Jump to content
SAU Community

Rb30Det, Head Gasket Blown Between Cylinders?

nicksamaniac

By nicksamaniac,
in Engines & Forced Induction

 Share

Recommended Posts

nicksamaniac Collaborator

nicksamaniac

Posted
Posted

Has anyone seen this on an rb before?

Mine has randomly let go between cylinders 3-4, oil is clean and pressure is spot on, not running hot at all, coolant is clean.

It just started running All of a sudden really rough, and after a comp test, cyl 3 and 4 have nothing, sooty plugs and that's it, every thing else seems fine.

GTRPSI Mentor

GTRPSI

Posted
Posted (edited)

Sounds like the seal between 3 and 4 is compromised, there will be no water or oil mixing issues, simply no compression if dead on right between the cylinders.

Good way to check is pull a spark plug out of one of the 2 failed cylinders, leave the other one in the other failed cylinder, turn over the engine by hand, when the cylinder that failed with the sparkplug fitted is in the compression stroke you will hear a hissing into the cylinder without the spark plug.

Same will happen if you swap the sparkplugs the other way around, whichever cylinder is going into compression with the spark plug fitted will leak out into the failed cylinder next to it without the spark plug.

Edited by GTRPSI
nicksamaniac Collaborator

nicksamaniac

Posted
  • Author
Posted (edited)

Only runs up to 8psi, standard r33 tune. Standard timing, it is an rb30/25 running the stock 370cc injectors and ecu, afr's are spot on at 14.7 @ cruise and up to 11.7 @ full boost,

Components look flat under a straight edge but may have to look closer with feeler gauges, maybe get some bits milled/surfaced.

Might be an excuse to build a full angry engine!

Edited by nicksamaniac
nicksamaniac Collaborator

nicksamaniac

Posted
  • Author
Posted

Sure am, even had it on the Dyno to check it! The afm goes over 5v at around 11psi boost, it's at 4.89v at 8psi, so that's as hard as I can run it.

I have a set of sard 700cc injectors but am waiting/saving for a power fc.

People say it can't be done but if you think about it it's the same as winding up boost on a stock 25.

Its only 500cc or 500ml capacity Extra.

Simon-S14 Grand Master

Simon-S14

Posted
Posted

Lol that's the craziest thing I've heard. just Because it runs Ok at 8psi on the dyno doesn't mean that in the real world it might not boost spike and max your afm out and cause detonation. Which is exactly what's happened.

500cc more is a biy more then winding the boost up. The comp ratio has changed. The airflow characteristics have changed all throughout the load and rev range. It's never going to work safely on a stock 33 ecu. Do yourself a favor and get the head checked. Gasket replaced and put a tunable ecu in it

nicksamaniac Collaborator

nicksamaniac

Posted
  • Author
Posted

Boost spike? With a 4 psi spring in a 50mm gate, bleeding off to get a MAX of 8 psi, with the boost controller at full bleed.

Funny how I've been driving on this setup for 22000km.

I actually have an answer now, head is not flat, out of spec over the length, explains why it went between 3-4.

GTSBoy Grand Master

GTSBoy

Posted
Posted

Lol that's the craziest thing I've heard. just Because it runs Ok at 8psi on the dyno doesn't mean that in the real world it might not boost spike and max your afm out and cause detonation. Which is exactly what's happened.

500cc more is a biy more then winding the boost up. The comp ratio has changed. The airflow characteristics have changed all throughout the load and rev range. It's never going to work safely on a stock 33 ecu. Do yourself a favor and get the head checked. Gasket replaced and put a tunable ecu in it

Actually, it's not all as silly as it sounds. The load is measured by the AFM, so the fuelling will be correct at pretty much all points, and where it is wrong, it will be richer than the original fuelling in the 25, so safer (if more wrong!). The timing will probably stil be OK, as the RB25/30 doesn't usually end up with more compression.

I'm not saying it's a great idea, but the ECU at least is able to do it. If it was an olde schoole MAP sensored ECU, then you'd have good reason to call foul.

533 RYC Proficient

533 RYC

Posted
Posted

^ +1. The capacity increase VS the amount of boost these engines can put up with COULD allow it to run safely. The fact that the afr's have been checked should confirm the state of tune is sufficient to support the load/demand of the setup.

Ben C34 Grand Master

Ben C34

Posted
Posted

A bit unlucky it let go. Good on ya for chucking it together and having a go.

To many people spend too long thinking about stuff and not enough time doing it and seeing what happens.

  • Like 1
nicksamaniac Collaborator

nicksamaniac

Posted
  • Author
Posted

Thanks for the positive reply, most forums only dish out negative stuff and false tech info.

At least I'm doing my own r&d (so to speak) if it doesn't work, at least it's only made/built from spare/leftover parts around the shed and hasn't cost $thousands in the first place.

nicksamaniac Collaborator

nicksamaniac

Posted
  • Author
Posted (edited)

Probably was always out of spec, it was just removed from a stock n/a rb25 (r32/cefiro) and bolted straight onto an untouched r31 rb30 bottom end. Using a cheap fiber head gasket.

Probably was a good thing I had a nasty gasket as aposed to a mls-r, it probably would of done head/block damage in the long run instead of chewing out the gasket.

I'll get it milled, fit some better valve springs (bin the non turbo ones)

and screw it down with a good gasket.

Edited by nicksamaniac

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

    • ToothDR32
      $5 Clock upgrade for R32 GTR

      By ToothDR32 · Posted

      Hello, sorry for being late to join the discussion, but my clock just died on me.   Ive tried to look at Michaels digital clock repair.docx and it doesnt work maybe the file has expired.   Please let me know if you can re upload it or take some youtube videos to show us how to get the clock installed? thanks
    • MissMintyR33
      R33 persistent issues. P/steering and lag/misfire

      By MissMintyR33 · Posted

      I thought that might be the case, thats what I'll start saving for. Thanks for the info 
    • jtha7
      Strange issue RB25DET wont start

      By jtha7 · Posted

      Ps i found the below forum and it seems to be the same scenario Im dealing with. Going to check my ECU coolant temp wire tomorrow    From NICOclub forum: s1 RB25det flooding at start up Thu Apr 11, 2013 7:23 am I am completely lost on this. Car ran perfectly fine when I parked it at the end of the year. I took the engine out and painted the engine bay, and put a fuel cell with an inline walbro 255 instead of the in tank unit I had last year. After reinstalling everything, the engine floods when the fuel pump primes. if i pull the fuel pump fuse it'll start, and as soon as I put the fuse back in it starts running ridiculously rich. I checked the tps voltage, and its fine. Cleaned the maf as it had some dust from sitting on a shelf all winter, fuel pressure is correct while running, but wont fire until there is less than 5psi in the lines. The fuel lines are run correctly. I have found a few threads with the same problem but no actual explanation of what fixed it, the threads just ended. Any help would be appreciated. Rb25det s1 walbro255 fuel pump nismo fpr holset hx35 turbo fmic 3" exhaust freddy intake manifold q45tb q45 maf   Re: s1 RB25det flooding at start up Fri Apr 12, 2013 5:07 am No, I didn't. I found the problem though. There was a break in one of the ecu coolant temp sensor wires. Once it was repaired it fired right up with no problems. I would have never thought a non working coolant temp sensor would have caused such an issue.
    • jtha7
      Strange issue RB25DET wont start

      By jtha7 · Posted

      Hi sorry late reply I didnt get a chance to take any pics (my mechanics on the other side of the city) but the plugs were fouled from being too rich. I noticed the MAF wasn't genuine, so I replaced it with a genuine green label unit. I also swapped in a different ignitor, but the issue remains. I've narrowed it down a bit now: - If I unplug and reconnect the fuel lines and install fresh spark plugs, the car starts right up and runs perfectly. Took it around the block with no issues - As soon as I shut it off and try to restart, it won't start again - Fuel pressure while cranking is steady around 40 psi, injectors have good spray, return line is clear, and the FPR vacuum is working. It just seems like it's getting flooded after the first start I unplugged coolant sensors to see if its related to ECU flooding but that didnt make a difference. Im thinking its related to this because this issue only started happening after fixing coolant leaks and replacing the bottom part of the stock manifolds coolant pipe. My mechanic took off the inlet to get to get to do these repairs. My mechanics actually just an old mate who's retired now so ill be taking it to a different mechanic who i know has exp with RBs to see if they find anything. If you have any ideas please send em lll give it a try. Ive tried other things like swapping the injectors, fuel rail, different fuel pressure regs, different ignitor, spark plugs, comp test and MAF but the same issue persists.
    • GTSBoy
      Freddy Plenum vs Genuine options RB25

      By GTSBoy · Posted

      My return flow is custom and puts the return behind the reo, instead of at the bottom. All my core is in the air flow, rather than losing some of it up behind the reo. I realise that the core really acts more as a spiky heatsink than as a constant rate heat exchanger, and that therefore size is important.... but mine fits everything I needed and wanted without having to cut anything, and that's worth something too. And there won't be a hot patch of core up behind the reo after every hit, releasing heat back into the intake air.
×
×
  • Create New...