hi, i was just wondering how long it takes before your rx7 to build 13lbs in the cooling system, i'm suspecting symptoms of seal falure because it takes me about 8 mins to build full pressure and my coolant gets pushed out into my overflow.

 

The pressure cap is to increase the boiling point of the coolant. I think 3 degrees for each pound. That comes out to 251F. being the boiling point of the coolant with a 13 pound cap. If your engine reaches 251 degrees in eight minutes you have a serious problem. Assuming the overflow coolant is no where near 251, it sounds like compression is leakong into the cooling system causing the excessive pressure.

 

thats what i'm fearing, gases getting to my cooling system.. it takes about 10 mins and my upper hose is tight... and within another 2 mins or so coolant is slowly coming out of my overflow tube.. every 3 days or so i have to refill my coolant about 1/3 a quart... but then again i never had this problem until i got a new radiator with an extra cap, (aftermarket rad)..

 

go get your coolant system pressure tested. Stop guessing by how long it takes to pressurize.

 

Check the rad caps.Make sure they are Both the OEM ones..the OEM rad Caps open at .9 Bar.now the Rad caps thet you may get from Koyo,Fluidyne,may not Open until say 1.3 Bar.Since the Coolant seals are Only Deisgned to take so Much Pressure Before Failing they Wil Let go,IF you have a Cap that wont release the pressure on the cooling system.(where else will the presuure go?).Now that being said,I noticed you have replaced your Radiator with an Aftermarket?..so you just may have some Residual Air left in the Cooling system..Open the Colling system(cap Off)..check the level.Fill the coolant up if needed.Run the Engine until it Opens the Engine's Thermostat(Having the Car's Interior Heater Goinfg Full Blast will also allow coolant to circulate in the heater core to Rid it of Air)..Once the coolant starts to Move inside the Thermostat Neck,Start to squeeze the Lower and Upper Air hoses(BE CAREFULL! ,There are MOVING PARTS TO AVOID!).Once you have done that,and the Coolant is starting to Come Out of the Neck.CAP the Cooling system.let run,go for a ride.(having the Overflow jug at a Decent level..For Reference)..Shut the car off,wiat a half hour..then Check the Overflow jug,and Also check the Cooling system.The TEMP Gauge on teh car should be Slightly Above the Cold Mark on an S$ at operating level,and about Half way on an S5 (operating Temp)..I hope that may help.

 

this being said i pressure tested the system and eliminated the pressure cap at the filler neck, no more leaks and no more overflow issuse, now i'm worried that my pressure cap at the radiator isnt' opening up any ideas on what to do? just pressure test and see if it opens up at 13 lbs?