Retro Wave Posted May 19, 2019 Report Share Posted May 19, 2019 Since Im doing a bit of cleaning in the engine bay, I wanted to make it look presentable by making it look less messy. I removed my original emissions thermostat housing (5 bolt version) to replace it with simple clean version (the two bolt version). When I did that I notice a small unknown hole on the left side of the head and a few hours looking on the internet i found out what it is.... its the A.I.S passage or the Air injection system. My question now is: *do I block it off with a cap, make a Thread and then block it off or do I leave it alone (open)? *What do i block it with? *Are there any problems when blocking? *if left unblocked would there be any problems? like leaks or fumes? I know these are newbie questions but I thought i ask before i damage something and maybe this can help someone else who is new to datsuns too ☺️✌️ "Not my pictures" Quote Link to comment
datzenmike Posted May 19, 2019 Report Share Posted May 19, 2019 Usually there is air from the pump pushing into the head through this hole and continuing on into the exhaust ports. If left open some will certainly back up and get out. You could drill and tap a suitable pipe plug. It's a long way from the hot exhaust and will only get hot if there is flow so crumple up a wad of aluminum foil and jam into the hole then top up with JB Weld. I guess your head is on the engine? that will be a little harder. I had to fill an unwanted hole into a coolant passage. I cut a piece of aluminum and hammered it in... Followed by JB Weld. Quote Link to comment
Retro Wave Posted May 19, 2019 Author Report Share Posted May 19, 2019 2 hours ago, datzenmike said: Usually there is air from the pump pushing into the head through this hole and continuing on into the exhaust ports. If left open some will certainly back up and get out. You could drill and tap a suitable pipe plug. It's a long way from the hot exhaust and will only get hot if there is flow so crumple up a wad of aluminum foil and jam into the hole then top up with JB Weld. I guess your head is on the engine? that will be a little harder. I had to fill an unwanted hole into a coolant passage. I cut a piece of aluminum and hammered it in... Followed by JB Weld. wow, ok thanks for that info & pictures I never thought of that, i appreciate it I guessing if you leave "open" then the exhaust soot comes out? yes the head is still on the car, I might go with a thread and plug... if not that JB weld/aluminum foil is another great idea. I'll post it up when it done. 🙂 Quote Link to comment
Retro Wave Posted May 25, 2019 Author Report Share Posted May 25, 2019 ok so here what we did, i ask my father to help me make a thread on the AIS passage so that i can plug it. My father thought it was a great idea but then were both afraid of the metal shards being left inside the hole. So he came out with another quick solution, why not make a block-off plate. It does the job well Quote Link to comment
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