R33 RB25 PCV grommet issues .

[discopotato03]

R33 RB25 PCV grommet issues .

Hi all , just a tip for those looking for vacuum/boost leaks on these old girls .

For a while I've been replacing water and breather hoses on the 21 yr old boat and found an issue that had teased me for ages . Silly tuning issues mainly right down low and a bit more boost lag than I thought I should have . Amongst other bits I had Kudos send me a genuine PCV valve grommet and hose . The old valve had been loose in the grommet and when I removed the original one the bottom third of the seals lip was missing . Not surprisingly the hose was old and hard and may have been leaking under boost as well .

Feels better to drive and shows lower manifold pressure at part throttle , goes into positive pressure a bit more easily and the slight lean spikes off idle are almost gone .

"Valve Control" Pn 11810-21U00 , "Insulator-PCV" Pn 11812-41B00 , "Hose - Blow By" Pn 11823-AA510 .

Grommet same on R34 GTt . Grommet around $8.80 , kit inc PCV $44 , all three around $70 .

Something to keep an eye on cheers A .

 

Edited May 11, 2017 by discopotato03

[t_revz]

My car drove fine but on the dyno it couldn't match equivalent set ups so I started testing everything. Eventually I hooked a compressor to the intake regulated at 20psi but gauge only showed 3psi. Set at 90psi to get 18psi. I found 13 leaks of various sizes, the worst being the PCV valve and grommet. It felt heaps better immediately after. I couldn't believe how bad it leaked. Might even make it a yearly check now that I've made the blanking cap and nipple

[discopotato03]

I'm interested to know what other leaks you found , I'm sure I have a few more .

Cheers Adrian .

[t_revz]

7 hours ago, discopotato03 said:

I'm interested to know what other leaks you found , I'm sure I have a few more .

Cheers Adrian .

i actually wrote a list which i still have

 

at 4psi began leaking from -

BOV mount Gasket

BOV signal line

BOV recirc fitting

BOV atmospheric port (which is capped)

then pressurised to 18psi and was now leaking from - 

turbo inlet elbow @ turbo (this one would make no difference as it never sees pressure)

turbo inlet joiner near MAF (as above)

LH rocker cover to turbo inlet hose fitting (as above)

turbo outlet hose @ turbo   

cooler pipe joiner @ LH side of cooler

cooler pipe joiner @ crossover pipe

PCV allowing air to reverse without restriction (by far the worst leak. would have leaked from 1PSI but it wasnt audible until enough air rushed through)

BOV adjustment dial (very minor leak) 

Turbo inlet leak from CHRA (very minor) 

pressurised to 25PSI and no further leaks

 

all are fixed except the last 2 but they are so small they wont be an issue

 

 

 

[MatthewT85]

hmmm i may need to check this as well as im chasing issues...

never really looked at it before

[discopotato03]

I've got some sort of vacuum leak drama giving mine idle issues speed and mixture .

Yesterday I pulled each vacuum hose off the plenum and used the highly scientific method of sucking on each hose and tongue over hole to see if it held partial vacuum . There are two on the back for brake booster and OE boost gauge . Three on the rear right hand side , two for the charcoal canister and one for the BOV . Last two on the front for PCV and fuel pressure reg .They seem good except the signal line to the Turbo Smart FPR which leaks off very slowly . Its the reg not the hose .

Had the IAC housing off the back of the plenum to clean , been done before but now extra clean .

Engine breather system . As I said the the PCV valve grommet and hose are new and the U shaped hose from left to right cam cover was replaced genuine a few months back . The upper hose on the right hand cover "T"(viewed from front of engine) is old and hard but doesn't appear to leak . This is the one that runs to a straight steel joiner and another hose runs down to the smaller fitting on the turbos inlet pipe . I've got Scotty's inlet pipe so it joins in slightly below and behind the larger BOV return hose .

For some reason I can hear a hissing coming from the PCV valve and if I pinch the hose it stops and the idle slows a bit and half returns , it sounds like that PCV is passing a lot of air but it can be intermittent which gives me idle issues . I would have thought its open or its not . Something I have to look into is that second old hard hose because I'm sure I've seen a pic of a genuine replacement and it had what looks like a short piece of aluminium bar inside with a hole drilled through it - restrictor .

Anyway to get that hose off the turbo inlet pipe the airbox and the two main steel pipes (to/from intercooler) had to come out and I didn't find any obvious leak points .

What's got me stuffed is why the PCV system is passing so much air at idle . I'm wonder if air is getting into the crank case somewhere else , dip stick is properly seated so it isn't there .

Anyone got any clues , cheers Adrian .

[hardsteppa]

Pcv valve itself gunks up with oil and crud, sometime doesnt seat proper or move freely. I didn't have much cleaning mine out so just replaced it, which fixed the issue in my boost leak testing.

[discopotato03]

Found one of the main issues . I had the crossover pipe off to clean the throttllebody and when looking under the inlet manifold I noticed a blue plug hanging down . Turned out to be the air regulator plug and what a mongrel job it was to get it back on . There's no room to do it in situ so you have to remove its mounting bolts and pull it forward to plug it back in . The R34 Neo turbo engine is better in that it has a wax pellet cold start air valve built into its IAC valve housing making the plumbing a lot simpler , no regulator and air hoses like the R33 version has . 

Upshot is it now warms up and idles better . The whole off idle and return to idle range from around 1700 revs is a LOT smoother . It used to flat spot and have lots of mixture control issues I'd say because the IAC valve was trying to work over a wider range than it was designed for . Those air regulators work off electrical current from the fuel pump relay as well as conducted heat from its mounting point on the water log under the manifold . 

BTW if you ever have to R & R that air regulator get one of those small mirrors with the ball mount on the telescopic handle , mine has small LED lights on the mirror and came from Bursons . You can't see under the manifold so the smallish mirror is a godsend . The bolts have 10mm heads and having a 1/4 drive socket set is also a big help . When refitting slide a small screwdriver through the lower hole to line it up and fiddle the top bolt in . Make sure the hose spring clamps are positioned so they don't block access to the bolts and you can get at them in situ . Bank on a couple of hours for this job .

A .

 

[discopotato03]

Rounding up R33 GTS25T crank case breather issues .

Just got from Kudos the last breather hose or "Hose -Air Inlet"  Pn 11826-21U00 . In the middle is an alloy reducer with an around 5mm hole .

I'm not sure if the original hose still has this because its gone too hard to tell . Its cracked at the right cam cover side and letting vapors out . I'll cut it open when I stick the new one on . 

A .

[MatthewT85]

That's interesting I might have to have a look at mine. The one that crosses the left and right cover at the front has a crack so might replace all of them while im at it

[discopotato03]

Just Jap keeps the one between the cam covers and the other one off the pass side I got from Kudos .

Just on this , with idle issues take a close look at the IAC Valve on R33 RB25s . If you've checked everything and cleaned the bastard yet still have a slightly fast or intermittent idle issue these can be the culprit . Expensive ex Japan ie 500 ish there is a few alternatives .

If interested look at the thread in the maint section .

A .

Edited June 13, 2017 by discopotato03

[dr phil]

Just replaced my pcv, hose and grommet. Old rubber was rock hard, couldn't get the old grommet out without it cracking to bits, half of it fell into the cam cover OOPS! Hopefully it won't do any harm floating around above the baffle...

[discopotato03]

I think you'll find that many OE hoses on our 18+ year old cars go hard and don't want to seal . If you have the original heater hoses on your R33 squeeze them and feel  them crackle . And the plastic hose joiners on the firewall won't last forever .

The EGR and breather hoses go hard and brittle as does the brake booster hose .

[-S-]

Not only heater hose but the radiator hose. Ask me how i know ...

[MatthewT85]

i know this is a big bump, but... ill try

so pulled the pcv out of the cam cover with the car started, put my hand over it and it was sucking(what i think its meant to do)

pulled it out with the hose to the manifold, and blew through the hose to sim "manifold pressure" i hope im right...

should it completely seal and not allow any air through? as i was able to get air to pass through, as if on boost, air would flow through and into the cam cover...

does that sound like mine has failed, or is blocked a little?