Critical Oil Pressure

[adam 32]

when i first start the car oil pressure is up around 4 which is fine, i drive gently to allow the engine to warm up.... once its warm it can hold good oil pressure for about 15minutes however after that it drops off really badly

at idle its on 0, then revving up it only gets just above 2 even at 4-5000rpm

my conclusions have been that its not the oil pump as it can hold pressure when you first start the car, could it be related to oil viscocity as the pressure only drops once the oil/engine is very warm.

*NOTE: all readings taken from std gauage*

[Clint32]

mines similar sometimes, just a dodgey sender I think, a common problem but apparently a new sensor is not cheap.

[Guest Stocker]

Could be a few things....what weight oil do you run? This sounds like loose bearing clearances or similar though...I had a car that would do the exact same thing once...I changed the cam once, and the bearings were shot. Had good oil pressure when cold, but barely registered when hot.

You could consider running a straight weight engine oil, not a multigrade..they tend to stay thicker at temperature.

Also, could your dipstick be suspect? Maybe the sump is overfull/underfull, and you have oil foaming?

Just some ideas....

Regards, Andrew.

[adam 32]

when you say a dodgey sensor you mean the oil pressure guage could be suspect?

well the tuning shop who are servicing the car in a couple of days had no idea when i mentioned it to them, however they suggested i should reassess once i have a new oil/filter in

could this low oil pressure be causing internal damage? what precautions should i take while the oil pressure is so low?

the oil im running at the moment is a BP oil which came with the engine (had to replace after piston fry).

what viscoity would you suggest running, 10W40?

[Clint32]

mine was a bit better after i changed the oil filter, but i have heard of the sensor stuffing up, my motor still runs fine and i have been like it for 12 months.

[adam 32]

i may get an aftermarket oil pressure guage then....

its just strange how it reads fine for a while, just when the engine gets really hot that it starts screwing up... the oil pressure still rises with revs, its just really low.

im just stressed about it cos i was going to up the boost in a couple of days and last time i did it i blew the engine (am running a T04E)

[51jay]

My engine is in good condition. These mornings in Brisbane I get 4.5 to 5.5 on the standard gauge when starting from cold thats at fast idle when fully hot it 3.5 to 4 at idle and a little more about 4.5 at around 2000 to 3000 I'm using Shell Ultra 5W 40W full synthetic. If I were you I'd get it checked out by a competent workshop be fore I upped the boost "cause it sounds to me like your main bearings are shot and you are heading rapidly for another engine rebuild

[adam 32]

haha thats not really what i wanted to hear but kindah expected it!!

would that make sense though, i thought if the bearings had gone then it wouldnt hold pressure at all, the fact that it holds pressure when the engine is cold/warm just nor hot is kindah weird

[Clint32]

adam how much power are you making with the turbo as i have a hks to4e that i am putting on shortly, do you know the specs of your turbo.

[adam 32]

i duno the exact specs, has been rated at 350-400ps

it all came from japan with HKS manifolds and HKS external gate

i was making 290rwhp before the engine blew, at the moment im at around 200-220.

before i was running std injectors with fuel pressure reg but i was gunah get new injectors soonish and then boost in aim for 300-320rwhp. although this oil pressure thing has got me a bit stressed, cos if i boost on low oil pressure ill blow the engine again

the only bad thing about the t04 is its pretty laggy, full boost kicks in around 3500-4000rpm so if you choose the wrong gear people can really leave you behind!!

[uLa32]

mine started to play up too. i installed an autometer one on a t-piece so my orignal one still worked. found out that it was my original sender which was faulty as it hardly ever moved, but the autometer one would move exactly according to the workshop manual specs...

[Clint32]

thats what I thought, were is the stock sender located on the motor?

[macka]

That does seem a little low get the guys to check the pressure and cross your fingers its just the gauge

If they dont know what your on about maybe u shouldnt take your car there for its service!

[adam 32]

i also located where my oil leaks from

a cracked oil hose from the turbo... this may be affecting things??

anyway the pressures all over the shop will get the service done tomorrow and then reassess. i have a feeling its now the guage cos ive been watching it recently and it fluctuates alot. sometimes its fine oil pressure then it looks like it gets stuck below 1!!

i may have to put off the injectors and buy an oil pressure guage!

[Evan]

Sounds like main bearing's stuffed....

Same as the last GTR engine i lunched ! (only now about to start rebuilding it almost 4 months after it went to god !, and no it wasn;t my oil, it was on the way out when it came from japan)

Notice nissan say the lowest rating oil for GTR is a 7.5wNN

I usually run 15w60 but 10w50, 10w60 etc is also good.

E

[adam 32]

well after changing the oil and filter a couple of days ago it does seem a little better, although the guage still fluctuates alot. ive decided not to make an conclusions until i buy an oil pressure guage.

when you say the main bearing is stuffed, what exactly does this mean?

[macka]

So you gonna come down for a thrash sunday adam?

[Evan]

Well stuffed as in, worn.

Allows oil to shall we say leak out the sides, and the thing is oil is leaking out there instead of being pumped up into the dead and sprayed where it should be.

E

[adam 32]

is there any way to test for this? or is it soley based on oil pressure??

macka: yeh probably, i might have a football game.... but will do my best! youre gunah run arent ya?

[macka]

Ill be there if im tuned @15psi with fuel pump and dump and new wastegate actuator so i better get my arse into gear. If i cant hold boost still i might come down and watch