ct12a turbo failure twice...

[trd-drifting]

As everyone properly knows suprafest is really close :s My supra turbos stopped boosting today. They are standard ct12a’s on a 1jz-gte. I am only boosting up to 0.9bar aprox 13psi. About 3 months ago they stopped and I replaced them the rear turbo, which was seized and the seals were pretty much gone. I have done about 1000kms since then put 2nd hand ones on and I was driving from Whakatane to Tauranga and they seized again, stopped boosting oil temp seemed to be a little hotter than normal 65°C instead of 50°c and they slowly just stopped boosting while in boost. It still drives fine but no boost. Also don’t know if it could be a factor but the oil was only ¾ up the of the dipstick (just before full).

What could be the reasons of this failure oil lines seem intact not leaking... could they be blooked? But seems unlikely as when I changed them I used all the oil feed and return lines as came all complete… Could it be the water lines… what is the easiest way to check for this or anything else I could check or opinions? Also I don’t want to go single just yet…

Secondly … Does anyone have a spare set of ct12a’s that are good condition for cheapish…?

I just wanta go to supra fest in my supra
Josh

[matt dunn]

what do you run for an exhaust.

When we ran the std turbo's on the 1JZGTE with a big bore brand new turbo's lasted a few laps before they died,

that was with a 3" and higher boost though.


Your oil temps are no where near a problem, wouldn't worry till past 120 deg,

3/4 on the dipstick wont have caused it either,

and water lines are sugested, but not essential so no worries there,

air leaks, or blocked oil lines etc etc are a possibility?

Best to get a turbo person to look into them just to see why the failed even if you dont want to repair them.

[d1 mule]

medium/big single

ct12a = shithouse

[MrOizo]

when you replaced the turbos you didnt use silicone on the oil feed now did you?

Hope you got new seals as using silicone can ooze out and cause a blockage to the feed/drain, starving the bearings and causing failure.

[YeMs]

you can run the turbos quite fine without water.. its just extra cooling. iv run various t3s/t28s/td05's without water and they have run fine as long as you cool the car down properly before shutdown (and no i dont mean a turbo timer!)

what oil are you using? its possible its just a case of siezed turbo's again.. they are common for f**n out. however.. are you 100% sure its siezed turbos? any chance your wastegate arms come off ? i know its a long shot but u never know untill you look

i know of a set of ct12's in tauranga off a 1jzgte that could be available before supra fest. chuck me an offer and ill go see him

[trd-drifting]

what do you run for an exhaust.

When we ran the std turbo's on the 1JZGTE with a big bore brand new turbo's lasted a few laps before they died,

that was with a 3" and higher boost though.


Your oil temps are no where near a problem, wouldn't worry till past 120 deg,

3/4 on the dipstick wont have caused it either,

and water lines are sugested, but not essential so no worries there,

air leaks, or blocked oil lines etc etc are a possibility?

Best to get a turbo person to look into them just to see why the failed even if you dont want to repair them

Exhaust is 3" of the standard dump pipe with a muffler coby etc... it boost spikes maybe 0.5psi everynow and then as shows on the boost controller, but this is said to be cause the exhaust is too big for the wastegates/turbos etc... and they also mentioned that after it got dyno tuned.

I am currently using castrol GTX Protec 15w40 i(Black bottle) and i only used silicon do seal the oil return (not oil feed) onto the side of the block... and did it carefully so when tightend wouldnt clog up. Would this have casued a problem could there be a internal blockage to the oil feed just to the rear turbo ie: coming out of the block...

It just seems weird the back turbo seizes (cant turn the impellor shaft at all) But the front one seem to stay normal.

Who would be a turbo specilist in hamilton that anyone would recommend, if not i will have a look in the yellow pages...

[mr_monkey]

are front and rear turbos interchangeable?

[phoenix]

Did you change the oil when you swapped the turbos? Have you checked the PCV valve(ever)?

[trd-drifting]

are front and rear turbos interchangeable?

Not 100% sure but pretty sure...

Did you change the oil when you swapped the turbos? Have you checked the PCV valve(ever)?

Call me naive but how do you check the PCV valve i know where it is how do you check it to see if it is open or closed... And yes did an oil Change

[phoenix]

PCV valve comes off passenger side cam cover, small plastic thing attached to a hose which connect to the intake plenum.

Under vacuum conditions it opens allowing the engine to draw filtered air through engine into the intake, under boost it should be shut. Often as they get old they leak under boost allowing the turbos to force air into the crank case. From what I remember this can most often lead to blown crank seals but people have also blamed turbo failure on them. It was just a thought but it might be something to cross off the list.

Also I don't think the turbos are interchangeable, they look symmetrical?