MarkRobinson

My turbo took a crap NYE putting the whooping on a modified Audi. Yay.

I was thinking it was the headgasket at first since I could feel the power suddenly drop a little as I was beginning to lift at about 6200rpm (3rd gear). A few minutes later as I pulled onto my street, I noticed my condensate exhaust steam was now blue smoke...aw crap.

NY day, the oil was clean, coolant was clean, blue smoke continued from my exhaust, so knew I had to start digging to find out what happened.

Find: I had rebuilt my EVOMS BOV when I first got the car 3 months ago as it was slightly bucking on lift-throttle transitions: sure enough the grease was gummy and it wasn't sliding well. I rebuilt it with Lucas grease and all seemed well. Well it was gummed up yet again..sticky, and it stuck during on of those Audi runs, where the backpressure slowed the turbo so quickly that it unscrewed the nut on the compressor wheel and the suction from the compressor wheel had pulled the wheel off the shaft nearly 3/8", allowing the turbine wheel to pull the shaft back towards the exhaust exit, dislodging the shaft seal and allowing oil to enter the exhaust & smolder. The nut fell out of the inlet boot as I pulled it, barely damaged all things considered.

*Swapped in a used k26/06 (Thank you Weston Dillard),
*Removed and flushed my IC, de-oiled it too
*found that my top AOS hose was not even tight on the inlet: oil residue everywhere.
*Installed my P&P head (valve guides pulled back for full P&P, then reinstalled & rheemed and sleeved to spec. 320 grit polish on intake ports. Spun valves and lapping only.
*Installed 944NA camshaft into my Powdercoated housing
*Installed the rebuilt TB I had sitting around for my 951 boat project
About ready to fire her up. NOT a fun job for someone w/o a lift :/

So, word of caution for those aftermarket BOV's, ensure it's opening evenly (not cocked to one side as mine was) and smoothly, fully.

Droops83

Whew, it is lucky that they failure didn't cause more damage!

When I started wrenching on these cars for a living, I didn't understand why prestigious tuners like Ruf and Andial retained the OE plastic diverter valves in their high-HP conversions and didn't go for the shiny aftermarket billet versions. This is why.

A few months ago I replaced the nearly 30-year-old plastic diverter valve on my '86 because the diaphragm was leaking, causing a vacuum leak/low boost condition. I replaced it with an expensive, but reliable piece of plastic!

Paulyy

That nut should not come off.

I know many many people running no bovs and doing compressor surge on purpose for noise only. And never seen a nut fall off.

Cyberpunky

Interesting Chris but not sure what you are saying the advantage of the plastic is ? Minimises damage if it fails because plastics do less damage to other metal parts? can't bend like metal ? I would be very interested if you could elaborate a little more please
cheers
Bruce

Paulyy

Probably means oem bosch product

Cyberpunky

He does Pauly but not sure what he is saying the advantage is over a metal unit exactly

Paulyy

Well aluminium can wear easy if the surface isn't lubricated correctly even if there's no side stress. Depends on what plastic is used, plastic doesn't wear as easy as there's no stress on the surfaces.

If you put a plastic valve on a aluminium body, the plastic will wear out even quicker if not maintained correctly.

MarkRobinson

the turbo appears to be stock, factory '89 unit. The nut's in good shape

rlm328

Its good to have a neighbor like West. Surprized he didn't get you to do a couple of minor mods (or what he would consider minor) once you were in there.

MarkRobinson

I guess we were both too busy to converse too much on this..but should be good enough for now until my Andial 2.8 is ready to go together.

Droops83

To clarify, I mean to say that the OE plastic diverter valve is much more reliable than the billet ones, as in they don't stick. Eventually, after 15+ years the diaphragm will wear out, but that is it.

I have never heard of a sticking diverter valve causing such a spectacular failure, but it is food for thought.

MarkRobinson

that is precisely why I posted this: I wanted to share this turbocharger failure as I felt it was unique.