I am driving a 2013 Porsche Cayenne, two local shops (Sears auto center, Mavis Discount Tire) flushed my brake fluid in past 4 years. One of them snap off one of my passenger side rear caliper valve strew's head. I noticed last month and decided to extract the screw by myself. I bought the WD-40 and screw extractor from home depot, but it could not pull the remaining screw out.

I tried to drill through the screw and install Dorman bleeder screw repair kit 13960 https://www.dormanproducts.com/p-840-13960.aspx, then I stuck again. I did not have a 1/8" NPT tap to make the screw thread for install the repair kit outer screw. At this stage, I did realized that, this project is beyond my experience.

I bought the replacement caliper as a backup plan, booked appointment from https://www.yourmechanic.com . A mechanic came next day, and found that I worked on my car, the wheel was taken off and being jacked up. He refused to work on it due to his company's insurance policy.

I am in a difficult situation, it seems like the only option to to toll my car to Porsche dealer and let them replace my caliper and perform full brake system flush. The other mistake I made is there had been some brake fluid leak since I drill though the valve screw, I wrap the drill with a plastic bag to stop brake fluid leak, I did not refill the fluid reservoir in time, so it seems like went below the min line. I was then topped it up with half Liter fluid, the fluid is currently above max line. After blocking the hole with drill head and plastic bag, the valve screw hole has been leaking small amount of fluid for last 3 days.

I am getting the right 1/8" NPT tap tool from Amazon today, if I preform the following steps, and then asking some local mechanics to inspect my brakes system independently, if all of them found no issues, will it safe to drive?

1 - install the bleeder screw repair kit
2 - tight it and check if no leaks when pushing the brake pad.
3 - Flushing my brake fluid and release some air from my brake system

I could ask the local shops to re-do the brake system flush, just to avoid potential issues. I read some good review about the screw repair kit, many people did fix the issue using it.

 

I am successfully made the new screw thread with Century Drill & Tool 93201 1/8-27 NPT Tap and 21/64" Drill
The original Porsche caliper valve was a bit smaller about 20/64" diameter, so the current hole is litter bit bigger, but Dorman bleeder screw repair kit fits it perfectly.

 

I cleaned the drill hole, and released some old brake fluid. After wiped clean the caliper, pushed my brake a few times, there was no leak. I also waited half day, and saw no leak on caliper. The new valve is siting on my caliper and tighten very well. I did not try to disassemble my caliper and my brake pads.

The only thing I am worry is the air and water went in to my brake line, there was half liter fluid leaked out during my repair, and the fluid reservoir went blow min line before I topped it up. I hope doing a full brake fluid flush will restore my brake system, Any expert here please give some advise, I look forward to hearing some suggestions.