Greetings,

Driving home Friday night I noticed the tempurature gauge started to climb to H, after idling for a few minutes I saw some steam coming out from under the hood. When I got home I popped the hood and I could hear a hissing sound coming from the radiator cap.
Saturday morning I refilled the radiator with a 50/50 mix, let the truck run for a while, and put on a new radiator cap. While driving Saturday afternoon and evening, I noticed the temp gauge start to creep towards H, remaining consistently at the 3/4 level. This morning I checked the radiator and the coolant level is down again. But I can't find any leaks.

Here are the vitals:
1996 Ford Ranger 4 cyl 2.3
Water pump replaced in Feb 2009.
Fan facing the engine is working
Barf bag level is consistent at cold fill.
cap replaced yesterday.

thanks for your help.

 

Check for a blockage in the hose from the rad cap to the reservoir.

 

Thanks,
I just checked this hose and there is no blockage.

 

sounds like a sticking thermostat or leakin heater core...if its losing coolant there has to be a leak somewhere...put a piece of cardboard under it...if its leaking it can help locate leak.