Jump to content

oil pressure problem.


gimmeaclue

Recommended Posts

Hi, sorry for starting my first thread with a problem but i could do with some advice.

 

Yesterday i bought my first 350z - 04, 66k miles, fsh but not with nissan.

 

Test drove the car and all was seemingly well, smooth sounding, good gear changes etc...

 

I drove home yesterday evening, a four hour trip and the car was faultless. I noticed the oil pressure gauge after about an hours driving was saying 60psi, this would rise to 70psi on quicker dual carriageway stretches.

 

This morning I checked fluids and to my horror found a lack of oil showing on the dipstick. I added a litre and it seemingly made no difference to my dip stick reading leading me to believe the dipstick is useless. Can you have a faulty dipstick? On starting the car oil pressure now shows nearly full 120psi. When i turn the key to arm the electronics before ignition it reads approximately 70psi. I dont know what it said at start-up yesterday as i didn't clock it on the test drive

 

What should it read on start up? as it was 70 psi under load i figured I have overfilled the oil for it to idle at 120psi but the dipstick seems to show anywhere between 1cm under minimum and 1.5cm over maximum so again no help.

 

Figuring I had over filled I removed 1ltr of oil, Restarting the car shows no difference PSI 120 even off the gauge, if anything worse than before i removed oil.

 

I don't want to keep starting the car as I have no idea what my oil level is and I figured removing 1ltr would have lowered pressure regardless but it hasn't. Car runs fine with no noises of any kind, no smoke and no noticeable leaks.

 

Any ideas??? All help gratefully appreciated.

Link to comment
Share on other sites

So I have managed to Bork the car after 1 drive :). Any preferred shops/dealers where I can order a sensor? and thanks for the help, I read the other thread linked and now realise i've just asked one of 'those' questions. I'l do an oil change tomorrow so at least i know how much is in there with some certainty. I'l have to learn how to read dipstick at some point or I will have the cleanest engine oil in Britain.

Link to comment
Share on other sites

So I have managed to Bork the car after 1 drive :). Any preferred shops/dealers where I can order a sensor? and thanks for the help, I read the other thread linked and now realise i've just asked one of 'those' questions. I'l do an oil change tomorrow so at least i know how much is in there with some certainty. I'l have to learn how to read dipstick at some point or I will have the cleanest engine oil in Britain.

 

Zmanalex is excellent.There's quite a few on here that are good.

 

Have a search or PM him. :pmzmanalex::pmclark::pmtarmac::pmcs:

Link to comment
Share on other sites

I think the OP needs to realise that temperature affects oil viscosity, cold oil will give a considerably higher pressure than hot oil, 120psi on cold start is not unusual, but the 70psi that the OP is seeing on a hot engine is normal.

 

....... Both normal then :)

Link to comment
Share on other sites

I think the OP needs to realise that temperature affects oil viscosity, cold oil will give a considerably higher pressure than hot oil, 120psi on cold start is not unusual, but the 70psi that the OP is seeing on a hot engine is normal.

 

 

So a 120psi start could be normal. How about 120psi idle after 10 minutes of driving? Not long enough to warm the oil to a lower viscosity perhaps? Don't really want to be changing £80 sensors for no reason. As I stated I have no point of reference for a normal psi range having only completed 1 drive in the car.

 

Guess I will do an oil change so I know that it has the correct quantity and grade of oil. I'l give it a quick run around and see if the psi will revert to 60/70 range. If not I will change the sensor next.

 

Many thanks everybody.

Link to comment
Share on other sites

Checking the oil level even with the awkward dipstick on the 350 is fairly straight forward once you get the knack. ;)

 

 

Leave the car over night on level ground ~ always (imo) check the engine oil level when cold.

 

Pull the dipstick out & wipe clean. Then slowly reinsert the dipstick using a torch to see exactly where the hole for it is & using the guide rails near the hole to help guide it in.

 

Wait 5-15 seconds and then very slowly pull the dipstick out of the hole ~ ideally (imo) the oil level should be up to the top mark. Pic below for example...

sentra_dip_stick.jpg

 

 

After you have checked the level just reinsert the dipstick again using a torch to insure it is going in the hole correctly & is seated properly.

 

If you are unsure of the level pull it out again, wipe clean & repeat the process above until you are satisfied of a true reading. :thumbs:

Link to comment
Share on other sites

You say when you turn the key to arm the electronics it reads 70 psi. If the key is at this setting then that would be the acc setting .. You shouldnt have any pressure at all showing. I had the same problem but mine was off the scale over 120 on acc setting of ignition. Changed the oil pressure switch. Problem sorted. They are known for this happening.

Link to comment
Share on other sites

Firstly hello and welcome

If the car is unknown, I'd always do a complete fluids and filter change.Even with a few stamps in a book, who knows what they put in it

Oil, water/antifreeze, gear and diff oils, air and oil filter possibly plugs too

A flush with Wynns engine flush prior to dropping the oil removes loads of crap from the engine, I swear by it

Ideally change to cheap oil, run it for 500miles, dump it and change to good oil and a decent filter

But do this after you've sorted the gauge

Never blindly ignore something because it maybe a faulty sensor.....

It may be telling the truth

 

I agree, gauge should read zero with motor stopped

When cold, 80-90psi depending on outside air temp

The gauge will read 120 if blipped from cold

Hot tick over around 20-30psi, no less than 14psi

As stated 2500rpm, 60psi or there abouts

Oil pressure is revs not speed related, but warm engines will read less than cold

If the gauge reads with out the engine running it can only be the sender or the gauge, most likely sender as the gauge is more likely to read out even with power off.

Ideally get a local mechanic to hook up a mechanical gauge to check the readings, if not, then you'll have to just swap the sender I am afraid and hope it's not the gauge

I am sure you'll sort this easily, I've only had mine 6 months and had virtually no oil pressure, but that ended well, wonderful cars

Good luck, let us know how you get on

Link to comment
Share on other sites

I think the OP needs to realise that temperature affects oil viscosity, cold oil will give a considerably higher pressure than hot oil, 120psi on cold start is not unusual, but the 70psi that the OP is seeing on a hot engine is normal.

 

 

So a 120psi start could be normal. How about 120psi idle after 10 minutes of driving? Not long enough to warm the oil to a lower viscosity perhaps? Don't really want to be changing £80 sensors for no reason. As I stated I have no point of reference for a normal psi range having only completed 1 drive in the car.

 

Guess I will do an oil change so I know that it has the correct quantity and grade of oil. I'l give it a quick run around and see if the psi will revert to 60/70 range. If not I will change the sensor next.

 

Many thanks everybody.

 

 

IF the gauge is reading anything else but zero when the ignition switched on, then the sensor is probably faulty, in which case replace the sensor and see if the gauge behaves normally, IE cold start anything from 80 to 130PSI depending on the oil pressure relief valve.

 

As I said previously if the oil is cold its not unusual to see that sort of pressure, but once the engine has warmed up anything from 10 to 20 minuets it should drop to around the 70psi mark at around 4k rpm,

However these pressures will change depending on the oil viscosity used, not by a lot but the difference between say 5w30 and 10w40 can be as much as 10psi to 15psi.

Link to comment
Share on other sites

Next question, does anyone know somewhere that stocks these sensors, All i am getting at the moment is american sites.

 

 

Edit. There are two different types for sale in rock auto, I know the engines changed between 04 and 07 will the sensor still be the same

 

http://www.rockauto.co.uk/catalog/raframecatalog.php?carcode=1437463&parttype=4588&ck[iD]=0&ck[idlist]=0&ck[viewcurrency]=GBP&ck[php_SESSION_ID]=hvpd178fhbc3o5dctadai6m4f7

Edited by gimmeaclue
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...