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Long story short, but I discovered a tiny hairline crack in my thermostat housing, as indicated by the silver sharpie marks in the picture below. I'm guessing when the PO deleted the AST and removed the nipple, drilled & tapped the NPT plug, there wasn't enough material left for support all around that plug - tighten a wee bit too much and cracks will follow. The leak barely allows any coolant out, it just slowly seeps out, and then only when the system is pressurized slightly above 1 bar (15psi). Anyway, it needs to be fixed...
Question is, how well do these cast aluminum housings take to welding over a crack like this to seal it up? Since I'm about to hit up my welder guy to weld up the piping pieces I cut for my custom SMIC install, I could tack this other welding job too. Reason I ask is I'm not skilled at welding, and it looks to me like the aluminum casting isn't terribly robust to begin with, plus my welder guy will need to grind off some of that powder coat finish that the PO put on there to do the job - might be more cost effective to just buy a used one?
That's a filler neck from the auto FD, that port is for the extra sensor for the auto tran, PO might've tighten the plug too much and cracked the housing. Why not replace it the housing with a manual one so there's no hole there?
I'm sure it could be welded and invisibly finished probably be a wash either way.
That bronze color is a powder coat finish that the PO had done, that's why I thing the pre-welding prep work may be more difficult - powder coat is tough to remove.
Originally Posted by ZE Power MX6
That's a filler neck from the auto FD, that port is for the extra sensor for the auto tran, PO might've tighten the plug too much and cracked the housing. Why not replace it the housing with a manual one so there's no hole there?
Had no idea that part was from an auto trans car, if a welding fix is too spendy I'll just buy a used one.
What's the P/N for the auto filler neck? I had a manual one tapped in the same spot. FWIW the new thermostat housings don't have a separate piece for the filler neck. Its all one casting.
No idea, I think it's the auto one because of the size of that plug. Coolant temp sensor usually only required a 1/8" NPT tap, his is pretty big. The casting on the housing also has a rise lip around the port (you can kinda see it in the picture), most likely due to the OEM sensor needed a flat surface to sit on, so that area is milled down a few mm from the original casting to create that flat surface.
To answer the original question, you can weld on the thermostat housing. I removed the steel pressed-in nipple for the AST and had a shop weld up the hole. I also removed the casting plug at the top (I think it's on top) of the housing and had it welded up to look cleaner.
