Engine overheats and smoking?

This one could be tricky to solve.
First, a bit of deductive reasoning.
In order to overheat the catalyst to that extent, an excess of fuel must be entering the catalytic converter. Since there is no other path to the catalyst than through the engine, the excess fuel must be coming through the engine.
Since a mixture that is sufficiently rich as to overheat the catalyst must exist, it would follow that the O2 sensor should see this and cause a trouble code to be set in the computer. This in turn would light the check engine light.

Now to the diagnostics.

First verify that the check engine light is functioning correctly. It should ligjht up when you turn on the ignition, and stay lit until after the engine starts.

Second, check for trouble codes. It is possible for codes to exist without lighting the check engine light. It would be an unusual condition, but this is an unusual problem.

Some possible causes of an excessively rich mixture would be:
Mass air flow sensor.
Air leaks in the intake path.
Bad O2 sensor or sensors.
Charcoal cannister overfull.
Fuel tank vent restricted causing excess fuel into the engine.

Also, there is a possibility that your catalytic converter is internally restricted.

These are a few ideas that come to mind, and should help you with a starting point to figure out this problem and work towards solving it.

Good luck!

Hi there,

If you just back flushed the radiator with a domestic hose, that will not do very much. You will have to have the radiator cleaned with the tank off. Do this if you have not already, replace thermostat as well also check the operation of the cooling fan.

Mark (mhpautos)

If coolant pressure test does not reveal any obvious leaks
and you have continually adding coolant to the system
I would suspect a headgasket failure and should check for that

I go with the ignition module, it's common and will eventually fail even cold. Remove it, take it to Autozone, they can test it before you buy the new one. Dont forget the thin coat of die electric grease on the back, it helps dissapate the heat!

Try bleeding the cooling system see below

BLEEDING COOLING SYSTEM

Always bleed air from cooling system after replacing coolant. Set heater for maximum heat. Remove radiator cap. Loosen drain plug and remove drain bolt (if equipped) from engine block. Drain coolant reservoir. Fill coolant reservoir to MAX mark with 50/50 water-coolant mixture. Loosen bleed bolt and fill radiator up to base of filler neck. Close bleed bolt when coolant flows out without bubbles. Tighten bleed bolt. With radiator cap removed, start and operate engine to normal operating temperature. Add coolant if necessary and check for leaks.