Hissing Sound, Head Gasket or Intake Manifold?
 

I have a 2001 Mazda Millenia 2.5 Liter that seems to be leaking air/water from an unknown source. The car recently ran hot and when I pulled over, I didn't notice any water leaking from the car. I did a visual check and a hissing sound is coming from the area marked with arrows in the picture. The area in question is deep down in the Intake Manifold area and not easily physically visible. I allowed car to cool off and added water/antifreeze and continued to drive. I did a check of the Oil Cap and Oil Dipstick and there is no "Chocolate Milk" mix indicating a head gasket (Could Be Mistaken,Correct me if I am). I am trying to determine if a leaking Intake Manifold Gasket can cause water/pressure leakage and Temp gauge to rise. Please indicate any ideas/solutions. Can someone also please post or email me instructions on changing a Manifold Gasket as well for a 2001 Millenia 2.5.


Thanx a lot


Christopher R.

First of all: I typically don't comment on the millenia because i am not familiar with the charging system that is built in. So take this into account.

The arrows point to the intake system. In most cars there is a loop for coolant going through the intake system to help with the vaporization of fuel. That loop is sealed with the lower intake manifold gasket and that gasket can fail. It may allow coolant to enter the intake manifold.
How does the exhaust smell? Any coolant in the air? If that is the case and the oil filler cap looks this clean I would guess that the lower intake manifold is to blame.

I don't have a how to but your library may have a copy of Haynes or Chilton's for your car. Our library has even online automotive manuals.