it also may sound simple- but are you sure there are no air pockets in the coolant? how did you bleed or burp it?

 

v-mount? you need very well placed ducting and reverse scoop bonnet or bonnet vents to force air through rad and inter cooler properly(and yes undertray). if it was your waterpump it maybe time to upgrade to ewp for better control over your cooling system.

 

How are you controlling this fan and what is the trigger temp?
How frequently is the fan cycling on/off?
Also, how are you monitoring the water temp?
Stock thermostat and radiator?

 

the fan is controlled by a manual switch and at the moment I am leaving it on all the time i am monitoring the water temp through my megasquirt i am using stock thermostat aftermarket rad. but i was having the same issue with the stock rad

 

was working on it today and after the car had warmed up and turned off i heard a hissing sound coming from the rad cap could this be my problem? I already placed the cap once.

 

hiss is normal if its really hot.

I have seen this same problem before. the fan was blowing the wrong way. it would stay cool at idle but when driving the fan was trying to push air through the radiator not pull it like its sopposed to.

make sure your fans are sucking air through the radiator. not blowing on to it.

 

My fan is pulling not pushing

 

Something is causing my coolant to go to the over flow bottle and its not coming back

 

If the coolant isn't flowing back into the system from the overflow, verify the overflow hose is sealed properly and crack free.

If you want to eliminate the possibility of a coolant seal leak, you can buy a block sniffing kit from Napa for around $40. It can detect trace amounts of combustion gasses in the coolant passages.

 

going to replace the coolant overflow hose tomorrow to see if that stops the overflow bottle from filling up.

 

I had the same problem with a 2700 cfm electric fan with an undertray fully sealed. tired everything. Three flushes, with different mixtures of coolant/h2o/water wetter... Finally just ordered a new factory fan with the old shroud and no problems at all. all day long at 179ish no matter what. With a front mount.

 

the his was at normal temp 70 degrees celsius or 158 fahrenheit

 

then you may have a tiny leak in the system somewhere