91 5.0 running cold and hot

My 91 5.0 has been running cold this whole winter. So I replaced the water pump because I knew it was starting to fail. (Water had to started to leek from the weep hole a couple months early, but then stopped and never did it again.) The water pump seemed to make no difference. So two weeks ago I replace the thermostat with a Duralast

192 degree. Again no difference. I installed it with the copper colored stub facing in the block. I dont think it is the temp sending unit because my fans dont even turn on until my enigine is nice and hot, according to the gauge. (fans have a thermostat stabbed in the radiator.)

Does any one have any ideas? I would like to fix the problem but it is not as big a deal anymore now that it is starting to warm up here in Utah.

Evan

Reply to
Evan
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Evan opined in news: snipped-for-privacy@g14g2000cwa.googlegroups.com:

Whaddaya mean "cold and hot"? are you referring to the temp gauge?

Or is this coupled with heater performance/output?

And "HOW HOT"? some people get alarmed when the gauge goes from "O" to "M" or v-v, depending on orientation of label..

Reply to
Backyard Mechanic

Backyard Mechanic opined

And look closely at the 2 other Regulator driven gauges (not alt volt) if they fluctuate at the same time, look for a ground problem near the cluster.

Also look at the block to firewall ground strap

Reply to
Backyard Mechanic

Yes I am refferring to the temp gauge. I am concerned becuase drving down the freeway at 80 the temp gauge still says the the engine is not warmed up. And the needle will actualy start to move back to the cold side. Then when I come to a stop the needle starts to rise, fans turn on and the needle slowly creeps to the hot side. All other gauges work fine.

The 5.0 has been put into a 66 and prior to this winter has not problems with running cold or hot, in either winter or summer.

Evan

Reply to
Evan

Yes I am refferring to the temp gauge. I am concerned becuase drving down the freeway at 80 the temp gauge still says the the engine is not warmed up. And the needle will actualy start to move back to the cold side. Then when I come to a stop the needle starts to rise, fans turn on and the needle slowly creeps to the hot side. All other gauges work fine.

The 5.0 has been put into a 66 and prior to this winter has not problems with running cold or hot, in either winter or summer.

Evan

Reply to
Evan

Yes I am refferring to the temp gauge. I am concerned becuase drving down the freeway at 80 the temp gauge still says the the engine is not warmed up. And the needle will actualy start to move back to the cold side. Then when I come to a stop the needle starts to rise, fans turn on and the needle slowly creeps to the hot side. All other gauges work fine.

The 5.0 has been put into a 66 and prior to this winter has not problems with running cold or hot, in either winter or summer.

Evan

Reply to
Evan

Evan opined in news: snipped-for-privacy@c13g2000cwb.googlegroups.com:

Sounds like an air bubble... you have coolant recovery bottle, right?

That's why newer cars have them. the pressure side of the system should have little to no air in it.

Any change in the heater output?

Reply to
Backyard Mechanic

Sorry about posting 3 times in a row, the computer frooze.

No I dont have a colant coolant recovery bottle.

The heater works about a 1/3 of the time. It blows cold when stopped, warms up when I am acclerating, and goes cold when the car is traveling at steady speed, and then randomly back to warm or cold.

It has only gotten hot once, when I was driving the car hard, but it still went cold too. Other than that is just warm.

Yestermorning I let my car idle 5-10s to defrost the windshield, came back and the temp gauge reading normal {needle straight down, fans on, but the heater was blowing cold air. It caused frost on the inside of my windows.

Evan

Reply to
Evan

Evan opined in news: snipped-for-privacy@f14g2000cwb.googlegroups.com:

That's a bubble, in both your engine and heater.

I have found you have to run the coolant into the heater bottom nipple and hook the top to the Water pump nipple. If you feed the opposite, the air gets into the core and just stays there.

Also get a coolant recovery bottle unless you have a separate expansion tank on your rad which is higher than your thermostat housing.... or even then.

Reply to
Backyard Mechanic

ok I will try that thanks

-Evan

Reply to
Evan

I had same problem with my Taurus and here is what I did:

  1. Replaced Water pump and Thermostat
  2. Bought 3 dollar coolant flush system from wally world
  3. Took hoses off heater core and put the nozzle of the garden hose (sprayer) right into the heater core to power flush it (yup it was clogged)
  4. Flushed the entire coolant system with water, let car run with just water in it for 15 min. I did this by installing the coolant flush " T " (where you cut hose) on one of the heater core hoses and screw on your garden hose.
  5. Drained as much water as I could, via the radiator
  6. Filled most of the system with 50/50 coolant at reservoir, and then ran clean water from garden hose at the installed heater core to completely fill the heater core (get the air out, which is common problem after a flush).
  7. Drive around Warm and Happy.

Total cost for New Coolant, Water pump, Thermostat, Coolant flush system - $53.00 (I'm sure if you take it to a shop it will cost $400+ just for labor)

Making Wife Happy - Priceless

Good Luck! (from someone who had lessons learned).

Reply to
wildatom

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