Running Hot

[fordgirl]

1995 f150 5.8L 2WD

My truck normally runs with the temperature gauge between R-M on NORMAL. Lately it has been running even further on the A (sometimes on the end of it).

I have replaced all spark plugs (all looked normal) and the thermostat with no change.

I did recenty switch from 10w30 to 5w30 on my last oil change, if that would matter.

Any ideas?

 

[smokey]

Could be the sensor itself. Best to check it with a actual temp guage.

 

[fatherdoug]

When does this occur? If it happens during idle or slow speeds, but cools down at highway speeds, you might take a look at the fan clutch.

 

[dustybumpers]

Stock guage isn't much more than an idiot light

Does it seem hotter than normal when you shut it down and walk past it?

More than likely, there is an accumulation of bugs and leaves on the condenser in front of the radiator, and it just needs a good cleaning

 

[fordgirl]

The truck is definitely hotter than normal when I pop the hood. Temp increases when I stop at lights. I'll check the fan clutch, thanks!

 

[fordgirl]

I'm looking for a good way to test it. Videos are only showing if the fan spins too much. Mine is really hard to spin. With all my might, my thumb spins it at most 1/2 turn.

 

[dustybumpers]

When cold you should be able to shove it around with no tension at all.
Once the engine bay is warm, after shut down, it should be stiff, but you should still be able to turn it

There should be no side to side movement at all

Never put your hand in there with the engine running

 

[fordgirl]

Ok I'll check tomorrow morning when it's cold, thanks!

 

[dustybumpers]

No prob
Watch, the blades could have sharp spots, and rip you open, make sure to wear gloves

 

[dustybumpers]

On initial start up, it should freewheel, then as the thermostat opens, and the heat starts to come in, you should be able to hear it come in, it will actually roar when the thermo springs tighten

There is no click like in the big rig trucks, it just slips in and out of freewheel

 

[fordgirl]

It still only turns ahout 1/2 revolution. Should I also replace water pump with fan clutch?

 

[dustybumpers]

Can you see the water flowing down in the radiator when it's running with the cap off?
How many miles on it? is the water pump original?

 

[fatherdoug]

They generally should be replaced together, since a worn out water pump will cause excessive wear on a new fan clutch, and vice versa.

 

[fordgirl]

The fan spins the second I start the truck. Water pump is 10 years old. Original 20 year old heater core, if that is a possible culprit.

 

[fordgirl]

What do you know...replaced the heater core. PROBLEM SOLVED!

 

[cbaker65]

What do you know...replaced the heater core. PROBLEM SOLVED!

I'm glad to hear that you've figured it out,atleast it wasn't a car!
Pickups are more easier to replace!...

 

[Fellro]

If it is showing improvement by simply running the heater, I would suspect the radiator is getting plugged up. That is an old get by trick for overheating engines getting additional cooling to get a little farther. You don't need a heater core at all for functionality, it is only for human comfort/window clarity.

 

[fordgirl]

So I know it was far-fetched idea, that is why I did it last. However, before I replaced the core the heater didn't work, my truck was over heating, and I had coolant leaks from multiple places. After I replaced the heater core my heater works, my truck temperature gauge sits below the middle (without having to use the heater for extra cooling), and I have no more coolant leaks.

My thought (and what I have read other people have dealt with) is that the heater core can get clogged and backup the system creating all these symptoms.

 

[Fellro]

But if that were true, the motor would over heat on systems that have shut off valves in them. The heater core is ONLY for heating the interior air, it serves no purpose directly for the motor. It is essentially a mini radiator. There are thousands of applications that have no heater core and those motors do not over heat, and they also do not have bypass lines. I have plugged the lines when I had leaking cores, and did not overheat. I assure you, that core or the circuit have nothing to do directly with the engine. It is simply helping remove a little more heat. They can possibly help a little on getting coolant flowing through the block, but it is not a primary function. The more likely explanation that makes this work is that the block itself is getting gunked up and not flowing properly.

I also stand by that the radiator is likely to be partially plugged.