So my wife's 2006 has had this issue lately and I'm about to take it to our local mechanic (I just don't have the time to dick with it). Wondering if anyone else has seen this issue.

So she had a overflow tank cap that was cracked (the OEM one) and it was slowly spraying a bit (not a ton, but enough to make a little mess under the hood) when the car was driven. So I ordered a new overflow tank and replaced it, simple right. Well now the new one has cracked the screw on cap and doing the coolant spray again. Wondering if its the radiator backed up or what could be causing this type of backpressure. Never seen it before. I don't know the history of the car that much as we just got it in Feb/March.

Any common issues like this or with cooling system? I've just been making sure we keep it full of coolant/water.

 

the plastic cap likes to crack! but I havent noticed any issues with pressure to have the cap crack in so short of time

 

Dont overtighten the overflow tank cap.

 

also, I bought JUST THE CAP from ebay.
way cheaper than buying the reservoir that comes with a cap

thoiboi is on to something, my cap cracked at the threads.

 

I'm assuming it's an aluminum head engine so lots of heat (I saw a thread by someone talking about a "hot" engine...so my thought is aluminum head) and maybe its just weakening that plastic? But I did just replace it (and will again). Will try going less tight on next one.

I also wonder if it may have a small leak at a gasket, hose, or thermostat housing. I had that happen on my old Ford Sport Trac (thermostat housing).

 

it is aluminium heads