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Engine Specific Info and Questions => TDI Engine -General Info => Topic started by: DonGTI on June 17, 2008, 02:28:33 pm
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abstract topic but my dad's mk4 golf (110 bhp 1.9 tdi) has 130,000 Km under its belt and the mechanic has told him to order a new vnt 15 since his should explode any minute... i told him i could get him a rebuild kit (tons of them on ebay) or maybe take it to a specialist turbo shop to rebuild it, however he insisted that vnt's at that milage are "beyond repair" and are a ticking timebomb...
is all this bullshyte? or as long as a VNT is still working it can be "saved" by a rebuild kit?
it has minimal up/down shaft play (tbh i've seen far worse) and engine is burning 300cc (i do dad's oilchanges myself after said mechanic broke sump drain TWICE) of 10w30 oil per 8000 km and does not smoke white (or black) so in my humble opinion it does not appear to be too bad.
can anyone shed me some light on this?
thanks
Daniel
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what kind of oil are you running in it???
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The turbine/shaft is hard to source, but the rest of the normal rebuild stuff is readily available on the net and elsewhere. It is actually the same as a GT15 from what I can see. The vanes can stick, but they are easy to clean, and if you don't drive it like a granny, they shouldn't get that bad. Also like any turbo, they can get damage from coking, like when you don't let them cool down after a drive.
Oh and obviously surge.
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after said mechanic broke sump drain TWICEl
I believe that says it all as for that mechanics opinion..
I've seen them running quite perfectly with a lot of shaft play, and a seized one, but with care and the right maintenance they are pretty tough.
there's a post around here about a full stripdown.
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what kind of oil are you running in it???
10w30 fully synthetic Shell or Torco
I believe that says it all as for that mechanics opinion..
if he just said all he said i wouldn;t be concerned, but he actually coughed up some ?fake possibly? vw service report that turbos be "replaced" after 130K Km since mean time between failures was 110-120K Km and thats what worried me...
if you don't drive it like a granny
saddly he does drive granny style... tempted to just take it off and put in an SDI manifold (and keep the vnt to play around with it...) however he won't have any of that... if its a TDI he wants it to stay a tdi... even though when he drives it it is probably safe to say that it has never seen more than 2500 rpm's on it... once a week i drive it for 2-3 hours and try o make up for that :wink: but still probably internals al coked up
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I sold my Leon tdi with the same engine with 184k miles and original turbo and it was fine, that suggestion is bollocks
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hmm you might want to run a thicker oil. or go with that special Elf 0w30 oil if you really want it that thin. turbo's do like thin oil though. helps them spool up faster by reducing the friction even more.
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If it's never seen 2500 rpms very often then the vanes are probably stuck or gummed up pretty bad.
I'll offer a contrary opinion about the VNT15, it's a very weak turbo and the main cause of catastrophic failure is snapping of the turbine shaft. It is thin and can break very easily. I saw about a dozen of these failures when I worked for VW. If you are running any amount of boost higher than stock, like with a chip or otherwise, you are pretty much guaranteed of the turbine shaft breaking. VW should have put the much stouter VNT17 on these stock.
Brendan
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VW should have put the much stouter VNT17 on these stock.
and they do, now.. :x
I would go for the stuck vanes, a log from vag-com could be better diagnosing that.
if the car never sees more than that, the turbo is pratically new, a good cleanup and some maintenance and its ready for another couple hundred km.
if not, you can check the damage while its out ;)
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you could just install a water injection system to keep the vanes clear. or how about disabling the EGR?
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vnt 17's and vnt 15's... there's more difference to them than just compressor size then?
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Functionally they are the same, but the shaft is necked down between the two bearing contact points on the 15, and is a constant size on the 17 and above.
(http://www.66rover.com/temp/shafts.JPG)
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Thanks again Jimfoo, not sure if my eye deceives me but the 15 (necked down one then) looks thinner on the exhaust bit as well?
Regarding clogged vanes, should they move freely with actuator off? took his actuator apart (?jammed solid?) will not move any direction. Vane button/lever thing has about 5-8 mm of travel with lots of effort but not too much that i break things... is this normal?
Actuator for sure is screwed, hence bought a new actuator off ebay and looking for a complete rebuild kit right now, how complete should the kit be with the vanes i think stuck?
thanks
daniel
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The diameters are the same. A 15 shaft will fit in a 17 and vice versa. The vanes should move freely, though the lever does have a fairly short range of travel. I haven't measured it. They can be taken apart and cleaned though, as it sounds like his needs to be.
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when taking it apart be sure to scribe the wheels to make sure that you put them back properly, as they are balanced.
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Will do :) and when rebuilt and cleaned will get a mate of mine who knows the dark ways of turbochargers to go over it again to make sure i haven't screwed anything during assembly...
as regards overhaul kits... which ones do you reccomend?
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If you have one that seizes on you and you have the luxury of time or an extra one , just fix it the Mr Hsu way- stick the seized one in a bucket with a combination of atf and varsol. Leave it in there for a couple of months and it'll be like new. Like i said if you have time and are too lazy to take it apart and spend money actually fixing it. I've seen at least 3 that were " fixed " this way.
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If you have one that seizes on you and you have the luxury of time or an extra one
well, how its actually going to work out is:
I give dad my VNT15 which i was planning to put on my car (professionally refurbished with les than 4000 miles on... car it was on written off in traffic accident).
I then keep dad's to "experiment" with repairing and running it and when i have played enough i'll install the modified vnt 15 i have hopefully bought from foxracer1 (unless jimfoo makes him a higher offer, or one "which he cannot refuse" )
cleaning wise my friend uses a chemical bath to clean engine parts (24 hour 150 celcius pressurised vat) and he offered me to clean it, but will keep your suggestion in mind for future parts ;)
Thing is if i have it all apart i really wished to put in a service kit, but as yet no ideas reards bands or what should i look for, for a complete kit
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Update...
took it off the golf and replaced it with the other vnt 15 i had... perfect fit/match, only difference is the actuator, its a non-original replacement item and has the boost/vacum input on the side rather than on top... Car started and running fine, performance also improved with the car pulling hard well into 4k rpm rather than loosing steam above 2800
The damaged one was taken to a turbo shop where it was taken apart by my friend and damage inspected. I have to say the first thing that struck me was how stuck the actuator was! it was as if it was superglued in one position... He kept disassembling it and compressor was fine, center section was fine, center shaft has a bit of play but just a bit, however he said that with a refurb kit it should be ok... Shaft was pulled out and inspected and since he won't be running any hard ammount of boost will stick with the original vnt 15 item rather than replace/upgrade to a 17... unless its a good idea.
The vanes were coated in a layer which the guy described as "more than he usually finds"... they were also very hard to move.
Right now everything is sitting in the heated chemical bath and to-morrow he will re-assemble it and hopefully will be able to start playing on how to fit it to my engine. I have the old 1.6 motor sitting on the floor, will mock fit on it and see what i get before plumbing it on the aaz.
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VNT 15 ready and refurbished...
It has a refurb kit in, not sure what was refurbished or what not but cost me $ 110 parts only. He also put a VNT 17 shaft in... just in case i decide to play with it a bit, that set me back a further $40... then balanced the lot and tested it on an air and oil thing (supposed to flow oil in housing, air in exhaust turbine and read off boost from the compressor). After 30 minutes operation at various pressures playing with vanes there were no visible oil leaks and shaft developed no play.
Got charged $150 for parts and $60 for the rest, not bad me thinks...