I have been here and I have done this. Bought the tee shirt and sold it at a yard sale.
You likely have a crack in a head gasket that only opens badly in heated stop and go traffic, but when cruising on the highway, the combination of cooling air rushing through the radiator and around the engine does not "swell" the crack open as far.
This crack in the head gasket is putting high exhaust pressure into the water jacket causing coolant to not move. That is why it gets hot but does not show on the temperature gauge. The Hot water cannot get to the gauge sensor because water is not moving.
The flip side of the coin is when you shut it off and let it cool, the high radiator pressure forces antifreeze into a cylinder and you get white smoke for a minute on cold start up.
You probably would not need to replace both head gaskets. You could probably pull the spark plugs and see evidence of antifreeze on one of them.
There are several cheap, simple tests for exhaust pressure in the radiator. The simplest is a radiator cap gauge. If it ever exceeds 17psi, then there you have it. You could get this checked for free or very cheaply if you call around.
By the way, just to entertain you, I live in a University town. A very rich out of town girl came to University for a 4 year law degree. She was given a new 93 Taurus to take to college. In her 3rd year, the car blew a head gasket. She took it to the local repair shop and they replaced the water pump and the thermostat. Not fixing the problem, she buys another car and just parks the Taurus. She waits until graduation week to place an add in the paper to get rid of this car. (I'm going away in 4 days and never coming back.) I start the car and it makes a vapor cloud 40 feet tall (until it burns it off). She says, "Reimburse me for the water pump and thermostat repair bill and you can have the car($165).
This is a clean, never been smoked in, deluxe Taurus with power everything, nice stereo, and great air conditioning.
I take it to the local car engine machine shop. For $1,000 they pull the heads, mill them, all new valves and valve springs, and head gaskets.
I give my wife a deluxe Taurus for $1,165. She drives it for 5 years. I give it to my daughter. She drives it for another 5 years and still drives it today.
You may laugh please,
Sunday, April 6th, 2008 AT 12:14 AM