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25Det Blowing Smoke, Shed Some Light

Whatskid

By Whatskid,
in Forced Induction Performance

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Whatskid Enthusiast

Whatskid

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As title states I've finished an rb25 conversion into my 32 rebuilt with cp forgies about 5k ago when I bought it, oil is visible ontop of cyl 4 and blows smoke under throttle so I pulled the head off had it flow and leak tested to show worn valve stems seals and guides, wasn't financially able to pull the bottom end apart at the time

Running catch can, cut and shut forward plenum 1200cc inj 3076r

Whilst the head was off we checked for cracks in the block, wear marks on the bore and movement in the pistons and all was mint

Just had a brand new hg and reco neo 25 head dropped on, so can't be valves/seals

Compression tested and pulled 174-180 across all 6 with the leaky cylinder sitting at 175

Turbo was fresh rebuilt by gcg and currently done about 0.1km's no sign of oil burning anywhere, none in the cooler piping

I couldn't see it being a bad oil ring/good compression ring because of the rebuild and cp aren't that bad of a company, but at the same time I could be wrong

Possibilities of it being a pinched ring from not being set right during the build ?

There is oil in the plenum but not a crapload

The only other thing I know about is there's a small piece missing from the pcv o ring but it still seals and doesn't seem to leak

it's getting tuned in a few weeks regardless of it's shitty issue cause 6 months in a mates shed is becoming too much

Will be ripping it down again after that, just seeing if anyone can shed some light

Edited by Whatskid
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sonicz Rising Star

sonicz

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Cant help but I'll be interested to see what it turns out to be since I've been having a similar problem for about 6 months now. My 25det never used to use up any oil then suddenly over night it started to emmit a dry burnt smell from the exhaust constantly at idle accompanied by a tiny amount of smoke under boost. But this adds up to about loosing 1L of oil in 1000k.

Did a compression test all 6 were 150psi, but my battery was dying and when i done it with a new battery it got close to 170. Some mechanics said its probably oil control rings but no way I have the money for a rebuild on a guess. Normal tiny amount of oil in intercooler pipes as well. Does it with any oil, but obviously slightly less with thicker oil. no mods or catch cans stock oil pump

Edited by sonicz
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Whatskid Enthusiast

Whatskid

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What oil pump, what oil and any oil control (restrictors etc) fitted?

Stock pump, no restrictors fitted that I'm aware of other than oil feed for the turbo, and running hpr10 through it.

Black smoke or white smoke?

Light blue Edited by Whatskid
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Whatskid Enthusiast

Whatskid

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When does it smoke?

The oil on top of one piston, coupled with slightly lower result on that cylinder is concerning.

Under throttle, I rev it, it puffs smoke

But it takes a small period of time to build up to it the longer I leave it on idle the more it does it

I though the same too, but it still had a higher psi than number 2 and on par with 6

Both have no issue, from general experience they should all be no less than 14psi less than the highest reading.

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Leeroy94 Enthusiast

Leeroy94

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I would suggest posting a photo of your engine bay. I rebuilt a turbo daily and it was having similar problems. Turned out there was an air breather on my rocker cover that acted like a valve, but it was installed backwards, causing my engine to puff smoke similar to when yours does.

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Whatskid Enthusiast

Whatskid

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must be the bottom end if the head has been eliminated?, do you know if they rebuilt it because it failed, maybe on the same cylinder?

Previous owner tried to run 340rkw through a stock bottom end, which I saw the aftermath of what's left in the shed, so had this one built

I've been leaning to the bottom end too, it's generally the number 1 thing but that doesn't explain how oil can be in the plenum but not in the piping or cooler etc

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Whatskid Enthusiast

Whatskid

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As you seem to only have oil in the plenum, I would try disconnecting the pcv line to the plenum and seeing what happens. It could be faulty.

That's the next spot, I'm waiting on cooler piping to be welded up, hopefully pickup today

Then I can tinker again

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Whatskid Enthusiast

Whatskid

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could be from breathing hard, could try blocking the pcv but would maybe need a breather on the catch can, that plenum may not be helping with engine lifespan

The plenum itself isn't that bad, the inside of it was reshaped and welded similar to a greddy

Once the motor etc is engineered I'll be going for a plazmaman

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