this should increase the oil pressure.
Sorry for writing a book, im at work and am getting paid so i figured might as well not leave anything out!
Build thread:
https://my350z.com/forum/engine-and-...gine-swap.html
Last edited by Speednz; 06-28-2015 at 05:52 PM.
06-28-2015, 10:09 PM
#2
350Z-holic
iTrader: (13)
I cant hear anything because your paint is too loud...
I'm a betting man and I would bet that your oil pressure sensor is going out. If you've driven 100miles and nothing has locked up I bet your oil is being circulated.
I'm a betting man and I would bet that your oil pressure sensor is going out. If you've driven 100miles and nothing has locked up I bet your oil is being circulated.
06-29-2015, 07:09 AM
#3
Registered User
Thread Starter
That's what in hoping it is. Zinc from the oil or a piece of sealant could have broken off and clogged the sensor.
06-29-2015, 10:05 AM
#4
Registered User
Speednz, there have been others here over the years with exactly this problem. The cause was a small internal oil leak from a misplaced or damaged gasket at the front timing cover. A bad pressure sender doesn't act in this manner. Right now I'm in a restaurant in Dubrovnik with just a tiny scrap of wifi so I can't look up any links for you, but if you google around you will find so info on VQ engine internal oil leaks
06-29-2015, 10:42 AM
#5
Registered User
Have you checked the pressure with a known mechanical gauge?
What are your bearing clearances, Rods/Mains? Your built motor could/should be a little loose vs stock, if built for higher HP.
As Op stated, there are places inside that can leak, post oil pump.
What are your bearing clearances, Rods/Mains? Your built motor could/should be a little loose vs stock, if built for higher HP.
As Op stated, there are places inside that can leak, post oil pump.
06-29-2015, 02:18 PM
#6
350Z-holic
iTrader: (13)
I'm giving you a ration of **** more than I'm (seriously) criticizing...so take it in the spirit in which it's intended - do whatever you want!
replace the sensor and go from there...read the factory service manual before you replace the sensor. Many, myself included, have messed up their upper oil pan by over-torque'ing the sensor...I think it takes something like 11 ft-lbs...essentially hand tight.
replace the sensor and go from there...read the factory service manual before you replace the sensor. Many, myself included, have messed up their upper oil pan by over-torque'ing the sensor...I think it takes something like 11 ft-lbs...essentially hand tight.
Last edited by bealljk; 06-29-2015 at 09:09 PM.
06-29-2015, 02:48 PM
#7
Registered User
Thread Starter
Jennifer 2,
Thank you!! I searched and was not able to find the thread mentioned. Was it on here or the "other" forum. Im assuming you mean one of the small orings could be the culprit? unfortunately i dont think its a faulty sensor and it may be a internal oil leak. But the car is not leaking any fluids nor does it smoke any at all under any circumstances. But would this explain the pressure being normal at cold temperatures then significantly dropping when the engine warms up? ( i know this is normal but to this extent)
i-break-things,
Im going to plug a mechanical guage up to it tomorrow. Hopefully i wont have to take my front timing cover off as i believe i may have stripped one of the bolts in the center. Did i just say that out loud?
bealljk,
Wow i did not know that, I tightened it way over 11.. Do you happen to know if one of the wires going to the sensor is a ground or if the ground is made from the threads of the sensor and the oil pan? because i believe i used thread tape and this could be causing a bad ground.. Probably would make the sensor unresponsive but may be the culprit.
Thank you!! I searched and was not able to find the thread mentioned. Was it on here or the "other" forum. Im assuming you mean one of the small orings could be the culprit? unfortunately i dont think its a faulty sensor and it may be a internal oil leak. But the car is not leaking any fluids nor does it smoke any at all under any circumstances. But would this explain the pressure being normal at cold temperatures then significantly dropping when the engine warms up? ( i know this is normal but to this extent)
i-break-things,
Im going to plug a mechanical guage up to it tomorrow. Hopefully i wont have to take my front timing cover off as i believe i may have stripped one of the bolts in the center. Did i just say that out loud?
bealljk,
Wow i did not know that, I tightened it way over 11.. Do you happen to know if one of the wires going to the sensor is a ground or if the ground is made from the threads of the sensor and the oil pan? because i believe i used thread tape and this could be causing a bad ground.. Probably would make the sensor unresponsive but may be the culprit.
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06-29-2015, 09:32 PM
#8
350Z-holic
iTrader: (13)
nah, one wire is a ground and the other is a 5v signal.
In the FSM(for my 2003), section LU-14(engine lubrication) has the torque at 9-12 ft-lbs. Section DI-46 (drivers information) has a procedure to check the sensor, the harness and the triple gauge pod which might solve and/or isolate your problem.
I think I have another sending unit you can have to test with if you want it...paypal me a few bones to cover shipping and it's yours. Came off a block w/ 100k miles and I am pretty sure it still works (I can test it before I send it out). PM me if you want it.
In the FSM(for my 2003), section LU-14(engine lubrication) has the torque at 9-12 ft-lbs. Section DI-46 (drivers information) has a procedure to check the sensor, the harness and the triple gauge pod which might solve and/or isolate your problem.
I think I have another sending unit you can have to test with if you want it...paypal me a few bones to cover shipping and it's yours. Came off a block w/ 100k miles and I am pretty sure it still works (I can test it before I send it out). PM me if you want it.
06-29-2015, 09:42 PM
#9
Registered User
Speednz, I don't actually wrench on cars so I can only be limited help here, but a bad sender usually just pins the gauge too high or too low. There are small oil passages in the timing cover to work the cam advance and chain tensioners, if there is an oil pressure leak at the gasket it will bleed off oil pressure. There will be no tail pipe smoke or external leak because the oil will just leak down into the oil pan. I don't know the gaskets or the route the oil takes but this has been a problem with some VQ engines used in a variety of different Nissan cars, maybe somebody else can help clarify.
06-30-2015, 09:18 AM
#10
Registered User
Jennifer 2,
Thank you!! I searched and was not able to find the thread mentioned. Was it on here or the "other" forum. Im assuming you mean one of the small orings could be the culprit? unfortunately i dont think its a faulty sensor and it may be a internal oil leak. But the car is not leaking any fluids nor does it smoke any at all under any circumstances. But would this explain the pressure being normal at cold temperatures then significantly dropping when the engine warms up? ( i know this is normal but to this extent)
i-break-things,
Im going to plug a mechanical guage up to it tomorrow. Hopefully i wont have to take my front timing cover off as i believe i may have stripped one of the bolts in the center. Did i just say that out loud?
bealljk,
Wow i did not know that, I tightened it way over 11.. Do you happen to know if one of the wires going to the sensor is a ground or if the ground is made from the threads of the sensor and the oil pan? because i believe i used thread tape and this could be causing a bad ground.. Probably would make the sensor unresponsive but may be the culprit.
Thank you!! I searched and was not able to find the thread mentioned. Was it on here or the "other" forum. Im assuming you mean one of the small orings could be the culprit? unfortunately i dont think its a faulty sensor and it may be a internal oil leak. But the car is not leaking any fluids nor does it smoke any at all under any circumstances. But would this explain the pressure being normal at cold temperatures then significantly dropping when the engine warms up? ( i know this is normal but to this extent)
i-break-things,
Im going to plug a mechanical guage up to it tomorrow. Hopefully i wont have to take my front timing cover off as i believe i may have stripped one of the bolts in the center. Did i just say that out loud?
bealljk,
Wow i did not know that, I tightened it way over 11.. Do you happen to know if one of the wires going to the sensor is a ground or if the ground is made from the threads of the sensor and the oil pan? because i believe i used thread tape and this could be causing a bad ground.. Probably would make the sensor unresponsive but may be the culprit.
The oil could be leaking, internally, as op stated. It's easy to pinch an o-ring. Maybe not so easy to replace, location, location, location...
If you have more bearing clearance than factory, fully you do, you could have lower pressure as well.
What oil pump are you running?
Do you know the width of the pump gear?
Last edited by i-break-things; 06-30-2015 at 09:25 AM.
06-30-2015, 10:12 AM
#12
Registered User
Thread Starter
Low oil pressure on newly built motor.
Bealljk, I'll take that sensor off of you just because of their tendency to go bad.
Jennifer and I break things, unfortunately this is what I believe may be the problem. The o-rings I installed seemed slightly smaller than the ones I took out. That's probably where my oil pressure is sliding out at. Guess If the mechanical guage I plug up reads low I'll be taking my timing cover off. Lots of fun that will be.. And ibreakthings, the car only has 70k, so I didn't replace the oil pump.. I would have if I had $200 laying around for an oem but I didn't. I didn't remove the crank but I did spec the rod bearings to Nissans recommended clearance. Not trying to build a race machine I just wanted forged Internals to ease my mind. Thanks everybody for the responses!
Jennifer and I break things, unfortunately this is what I believe may be the problem. The o-rings I installed seemed slightly smaller than the ones I took out. That's probably where my oil pressure is sliding out at. Guess If the mechanical guage I plug up reads low I'll be taking my timing cover off. Lots of fun that will be.. And ibreakthings, the car only has 70k, so I didn't replace the oil pump.. I would have if I had $200 laying around for an oem but I didn't. I didn't remove the crank but I did spec the rod bearings to Nissans recommended clearance. Not trying to build a race machine I just wanted forged Internals to ease my mind. Thanks everybody for the responses!
06-30-2015, 10:14 AM
#13
Registered User
Thread Starter
Low oil pressure on newly built motor.
And the oil pressure sensor doesn't have a gasket. I've owned a few Zs and none of them did. Just a pipe threads that make a Good seal. I have seen people put o-rings on the sensor so it doesn't have to be torqued as much. I've just used thread tape and never had a leak.
06-30-2015, 10:56 AM
#14
Registered User
Thread Starter
Low oil pressure on newly built motor.
Guys and girls I have "fixed" my problem. Just gave it her first oil change and while I had her up I took the sensor out. I blew it out with compressed air and used electronic cleaner on the inside, then blew it out again. Also I used 10w-30.... Kinda had to try both things at the same time since the sensor acts as a drain plug. But I put the heavier oil and the clean sensor back in and the oil pressure skyrocketed. It's idling at about 20 psi and the pressure is a lot more responsive when I give it gas. I have only run it about 15 minutes but the engine is warm. So now I'm just hoping that it was just the sensor and when I switch back to 5w30, the pressure remains. From what I've read about people using straight 30 to break in oils I think I'll be fine with conventional 10w30.
Thanks everybody for your help and I still might buy that sensor off of you!
Thanks everybody for your help and I still might buy that sensor off of you!
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