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Actual oil pressure?

16K views 61 replies 9 participants last post by  Pale Rider 
#1 ·
So I recently Installed an oil pressure gauge in my 07 Titan and I'm a little concerned with what it reads. Once the truck is fully warmed up it reads 50 psi at idle and by 2500rpm its at 100psi (max of the gauge), seems to be a little bit on the high side. I hooked up an analogue gauge to confirm and got the same reading

I was running an Amsoil filter but changed it out for a Mann filter and the reading was the same, I plan to pick up a Nissan filter tonight.

so far the only information I've been able to find is in the Nissan manual PDF it states oil pressure should be more than 14psi at Idle and more than 43psi at 2000 rpm, unfortunatly it doesnt state how much more :frown:

I also found this thread where a guy has similar pressure in his vk35hr and everyone says its normal

Oil pressure running to high???VQ35HR : 350z / 370z Technical

It would be helpful if anyone out there has installed an oil pressure gauge and can share their results

here is some pics of the gauge install if anyone is interested:











 
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#2 ·
Well I picked up my Nissan filter and before I switched it I figured I would take my oil cooler off and have a look at the relief valve, it would also give me a chance to change the o-ring for the oil cooler. The relief valve seemed to be functioning properly and everything looked really clean so I put everything back together with the Nissan filter and for the most part the oil pressure was the same ( maybe 2-3 psi lower)

So I'm just going to have to assume this is normal oil pressure for the vk56, my engine runs smooth and quiet and if I had never installed the oil pressure gauge I would not be questioning anything.

Anyways I wanted to post my findings in case someone finds themselves in the same boat as me maybe this info will be usefull







This pic is after a pretty hard drive

 
#6 ·
ya my factory gauge is right in the middle, even when the pressure is above 100psi, but It does read 0 when the engine is off and it also read 0 with it open to atmosphere

SERVO, is it possible your gauge is displaying a metric value instead of the normal PSI?
I'm sure its psi, the metric unit for pressure is pascals and 20 psi is equal to 137 kPa
 
#4 ·
SERVO, is it possible your gauge is displaying a metric value instead of the normal PSI?
 
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#7 ·
dig a little more digging in the Nissan manual pdf and looks like the factory oil pressure switch (2007+) is a normally closed switch and the continuity is broken at only 4 psi, so basically it will only alert you if the oil pressure drops below 4psi! :confused:
 

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#8 ·
holy crap, funny how I found this when looking for the actual oil pressure.

yes, the FSM for my year states 14 psi @ idle, and more than 43 @ 2000K, and 57 psi @ 6000 rpms...

well I have the same dam issue and seeing 50 psi when warm at idle , and over a hundred when nailing the gas... wow... thought my gauge was defective...
 

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#10 · (Edited)
What are you guys getting for cold oil psi?

Are you taking your readings from the stock sending unit location Pale rider?
 
#12 ·
Seems you may have opened a can 'o worms here. That much pressure can actually have an effect on you mpg.
I would look for another place to possibly get a reading.
 
#13 · (Edited)
I`ll have to look into that if there is an optional port for the pressure sensor.

what`s really sad here is this forum is so focused on what tire, what lift, how do you change a head light bulb, that no real tech or data exists anymore.

my mileage was very good when I was NA, and not to bad for being boosted at 13-15 depending on the smile factor.
sure it will get crappier mileage if I always lay into it, but for the most part cruising gives the best results.

I found this thread after the fact from a google search when I saw what the actual pressure was. I believe it is the "only" thread with these numbers on the forum., and Thank Servo for the thread.

so many threads about the failing OEM sensor, and people whining about the factory gauge, yet I didn`t come across anyone doing an actual pressure test with a mechanical gauge to verify pressures as of yet.

I communicated with the author and in all of his research and speaking with Nissan techs, this is normal for a healthy VK engine...

My truck has 44xxx miles on it and early OCI`s with good oil and filters always., so I doubt any blockage exists.

seems the VQ35 guys have similar issues as well...
 
#15 · (Edited)
My VQ only runs about 60-70 psi warm at full rev and can dip into the 15 psi range when fully heat soaked at idle. I've never seen anyone complaining of high pressure in my 8 years on "my350z.com"
Something just doesn't seem right here, no healthy car or truck engine needs to run 100 psi cold or hot.
 
#16 · (Edited)
My VQ only runs about 60-70 psi warm at full rev and can dip into the 15 psi range when fully heat soaked at idle. I've never seen anyone complaining of high pressure in my 8 years on "my350z.com"
Something just doesn't seem right here, no healthy car or truck engine needs to run 100 psi cold or hot.ł
agreed, this is a first for me. and I would have never known if I had not decided to install this gauge.
who knows how long it has been running like this. with all the unqualified info on the oem sensor and its exact function plus the model year changes and the descriptions of the factory gauge movement here on the forum, I have yet to come across any factual findings besides the FSM data.

it is possible I have a defective sender or gauge itself, and can do an exchange to rule that theory out.
it was just coincidental that I came across this thread with the very same symptoms and almost near identical pressure readings.

the OP utilized a mechanical gauge to verify his readings. He states that Nissan techs told him it was normal. the FSM specifically states the words "more than" at each rpm interval mentioned for pressure data.

at this point all I can do is retest with a different set up and continue to search, ask, and call around to see what`s up.

my engine doesn`t use oil, it doesn`t leak oil, it doesn`t run poorly. I agree... there has to be a valid answer, I just haven`t found it yet.

this link the OP provided in the first post has someone with "similar" pressure issues.
http://forums.nicoclub.com/oil-pressure-running-to-high-vq35hr-t303761.html
 
#17 ·
Maybe the sending unit port is located ahead of the bypass valve?
Those numbers are high even for an all-out race engine.
 
#19 ·
If I'm understanding that pic, ou r trucks read oil pressure on the intake side of the filter. That should, in theory, be the high point of pressure (after the pump, prior to the first (and likely highest) restriction). I'd like to see a measurement further up the pressure chain, as I can't imagine the valve covers are containing nearly 100 psi with their gaskets. It should at least blow through the PCV system at those pressures.
 
#21 ·
I would think the VVT, passages and solenoids knock down quite a bit of pressure as these delicate valves need to act on demand. I also think as well that the pressure switch is in the galley directly from the oil pump.

very strange that the FSM shows installing a mechanical gauge for testing the pressures at those rpm intervals, yet when the OP did just that to verify his concerns, he saw the same higher psi within 1+-.
so if this were absolute and true, how does a nissan tech test the same way and see higher pressures? do they just dismiss that bc it is "more than"? wish I knew what the "more than" quote was in numerical terms...

PR, I know it's not the issue, but out of curiosity, what oil are you running, currently?

IMO, 50 psi at warm idle in a good, tight engine isn't an issue. What's the pressure, fully warmed, at 2500-3000 rpm? If your gauge still "pegs" with engine fully warm, then it's likely that the pressure relief valve is either sticking, clogged, or the spring pressure is too high. Since the valve uses a sliding cylinder (going by the FSM diagrams), and Nissan specs the relief valve clearance to it's bore, I'm thinking it's critical and that there may be something interfering - piece of debris, "varnish" on the bore, something. Or there is a significant clog in the oil passages... which I wouldn't think likely.

Looks like getting to the relief valve for inspection is major surgery. That sucks.

A couple of the NICO club threads are pretty scary, as most didn't even know what the bypass valve is there for. Interesting that Nissan has a typical relief valve at the oil pump (which sets oil pressure), and a second under the "oil cooler" at the filter mount. Must not trust the built-in relief valve in the filter, or do the OEM filters not have a built in bypass like the aftermarket filters do?

Hi d!, that`s what is strange to, no trash in the oil, recent reports came back very good using both Amsoil and Valvoline Synpower 5w30. I`ve been using Synpower for the last few OCI`s.

the pressure is def fluctuating with the go pedal, and hot idle in drive shows 30 psi. it will go to 82-88 @ 2k easy, but when hot and running, and when I`ve pushed it I haven`t seen it go past 90 something.

yes the OEM`s have a bypass, as does the Fram TG< and the Wix currently on there now. I am going to try Frams redesigned HP filter, but highly doubt there will e any significant change in psi even though it is a filter suited for flow and around 92% efficiency @ 20 microns... if memory serves.


the OP looked no further in his investigation after repeatedly hearing that this is Normal from the nissan techs...
I`m waiting for a reply from a shop and waiting to get in touch with a buddy who might get me some answers.
 
#20 ·
PR, I know it's not the issue, but out of curiosity, what oil are you running, currently?

IMO, 50 psi at warm idle in a good, tight engine isn't an issue. What's the pressure, fully warmed, at 2500-3000 rpm? If your gauge still "pegs" with engine fully warm, then it's likely that the pressure relief valve is either sticking, clogged, or the spring pressure is too high. Since the valve uses a sliding cylinder (going by the FSM diagrams), and Nissan specs the relief valve clearance to it's bore, I'm thinking it's critical and that there may be something interfering - piece of debris, "varnish" on the bore, something. Or there is a significant clog in the oil passages... which I wouldn't think likely.

Looks like getting to the relief valve for inspection is major surgery. That sucks.

A couple of the NICO club threads are pretty scary, as most didn't even know what the bypass valve is there for. Interesting that Nissan has a typical relief valve at the oil pump (which sets oil pressure), and a second under the "oil cooler" at the filter mount. Must not trust the built-in relief valve in the filter, or do the OEM filters not have a built in bypass like the aftermarket filters do?
 
#22 ·
Just a little off topic, do any of you know if the trans temp gauge acts similarly to this? I notice when leaning on the skinny pedal quite a bit, the trans temp does climb, but doesn't ever go past the center of the dial face...ever. I haven't really tried to induce heat to see if it will chooch higher, but now I think that maybe a trans temp gauge from aftermarket suppliers may be worth installing for science. I notice PR doesn't have a visible trans temp gauge in his cluster(s) from what I can see, maybe in the works? I am now starting to question my instrument console from this information...Thoughts?
 
#23 ·
I notice PR doesn't have a visible trans temp gauge in his cluster(s) from what I can see, maybe in the works? I am now starting to question my instrument console from this information...Thoughts?
I use my Bully Dog GT to monitor trans temp.

from top to bottom on the BD GT:
Throttle %
air intake temp
AFR (what the ECU see`s)
Trans temp.
 
#24 ·
If there are in fact two valves I would have to assume the second is there to prevent drain back when the engine is stopped. Nobody in there right mind would trust a cheap filter with that job.

I'm also thinking the readings are high due to the needs of the valve train and related components on these engines.....which probably recieve oil first. You have at least 2 tensioners, 2 phasers, chains, guides, sprockets and a bucket over shim style valve train. There must be a few oil squirters in choice locations.

Once the pressure is reduced in the valve train, it becomes acceptable for the lower end.

100psi at the crank would be a bad situation for an engine with fairly tight clearances.....As compared to a race engine that needs high pressure and has looser tolerances.
 
#25 ·
again, agreed, lol

now if this were Gospel, why in the world would the nissan think tank design the system to have that much pressure at that switch.
keep in mind the variance of sender from the older to newer model years where the gauges actually were a gauge then switch to an elaborate idot light per say...

I remember years ago when the old school senders would leak, Dodge, GM, and can you imagine pushing 100 psi through that leaky bastard and blowing the plastic body right off the threaded portion, lol...

just doesnt make sense to me that Nissan`s own FSM dictates specific values, then throw that "more than" clause in there, then to mention to use a test fixture of a mechanical nature to test pressure... Possibly knowing that it is not 14, 43 or 57, what were they thinking?
if this is the case....
 
#27 · (Edited)
The sending unit can handle well over 100 psi, since it only has a small orifice inside it.
It's no different than small, thin diesel injector lines handling several thousand psi.

I thought to myself after the last post, that the oil pressure probably goes up and through the crank simultaneously. The thing is, the top end on these engines have a lot going on. I'm sure 100 psi diminishes quickly by way of orifice sizing. I'm still confident that the crank gets a normal amount of pressure.

As for the possibility of a clogged passage or bad regualtor valve......highly unlikely.
I'm also sure the sending units are configured to read normal at that high pressure.
I would like to see how an older gauge cluster reacts to this newer truck though.....since those gauges moved in real time.

This is puzzling!
 
#29 ·
well while I`m waiting for further info, I decided to try a Dakota Digital 150 psi oil pressure gauge and sending unit. This particular set up will use the wiring I have in place for the autometer gauge but using different terminal ends.
I also ordered a Fram HP17 filter, which is designed for street cars, track cars and has more flow with a little less efficiency... The filter change will have to wait till my next OCI tho...

eventually we will walk away knowing something or still scratching our heads... or balls, lol...
 
#30 ·
Looking again at the schematic (thanks Dreep) I can see 10 places where oil pressure will be lost to "jets"...... Aka squirters.
My main concern though is the location of the pressure port in the system....it's directly after the pump as opposed to being farther down the line like some other engines.
 
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#33 ·
I've even had my trans temp run low during a night drive up to Memphis in low teen and high single digit temps. I guess at those temps, the 80mph wind chill was just too much for the trans to warm to. The engine coolant was running about 165-170 for that trip, too. Trans appeared to be around 120-ish, based on the gauge position and what I know a couple of spots represent in terms of temp.
 
#34 ·
There is no thermostat in the Titan transmission. So if you're bypassing the radiator or the radiator is the first item in the loop (followed by the coolers) then you end up with very cold fluid going back into the transmission. I've managed to drive almost 400 miles with no perceptible reading on the gauge when it was really cold out.
 
#35 ·
Yeah, but I'm bone stock, with no bypass. Only thing not stock about my drive train is the Mobil 1 oil in the pan and the BFG TA KOs at the corners. Neither of those are cooling my trans.
 
#36 ·
Until I did put in the extra cooler and sort of did the bypass my transmission fluid always came up to temp without regard to outside temperatures.
 
#37 ·
Hmmm...makes me wonder. Hate to think there is something wrong with this trans (remanned from Nissan to replace mine under powertrain warranty) but it pulls great and seems to have no issues otherwise.
 
#38 ·
If it works like it should and the fluid looks right then nothing is wrong.

Fluid temps will fluctuate drastically any time you have an external cooler in the loop. I've watched both of the temperature readouts with mine going through the radiator and with 2 external coolers and no radiator in the loop. It fluctuates less while using the radiator, but still fluctuates.

You must also consider how much difference there is between engine rpm and input shaft rpm, since this indicates how much slipping your torque converter is doing. When locked in OD the trans will cool down, climb a hill or mash the gas, it will climb.
 
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