Rb25 Head Leak

[Tangles]

hi'yas

since start of December had my car in the shop doing a big head upgrade job, port etc with poncams, etc

the head was fitted and everything setup but was hell smokey while running

a pull down of the head reveals oil on top of piston no.6, other 5 are dry and fine

what can cause a failure in around the back area of the head?

oil pressure has been restricted at the head with x2 tomie oil gallery restrictors, then again at the turbo becuase pressure was too high there.

the turbo oil restrictor is now set and works well for the correct flow (journal bearing turbo)

however head has the issue with piston no.6 oil on surface area, ie leak from head in that specific area. was "wet" on top when others were dry

used 6mm new valve seals, new valve seats and guides but stock valves.

head was ported etc, by a rebuilder outsourced by the garage, with a Cometic head gasket (1.2mm x 87mm) & arp head stud kit, along with 8.8mm lift kit and poncams (tomei) with oil restrictors

Please - any thoughts on what may have failed?

Ive said to the tuner that it must be a head installation problem, car was fine beforehand; want to send the head back to the rebuilder to be redone properly - or at least redone over piston no.6 area.

whats the go here?? thoughts ??

[Tangles]

all I can think of is a faulty valve seat or seal. or a faulty port job.

any thoughts ?

[PM-R33]

Hmmm i've been thinking about this and the only thing i can think of is oil leaking through the head past the valve stem seal into the intake and then past the valves. So to me it looks like a valve stem seal not installed correctly?

Im sure some one on here a bit more experienced in head building could answer this question.

[Jet 20]

maybe the head was ported too big and has cracked through to an oil passage???

[James_03]

Yeah another vote for bad valve stem seal. I highly doubt the porting has caused this type of issue.

[Tangles]

valve stem seals were seen to be all within tolerance. although Im pretty sure Neo stem seals were sent to me in my parts order.

the valve guides have been replaced and the original install work re-gone over, builder couldnt find a fault as all was within 'normal' scope.

being re-installed now, tuned tomorrow so we'll see how the story ends.

[Tangles]

reinstalled and taken back off again

leaking oil still on top of piston #6

fk me

what could be wrong with it? told em to replace the seat, seal and guide, its been pressure tested and passed - perhaps a cracked head?

if a cracked head, how can that fkn happen, when the car was fine before the tune - no oil usage, no smoke etc.

how do heads crack? possible that the machinist dropped it??

any advice plz

[mid life crisis]

sounds more like a head fark

ok doe's the inlet port show any signs of oil in it compared to the other inlet ports ?or do they all look the same .check the inlet yalve stem for straightness or and grooves along the stem that oil could pass thru .

check the valve guide for wear on one side of it or is showing that its wearing evenily.

it could be a crack from under the cams going into number 6 port i was hoping you would have had this sorted out by now bit hard to offer any more advice without seeing the head .

did they check the head for softness b4 starting the work ?

cheers mid life crisis

[Tangles]

I'll chat to the tuner again (unless you wanna give shaun a call? to offer advice?), but its not in his hands either - outsourced to a machinist.

they should be replacing everything around #6 piston area of the head, and the pressure test came up ok anyway.

hasnt been xrayed because before it went in for some work it was 100% perfect and 200kw easy, no strain.

massive head fK because its out of my hands (here for advice to pass on - ) plus my fund$ are short!

im 200% positive the head was fine before it went in for upgrades. wonder what happened at the machinists? dropped the head and cracked it? faulty stem that hasnt been picked up twice now? (3rd time back at machinists, been bolted on twice and blew oil)

basically now just want the bloke doing the work (not the tuners, good peeps) to fix the fkup with all-new components / handywork around piston 6 area.

[Tangles]

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cracked head.

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1

around the guide area the metal has deformed.

second head has been sent with mine to the machinist (who the tuner backs 100%) to swap it all over and redo again

just on of those things apparently.

close thread, unless ppl need advice on what not to do.

ie dont buy valve guides off the internet, let the shop doing the work supply them.

I'll learn from that.

[PM-R33]

So it was the valve guides afterall, thought so.

I should have my head back from them next week, fingers crossed mine turns out fine, the only thing i supplied was the valve springs.

Edited January 8, 2009 by PM-R33

[Tangles]

ooo getting excited

should be p/up tonight, I hope.... just waiting for that phonecall arghhh!

[Fastrotor]

Are you saying the new guides you supplied somehow caused the head to crack ? ie too big or something ?

Were they the wrong type ? just looking for abit more clarification Tangles

Gary

[Tangles]

Not wrong type gary, just bad luck?

Im told they were frozen then tapped in, one has made a bulge of sorts when expanded, resulting in a micro crack. as far as Im aware

hasnt been xrayed but swapped and left with the tuner. no charge. was fully pressure tested and ok there, but spat oil. fixable / patchable I reckon.

end result was a new head being decked out for me, but just one of those things.

was a 7.5 week job but nothing but praise for the tuner (Boost Worx)

fantastic on the road. beautiful end result, very punchy, pulls hard, & isnt held up anywhere - on the road

cat converter is holding it back power wise, resulting in boost drop still.

will fix that up next tune midyear and be happy with it for a while

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