For a bit of backstory, I've been to hell and back with this car in the year I've owned it. I wanted a project to work on and got exactly that lol.

Long story short I bought the car with the balance shaft seal popped out and pouring oil everywhere, alone in my garage, never owned or worked on a JDM car I tore the timing side of the engine down and did the full seal, belts, pulleys, and gasket kit, then fought for months chasing a related issue and replaced a bunch of sensors and other small parts.

Over the winter I didn't get to drive the car very often, but when I started running around in it a bit more I noticed a coolant leak on my garage floor, not massive or anything but definitely leaking. After doing some investigating it seemed like coolant was dripping from the bottom side of where the thermostat cover and block mate together, somehow the gasket on the thermostat had squashed its way through the gap, eventually to the point where it made a hole and was leaking from there. Replaced the thermostat and gasket and that seemed to fix the issue.

Fast forward about a month and I notice it leaking again. But here's the kicker, its not consistent at all. It only seems to leak when it sits after driving it, but not every time. It seems to happen when I drive it around and then park it, a day or so later I will either notice the spot on the floor or that the overflow reservoir is low. Problem is, when I try to intentionally cause this scenario and then sit and watch the car it doesn't seem to leak. I did finally catch it leaking right at the base of the transmission, and it appears to be coming from the back right hand side of the motor in a location that results in the leak going down the left side of the transmission, not the outer side.

Upon doing to digging I noticed it was pretty wet with coolant where the 'Heater Valve to Engine' Hose meets the block. Assuming this was the issue I replaced that hose. After a few days initially assuming it was just cycling the coolant through to replenish what had leaked out, I'm still noticing the leak and drain from the reservoir. Still like before it doesn't seem to leak to a noticeable extent while running, or parked for a short time like running into a store, but when I leave it in the garage overnight or for a couple days there is a puddle and I have to top off the reservoir again.

To me this makes absolutely no sense and my Dad is stumped as well, I can't seem to pinpoint the leak, and it doesn't consistently happen while Under pressure, or while not under pressure. Any advice welcome.

 

Sounds like it could be leaking from the end of the water pipe at the back of the block.

 

I just picked up a 93 Accord EX sedan 5-speed F22A6 with a VERY similar issue, I replaced the connecting pipe that runs from the back of the thermostat to the water pump/back of the block, and it did seem to help with a good portion of the leaking that was going on, but now I also have to replace the heater hose that connects to it and reroutes into the body/heater core too, since it is leaking as well. If it's an odd leak that happens to get worse after driving some time and parking it, it's more than likely one of those two things, typically old heater hose or an expanded O-ring inside the block or thermostat on the connecting pipe. When I yanked mine off, the thermostat side wasn't too bad, but the water pump side O-ring was almost double the original size, and was a good portion of the culprit for my current repairs. You can get to it from underneath, you'll just have to unbolt/unhook the thermostat and ignition coil, and there's a 12mm bolt that secures it into the back of the block. From there you should be able to pull the thermostat off it and pull it free from the block. Hope this helps.

 

Did you check the oil cooler lines??? Right where the oil filter goes in there is the cooler and two hoses that supply coolant to it. Good luck