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Rb26dett Excessive Blowby - Need Help...

StageZilla

By StageZilla,
in Engines & Forced Induction

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StageZilla Rising Star

StageZilla

Posted
Posted

hey guys i got a rb26 that hasnt been used much in the past 6-7 years, its done about 300 or so km since on and off, having problems, and using it in a dedicated race car so i didnt clock up any street driving

but i recently put the engine into my stagea, with gtr gearbox and diff, and i got some rocker cover baffles made up from a shop in perth and they said it would stop the excessive blowby but i put em in and its still blowing out about 300ml in a short 5 min drive giving it heaps though, but does this mean the rings r gone? or could my catch can outlet with the filter be too small and causing it to pressurise (as its blowin oil outta the little catch can filter)

is the fact its been sitting around for a long time without oil be the cause of rings going?

oh and it drives perfectly, goes really hard on 18psi boost (engine made 360rwhp in the old car), and compression test showed 158 on all cylinders, maybe a leakdown test will show it up?

also it never seemed to ever blowby much when the engine was in the vl with a different catch can :)

any info appreciated guys ;)

Brad

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SteveL Mentor

SteveL

Posted
Posted
did a comp test today again and 100psi on cylinder 3 and 150psi on the rest, and 40% leaking from number 3  ;)

Your first post says 158psi on all cylinders but now 100psi on one......this is the problem with compression tests, you can get a fair degree of variation. DON'T rely on the compression test, get a proper leak-down test done before making any decisions. You also say the car is running 'perfectly' and if that's the case I'd just live with it, plus that doesn't fit with the 100psi result on one cylinder.

If what you have is indeed excessive blowby (compression leak past the rings) then a leak-down test will reveal all. From your decription tho, the problem you may have is oil surge possibly due to excessive oil in the cam area, which might be solved either by a larger/better catch can arrangement or by changing the restrictors in the block. I'd try the former solution first.

Race__24 Experienced

Race__24

Posted
Posted

Double check all your lines as well, i once plumbed up a V8 pollution system the wrong way. The manifold vacuum sucked oil from the heads, through the pollution system and then eventually into the manifold. Boy did i get a scare when i started my freshley rebuilt engine, you should have seen the smoke!!!!!!

  • 1 month later...
madcabbie Contributor

madcabbie

Posted
Posted

Who can do these leak tests guys? I live out central western NSW, and a mate has a GTS-T. He tells me that he things he has done a seal, and that the oil is comming out the dipstick.

He recently turned up his boost to 10spi.

I don;t trust the local mechanics, So who would you advise him in Sydney to check his car out? CRD ? SAS? anyone esle?

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