High coolant pressure.... Maybe?

[Jay Weston]

My wife has a 02 Mazda Protege5 with high miles (220K) that is having a problem that is baffling us.

In December the upper radiator hose broke, so we replaced it along with the lower hose. This caused a leak in the heater hose (I believe), which is understandable because it was old to. The problem is that last week the upper radiator hose sprung a leak again (there was a gash in the hose that was spraying fluid everywhere). We thought that we might have gotten a defective hose so we replaced it. Well we checked the car again and the new, new house is now leaking. When we replaced the hose the first time we bought new clamps and they seem to be on tight enough.

The radiator was replaced 70K miles ago.
New radiator cap 6 months ago.
new thermostat when we replace the lower hose.

The car is miss firing when we take off from a dead stop that can be felt by the car studdering. We also have 2 cel codes (P0133, P0421), but this might be caused by the coolant dripping on the o2 sensor connection.

 

[hornsfan10609]

The upper hoses keep leaking? The coolant system only runs up to 16psi with a stock cap, even if you don't have the correct cap it should not be enough pressure to burst a hose open.
The misfire may be from old coilpacks, wires and plugs and it sounds like the primary O2 sensor may be failing. With that many miles it is also possible for the primary cat to be clogged. The leaking coolant is not causing the misfire unless the ignition coils are soaked.

 

[CHIQLES]

Are you sure the radiator isnt clogged