ive posted on zilvia and also on skylines australia, but nobody really has any input so maybe you all might have some insight
so this is my predicament,..

i just finished refreshing my rb25 last week.
new oil pan, new oil pickup & gasket, rb25 neo water pump, rb26 oil pump, new belt and tentioner, new head gasket and arp head studs. ran perfect up until yesterday. i was on the highway and i went to neutral to pull into a store and my oil pressure dropped to almost nothing. i pulled in an shut it off. started back up and hear lifters clattering.
oil pressure is about 5psi idling and at 2500 rpm its about 20psi. (using mechanical oil press gauge)
wtf could have happened. if i installed something wrong it should have been evident from the first start up, not 5 days later. nothing is leaking from anywhere.
also i pulled off the oil filter and the oil that came out was incredibly dark and had swirls in it which im guessing are my bearings, despite the oil being brand new.
i used "the right stuff" rtv sealant for everything (exept head gasket of course). its highly recommended on lots of forums ive been on and ive seen people use it on water and oil pumps all the time.
any comments/advice are appreciated. thanks

Did you forget the o-ring that goes on the oil strainer pickup? You might be sucking air/oil mix if your missing this gasket...

no i installed that along with locktite, and now its a little flat black metal gasket instead of a copper o ring. im not sure if its always been like that but thats what came with the gasket kit

OK that is correct rb25 one is a black metal deal, rb26 is an o-ring (installed one yesterday). Do you have an extended pump drive?

What grade oil are you running? Whats your idle rpm? Oil level is at full (should take around 4.5 quarts)

My car just reached operating temp at about 175f. Idling at 1100rpm, its always idled a little hight though. Oil press is at 10psi. Was up at 50psi when I started it cold and its been slowly falling and now down to 10psi. I'm about to change the filter again and add some oil.

No it doesn't have the extended drive. I'm running rotella 5w40 syn. I've had no problems with anything up till now. The damn cylinder walls still had the hone marks. Now I might have to relace everything, this fckin sucks balls.
Why would it have good oil pressure but as soon as it warms up it drops off to nothing?
Could the rtv that I used to seal the oil pump with have come loose and clogged the oil passages in the block and head? What are the odds of that actually happening

I mean that sounds a little low but not crazy low... sure that's possible that RTV broke off if you gobbed on WAY too much.. but your filter on the strainer would catch that.. Your oil pressure backs off once your engine is warm because the oil warms up and becomes less viscous, the oil shears easier with temperature. What were your previous values around idle before (when warm)?

I've changed the oil filter 3 times now and nothing has changed. I'm considering running an engine flush before I pulll the motor just to get all the little stuff that could be stuck in there.
With the old rb25 pump I had about 15-20 psi of oil pressure idling at 900rpm

That sucks. Sounds like you have to pull the motor regardless.

i know it's a pain but the screws on the back of your pump may have backed out. There have been reports of this online. One thing to check is the front main seal area. I have heard that if the pump screws are backing out, there may be some seepage in that area behind the lower timing cover.

Only other thing I can think of is a loose oil pump pickup bolt, clogged screen, etc.

Try pulling the pan, then check the pump.

I tried to to take those bolts out and red locktite them but I couldn't get the damn things out they were so freakin tight lol. I did my research on everything before I started, that's why I went with the 26 pump and neo water pump.
Ill hopefully have the motor out and pan off tonight and maybe then ill figure out what the fck is going on.

Motors out, pan is off.
Every rod is loose and every crank journal has a groove for the feed hole.
Oil pump screws were tight as hell....tried to get them off and 3 stripped out.
Oil pickup is tight and was completely clean where it sealed.
Everything is completely fcked and I still have no clue as to what happened.
FML

as240 wrote:Motors out, pan is off.
Every rod is loose and every crank journal has a groove for the feed hole.
Oil pump screws were tight as hell....tried to get them off and 3 stripped out.
Oil pickup is tight and was completely clean where it sealed.
Everything is completely fcked and I still have no clue as to what happened.
FML

Is this a factory block? Did you refresh the bottom end at all? Did this engine run to your knowledge before you "refreshed"?

Yes it is a factory block.
I dailyed this motor in my car for 2 years and went to 5 drift events and I never had a single problem with anything.
I did not touch the bottom end at all, I didn't need to because everything was perfect.
The only reason I refreshed it is because I was about to put a precision 5857 on it and I wanted to make sure it would hold up

I just read the zylvia thread. First off, the RB26 pump will be absolutly fine on an RB25. That's what I ran for 4+ years with zero problems. Second, that Sileighty_85 has no clue what he's talking about with tomei oil restrictors. He doesn't understand what "cavitation" is, and he's just repeating crap he read off the internet. You do NOT need them. Nobody here on Oki runs/ran them (including myself) and lots of people bang their motors off the the rev limiter with aftermarket oil pumps for LONG periods of time and NO restricotrs and have ZERO problems. The whole "oil stuck in the head problem" is an internet fantasy created by Tomei and perpetuated by people who like buying their over priced parts. That dude has proclaimed himself an "SR/RB guru"? Tell him he's full of s*** for me if ya don't mind

If the pick up isn't clogged and every bearing in the motor is toast, I'd guess it was the pump that gave up the ghost for whatever reason. You said you were just tooling along when it died, right? How does the crank snout look?

Also, I just noticed what you posted about your pressure before and after the RB26 pump. My pressure stayed exactly the same. I think the only difference is a higher pressure spring in the relief valve which would allow for a *little* higher max pressure. If you had 80psi of pressure at hot idle with the RB26 pump, that's WAY too much pressure and could be part of the problem. If the pump is putting that much out, that means it's wicked hard to spin. If it's that hard to spin, that's that much more pressure on that little contact patch on the end of the crank snout that has to spin the pump. The "extended crank snout" issue is often over stated as a huge issue with RB's and I think that's not true, but it is an issue that can affect people on occasion.

thats exactly what i was thinking about that dude. they seem to just repeat what they read on the first forum they see. i did weeks of scouring and comparing parts before i ordered anything.
the snout looks fine, there is marks on either side of the drive but there isnt excessive wear.
i just posted up another thread on the internals of the old 25 and the new 26 pumps.
tell me what you think about those pics. ALSO, does the 26 pump have 1 or 2 relief springs?

**and my cold start up idle was at 80psi but warm idle was 15-20psi. the man difference i notice with the 26 pump was that the oil pressure didnt jump around when i did a WOT pull

check out these pics....they look to me like the drive was slipping on the pump
this is the *brand new pump*




you can see a ring all the way around the gear where it was rubbing on the snout
the drive on the crank has the matching ring

Looks like that's what happened. That sucks, sorry. BTW, the crank has just as much to do with it slipping as the oil pump, so new or old pump, doesn't matter.

I would rebuild this abomination, but since everything is pretty much toast, I'm just going to get a whole new longblock.
So should I go all in on another 26 pump since the one I have is fcked, or just use the one its coming with?
Cjmark, did you personaly see any benifits using the 26 pump over the 25?

I would slap a new pump on there if the condition is unknown on the old one. Cheap/easy insurance when the motor is already out. I think the only benefit on the 26 pump is the little higher peak pressure it's able to make before the bypass valve opens, but I'm not sure the difference. My car shop guy ordered it with out asking me and said it wasn't much more so I was like ''whatever". What is the price difference in the states?

i got all my parts from my local nissan dealer. im cool with all the service guys so they "hook it up". lol
i got my new 26 pump for $165, i can get the N1 for $180 if i wanted but i dont need it.
tell me this: is it true that the 25 and 26 pumps have 2 springs in the relief and the N1 only has 1? because my 26 has only 1?
check out this pic you may remember and look at the comparison of the stock 26 (top) and N1(bottom)



now look at this pic i took. the stock 25 pump on top and the 26 on bottom....its the exact comparison of the pic above
so did nissan change the designs of their pumps?

Never taken the pumps. Sorry man, no idea. Maybe post this up on skylinesaustralia? They are full of s*** on a lot of things and make up lots of "facts" about needing tomei oil restrictors and many other things, but they love their oil pump debates and they might be able to help out here.

haha alright. a longblock is coming in next week so i get to freshen it up and swap all my new parts to that one up and hopefully the same crap doesnt happen.
thanks for all your help man, ill let ya know how it turns out this time around.

The passages look a bit different. Y not just run the 25 pump to eliminate any differences?

my nissan parts guy convinced nissan motorsports to send us another 26 pump to compare to the old pump, in case they sent the wrong one.
i feel better about running the 26 pump because it is made for a motor that hits 8k rpm regularly instead of the 25's limit of 6800.
and it wasnt the pump that failed. it was either the drive on the crank that was worn too badly, or some of the old head gasket clogged up some oil gallies in the block or head.

Dude fix your crank snout it's cheap and if you drift then you will be bouncing the rev limiter so the chances of your crank walking/returning and snapping that oil gear is higher... and get everything flushed oil cooler is key...Been there so good luck and be meticulous or you will be doing it all over again...

im not one of those ls1 guys that just lays into the rev limiter..i know how to my my foot and brain in unison
http://www.flickr.com/photos/8410334@N04/5510927747/

the new motor is in with another new 26 pump. everything is great so far. ive already put about 100 miles on it and changed the oil and filter twice.
what is normal oil pressure for a rb26 pump at wot? my oil pressure his 90+psi with ease.
idling at about 900rpm the pressure is about 35psi and when cruising at 2800rpm the pressure is around 65-70 psi.
does anyone know if those pressures sound correct? they seem a little high to me, but i may just be used to my old rb25 pump.
thanks again for the input everybody.

My oil pressure is that high with an rb25 pump.

Yesterday I nailed it in first gear and spun immediatly. Oil pressure shot up just past 100psi, maybe around 115psi. Now is that normal? My engine temp was about 170F and I'm running rotella 10w30 blend

Those sound about normal to me. 2 bar at hot idle, 4-5 bar cruising, and I think the pressure relief valve is like 8 bar which I think I'd hit every time over 7k rpm.