KKK K24 Turbo disassembly

[fspGTD]

I got the turbine wheel out yesterday...

Here is the thrust bearing exposed.  It is resting on two dowel pins in the center section:


This shot shows the back of the throwout bearing and the oil supply passage in the center section.  You can see the channel machined into the back of the thrust bearing, (shaped like a "C"), which routes oil from the center section supply hole to the thrust bearing surfaces through two tiny oil galleys that are drilled in the thrust bearing:


To get the turbine wheel/shaft out from here you just have to pound it out squarely on the end of the shaft, to overcome the tension from the piston-ring type oil seal which is holding it in.  The seals on both turbine and compressor side are two little piston rings with their gaps offset 180 degrees.  Here is how coked-up mine looked just after it came out.  There are some really hard, nasty carbon deposits around the turbine seal:

[jtanguay]

Check this out

http://cgi.ebay.com/ebaymotors/KKK-K03-rebuild-kit-VW-Golf-Audi-a4-jetta-turbo-1-8_W0QQcmdZViewItemQQcategoryZ33742QQitemZ7992189165QQrdZ1

this person has an ebay store that sells rebuild kits for K14 and K24

[fspGTD]

Thanks, I sent them an e-mail asking about rebuild kit for my turbo.

I also found this place, which looks promising...
http://www.turboparts.info/pages/634268/index.htm
They sell kits as well as individual parts for many turbos including KKKs, and their prices look pretty good.

[A_Lex_Ass]

Hey Jake,

I'm new to TD's and it looks like I need a rebuild on my 1.9 TD turbo. It looks exactly like yours from the pics. Except I'm missing that round orange rubber gasket on the intake side. That could be why I'm consuming so much oil.

I think my turbo performance is healthy aside from the abnormal oil use and excess smoke. Is it possible to buy just the orange gasket? or should I attempt a rebuild. Do you have an FSM or turbo manual for the rebuild?

[therabbittree]

Jake nice work again well documented..as always. I would like to redone one of my kkk's.. In fact i am in the middle of swapping a kkk 24 from a 1.6 TD into a '98 jetta tdi ..with the turbo on top of the exhaust manifold like a 1.6L TD..i had to modify the intake with a grinder but its bolted in now..just have to make up the oil drains and feed and the air hookups.. The stock Tdi turbo is SO SMALL !!! it is puny and it had a lot of in and out play on the turbo shaft..i was a little worried as up and down is okk but in and out isn't as cool.... I hope the kkk is the good swap choice as it was great in my 1.6 TD 35 psi no problem..etc of course its not gonna see that that ..now but it should last longer.. the small kkk in the tdi had no o ring at all but a shellac like paste gasket seal..i was not too impressed with that so i hope to see how it works out now.... i can post pics if you guys would like to see.. i hope it runs good..im making a custom down pipe too..it has a chip and will get a set of kerma nozzles  the power plus 216's etc...gauges of course also..
thanks
Deo

[malone]

I hope the kkk is the good swap choice

You'll love it. There's a local 1998 Jetta TDI that put down 152whp on a dyno with that setup including the other mods you're getting. I went for a ride two days ago and it accelerated a lot like one of my friend's stock MK3 VR6. Exhaust smoke wasn't that bad, almost non-existent above 3,000 RPM. The peak boost was between 18 to 22 PSI.

He has an Upsolute Stage III TDI chip and wants to upgrade it to a custom chip.

[therabbittree]

cool if it runs well like that ..i will do my wifes '96 passat up also..heck this is another thread almost ha..
Thanks
Deo

[fspGTD]

Hey guys, I went to look at turbo rebuild kits the other day at the local turbo shop that also happens to be a borg-warner/3k parts distributor.  The K24 kit he pulled out didn't fit the VW 1.6lTD KKK turbo, as the shaft size was too small.  Thrust bearings and journal bushings were different.  So he pulled out a K26 kit (part number K53267110001).  It almost fit perfectly, every piece.  The journal nushings and the thrust bearing and the piston rings all fit.  The only thing that didn't match was the orange compressor o-ring.  The K26 kit compressor o-ring was bigger than the one on the VW turbo.  So if you guys are shopping for rebuild kits for your 1.6lTD KKK turbos, keep in mind that our turbos have K26+ bearing sizes (the ID of the journal bearings on our turbos is roughly 10mm).  I don't have any manual for rebuilding this turbo, all the VW literature seems to just say "if there is a problem, replace the turbo".  But I am taking notes as I disassemble and writing down things like the torque of the compressor nut, etc.

--------------------------

Check it out...  A blow-up parts diagram with parts numbers for the 1.6lTD Garrett TA0304B is available on-line  here and specs on the compressors are available here, and turbine wheels here.  Referencing the appropriate part numbers to these tables, and using the measurements I took directly from the guts of the 1.6lTD KKK turbo, we can compare these turbos more closely...

garrett compressor:
  blades: 6
  wheel diameter: 60.00mm
  inducer bore: 35.40mm
  tip height: 3.00mm

kkk compressor:
  blades: 6 major, 6 minor (12 total)
  wheel diameter: 60.5mm
  inducer bore: 37.5mm
  tip height: 4mm

findings: nearly identical compressor wheel OD means pressure ratio capability of the two are about equal.  However, ~6% larger inducer bore of the KKK means it can flow a bit more air.  There is also a very significantly greater tip height with the KKK turbo (33% greater on the KKK).

garrett turbine:
  blades: 11
  wheel diameter: 59.00 mm
  exducer bore diameter: 49.00mm

kkk turbine:
  blades: 12
  wheel diameter: 59mm
  exducer bore diameter: 49.5mm

findings: except for one additional blade on the kkk turbine, the turbine sections have nearly identical specs.

[Maarten]

How do I calculate the AR and trim from these figures (tried a search in google already)

[fspGTD]

The trim of the compressor and turbine wheels can be calculated from the major and minor wheel diameters using this formula:
trim = (minor_diameter ^2 / major_diameter^2) x 100

I'd love to measure the A/R of the K24 turbine housing, but to do so requires the accurate measurement of the cross-sectional area of the turbine housing and also of the radius to the "centroid" of the area.  I don't know how to do these measurements... got any ideas?

[fspGTD]

Here is a pic of the turbine housing where it has numbers on it:


Best I can make sense of these numbers is:
"NI CR 202" - the alloy of the metal in the casting.  Nickel - Chromium 202, an austenitic grade stainless steel.

"/03 05 83" - looks a lot like a build date.  1983 Jibes.

"5324 101 7097 [1?]"  The 5324... number sequence of 11 digits indicates a KKK part number.  The 1 at the end might be a casting mistake.

"[1 ...] 39" - unidentified number.  Could the "39" be the A/R ratio of the turbine housing - .39?  That would be right in the ballpark of what we might expect.

[Maarten]

I'll check my K24 when I take it off to take a look at the leaky oilretour for my numbers (the compressorhouse is '84 but that came from another K24)

KKK is not very communicative about their specs, I've asked a turbo refurbisher about the specs but they didn't have any info about the OEM turbos

[fspGTD]

I leakdown tested my wastegate:

I found a steel plate that I drilled and tapped for an air fitting and bolted it sealed to the turbine inlet.

Here's how I sealed the turine inlet area.  I jammed a couple thick rubber wedge-shaped pieces deep into it and sealed the cracks with grease.  The only route left for pressurized air to go was to to the wastegate valve, though the side port.


Results: Sure enough, the wastegate valve was leaky.  At 30psi pressure, it only held 25.5 psi (so it had a 15% leakdown.)  For engine cylinder head valve standard, that would be a very poor valve seal.  But I am not sure about what is expected for wastegate standards.  What do you guys think?  Would that much wastegate leakage cause a noticeably added lag in turbo spool-up?

To make sure all the leakage was through the wastegate valve, after the test I remove the wastegate, sealed it's valve, re-assembled, and re-tested.  It had 0% leakdown (held the full 30psi.)

[VWRacer]

I'm not surprised that the wastegate valve is leaking, Jake. They are nothing but a poppet valve, but without the good engineering that goes into a proper exhaust valve. I suggest getting some valve grinding paste and lapping the valve seat. I'll bet it seals right up!  

[fspGTD]

The valve itself has minimal wear on its sealing surface, and looks like a high quality grade of hardened, stainless material.  But the valve seat is a different story.  It's just machined right into the turbine housing, a lower quality cast material, and not as corrosion resistant.  As a result there are high and low spots where rust / voids / putting has occured.  This is probably what is letting the air slip past.  I tried cleaning it up with scotchbrite, but obviously it didn't work.  I'll probably go ahead and try the valve lapping compound.

I'm guessing this problem is common among 25 year old turbos with internal wastegates that lack hardened valve seat inserts.  I'll bet an aftermarket type external wastegate with a hardened valve seat insert would hold up better.