Brodie121

iTrader: (8)

Had a turbo fail end of last year turbine blades all bent and puking oil so i just assumed i had overheated the turbine wheel/chra and toasted a bearing.

Put a spare CHRA and ran it for about 100km, started making noise, pulled it turbine wheel showing obvious signs of foreign object damage.
Pull the manifold see something that looks familiar," it can't be gotta be part of the turbo manifold. Shove my borescope down the turbo manifold and find this:

Looking into the exhaust port



Anybody seen this before?

Somehow the engine seems okay, pulling it tomorrow for a better look and then tear down...

jetlude

iTrader: (9)

Never seen that

arghx

iTrader: (3)

Were the sleeves ever messed with? Were the exhaust ports enlarged?

Brodie121

iTrader: (8)

Rear housing is a 20b housing, so i swapped the 20b sleeve out for a 13b sleeve. Stock port stock sleeve though no porting.

Piece that i recovered had the crack running right through the centre of the emissions hole in the sleeve. Looks like a brittle failure going by the cracks surface appearance, piece was ductile but that doesn't mean much since it was in the turbine housing for quite a while.

Guess i should add a bit more info.

Engine is rebuilt with about 10k km on it
stock ports
Holset hx40 turbo with big exhaust housing, 4 inch DP, tial mvr44mm, greddy manifold
550 pri 1680 sec, twin walbro pumps
blitz fmic
Programmable water/meth setup, ~400cc nozzle on the throttle body elbow. Running 50/50 water/methanol.
Tuned on the rich side with power fc except for cruise areas which are around 14 afr.
94 octane.
9 heat range plugs
Usually running 10 psi but sometimes 14. Never been above that.

Brodie121

iTrader: (8)

well, looks like the roll pins failed. sleeve is pretty much moving freely in the housing.

Used non-oem roll pins on that one, ugh.


Trying to decide if i should pull the keg or cut it out, put a spare in , use set screws and weld them.

heynoman

iTrader: (5)

That's a bad one I've seen it happen to a 20b sleeve but not that bad.

Brodie121

iTrader: (8)

Better shot, The hole where the roll pin goes through the housing is enlarged significantly from it rattling around, scoped inside the housing and felt around and i couldn't feel any major damage but better safe than sorry so im gonna pull it and go through it. 200 bucks in gaskets is a lot less than grenading an engine with a little piece of metal stuck somewhere.

I woould have thought the turbo manifold would keep it in place tho, Don't see how it developed that much play.

alexdimen

iTrader: (13)

That's really odd that the spring pins failed. There is no mechanical stress on them and they should be able to take some serious heat cycling unless they're made out of crap.

Is it possible they weren't long enough and were barely gripping the sleeve?

I swapped mine out because I used a brand new set of S5 NA housings for my build. I think I used stainless from McMaster-Carr.

Brodie121

iTrader: (8)

Just getting ready to pull it but it wasn't the actual pins that failed, where the pins pass through the housing is worn away and seems like its a good 1/4-3/8 diameter now. But i don't see how the exhaust sleeve could move with the turbo manifold on.

alexdimen

iTrader: (13)

Post up pics when you do. That is bizarre. The only way I could see those holes enlarge is if the pins were getting over 1250 F and melted the surrounding Aluminum or they were already loose and vibrated a hole.

If the sleeve failed I can see a lot of heat being transferred to the area because the flow path gets pretty tumultuous with the surface interrupted like that.

Is it possible your EGTs are too high from running lean as well?

Brodie121

iTrader: (8)

Welp, both housing are trashed. Front more so than the rear, front had the good sleeve too.
Roll pin cracked in half which i would guess was the root of the failure...
Engine ran good too, started in 2 seconds after sitting all winter

All the major damage is after the exhaust port and before the intake port opens so probably why it ran fine.
Lot's of chatter marks, only one seal showing a slight ding. Rotors and irons are good. Housings where mint when i built this engine, only had like 10k km on the rebuild.

Atkins seals, definitely not happy with the chatter.

neit_jnf

iTrader: (17)

they can be resurfaced

Brodie121

iTrader: (8)

Yeh was looking into that, my only concern is that the hole for the roll pin in the housing is worn quite large. I can just see same thing happening again. May get one housing resurfaced and use my spare.

Don't know how i feel about maybe welding the roll pin hole up and redrilling to size, seems like any sort of distortion would ruin the housing tho

Brodie121

iTrader: (8)

So going back together once i get another housing, Probably gonna pick up an EGT gauge but any other ideas how this happened?

With the turbo manifold on the exhaust sleeve is squeezed tight into the housing so even without the roll pins i don't understand how it got so loose...

alexdimen

iTrader: (13)

Looks like a steel roll pin. Steel roll pins are usually hardened and are quite brittle. My guess is that it may have been oversized and cracked during installation or stress due to heat.

Did you use a metric size or US inch? If it was an oversize inch pin that could have stressed it enough to crack.

I would use 18-8 stainless unhardened metric. If you wanted to get fancy to could go for coiled spring pins.

Get a shop to measure the hole location, tig weld up the hole, and re-drill it. OR drill oversize in the housing and new sleeves.