ceramic wheel letting go

[wrxhoon]

hang on gary ,

i said the 3 rear pistons were badly scored and the 3 REAR bores as well ( the rear turbo let go ) the 3 front are very lightly scored ( compression was normal in the 3 front cilinders the rear 3 were all down from about 70- 100 if i remember right ).as the dust got sucked in the rear 3 and it damaged the 3 rear bores some went past the damaged pistons , bores and rings went in the sump and yes some found its way in the bearings as well but obviously very fine stuff because they were marked only very little .

i had everything changed or rebuilt , reground crank + new bearings ( big ends + mains ) , rebored to 87 mm + arias pistons , new oil pump ( yes the other one had very fine score marks in it ) done all the valve sets ground valves ( yes a couple valve seats were leaking from that ceramic dust that got there ) .

i guess you are still not convinced ..............

next you are going to say ahhh the engine was on its last legs right ?

well i'll jump in first and tell you that the engine was rebuilt 6 months before that .

anyway its not the firt one that has that happened , i know of another one .

Let me make sure I have this right...........

The front 3 pistons are damaged because there was ceramic dust in the oil.  How did it get there?  Past the rings in the rear 3 cylinders.  Down into the oil, picked up by the oil pump.  Then through the oil filter.  Hang on, let's stop right there...

How does 100+ micron dust get though a 10 micron oil filter?  (For those that don't know a human hair is ~140 microns). :freak:  

Let's move on.....

Assume by some miracle it makes it through the oil filter, then gets sprayed via the oil squirters onto the bottoms of the pistons then onto the bores.  Then gets past the rings and onto the top of the pistons. :freak:  

Was there any ceramic dust in the bearings?  Ceramic dust would rip a bearing to shreds in seconds.  The oil flow at the main and big end bearings is far greater than the oil scrape of the bores.  Was there any ceramic dust in the oil filter?  Have you had the pieces on the pistons spectro analysed to ensure they are the same material as in the ceramic turbines?  Have you had the oil analysed for ceramic contamination?

On the race GTR that put the ceramic in the cat, I had the oil analysed by Castrol to make sure that the bearings were in good condition.  Absolutely nothing to do with the turbine failure, that's not why I had the oil tested.  I was simply following our normal procedure for checking a recently rebuilt and run in engine.  There was not a single trace of ceramic in that oil.  And it finished the race on one turbo, drove onto the trailer and into the workshop.  

Bottom line, I still remain extremely sceptical.

[mark morris]

sorry to butt in here guys, but could the dust have got in to the oil system through the oil return from the turbo, would the compressor wheel have moved forward, removing the shaft from the seal surface,(is that possible? or dose the ceramic wheel take the shaft with it when it seperates?) if not than I spose the oil preasure would have kept it out.

wrxhoon. are you sure its not parts of the compressor wheel or somthing else?

still dosnt explain how it might have got past the filter, unless, dose the rb26 have a buy pass? ie. for too high a preasure or blocked filter so the engine is not starved of oil.

Im no RB guru just trying to relate it to my trade, which is large turbo charged diesles.

[wrxhoon]

sorry to butt in here guys, but could the dust have got in to the oil system through the oil return from the turbo, would the compressor wheel have moved forward, removing the shaft from the seal surface,(is that possible? or dose the ceramic wheel take the shaft with it when it seperates?) if not than I spose the oil preasure would have kept it out.  

wrxhoon. are you sure its not parts of the compressor wheel or somthing else?

still dosnt explain how it might have got past the filter, unless, dose the rb26 have a buy pass? ie. for too high a preasure or blocked filter so the engine is not starved of oil.

Im no RB guru just trying to relate it to my trade, which is large turbo charged diesles.

mark it hapen how i explined above , i found the little ceramic pieces imbeded on the tops of the rear pistons some are still there if you have a close look in the pics .

the ceramic pieces got sucked back through the exhaust ports , there no doupt about that . now when they in the combustion chamber the scored the bore , piston sides tops and rings , then much smaller pieces went down the the bore and in the sump ( i found small pieces in the sump), all the oil was contaminated with them .

if you guys dont want to believe it its up to you , why would i want to make it up ?

i'm just trying to warn you what happens when the ceramic wheels fly off in an rb 26 , so it doesn't happen to you ....

[mark morris]

No offence dude! not calling you lyer, just trying to convince my self, not fishing for a bite, although I think I got one! :uh-huh:

[wrxhoon]

no not at all mark ,

its just that i thought gary (sk ) would know better .

the engineering shop that does our machining told me that he had one go about a month before mine did .

the same thing , rear turbo let go and the ceramic dust went in the engine , damaged the rears just like mine .

anyway you guys can believe whatever you like .

i must admit that i never seen it before either ( in any other car but then again the gtr is not a normal car is it ? )

[GTRgeoff]

It does seem odd, but if it happens then there is more to understand here, and I am not seeing it clearly yet. Not doubting it happens, but really want to understand how, physically, it can. With the GTR for example, if one turbo blows the other will continue to provide some boost. SAAB have done this to good effect on V6 engines running the turbo off one bank. So with one turbo still running there is a considerable exhaust velocity to overcome which should prevent any particulates being drawn back into the engine, and the turbine housing design doesn't facillitate reverse flow.

Still intrigued.

[Cubes]

wrxhoon,

I know this is a little off par but how well was this engine building doing in his line of work?

Maybe he needed the extra money and this was a damn good excuse to make some.

I've known some dodgy mechanics in my short time. (replacing heads when they don't need replacing etc)

I trust no one.

[Lukas]

wrxhoon,

 

I know this is a little off par but how well was this engine building doing in his line of work?

 

Maybe he needed the extra money and this was a damn good excuse to make some.

I've known some dodgy mechanics in my short time. (replacing heads when they don't need replacing etc)

 

I trust no one.

I think you solved the problem Joel!!! LOL

[Cubes]

Well its always a possibility....

[wrxhoon]

wrxhoon,

 

I know this is a little off par but how well was this engine building doing in his line of work?

 

Maybe he needed the extra money and this was a damn good excuse to make some.

I've known some dodgy mechanics in my short time. (replacing heads when they don't need replacing etc)

 

I trust no one.

no it was not the owner ( as he knows he wouldnt get any mechanical work from , i do my own ) it was a guy working there that took it for a drive to get a brake meter reading in order to get a pink slip , its an annual thing in nsw after the car is 3 years old .

i dint knock the the power f/c back to limit the rpm ( i usualy do to 3000 rpm )

[siksII]

jerry, i think he was asking about who built the engine, (ie maybe they stuck it together bad so it would blow uP)

joel, in answer to that he has stated that he built it himself, and only outsourced the machining work, which he checked when he got it back anyway. so it wasnt put together wrong if thats what u meant..

[Cubes]

I must have missed a post some where along the way as I didn't realise wrxhoon pulled the motor down him self and noticed the scores himself.

I was under the impression that he took the car some where they looked at it and said "nup she needs a full rebuild mate" this is wrong with it "blah blah".

[siksII]

nah..

to summarise what happened.. he took it for a pink slip inspection, when he went to pick it up it was blowing heaps of smoke.. he took it home and pulled the motor down himself straight away to see what was wrong, got new turbos and rebuilt it himself.

have a look at the pics of the pistons, pretty obvious they are stuffed

also i saw first hand that it was the ceramic turbo peices that were the only thing that seemed to contribute to the engine being stuffed.

[wrxhoon]

i have no doupt at all as to what happened , i'm 100 % sure that the ceramic stuff from the rear turbo stuffed everything up .

all this bulldust that it cant go down the dumps front pipes and the u turn up is just that bulldust .

it gets sucked in from the turbo in to the exhaust manifold in to the exhaust ports and to the combustion chamber , some pieces are still imbeded in the top of the pistons.

anyone that doesn't believe it you are welcome to look at the pistons and the turbo , i still have them .

the evidence is conclusive and my engineering shop had another engine that was the same ,about the time went .

maybe it wouldn't happen if the gtr had a one piece exhaust manifold instead of the 2 , 1 for the 3 rear cil and 1 for the front 3 .

[Cubes]

Any pics it would be interesting to see?

[wrxhoon]

Any pics it would be interesting to see?

they are already there look in post 16

[Cubes]

Cheerz big earz..