My 93 Ranger 4 cylinder is starting to run hot. After running on the interstate for about 30 minutes the temp guage starts to climb. It gets to about 3/4 hot. When I stop I hear bubbling from under the hood. It is the reserve tank bubbling. I replaced the thermo and pump last year. Any suggestions.

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1993 Ranger XLT 4x2 2.3 L Engine
216,000 + miles

Clogged radiator maybe.....how does the coolant look? Does it overheat any other time or just when on the freeway for awhile?

It would not be impossible for your "new" pump to have gone bad already.

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2000 Ranger XLT 3.0L V6

Rancho 9000XL's

If I drive it around town for a longer period it will start to get hot as well.

The fluid is rusty green in appearance.

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1993 Ranger XLT 4x2 2.3 L Engine
216,000 + miles

sorry to thread jack, but when is the recommended mileage change for your radiator fluid

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2003 ford ranger xl single cab, 5 speed 2.3l, k&n 57 series CAI, hurst equipped, 60/40 seat mod, full length exploder console, flowmaster super 10 ran out the back with 2.5 inch piping, 15x7 Cragar soft 8's,general grabber at2, kenwood kdc-x794 excelon series headunit with amped infinity kappa 6x8's with a 10 inch kicker solo classic run by a 750 watt mono block kicker amp with 2 gauge wire in a sealed box with 2.0 farad capacitor, ultra gauge and 2 kc daylighters 130 watt.

Look in your owners manual!

I would suspect the new water pump you installed has rotting impellors. How many miles has it been since you replaced the pump? Did you flush out the coolant really well?

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2000 Ranger XLT 3.0L V6

Rancho 9000XL's

Usually my first though is low coolant followed by water pump rot. But I doubt the water pump is rotting out already. Those things last a lot longer than that.

First things first is to make sure your coolant is topped off. On a COLD engine, fill the radiator up. Start the engine and let it warm up with the cap still off the radiator. Once it reaches operating temperature, it will start flowing through the radiator and the level may drop. Keep topping it off as the level drops until it stays level. Put the cap back on. Done. See if the problem goes away.

If you have boiling coolant in your reserve tank and the needle isn't way up, then your radiator cap is probably bad too. The cap is a pressure regulator. If it is opening up within the normal operating range of pressure, then it will vent coolant into the tank when it shouldn't be. It could also be due to low coolant allowing the coolant boil which would exceed normal pressure and open the cap.

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(Formerly)
FireRanger
2003 Edge 4.0 4wd

How to: Aux light wiring, relays, & fuses
Info: 300+ intake threads here on FRF
Info: HID Projectors
How To: NO HEAT Troubleshooting Guide

about 12-13,000

yes, flushed the system well

it still has the original radiator---should i take that out and flush well first?

what is the best way to test water pump?

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1993 Ranger XLT 4x2 2.3 L Engine
216,000 + miles

There is no way to "test" the water pump. It's process of elimination or remove it to look at it. First make sure the coolant is properly topped off like I described. Swap the radiator cap, it is $5 and 5 minutes. If the problem presists, my next suspect would be a plugged up radiator. If its that bad, flushing may not help and it would need to be replaced. The water pump is the least likely and most difficult. Save it for last.

__________________
(Formerly)
FireRanger
2003 Edge 4.0 4wd

How to: Aux light wiring, relays, & fuses
Info: 300+ intake threads here on FRF
Info: HID Projectors
How To: NO HEAT Troubleshooting Guide

Could be as simple and cheap as a rad cap. The valves/seal in the cap could be bad and not pressurizing the system causing it to boil.