My Diy Attempted Rb25\30 Build - Is Running But There Are Some Issues

[The Mafia]

Hi Everyone

I've just finished building a RB25\30 all by myself. I got my ass handed to me by an engine builder that charged me $6200 and then told me to f**k off when it went to shit at 800kms or so. Bores were marked, etc. The entire engine is off to get a "forensic" style report written up on it. f**k him I say, he could of at least looked at it. anyway...

So, I decided to go to a wreckers, get a RB30E, got a Series 2 RB25 Head, and rebuild it with standard parts. OR what they gave me at the engine parts shop.

Hastings Chrome Moly Rings ($110)

King Bearings ($120)

Gaskets, seals (About $250)

Sealant, extras, etc (about $100)

VCT modded the head, and grub screwed the oil feed. (Cost about $20 in taps, drill bits, grub screw etc)

Anyway - I got it all together, and everything seemed to be running ok. Car ran good, kept the revs between 2000 and 4000 and under a bit of load to bed in the rings.

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Problem 1: After about 60kms, it started to idle on 5 cylinders, but I couldn't pick which one, I tried disconnecting a coil pack at a time but I still couldn't pin point it. Changed the coil packs, still doing it. ONLY on idle, and ONLY when its hot. Cold, its fine.

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Problem 2: Water in the oil. I have noticed the oil dip stick has milky marks up the neck. The actual oil itself looks ok, that nice clear orange look, no black or dark yet. The breather pipes though, have traces of fresh water in them, maybe 2-3 drops worth. (No coolant). My mate says we need to find out why, and I agree.

I have removed the plugs and checked each cylinder, and there is no water in them. All the plugs look the same too - No unusual patterns on any. I have also done a compression test, and they are all 155psi. Nice and consistent.

Rediator seems to lose about a 1L every 3 or s days of general running. None on the ground though.

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Any ideas to help me get started on the diagnosis?

Edited January 16, 2011 by The Mafia

[NYTSKY]

Check to see if all the injectors are firing.

Also could be a loose connection in the coilpack loom, maybe swap it with one you know that works.

Water in the pipes could just be condensation? Or is it more than that?

[The Mafia]

The missfire - Seems to only be on idle. If the aircon is on, or its above 900rpm, it runs fine. no misses. Injectors seemed perfect on the last engine. They are Nismo 555cc.

As for the water - Its got a milky residue up the dipstick tube. Not much at all though. And yeah, the breather hoses has a bit of water in them. Its mackay though, its humid as hell. You think it could just be the moisture from building the engine making its way out?

Filled the radiator and ran it to operating temps again for about 15 mins, and just waiting for it to cool again to see the level, and see if 1L has disappeared.

Edited January 16, 2011 by The Mafia

[JonnoHR31]

light idle misfire is usually ignitor module if you have a s1 head?

[NYTSKY]

Are you still running the 25 tune?

[The Mafia]

light idle misfire is usually ignitor module if you have a s1 head?

Its a series 2 - So no ignitor module. I've changed the coilpacks (Splitfires) with another set of splitfires, and no luck. Tried re-seating all coilpack plugs, and wiggling\seating them firm.

Are you still running the 25 tune?

Nope, I have retuned it for the RB25\30, as I can tune. The last tune on the engine that was shitted by the engine builder, was good for 1 bar, and good rich\safe maps. Currently only running 8-10psi.

[r33_racer]

Thats strange, normally you get oil in the coolant as oil pressure is always greater then cooling system pressure.

[r31 25t]

Thats strange, normally you get oil in the coolant as oil pressure is always greater then cooling system pressure.

Not if it's leaking into the oil return side.

Have you re-checked head bolt torque?

[The Mafia]

not yet, was going to at 200kms, but now that I have the packs out and need to sus out an oil leak behind the cam pulleys, I might do that.

Running ARP Studs at 80 foot pounds of torque on a durotek graphite gasket with "fire rings".

Also, you know those three little bolts that are a bitch to get to that hold the head down? Do they play a big part in it? You can't exactly get a torque wrench on them.

[brother_david]

I would say that you should check if theres oil residue in the coolant, most reapir shops and some gas stations have these. Even though it doesnt shoow as oilreflections in the water there scould still be some. After this you could clean off the milky oil and start it to see if it comes back, though i would recommend you to check most other possibilites before this. When i build my RB30/26 it had milky oil on the oil lid but that was just vapour.

I had a problem with missfire but i traced that to aluminium blocking one of the injectors, a small piece was left in the fuelrail after the bore (ordered a custom length fuelrail and bored it myself due to the size of the injectors).

If theres nothing wrong with either the fuel or the ignition side there must be a problem inside the engine, though it doesnt seem likely to me since it should appear when under load rather then on idle.

[DVS JEZ]

my mate had his oil and water mixing, narrowed it down to the grub screw was leaking extremely slightly, had to pull it off and get it pressure tested, hope its not it but thats what his was.

try richening up the idle tune, i did an r33 today and it started to pop constantly when idle was leaned out, didnt like idling any leaner than 12.0

[The Mafia]

I would say that you should check if theres oil residue in the coolant, most reapir shops and some gas stations have these. Even though it doesnt shoow as oilreflections in the water there scould still be some. After this you could clean off the milky oil and start it to see if it comes back, though i would recommend you to check most other possibilites before this. When i build my RB30/26 it had milky oil on the oil lid but that was just vapour.

I had a problem with missfire but i traced that to aluminium blocking one of the injectors, a small piece was left in the fuelrail after the bore (ordered a custom length fuelrail and bored it myself due to the size of the injectors).

If theres nothing wrong with either the fuel or the ignition side there must be a problem inside the engine, though it doesnt seem likely to me since it should appear when under load rather then on idle.

I'll check all of these and let you know.

my mate had his oil and water mixing, narrowed it down to the grub screw was leaking extremely slightly, had to pull it off and get it pressure tested, hope its not it but thats what his was.

try richening up the idle tune, i did an r33 today and it started to pop constantly when idle was leaned out, didnt like idling any leaner than 12.0

I hope my grub screw isn't. I taper threaded it, and then used loctite 567 to seal it, and put it in there nice and tight. Not tight enough to strip the threads though.

Also, 12:1 is way to rich for idle. If you need to make it that rich, then something is wrong. Lowest I have gone is about 14:1 on most skylines.

[DVS JEZ]

try richening it and see how u go.

i know its too rich but thats where they purr without popping, mine is at 13.2 and another GTR is at 13.5 before it pops.

[Adriano]

Did you weld the head up around the front drivers side, where there is little overlap on the headgasket?

[The Mafia]

no, I simply grub screwed it.

Are you supposed to do this?

[Dale FZ1]

I have experienced much the same thing - 30DET with cams did not like a lean idle. Fatten it up and it behaved nicely.

[GTRNUR]

My guess is that the cylinder flame out is due to the water in the oil.

What is happening is that when the engine is hot the water boils off the oil and ends up in you head and blow by re-breather hoses. Its then sucked into your plenum. The temp drop and pressure drop as the vapor enters the head causes it to condense back into water. Once there it will go the shortest path to the nearest cylinder where it will cause the engine to flame out. You can spot the issue by seeing which plug is too clean.

If the grub screw on the VCT isnt leaking then its your head gasket, which isnt uncommon. Hylomar is your friend. A good spray on the gasket before torquing the head down is the only way to eliminate this sort of thing.

Now the bad news... Chances are the water in the cylinders are causing a lubrication failure issue, and will be resulting in the rings scoring marks in your bores. Cylinder material particles will also end up in your oil, damage your pump, and your bearings. You need to pull the head off and have a look at the bores. With any luck you will have caught it in time.

[The Mafia]

Sounds like a likely story. I'll start checking things.

But before I get drastic and remove the head, are there any little tell tale signs? All the plugs where normal, no clean marks, and all looked the same.

All pistons looked the same too.

Going to get a mate over with a bore scope today.

[r33_racer]

not yet, was going to at 200kms, but now that I have the packs out and need to sus out an oil leak behind the cam pulleys, I might do that.

Running ARP Studs at 80 foot pounds of torque on a durotek graphite gasket with "fire rings".

Also, you know those three little bolts that are a bitch to get to that hold the head down? Do they play a big part in it? You can't exactly get a torque wrench on them.

Just out of curiosity, how come you torqued them to 80ft/lbs and not 72ft/lbs as per ARP spec?

[GTRNUR]

Shutting down the engine immediatly from hot and checking the plugs should reveal which plug is being steam cleaned, though thats not a fool proof method, as steam cleaning requires some combustion to happen. If the cylinder doesnt fire at all, the plug will just be wet and smell of fuel.

The scope will only spot damage after its happened. Having water in your oil is good enough reason to pull the head off and check the gasket is covering the water and oil passeges properly. Your going to have to do it to fix the issue anyway, so why delay...

Did you do a test alignment of the gasket on the head and the block to make sure it covered the holes?

What kind of gasket did you use?

Was the block decked and the head re-surface before you put the head back on?