oil pressure on gauge erratic

N

nickr

New Member
Hello, I'm having some oil pressure issues. On the factory gauge when cold, it's showing normal above 4bar cold, 4bar at cruise, 2 bar at idle.

However once the car is quite warm or have been driving around awhile, the oil pressure gauge falls off to below 2bar, and at cruise will not rise past my estimate of 2.5bar.

Occasionally the oil pressure will jump back up, and idle will be at 2bar and cruise at 4bar as normal.

Is it the oil pump regulator going? or the oil pressure sensor going?


Any feedback would be appreciated.

Regards,

Nick
 
PobodY

PobodY

Moderators
Staff member
My first question would be what oil are you using? - Is it possible that the 'hot' viscosity is too low? 10W-30 for example would explain what you've described.
I'm not suggesting that you are some kind of idiot, but it's probably a good idea to eliminate the simple (and obvious) problems first.
 
N

nickr

New Member
I'm on my 3rd oil change, its not the oil. 0w40, 5w40, 5w40 mobil1, liquimoly, shell.

This is also through winter, -5 temps through to +10.
 
Major_Sarcasm

Major_Sarcasm

Member
The likelyhood is the sender unit is past its sell-by-date. The Nissan stock sensors seem to have a limited lifespan. I replaced the one on my GTR Skyline due to erratic pressure readings and it stabilised the gauge immediately. I had fitted a brand new one however.

I fitted a second hand one to my Pulsar recently and it was still fairly erratic. So I fitted an aftermarket sender and gauge instead. All good now.
 
N

NME_RR

New Member
Mate!!!

Check you sump pan isn't dented!!!

The oil feed pick up is almost at the lowest point in the sump, , even the smallest dent in the sump area will cause major oil pressure issues like what your experiencing!!
 
olliecast

olliecast

Active Member
yeah first port of call is the sump. I¬d then change the sensor as i`m getting similar readings with mine.

can the sensor be removed without draining the oil?
 
N

nickr

New Member
I've removed the sump pan recently and banged the crap out of it. So there's no dent. I'll try replacing the sensor first. Thanks.

Is the pressure sensor shared with any other vehicle other than the gti-r?
 
Mr GTiR

Mr GTiR

New Member
Without looking at an oil pressure guage but i'm sure good oil pressure at start up is 6 bar. Once warmed up it drops to 4 bar. I'm running the factory unit as well as a HKS aftermarket guage as well.

If your not having an low oil warning light coming on then deffo the sender unit is on it's way out.
 
PobodY

PobodY

Moderators
Staff member
Mine is normally at about 4 when it's cold... then drops to 2.5-3 when cruising... then back up to 4 when she comes on boost.
I'm happy with that - I've just filled it with Silkolene 10W-50 so I'm sure it's right.
 
PobodY

PobodY

Moderators
Staff member
Is the issue that with a journal bearing turbo 0W-XX is too low for a cold viscosity as it is likely to seep, but it's fine for a BB turbo? Plus, the older a car gets, the bigger the tolerances are on all the parts... so logically the thicker the oil required. A new Porsche might have much tighter tolerances and can therefore run a thinner oil?

We need the oilman to give us his opinion!

EDIT: The search tool is my friend.
Riske runs 0W-40 and Guy says it's ok! (clicky) However, he does also say that it needs to be a good, shear-stable, synthetic oil at that viscosity to prevent the oil from over-thinning and giving low pressure... not quite my seepage theory then!
 
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N

NME_RR

New Member
Correct me if im wrong but im just using my little ammount of intelligence to work this out!!



Oils are measured in Hot/Cold or cold/hot weights??



eg 10-60 ........ is 60 weight when cold and 10 when warm??

and 10-40.......... is 40 when cold and 10 when hot??


My therory behind this is that gear oils are much thicker!!

eg 80-90 weight is a much thicker oil than a 10-40 engine oil!!


so the higher the figure the thicker the oil???


basically if your running 0-40, your oil is the thinnest oil it can be, at your running temperature,,! Am i correct??

and the 40 is from cold start??

Some oil man please explain,


I use 10-60 Castrol Formula RS,
 
R

RU55 GTR

Member
Just thought I'd add my bit to this incase it helps?!?!?!

My stock oil pressure guage shows 4 (or just above) on start-up and when warm on idle, drops to 2 or just above. Cruising it holds around 3.

On purchasing my R, the sump had a significant dent in it which has struck the oil pick-up. I have had now replaced the sump plate, but not the pick-up (yet) as it's all working fine as is. There has not been, so far, any difference in oil pressure readings between dented sump & non-dented sump.

The oil I use is Millers (or liquidmolly when flushing) 10w60 all year round. Seems to work fine for road and track. My friends are also using the same in their 200sx's.

It would seem like a sender problem to me, but everyone is right by saying start with the simplest and cheapest options first.

Good luck with it and keep us posted please. :-D
 
R

riske

Guest
Your readings seem fine to me?? But your best looking at getting an uprated sender and guage. I'm getting R spec guages and the stepper oil pressure guage comes with the sender and its only £50, cant go wrong. Very accurate and use the same senders as the Defi guages. Look the dogs bollox, cant wait to fit em.
 
N

nickr

New Member
NME_RR said:
Correct me if im wrong but im just using my little ammount of intelligence to work this out!!



Oils are measured in Hot/Cold or cold/hot weights??



eg 10-60 ........ is 60 weight when cold and 10 when warm??

and 10-40.......... is 40 when cold and 10 when hot??


My therory behind this is that gear oils are much thicker!!

eg 80-90 weight is a much thicker oil than a 10-40 engine oil!!


so the higher the figure the thicker the oil???


basically if your running 0-40, your oil is the thinnest oil it can be, at your running temperature,,! Am i correct??

and the 40 is from cold start??

Some oil man please explain,


I use 10-60 Castrol Formula RS,
Click to expand...
you've got it backwards.. a 0w40 is a 40 weight oil that flows like a 0 when cold. besides you should look at the hot and cold cst values of the oil. the hot cst's on all my 40 weight oils are fine.
 
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G

GTiRlover

New Member
riske said:
Your readings seem fine to me?? But your best looking at getting an uprated sender and guage. I'm getting R spec guages and the stepper oil pressure guage comes with the sender and its only £50, cant go wrong. Very accurate and use the same senders as the Defi guages. Look the dogs bollox, cant wait to fit em.
Click to expand...
Post up some pics when you have please! Any links?
 
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