I was zorching along a county trunk road in the extreme northen reaches of Wisconsin friday evening in the '79 Soot Rocket when I hear something rattle down the exhauste pipe.
I let off on the foot feed, and then apply it again and I notice that I can hear the turbo at 2 PSI boost, and its really singing at 10 PSI. Above that a second harmonic joined in that had a rather un pleasant sound.
Since I've been running stupidly high boost (28 PSI), I figured I had over heated the turbine wheel and lost a whole blade. So I limped 'er in to my weeked destination (European Car Service).
I had intended to change the shocks on the audi 5000, and finish wireing in my 12 gage relayed head light harness for my H4 headlights. You know, a nice lite weekend of wrench twirling.
Instead, it was turbo rebuild time:
This turbine wheel had been in 5 different cars, totaling over 500K miles, so I wonder if a bizillion heat cycles took its toll in metal fatigue.
What amazed me is there was no evidence of heat damage, and only the corner of the trailing edge of one blade had snapped off. It also dinged the first blade down wind of it, and that was the extent of the damage.
Fortunately, there was one more K24 laying around that needed rebuild, so I robbed the turbine and compressor wheels out of that one and put it in mine as I had rebuilt it last winter.