Hey all! I've come across a problem with my ride. The engine temp. seems to be a bit higher than normal(indicator is around the halfway mark bet. cold and hot). The thermometer creeps slowly to about halfway, and the "check engine" light comes on when I try to keep speed on hills. The light turns off when I'm coasting downhill or just cruising on the flats. The thermometer just goes over the halfway mark sometimes but never more.

The serpentine belt seems to have good tension, but there might be a small leak in the water pump, but nothing that reaches the ground...

Any suggestions? Do I have to replace the pump or is there an alternative measure I can take?

Thanks in advance for any/all ideas!

 

we need more info on your truck...year, engine and mileage

 

Right, sorry about that.

She's a 1993 Ranger XLT 4.0L V6 4WD with about 173K miles. I don't think the water pump has been replaced or worked on before, but the belt looks good and had good tension.

Someone told me that the thermostat might be stuck and recommended to tap the thermostat. I did and the 'check engine' light still comes on when I push the truck up hills...

 

impellers might be rotted away/starting to on the water pump...resulting in truck starting to run a little hotter

 

The temp gauge only goes halfway though? Is it low on antifreeze? Does it seem to "shudder" when the light comes on? Are you sure its getting hot??

 

Don't know exactly what overheating is(I can still grab and hold on to the upper radiator hose just after I turn the truck off). She doesn't shudder at all when the light is on or off. I'm not mechanically inclined but I've got some tools...should I try and inspect the thermostat before attempting the water pump?

I went to get my oil changed and get an 'experts' opinion about the problem, and he said the coolant levels are fine, and the boiling point, etc. of the coolant is fine.

The tapping of the thermostat idea while the truck is running seems like a bad idea as the thermostat is damn close to the serp belt and fan...

 

Someone correct me If I'm wrong but isn't the thermostat on the water pump? So if he was to change one he might as well change both. Right?

 

ranger gauges suck end of story.

but halfway on the temp gauge seems pretty normal to me....mine always is anyhow

 

Yea, mine is half too. I think my ultra gauge says 195 degrees.

 

Partially plugged radiator is my vote.

Eventually the end tank will crack from excessive pressures and heat if this is the case. Ask me how I know.

Could also be a temp sending unit going bad.

Or rotting off impeller blades in the pump, rendering it less effective. You would notice rust particles in the over flow reservoir however.

Or it could be a stuck open thermostat.

Has stop leak or any other kind of block sealer been used in its past life?

One can tell by looking in one of the hoses, as there will be a fine coating of either orange or silvery looking stuff. Some times it even accumulates in the bottom of the overflow reservoir.

 

You can have an air bubble in the engine causing erratic readings even though it looks full.

Cold, take the cap off, heat on full hot, let it idle for about 15 minutes, then fill if it needs it. Also make sure the reservoir is full.


I change out my tstat every few years when I change my coolant, its a real PITA with the stock fan in the way but I dont have one anymore. 175k on the factory water pump is pretty good, changing it would be a good investment even if it is not the issue right now.

 

I bought a new Ranger back in 94 with the 4.0 and all they yada yada stuff. What I found as time and miles went by was:

a) It's hard to get a decent thermostat for the 4.0 OHV that works correctly. Best and final result was buying them at the dealership. This put and end to the wandering temp gauge that Stants and everyone elses product produced.

b) If you have A/C, and if you loosen the top of your radiator and push it back a bit and inspect between the radiator and the condenser, you may find a large quantity of dead bugs and other crap. Like I did, and found something like 1/4 - 1/3 of the radiator was covered with said crap that blocks airflow. Radiator removal and a good cleaning fixed that. And like was noted, make sure all air is purged from the cooling system when refilling. I found this is easier and faster if you can park the vehicle with the nose higher than the rear.

c) Can't/won't comment on the CEL until you pull it. Make sure to identify if it's CM, KOEO, or KOER. The code will be stored for 50 duty cycles after it first appears, then will be erased from the ECM.

 

Stuck or partially stuck thermostat is my guess. Would explain the warm engine and cool upper rad hose. They're like $15 plus a gasket, worth trying, it's a maintenance item that should be replaced once every couple years anyway. Plus with winter coming, now would be good time to drop in a 195 t-stat.