I dont understand whats going on. I put in coolant in my overflow tank to the max line the other day. I notice it disappears. The radiator is full. So I fill it up again, and same thing happens. Ive checked for leaks under the car, no cracks or holes in radiator, hoses are not cracked or leaking either. Concluding that no physical leaks to be seen, but rather going somewhere else or evaporating from somewhere assosiciated with heat. I do an oil change and no coolant in the oil. I do a compression test and its fine all cylinders. No smoke from the exhaust which smells or looks like coolant smoke. Is my water pump going bad or something? Car does not over heat, coolant temps are fine which I tested at Honda using their laptop and honda software.

 

Are you positive the radiator is full? Maybe the radiator is empty and it needs the coolan you keep puting in the resevoir

 

Yeah Im certain it's full. Checked it multiple times. I put in coolant in overflow. Drive for like a little until car is warm. Let it cool down for a couple hours. Check again, and its gone, but radiator is full.

 

The radiator can still be full with air in the system. Are you certain all the air is out? How much coolant have you added?

 

This is what I'm assuming. I have been meaning to bleed the system. I have my appt on Monday at Honda (buddy is going to do it for me properly). Could that be the case? If so, what a sigh of relieve.

 

This exact same thing is happening to me. I drained the coolant and put fresh stuff in as soon as I bought the car, which from reading on here afterwards I didn't properly bleed the system. Ever since then I have been losing a about a half inch in the overflow resevoir every 2,500 miles or so. VERY slowly, obviously. My overflow reservoir also has a higher liquid level when hot than when cold (or the other way around? I forget).

I think it's just that I didn't bleed the system correctly. I ordered one of the Islse spill-free funnels from amazon yesterday and will bleed the system correctly probably this weekend. My AP2 has been happy at 8 bars though (never higher) on the stock gauge so I don't think it's terribly concerning or anything.

See this thread: https://www.s2ki.com/s2000/topic/101...leed-problems/ Post #11

 

If you're filling it to the max, then driving it, you're losing coolant due to expansion. It can't stay at the full level. It should be at the full level with a hot engine, but when everything is cold it settles to a lower level.

I'm not saying you don't have a problem, just that you may be overfilling it.