I was at the track with my 818 and got an O2 sensor CEL. My tuner told me not to beat the **** out of the car anymore and limp it 140 miles home. When I pulled the sensor, the tip was missing. I pulled the header off hoping to shake the broken parts out, but they weren't there. So, I ran a scope up the pipe and discovered the beat up turbo blades. Sent the turbo off for a $600 rebuild. I called the tuner to ask him if it would be okay to move the O2 sensor to a location after the turbo, so if the O2 sensor failed again, at least it wouldn't take the turbo with it. He said "go ahead then send me some data logs." Got it all back together, started it and it ran like dog ****. So, I moved the O2 sensor back to its original location and all was well with the world again. I think it broke after 43 track days of extreme EGT heat cycles. After 20 or so track days, I'll start inspecting it after every track day. It takes just a sec to pull off. Maybe replace it after 30 to 35 track days regardless.
To pull the turbo off, the oil feed and return lines need to be disconnected. To keep the oil feed hose clean, I zip tied the finger of a rubber glove around the banjo fitting. While the turbo was off getting fixed, I decided to do a compression test. While turning the engine over, oil started dripping on my head from the ceiling of my garage! Turns out, as I was turning over the engine, the rubber glove finger was filling up with oil... until it popped! Yep. I did that.
I also had to remove the turbo cooling supply and return hoses. The supply hose is the heat shield covered hose that connects to a hard line under the turbo. But, a short section of that hose does not have the heat shield because of the hose clamp. I have had this section of hose fail a couple of times due to the extreme (track) heat. After a couple of times, what I have learned is, that hose needs a constant tension spring band clamp (OEM type). Although, a worm gear will get you home if it starts to leak, but a new hose and clamp is needed when you get home. Pro tip - that hose and clamp are one time use items. If that hose is removed for any reason, replace it with a new hose and clamps. I now carry a spare hose and clamps in my track bag. I also wrapped the hose clamp in heat shield. I don't have a sense for when the hose needs to be replaced on a preventative schedule. I'm hoping not reusing a hose, returning to spring clamps and wrapping the clamp area with heat shield will be a permanent fix.
While I had the turbo off, that gave me easy access to the low oil pressure warning light sensor. My warning light and gauge have independent sensors. That sensor has failed multiple times due to the extreme (track) heat on top of the block. I know it's a false positive warning because it only happens on extremely hot days and my gauge says pressure is fine. I remote mounted the sensor away from the heat.
These are track car issues. And in these cases, related to track induced heat. Come to think about it, most of the stuff I've done to the car to make it track worthy are related to heat management.
I hate cutting a track day short due to mechanical failures, especially if it involves a tow home. To that end, it's important to develop a preventative maintenance plan. Routine O2 sensor replacement has been added to the list. A spare O2 sensor and turbo coolant supply hoses just arrived. Hopefully I won't need to routinely replace the low oil pressure sensor anymore.
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