lack of oil kill turbo?

[gldgti]

hey folks,

well on a trip today in my mk3 aaz with newly installed T3, i believe my turbo is basically dead.

began making nasty noises when above 15psi (grinding, harsh noises, imagine turbine touching housing). we were a long way from home yet and i didnt wanna pay for a tow, so i drover her all the way home (150km) just gently so as not to make the bad noises come too much :-)

anyway, once home i pulled off the intake boot on the inlet and also the compressor outlet - no evidence of compressor wheel bits anywhere but seems to be a lot of shaft play. with the intake boot removed, i can see into the compressor wheel (high mounted turbo) and so i started her up and i can clearly see when the compressor wheel is spinning that its not true - ocsillates around as if its unbalanced and wuite a large movement at that! i would have taken a vid for you folks for kicks, but you cant tell from the video :-(

I rebuilt this T3 before i put it into the car with a KAMAK (OEM supplier) rebuild kit, and upgraded it to a 360deg thrust bearing too. the thing still seemed to make good boost but on the last hit (i was close to home, so i thought stuff it, lets see if its really broken) it made an aweful noise at 16psi and didnt keep going up to 22 like normal, so i guess the turbine was fouling on the housing.

now, i have brand new oil lines (custom ones made up for me by a turbo place) but i am a little bit concerned that the supply line might not be large enough diameter.... anyway, will likely pull the turbo tomorrow and do te post-mortem, we'll see about the bearings then. who wants to bet that the problem has been lack of oil?

[GEE-BEE]

What size ?

I installed a new oil feed per GPOPSHOP.com , what's 76.00 dollars when I spent the money for a hybrid ?

GB

[burn_your_money]

Bummer

Did you balance the turbo after the rebuild?

[gldgti]

so i pulled the turbo this arvo - its not as bad as i thought, pics below show all the wear i can find...





the bearing on the left is an old one for comparison - on the right is the new bearing that is the one towards the cold side of the turbo. the wear groove you can see has been made by the bearing pushing outwards on the outer circlip on the cold side. the hotside bearing appears normals and doesnt show any signs of abnormal wear. the bores in the housing are fine and within spec, and there doesnt seem to be any abnormal wear on the thrust bearing surfaces.

the wear we can see in the pictures is as if this bearing has been pushed against that circlip and has worn away that shoulder. like i say, there doesnt appear to be any wear in the thust bearings, and this is backed up by the fact that there is little to no axial play in the shaft (as normal). i installed the old bearing on the left to test for play, and everything seems normal - not too much lateral movement at all, just like a new turbo. when the worn bearing is installed, the bearing can slip forwards and somehow this allows a huge lateral movement!

anyway, the turbo is largely unharmed im happy to say - theres only very minor scoring on the compressor housing, none at all on the exhaust housing, so all the noise was coming from the compressor wheel. to make it even better, there is still enough of the compressor wheel left not to make any real difference - i've seen worse on other turbo's, its still ok i reckon.

so, now all we need to do is figure out why this bearing is being eaten by the circlip!

any ideas?

[gldgti]

Bummer

Did you balance the turbo after the rebuild?

nope, but i did put it back together the way it was before it came apart - only changed bearings, etc.

i'm pretty sure now that all the movement i saw in the shaft yesterday when i watches it going around was a result of the huge lateral movement that was allowed by the bearing wear in the picture, rather than unbalance. the turbo ran very nice and quietly before i had any problems.

[gldgti]

What size ?

the oil line i have has ID 1/8" or thereabouts..... always seemed a bit small to me, but the shop i bought it from assured me thay put that size line on lots of the cars that are built there... infact, the only reason it was custom made by them is because i wanted such a long one... they only had quite short ones for Nissan and Toyota turbo gasser cars in the shop. 2 cars in the shop had the exact same feed line as he supplied me with..... but they had bigger turbo's too.

i dont know if this is the cause or not, seems unlikely now as there is no real wear on the actual wear surfaces of the bearing, only on the end of that one cold side one.

I have a rebuilt k14 that i am thinking of chucking on the car now..... might do that now and see what you guys think about this.

[rabbitman]

I think 1/8th is too small............

[GEE-BEE]

Not less than 5/16

Return lines are 1/2 I.D.

Gee-Bee

[gldgti]

well, i think i've traced it to the turbine shaft being not quite as smooth as it should be. basically, in order for the bearing to wear as it has done, it must have been turning mostly with the shaft. there is some slight roughness on the shaft due to surface corrosion that i think has caused the problem - its not much but its there. i'm not convinced lack of oil is the problem, since there is no wear evident on the wear surfaces at all.

i amd going to throw 2 more bearings at it and linish the turbine shaft nicely, and put it back in.

[rabbitman]

If the bearing spins with the shaft or faster than it should the oil will get flung outward by centrifugal force and won't lube the shaft very good.

Having a small feed line and/or low oil pressure will make the situation worse.

[gldgti]

yes, i agree it probably doesnt help to have the smaller than stock oil line - i'm going to rectify that at the same time :-)

[53 willys]

1/8" and 1/4" are the most common turbo feed line sizes..or -3jic and -4jic

I was told journal bearing turbos like higher psi while ball bearing like lower psi...
smaller the line the higher the psi will stay.
drain should be a minimum of 1/2" so you get really goo drainage.

[rabbitman]

1/8" and 1/4" are the most common turbo feed line sizes..or -3jic and -4jic

I was told journal bearing turbos like higher psi while ball bearing like lower psi...
smaller the line the higher the psi will stay.
drain should be a minimum of 1/2" so you get really goo drainage.

Possibly I misunderstood, a smaller feel line will cause lower pressure at the bearing since the oil will drain out almost as fast as it gets there.

Whatever the case you want the oil to flow to the turbo completely unrestricted, the bearing will be the "restiction".

[gldgti]

qutie right rabbitman, the pressure after the small line will be less - i and going to basically make up a new 1/4" line, then i am atleast surethat all is OK.

my drain line is 3/4".

1/8" and 1/4" are the most common turbo feed line sizes..or -3jic and -4jic

I was told journal bearing turbos like higher psi while ball bearing like lower psi...
smaller the line the higher the psi will stay.
drain should be a minimum of 1/2" so you get really goo drainage.

Possibly I misunderstood, a smaller feel line will cause lower pressure at the bearing since the oil will drain out almost as fast as it gets there.

Whatever the case you want the oil to flow to the turbo completely unrestricted, the bearing will be the "restiction".