oil pump failing? (low oil pressure)

[krayton]

looking for some insight. i have a fresh rebuild but now having oil issues.

the oil pressure has fallen way way down. with cold oil its got good pressure, but as it warms up the pressure just starts dropping.

i have a brand new n1 pump and jun crank collar. not to sure whats going on. put almost 800 break in miles no problem. go to the track, run a few laps and the car dies with low oil pressure.

replaced oil and no signs of metal. now it starts fine. good oil pressure with cold oil, but it just starts falling to below what it normally runs at as it warms up.

ive got 2 guesses one being the oil pump failed, or the crank collar is slipping. the crank collar was installed by a reputable machine shop but im still skeptical. anyone have any other guesses or have some advice as to what it is? before i rip into it i was thinking about getting a mechanical oil pressure just to be sure the gauge is working. otherwise im gonna rip into the front and go for the oil pump

ps. not to sure if it has anything to do, but before the event i switched to synthetic. no problems with pressure at the begining, but after a handful of laps the oil started dropping until the car didnt run. after getting the car home i switched back to dino oil and thats where im at now

[leesredgt]

have you check the oil pressure sending unit?

[Joe]

the car is shutting off. its not a bad connection with the gauge.

[rotorimp]

Does that collar weld on or is it just the set screw. Put a T down by the sender and monitor it in the car. I run 20w-50 here in AZ in most of my cars--makes a big difference in oil psi. If that collar is just being held onto the crank by a set screw then you might be in trouble.

[chicos240]

Have you looked at your oil pickup? I had the same problem after rebuild. It turned out I had not torqued the oil pickup bolts. WHich meant it was not creating a good seal, which meant it was sucking air and not priming correctly which meant no oil to the head. O

[krayton]

Have you looked at your oil pickup? I had the same problem after rebuild. It turned out I had not torqued the oil pickup bolts. WHich meant it was not creating a good seal, which meant it was sucking air and not priming correctly which meant no oil to the head. O

oooo, i like that one. i didnt torque it down, but i put it on tight.

i think i might have to pull the engine to just check all these.

the collar is set on with screws, but according to JUNs instructions that was the way to put it on. either way i think im just gonna pull it and check both those issues.

[krayton]

im really thinking about the pickup now, thanks chicos

i had some lifter issues with oil before this started happening

[chicos240]

I know you really sooper doooper want to pull your engine. I know in an SR you just take off the steel oil pan, and theres the pickup. Is it the same in an RB? What im getting at is, try the easiest first.

[Joe]

cause a RB is so long you basically have to yank the engine to get the pan off fully

it would be quicker to pull the motor/trans (1.5-2 hours of work) rather than trying to JUST get the pan off.

[l0nestar]

Chicos,

Kamin is correct (as normal ) The SR oil pan has like 8 bolts holding it in and can be dropped with in minutes without removing the engine. The RB on the other hand, has 30 bolts and the engine (realistically) has to be removed from the chassis to get to it properly (and remove the oil pump to inspect the collar).

On the subject of tq specs, seriously, use the FSM... Nissan did not make up arbitrary numbers - follow them! Also, try and find a TQ wrench that reads lb-ft AND nm (like mine does ) no conversions needed when following the FSM!

I can look up the specs, but I'm at work and both my electronic and hard-copies are at home :-\

hope this helps

[rb25drag]

When you rebuilt your motor did you replace the Crank bearings in the motor?

The RB has very tight clearances on the bearings. If they are not in tolerance with factory spec it will have bad oil pressure.

IM using ACL race bearings, Factory pump and 10w40 synthetic and I hold 100lbs cold at idle and 50-60lbs hot at idle.

When I rebuilt my motor all of my clearances were dead nuts to +-.001

[rotorimp]

Dead nuts is .0000

[krayton]

yeah im also using acl bearings.

havent had time to dig into it, but hopefully this weekend.

for the first 1000 or so miles i had perfectly fine oil pressure. so hoping its the pick up. ill be able to check the bearings down there too

[Joe]

Dead nuts is .0000

thats a seized engine

[l0nestar]

When you rebuilt your motor did you replace the Crank bearings in the motor?

The RB has very tight clearances on the bearings. If they are not in tolerance with factory spec it will have bad oil pressure.

I used King main and connecting rod bearings. Everything was well within factory tolerances. I don't have an oil pressure gage (yet) but that is going to change in the next week or so -- but my car is still not ready for the road.

[Carl H]

ive found that 10w30 isnt thick enough for a motor that sees heavy abuse...it thins out so quickly.i run 20w50 w/ the n1 pump and proengines collar...i see 6bar at full stick and about 2 bar at idle.

[rb25drag]

I wouldnt run anything lower than 10w40. I like 20w50 I use to run it on my first engine, But I have switched to synthetic 10w40 and it seems very good.

Although I don't run my engine much other than on the track, and I also change the oil when it starts looking dirty. I don't have too but I like keeping my engine running fresh. I abuse it alot on the track so its better to keep it healthy in the lube section. Just a personal thing.

[gawdzilla]

krayton- some people have had problems with the screws on the back of their oil pump backing out of the housing..

When you rebuilt your motor did you replace the Crank bearings in the motor?

The RB has very tight clearances on the bearings. If they are not in tolerance with factory spec it will have bad oil pressure.

IM using ACL race bearings, Factory pump and 10w40 synthetic and I hold 100lbs cold at idle and 50-60lbs hot at idle.

When I rebuilt my motor all of my clearances were dead nuts to +-.001

that is a lot of oil pressure, why strain your pump unecessarily? stock pump calls for 21 psi hot idle - 65 psi hot high rpm. with the n1 i see ~23-25 psi at hot idle, and ~75 psi high rpm.

+ or - 1 thou is pretty bad for oil clearances, considering the oil clearance tolerance is less than .001.

[Booztd 3]

stock pump calls for 21 psi hot idle - 65 psi hot high rpm. with the n1 i see ~23-25 psi at hot idle, and ~75 psi high rpm.

+ or - 1 thou is pretty bad for oil clearances, considering the oil clearance tolerance is less than .001.

Thats what I'm going off of. My stock sending unit was sucking major balls. It would start out fine but as the engine warmed up it would just lose any readings. I had a Defi BF oil presure gauge and a sandwhich plate that goes between the oil filter and the housing, installed that last week. I am RIGHT at 21-22psi at idle hot, and around 60psi at 3k rpms. I am using 10W30 valvoline conv. oil at the moment.

I have noticed that no matter what, if the stock gauge actualy happens to be reading, its always 10psi lower than the defi gauge reads.

[gawdzilla]

Thats what I'm going off of. My stock sending unit was sucking major balls. It would start out fine but as the engine warmed up it would just lose any readings. I had a Defi BF oil presure gauge and a sandwhich plate that goes between the oil filter and the housing, installed that last week. I am RIGHT at 21-22psi at idle hot, and around 60psi at 3k rpms. I am using 10W30 valvoline conv. oil at the moment.

I have noticed that no matter what, if the stock gauge actualy happens to be reading, its always 10psi lower than the defi gauge reads.

i run 10w30 mostly, and i ran 10w40 at the circuit track cuz oil temps would go over 240 F. keep in mind the FSM calls for 7.5w30 which i assume is between a 5w30 and a 10w30. I may even switch to thinner in the winter time.

[rb25drag]

I would never run Valvoline oil in my car. I think its crap, After a long period of time it looks like wads of grease stuck everywhere. Makes your motor look like it has 100000000 miles on it. Plus it seems to break down under high heat and pressure, That will cause some bad bearing quickly.

Its Castrol or Pennsoil, Nothing better in my book. Just my opinion.

[rotorimp]

If it is a car that I'm going to beat the crap out of then I like the Royal Purple--hell I've already pissed away enough money on the car why not more!

seriously I have seen Royal Purple take abuse that no motor should have to.

[gawdzilla]

you know what they say... opinions are like @ssholes, everyone has one. everyone swears by their own oil brand and has their own personal experiences. i think its just a case of the grass being greener on the other side.

[Booztd 3]

you know what they say... opinions are like @ssholes, everyone has one. everyone swears by their own oil brand and has their own personal experiences. i think its just a case of the grass being greener on the other side.

I was gonna say different strokes for different folks

I think PENZOIL looks like muck straight out of a fresh bottle. Valvoline is much cleaner appearing. I've never had any probs with it, so no reason to complain. I've used all types of oils and they all come out the same color when their time is due........black

[fast_s14]

Lets not get crazy here, i like super tech from walmart. lol jk!

I stick with valvoline, i have been using it for years and never had any engine problems with it. I guess it is your own personal preference.

[1WheelWonder]

Would a thicker 20w 50 create more oil pressure than a thinner 10w 30?

[gawdzilla]

yes, but it will cause more strain on the pump and more heat.

[HOMEMADE240SXTURBO]

yes, but it will cause more strain on the pump and more heat.

I know this is old but i got a question.

What's the advantage of using a thicker oil? because u said that it put strain on the oil pump. But isn't it that heavier oil lubricate the bearings better?

I'm confused b/c I'm running 15w40 royal purple in Georgia.

[Shocker]

Higher oil pressure from heavier weight oil puts more strain on pump and seals although it DOES help choushin the rotating assembly a lot more, provides that slightly thicker/heavier pillow or lube between metal rotating parts.

It has its benefits and its negs. Just make sure your motor is properly up to operating temperature (generally once the T-stat opens) before you go pounding on her and you shall be fine.

[HOMEMADE240SXTURBO]

I've only been driving on this engine for a month with a 15w40. should i switch to thinner oil after break in just to be safe? or will i be fine with 15w40 like u said on the earlier post?