Jump to content
SAU Community

Comman Problems With Rb25det

old mate

By old mate,
in Engines & Forced Induction

 Share

Recommended Posts

old mate Collaborator

old mate

Posted
Posted

i did a search and went back to about mid 07 and thought no point going further back due to development. or i typed the wrong shit in.

any ways i have an rb25det s1 pulled down and it will be rebuilt with pistons and rods, bearings, studs, gaskets of major brands. the motor will see drift work plus track/grip. is there anything i should spend my money on to avoid say oil problems or somthing simialr which is easy to fix but can cause big problems if i dont.

any help you can give would be great.

cheers, steve.

Link to comment
https://www.sau.com.au/forums/topic/249968-comman-problems-with-rb25det/
Share on other sites
The Mafia Grand Master

The Mafia

Posted
Posted

there is a massive thread based on the oiling problems that plague the RB25.

I'd find it and do everything that it suggests, because most of the problems arise when doing track work, in high revs.

The Mafia Grand Master

The Mafia

Posted
Posted (edited)
Dry sump will fix everything :P

But upgrade the oil pump

Good catch can and breather setup

Maybe head to sump oil drain

500mls extra oil.

dude, putting a bigger oil pump on, and not doing the rear head drain, or blocking the rear oil feed in the head makes the problem worse.

The whole problem is oil pooling in the head do to bad drainage at high RPM. If you put a bigger oil pump on, it will simply pump more up there and into the catch can, creating a disaster. I've seen this happen - GTR oil pump on a RB25 with no extra drains... or the rear feed blocked. Blew most of the oil into the catch can.. and then when the sump was starved... bang.

You're giving bad advice I'm afraid...

Edited by The Mafia
MBS206 Grand Master

MBS206

Posted
Posted
dude, putting a bigger oil pump on, and not doing the rear head drain, or blocking the rear oil feed in the head makes the problem worse.

The whole problem is oil pooling in the head do to bad drainage at high RPM. If you put a bigger oil pump on, it will simply pump more up there and into the catch can, creating a disaster. I've seen this happen - GTR oil pump on a RB25 with no extra drains... or the rear feed blocked. Blew most of the oil into the catch can.. and then when the sump was starved... bang.

You're giving bad advice I'm afraid...

The advice I've been given by most engine builders is not to restrict the oil getting up top. It's all in freeing up getting it back down to the sump.

IE, you REALLY want a good drain setup to get it out of the head. Then, you're all sweet.

The issue is only at high RPM, so who knows what it's doing when you're blocking an oil feed off and sticking to low RPMs. You might be starving the head of oil slightly.

MBS206 Grand Master

MBS206

Posted
Posted
I did see a drain set-up for RB30 heads on ebay, was simply a fitting tapped into the rear of the head for extra drainage. Would thios also work on an RB25?

I'm just using the fitting that TUF_RX3 from here made, which is press fitting into the back of the head.

Others drill and tap a fitting in.

The Mafia Grand Master

The Mafia

Posted
Posted
The advice I've been given by most engine builders is not to restrict the oil getting up top. It's all in freeing up getting it back down to the sump.

IE, you REALLY want a good drain setup to get it out of the head. Then, you're all sweet.

The issue is only at high RPM, so who knows what it's doing when you're blocking an oil feed off and sticking to low RPMs. You might be starving the head of oil slightly.

Well, the GTR have a blocked feed from the factory, and a restricted feed up the front. So less again.

I'm pretty sure SK has said that even with a blocked feed at the back, there is still more than enough oil for the hydraulic lifters in the RB25.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • fatz
      Neil's R33 Gts-t Build

      By fatz · Posted

      Give it 40psi and send it to the moon
    • GTSBoy
      R32 GTS (RB20DE) Injectors Replacement

      By GTSBoy · Posted

      I suspect 550s are on the large side for happy operation with a stock/Nistune RB20 ECU. The Hitachi ECU doesn't love short pulse width operation, and the RB20 doesn't need much fuel at idle. Big injectors can be unpleasant. This could be contributing.
    • joshuaho96
      R32 GTS (RB20DE) Injectors Replacement

      By joshuaho96 · Posted

      Yeah, I still don't know why the idle speed control can't catch the falling RPMs. In the Consult logs I see the AAC duty cycle rising, but suddenly it goes lean and the engine stalls. Anyways, the relevance here is the DW 550cc injectors are probably the same. So if OP has similar issues I would be tempted to finger those injectors as problematic for whatever reason vs the ECU failing for some reason.
    • GTSBoy
      R32 GTS (RB20DE) Injectors Replacement

      By GTSBoy · Posted

      Yeah, sort of blurring two different things together, aren't we? I just meant O2 feedback closed loop. I used to have a 0-1V LCD meter on my dash, wired directly to the O2 sensor signal. So you could easily see what it was doing. Normal running it would flick back and forth nicely. Slow down to an idle and it would keep flicking, as the ECU tried to servo to maintain stoich, but it would slow down as each swing happened until it would stay at one end of the scale. As I said above, the sensor heater is not enough to keep it hot enough when there is also little heat in the exhaust flow. Give it a blip and it would start swinging again, then peter out again. Meanwhile, idle speed control would run just fine, because unrelated.
    • joshuaho96
      R32 GTS (RB20DE) Injectors Replacement

      By joshuaho96 · Posted

      It's not even O2 feedback, it's just simply when the ECU sees the closed TPS signal for whatever reason the idle will start steadily dropping until the engine dies. With the TPS adjusted to not trigger closed TPS it will idle at some ridiculously high RPM and something like 6 degrees of timing. In the absence of getting eyes on it personally and a lot of quality time doing diagnostics I couldn't tell you what the real problem was but it was interesting nonetheless
×
×
  • Create New...