Parker240,

Since you have billowing steam coming out of your engine area, we can safely infer that you definitely have a cooling problem and not just a temp compensation board "false indicator" problem in the dash. ;)

I don't know about the heater core issue that the mechanic is pointing to, I would think not. Some on the board have suggested in the past that if the temp goes up, open up your heater control to full hot and see if that helps bring the temp down. This is not a fix, of course, simply a diagnostic.

If it were my car, I would check the condition of the radiator, now that you've already replaced the thermostat. Use a garden hose and with the engine *off* ;) spray water through the fins of the radiator from the engine side out. This will clean the fins and allow much more air to flow through the radiator. This will greatly improve the efficiency of the radiator, if it has become plugged with bugs, sand, dirt, and miscellaneous *crap* over the years.

Also, what is the condition of the anti-freeze? It should be a 50/50 mix with distilled water (I believe - please someone correct me if I'm mistaken on that) and that will carry the most heat away from the engine to the radiator.

Is the radiator plugged? Is the cooling system holding pressure?

If the radiator is plugged, obviously it cannot radiate the heat from the coolant to the air. Check also to see if the system is holding proper pressure. The coolant will boil at a lower temp if it is not properly pressurized.

Lastly, is the fan pulling a good amount of air? I don't know much about cooling fan clutches so I can't comment from experience on this, but others on the board have mentioned that the clutch can fail or wear out and not pull the necessary air through the radiator for proper cooling.

If all these things check out ok, you might try to determine if there is some reason why your engine is running so hot... usually this happens with a lean mixture or too hot a plug range... Also, is your exhaust system working well and no plugged cat?

Just some ideas, I hope you find it and report back so that we can all learn from it.

Good Luck!

Regards,

TomD
'86 240
'93 240