leaking from over flow bottle
 

Hi,

i have a 2000 rx7 FD bridge ported bigger single turbo GT4294. i hardly drive it like ever maybe 1ce 2ce a yr. after a fresh build i didnt drive it for a good close if not a yr. it was running fine then when i started it the overflow bottle started to leak after warming up. it seems to keep pressure at the filler cap even after a day or 2. i flushed the coolant and put new fluid in. smoke came up but not as aggresive as if i was to have blown water seal jacket. would anyone know what this is or whats causing it to do this as i dont want to risk it being damaged. also how would i block off the water hose connecting to the turbo as i have the above turbo

i done a pressure test and it still holds psi.

You pressure tested the system but did you pressure test the cap? With that, typically when your overflow is leaking over like that you just need to bleed your system. You may not think there's air in it but there is. Get a lisle funnel and bleed it.

for capping off the coolant line, you have a few options. The first is to get a SILICONE cap and a non serrated hose clamp and just cover it. Those nipples that come off the water pump housing are actually inserts and can be removed. Some strategic taps with a hammer and they come right out. Then you can either get the ports welded shut or tap them to install a plug.

when i try bleeding the cooling system with funnel i noticed it wont leak out of overflow only when cap is on filler neck. does this sound like bad seals or just air in my system? the car was barely driven when rebuilt under 100km but did sit close to a year not started. could this be the cause of the seals to go bad? would removing the ast help anyway?

I agree you first need to try and burp the system of air entirely with the funnel approach. Do you have an AST still in the car? If so, you might want to replace that cap too. If that doesn't help, see my answer below...

I'll give you my experience as it relates to my last car. I had a very low mileage FD at the time (38k original miles) that was exhibiting identical symptoms. Mine would hold a pressure test for DAYS. The end result was it was a minimally blown coolant seal on the combustion side of the housing. What happened was the seal rupture was happy to hold 15-18psi indefinitely (pressure pushing IN) but the seal couldn't hold the immense pressure of the combustion cycle (a LOT more than 18psi). This lead to no coolant being leaked INTO the combustion chamber (thus no smoke) and it resulted in massive air pockets getting into the coolant system which pushed the coolant into the overflow tank.

when using the lisle, coolant has no way of getting to the overflow for it to leak out. There are ways to test for a bad coolant seal. Look up the champagne test and also a pressure test will work. Unless you're like the guy above.