Cooling

[Black_Splash]

I've posted this question before, but don't know what answer I got anymore. My temp. gauge goes up real high if I idle to long or do a lot of in town driving. Out on the open road it stays down low. I did put in a new Ford thermostat in and gave it a flush and put in new coolant 50/50 mix. I think it does it more with the AC on, but I haven't monitored it close enough to be sure.

[srteach]

On your 94 ranger? Do you have an electric fan or is it standard? It seems, from what you are saying, that the coolant is not circulating. This could be from a couple of things. If not an electric fan, the water pump may have failed (the vanes can come off the shaft without failure of the seals). The radiator could have poor circulation. The thermostat could be bad (even when new).

First, check the radiator for cloudy or chunky coolant. Remove the serpentine belt and hand rotate the water pump shaft (where the fan is attached). Feel and listen for rough operation or stiff turning. Let us know what you find.

[MAKG]

The usual causes for low-speed (especially idle speed) overheating are a failed fan clutch and a plugged radiator. The water pump failing in the manner described does happen, but this is not anywhere near an everyday occurrence. Plugged radiators are.

Other common reasons are 100,000 mile coolant (i.e., rust water), use of Barr's or block sealer, excessive antifreeze use (should be 50/50, or more water than antifreeze), debris in the radiator core (e.g., bugs), and so on.

[Black_Splash]

I haven't checked the water pup yet. Since I was replacing the thermostat I flushed without the thermostat in and the return line off the radiator. It seamed to pump the water through O.K.

That was last fall and it was a 50/50 mix. I didn't use any bars or sealer.

When I talked to someone about my fan clutch he said it seemed O.K. but I am going to get a second opinion on that. He did say that I need to hose off the radiator the get rd of the debris so maybe that's all I need to do. I haven't had time yet.

[almostclueless]

It usually airflow issues as mentioned......

[Bent Screw]

Check for fuzz and crap between the a/c condensor and rad. Restricts air flow through the rad.

[Black_Splash]

I had the chance to work on my truck. Even though the old fan clutch was working, it wasn't working good enough. The problem went away after I replaced it. I did replace the cracked fan also.