Hi, everybody...

I have a '94 Ranger 3.0 liter, 2WD extended cab with A/C. She has over 186,000 miles on her, and until recently has given exceptional service. The engine's temp gauge has always been nearly smack in the middle of the scale. About 4 years ago I replaced the radiator bacuase of a leak and since then, no problems.

About a month ago I noticed the engine temp gauge going to the high side of the scale. After warm-up then needle would rest right at the 'L' of the 'normal' on the gauge face; when sitting at a stop the needle would drift a bit higher. After I'd start moving again the needle would drift back to 1/2 scale or a little lower, especially at highway speeds. I consulted the service manual, did a few checks, and replaced the thermostat. That didn't solve the problem.

At that point I went to my mechanic. He checked the system out, did his diagnostics, and replaced the thermostat again (thinking I might have gotten a bad one). The temps seemed okay to him after his testing (probably not long enough), but he commented that the coolant looked "pretty dark and sludgy." He advised a flush and fill as soon as I could, and commented that the radiator might need to be removed and boiled out to eliminate the sludge. His fix didn't help, so back it went to have the radiator pulled.

He said the shop that cleaned the radiator commented that the radiator was pretty gunked up, but they cleaned it out and all was well. Indeed, after picking up the truck I verified what the machanic found on his tests: the temp gauge would go a bit high from cold, then when the thermostat opened the needle would go back to well below 1/2 scale. It operated just like this for several weeks.

Today I noticed that the gauge had gone back to the high 'L' position again when I stopped at a drive-thru. After leaving and getting back up to highway speed, though, the needle never went back down as it had before. It stayed right around the 'L' until I got the truck home and shut it off. After the engine cooled and I restarted the truck, the needle started at the cold end of the scale and worked it's way up to the high position after warm-up.

Okay--so where should I look next for the cause of the problem...?

 

I am just guessing here but was the engine block flushed out when the radiator was being cleaned? On one of my previous rangers, a 93' 4x with a 3.0 I had a similar experience. I had sludge build up and not only did I have to clean out the radiator but I flushed gunk out of my block for quite some time before I got all the gunk out of both the block and radiator. I was having thermostat sticking issues and gunk from my radiator was causing the thermostat to stick. I tried flushing the radiator out but once I ran the truck and the thermostat opened and closed a couple of times the coolant was back to looking like crud so I went back and flushed the block and radiator to rid the entire system of the gunk/crud and that solved the sticking thermostat issue I was having. Anyway good luck with it and keep us posted on your progress -

 

Just a guess but if it's not gunk that's clogging things up in there maybe you have air trapped in the system?

 

How is your fan clutch operating? It seems like the main problem is at idle, or no airflow.

Next time your drive your truck, and it gets hot on you, shut it off, open the hood, and try spinning your fan, it should move, but it should have some resistance to it (like if you spun it and let go, it would maybe make 1 revolution). If it spins freely (like a few revolutions after you spin it) then replace your fan clutch.

 

Hi there,

About 2 years ago my wife had a '96 Mercury Sable with the 3.0L OHV engine. The engine started running warm and there was no heat coming from the vents. I started seaching the web looking for a fix and came upon a Tarus/Sable site. From my research there I found out that the water pump was a very possible culprit and was prone to losing the vanes on the propeller. I bought a new water pump for it and started tearing the old one off. Sure enough, the vanes on the water pump were completely eroded away. The vanes were originally "L" shaped, but were worn down to a "l" shape.

The most telling thing I found was there was no heat coming from the vents unless I spun the engine north of 3000 RPM. With the vanes being worn away, the water pump was unable to do its job. Revving the engine high enough allowed the water pump to pump a little better, thereby cooling the engine and producing heat out of the vents.

Do you have heat coming out?
If you rev the engine high for a few minutes does the temp come down?

If the answers are 'No' and 'Yes' respectively, I would look into your water pump. My wifes car had ~120K-125K on it when I replaced the pump.