So I've got a few scratches on the mating surface of my upper intake plenum and the machinist that's boring my block and doing a valve job on my head wants a fortune to fix it because the mating surface doesn't clear the mix chamber so he can't just put it flush on his machine to flatten the mating surface. I can buy a replacement for under 50$ but I'm just wondering if anyone has any suggestions to clean it up DIY? It's a few scrapes caused by me when trying to remove the gasket the previous owner stuck on with RTV.

Also does anyone have experience with breaking the head off the bolt that connects the heater coolant pipe to the bottom on the lower intake plenum? This is the metal coolant pipe that wraps around the back of the head and connects to the intake with two bolts. I was removing it and everything felt smooth and sudenly the wrench slapped the block because the head of the bolt just snapped right off. I tried sourcing pick n pull intakes but literally all of the ones that were still in the engine bay had the same broken bolt, 3 days worth of driving around northern CA looking for intake parts and nothing to show for it so far. Has anyone successfully used something like an easy out to get that bolt out? Judging from what I saw at the salvage yards it seems like a common issue.

Any help is appreciated.

Intake plenum gasket should be good with scraping, new gasket, more rtv.

for the broken bolt just drill it out using increasingly sized drill bits and run a tap in the hole. If you damage the threads, then you would just tap for the next bigger sized bolt or helicoil. Ok to get creative on something so minor.

so regarding the gasket, should I be coating both sides of the gasket in a thin layer of RTV then installing?

i have learned thst but we were just discussing salvaging what I have. It sounds like salvaging what I have is more trouble than it's worth since I can buy an upper and lower that isn't scraped up and has no broken bolts for less than 100$ ... I was actually looking for advice to surface the mating surfaces without going the machine shop route. Cleaning the RTV off these mating surfaces was a major pain in the ass and the pitfalls are obvious. Anyway, I've already got OEM gaskets waiting to be used. I'll just replace the plenums because I'd rather it work when I put it back together than to have a coolant leak into the combustion chambers or externally.