Silvia Club of NSW

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PostPosted: Thu Jun 10, 2010 10:07 am 
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T25

Joined: Wed Nov 07, 2007 10:45 pm
Posts: 6
Car: S14
Hey guys

Sorry for the long post but I wanted to add as much detail as I could. Car is a 97 S14a

Symptoms:

1 - Firstly its loosing oil; 250ml/week+ Started slow about 6 months ago but as expected got progressively worse after it was finally tuned and started getting leaned on (also worth a mention - car was running around for a good few months maybe more, with an old map running bloody rich which may have resulted in rings scoring the bores - highly probable)

2 - A few months back I finally got round to replacing the VTC sprocket because I couldn’t take that shitty noise anymore. Did what most suggest – clean and test solenoid …soak in kero over night and supply 12V etc. Solenoid came up good so a replacement unit/sprocket was ordered and fitted (fresh oil changed, etc) the noise went away instantly … man that was a great 2 and a bit DAYS !! lol

Rattle is slowly coming back - unit was replaced 2000 km ago and I could hear it slightly rattling after day2 (not a good sign) tensioner checked out fine and I removed top guide to eliminate that as well …no change and chain doesn’t have excessive amounts of play, etc.

3 - Every time a put my foot down I can see a massive plume of smoke PUMP out the back and I also get an equally bad puff after brief periods of over-run and light throttle applications

Smoke is black which suggests fuel but I know theres oil in there cause im finding tiny oil splatterings/spray everywhere I go ie garage door has a fairly descent oil stain around where my exhaust sits (little bit of carbon build-up but mostly oil.) On mates drive ways where I normally park (its left a distinct oil spray pattern from the exhaust - If I put my hand behind the muffler it slowly covers it in a fine oil spray and that’s just at idle let alone when it cracks 22 pound


Possible causes

Oil leaks - Front crank main seal leaking, slow and steady (few drips a day) this accounts for the small splashes of oil that started to appear on the trusty garage floor but it doesn’t account for the total amount I’m losing.

Rings / Head gasket cactus - Rings or head gasket were my first thought but seems unlikely after testing – comp test came up 138-140 across the board and Im not losing any water. Haven’t done a leak down test yet so can’t rule out valves at this point

Valve steams – Old motor (189,xxxkm on the clock)

Turbo shagged – Is a T518Z, with 10-15000kms done. Bought brand new from nengun.
Minimal play up and down but has roughly 1-2mm play laterally (back and forth) which means rebuild? – either the thrust bearing or oil seal has shat itself or both but either way its rebuild time.
Also probably worth mentioning the comp housing and IC piping only had the slightest/finest film of oil coating IF ANY. If a seal on the compressor side is leaking, its not letting much into the motor.

Starvation due to poor pressure or blockage - Maybe clogged oil galleries but Oil/filter and plugs changed every 5000kms or less (as previously mentioned this things spends more time in the garage than on the road but I still drop the oil every few months - the last few changes oil has come out filthy black and there is no way it could be breaking down that quickly)

Oil used Shell helix ultra 10w40 since i've owned it but switched to shell helix 15w50 ($35 x 5lt) after the oil usage became ridiculous

No metal filings in the oil or filter either

Oil pump possibly cactus – don't think so, my oil pressure shows everything within spec at all appropriate rev ranges (taken from the workshop manual) and readings taken when the oil levels half full or above on the dipstick.


So I'm looking for suggestions/similar experiences as to what would cause a basically brand new trust turbo to fail this prematurely (ran 22-24pound no worries…..until now haha ) and could also be contributing to my other issues. Are oil pressure / loss issues causing the VCT and smoke, or is the turbo causing the oil issues…

I Have no issues rebuilding the turbo but I just don’t want to have to rebuilt it again in another 6 months because the engine has oil issues etc. Would also like to get to the bottom of my VTC rattle issue (ie why the f@%k a brand new unit would already be making a rattle after so little time)


Any suggestions, experiences or thoughts would be massively appreciated in the matter!!

Regards
AT

Side note: apologies to anyone who has already seen and responded to this thread on another forum - everyones input is really appreciated, Im just trying to maximise different opinions/suggestions/sollutions


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PostPosted: Thu Jun 10, 2010 12:26 pm 
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Quad T04
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Joined: Wed Sep 03, 2003 12:08 pm
Posts: 1976
Location: Sagami-ono, Kanagawa Ken
Car: S13 Silvia
138-140psi compression is a bit low, but probably (from memory) still within spec from the workshop manual.
Was this done cold or hot?

Where is your oil going? Do you think it's burning it or is it weeping out the front cover or what?
It's a fair bit of oil to be going through!

Is the crap coming out your exhaust actually oil? My car sprays out a bit of carbon and water when it's first started up, not a big deal. It's not oily though, just black.

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PostPosted: Thu Jun 10, 2010 4:16 pm 
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T25

Joined: Wed Nov 07, 2007 10:45 pm
Posts: 6
Car: S14
Yeah the Comp test was done when it was hot - FSM says 128 is about the minimum but i was just happy they all came up even haha - so rings and head gasket are out.

not sure i think its a combination of both - I can't see any other leaks apart from the front main seal but the leak is so slow it doesn't seem likely that its the only place im losing it from so it must be being burnt off aswell

yeah its definitely got oil in there - I understand the carbon/condensation mix your talking about but this seems to still be happening even after a drive - doesn't seem right to me

so as far as the oil being burnt off/eaten goes im guessing 2 things - If the rear oil seal (turbo) has let go this could possibly account for the oily spray/mist being ejected and excessive amounts of smoke (due to oil being burnt off when its thrown onto a hot exhaust)

or the other is valve/s aren't seating properly and/or seals have gone.

this sounds logical yeah??

Cheers for the input - its greaty appreciated :)


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PostPosted: Thu Jun 10, 2010 4:28 pm 
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Quad T04
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Joined: Wed Sep 03, 2003 12:08 pm
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Location: Sagami-ono, Kanagawa Ken
Car: S13 Silvia
Yeah, the even comp sort of rules out some kind of catastrophic failure in the rings/head gasket area.
Lots of people have a weeping front cover, but on my cars at least it's never accounted for any appreciable loss in oil level.
I would have thought that leaking valve stem seals WOULDN'T show up when you have the boot in, it'd be hard to leak oil into your inlet tract when there is positive boost pressure in there and around ambient pressure on the other side of the seals (ie inside the head).
I'd expect them to leak on backing off instead.

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PostPosted: Thu Jun 10, 2010 5:36 pm 
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T25

Joined: Wed Nov 07, 2007 10:45 pm
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Car: S14
Cheers this is exactly the kind of response i was looking for - so i guess it still points to the turbo.... and I know the turbo is up for a rebuild but im still stumped as to why its let go so early. There must be something im missing or haven't thought about... because the likely-hood that I got the 1 defective unit in every 10,000 produced for both my T518z AND new VTC unit is slim to non.

I just don't want to have it rebuilt only to have it fail again in 6 months because i've missed some under-lying problem ie blocked or partially blocked oil feeds, etc that can really only be sorted by pulling the motor down and giving it a full clean and proper rebuild.

any other idea's on what might cause this


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PostPosted: Thu Jun 10, 2010 6:53 pm 
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T25
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Joined: Thu Jun 10, 2010 6:30 pm
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Car: BNR32
Agreed, when WOT with pressure in the inlet tract, and vacuum in the rocker covers (correctly working PCV setup) you wouldn’t think oil would be making its way into the motor and out the back… but then is there white smoke on WOT?
Regardless, its all the gentle boost transients a motor gets when toddling around that should upset it. With little oil being found between where the PCV pipes joins your pipe work, and the turbo mouth, you may be able to safely say that the rings and valve guides are sealing adequately
Oil being lost through the front c.shaft seals seems pretty likely (and cheap / easy to fix to boot) at this point AT


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PostPosted: Thu Jun 10, 2010 7:45 pm 
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Quad T04
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Joined: Wed Sep 03, 2003 12:08 pm
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Location: Sagami-ono, Kanagawa Ken
Car: S13 Silvia
Have a good look at your oil rails above your cams and your cams themselves. Being last in line for oil (ie at the top of the motor) you'd expect oiling issues to show up there early on.

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PostPosted: Fri Jun 11, 2010 12:08 am 
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T25

Joined: Wed Nov 07, 2007 10:45 pm
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Car: S14
Awesome thanks for all your input guys – its massively appreciated. Always good to get other peoples thoughts on issues like this

Looks like I’ll be changing out the front main seal asap, stripping off the turbo and sending it in for a rebuild and go from there.

Still might have to look at the valve seals due to the epic black plumes after over-run but I’ll see where this gets me first

I’ll check out the oil squirters as soon as I can but from memory they looked fine a couple of months ago when I had the cover off to remove the top chain guide (when I installed my poncams a while back I removed and soaked the squirters overnight in degreaser and then used a brake cleaner pressure pack to ensure everything had been dissolved and removed and everything was flowing freely – they didn’t look bad to begin with but man they were clean and flowing when I was finished ..lolz)
Also inspected the cam lobes while I was in there and they all looked/felt fine – no signs of oil starvation but I’ll definitely check again hopefully this weekend and report back


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