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Minor overheat, now engine idles just a little rough


New Member
August 14, 2012
Reaction score
City, State
Austin, Texas
Year, Model & Trim Level
04 Explorer XLS 4.0 SOHC

A couple of months ago my wife got home from work and complained about smelling coolant coming from her 2004 Ford Explorer XLS (with the base 4.0 SOHC). I went outside to check and found a very large puddle (pool?) of coolant on the ground. Looking around I found a pretty big leak coming from the original radiator (it has about 150K miles).

The car did not overheat in relation to that incident. We had it towed into the shop, where they put a new radiator in along with new upper and lower hoses. The fan was (is) still apparently working just fine.

Fast forward to Friday. Wife calls me on the way home from work to tell me she smells coolant again. She's sitting at a light about two blocks from my house when the check gauge light comes on (from a high temp) and she drives home, where she sees steam coming from the hood as she parks.

I spent an hour or so Saturday looking around. Finally figured out the thermostat housing had sprung a small (very small, took me forever) to find it. Okay. Replaced the housing (and the thermostat and sensor). Topped off the coolant. This may sound odd but I used a funnel to fill it using the port for the temperature sensor. (I was worried there wasn't enough coolant in the engine, and that by the time the thermostat opened I'd cook it.) Once I filled it up there, I put the sensor back in and made sure the expansion tank was also up to the "Cool Full" line. Then I started the car and let it warm up with the heater on.

The car almost got to the high mark, just before where the check gauge light would come on, before I started to get heat from the heater. Once that happened, it went down to normal and has stayed there when warmed up. I just drove it about 20 miles and it looks good; I probably need to add a couple cups of coolant to the expansion tank once it cools down so I think I got practically all the air out.

So two things concern me:
1. I had to add in about 2 3/4 gallons of (50/50) coolant. That to me seemed like an awful lot.
2. After driving it for a while, I pulled into my parking spot and just sat a minute. The car is certainly not idling rough by any means - certainly not threatening to stall or anything - but it's not idling smoothly either. I'm worried about this. Any thoughts?

A couple more items: I did check the oil -- it looked normal (though it's almost time for a change); I never saw any abnormal exhaust; and when I'm driving it at any speed it's behaving completely normally. (I haven't driven it enough to see what mileage it's getting yet.) I also can't say for certain it idled perfectly smoothly before all this happened, so maybe I'm just being paranoid.

Should I be worred about the idling? Or anything else, here?