Posted earlier in my Expedition and in General Tech areas. Sent here as the motor is the Ranger 3.0 also. I sure am appreciative of the help... here's what I originally put up on my new wagon..


Recently bought a 1996 Taraus wagon to save wear and tear and gas on the Expedition. 3.0 V-6. Temp flucauates form lower end of normal to nearly overheating and then drops backs. Back and forth every 30 seconds to min. while driving. Added coolant as it was at the low. Sound like a temp sensor(s), fan relay, or air in the system? Or anyone know a good site to hit for st ation wagon tech? Thanks



Here's a link to that post for what else we have covered ...

https://www.ford-trucks.com/forums/s...d.php?t=468805



Thanks AGAIN in advance!!

 

The link in your post wasn't valid, so I could not see what had already been discussed.

I had the same problem with my 95 Aerostar a few years ago. I tried flushing, new hoses, new thermostats, etc, etc. If I topped up the coolant (it was losing coolant at the time) it would be fine for a couple of days and then the temperature would start surging.

It was the water pump. When I pulled it out the impeller was almost completely gone. No blades left, just a spinning disc. To my eyes, it looked like cavitation damage, but then I'm a mechanical engineer...

What I think was happening was this: The cooling system started out low on coolant. The stagnant coolant in the engine would boil & the gauge would rise. The thermostat was slow to open in steam (not as efficient as in liquid coolant), but when it did, the hot coolant surged out into the rad by convection (early model T's didn't have water pumps & relied on convection to ciculate the coolant through the rad if I'm not mistaken). The cold coolant flowing in from the rad dropped the engine temperature drastically and the termostat closed again. Then the cycle started again.

The problem never came back after I replaced the pump.

Hope this helps.

Cheers,
Eric

 

I have gotten alot of feedback stating problems with corroded impellers on the water pumps now. Pretty common theme. I will be trying the easiest stuff first...thermostat, and a new sensor, but I am getting real suspicious of the rusty impeller situation. The more I drive it the less it "swings", maybe for once I'll get lucky and it will free up and be ok?????

 

If you are losing coolant then check the underside of the water pump for coolant coming from the weep hole. Another problem with the 3.0 is head gaskets, I just did a a HG job on a '99 Sable and the gasket around cyl #1 and #5 was corroded badly and allowing combustion gases into the coolant system. Look at he coolant tank while the engine is running "hot" to see if there small bubbles in the coolant or if the tank expands.

 

Never did loose any coolant. No bubbles or expanding tank. I have now replaced stat and water pump. It appears to be something electrical effecting the gage and not actually temp. Just drove 60 miles into work today and the gage constantly cycles. Starts at about 1/4 of it's travel(1/4 above the COLD mark) spends about 15 seconds-30 seconds slowly gaining until it reaches about the 7/8 (almost HOT) point, then drops rapidly back to 1/4...over and over. It has been suggested that I need a "dropping resistor" for the cooling fans on my other post of this. I put a link below to that one.




https://www.ford-trucks.com/forums/s...d.php?t=468809