Too hot at still, too cold when moving
08-26-2016, 03:10 PM
#1
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Too hot at still, too cold when moving
When moving, you get air exchange and the motor cools better. At still, there is little air movement and it heats up. That's physics.
But if the fan is working, it should not get TOO hot, right? The fan is definitely working.
When moving along, the temp gauge never even reaches the "N" in normal. Stays pretty cold. But at stop, it slowly rises until it's at the "L". That's too hot. I turn it off at that point, not sure if it will go higher. I've been blasting the heat to keep temps down but that certainly doesn't address the real problem. Blasting heat makes the temps rise very slowly. AC obviously makes the temp rise more quickly.
Is this likely a thermostat problem? I plan to replace it this weekend but I've never done the job before and don't wanna change it out if it's working properly.
Heater hoses get hot, upper rad hose gets hot, no leaks that I can see (but after I turn the motor off I can hear a little quiet whining from the stat housing). There seems to be coolant flowing but I don't know for sure.
I did some research around the web and on this forum but I couldn't find any solid data. I appreciate all the thoughts and suggestions you kind fellows can offer.
But if the fan is working, it should not get TOO hot, right? The fan is definitely working.
When moving along, the temp gauge never even reaches the "N" in normal. Stays pretty cold. But at stop, it slowly rises until it's at the "L". That's too hot. I turn it off at that point, not sure if it will go higher. I've been blasting the heat to keep temps down but that certainly doesn't address the real problem. Blasting heat makes the temps rise very slowly. AC obviously makes the temp rise more quickly.
Is this likely a thermostat problem? I plan to replace it this weekend but I've never done the job before and don't wanna change it out if it's working properly.
Heater hoses get hot, upper rad hose gets hot, no leaks that I can see (but after I turn the motor off I can hear a little quiet whining from the stat housing). There seems to be coolant flowing but I don't know for sure.
I did some research around the web and on this forum but I couldn't find any solid data. I appreciate all the thoughts and suggestions you kind fellows can offer.
Last edited by quipstad; 08-26-2016 at 08:40 PM. Reason: Engine info
08-27-2016, 04:36 PM
#2
I don't know what you have, how many miles you have nor when the last time your cooling system was serviced so I will throw some thing.
Would not be a bad idea to replace your thermostat. Your hoses as well if you have a lot of miles or age on them. Also have you had the need to add coolant? Check your water pump as well.
Would not be a bad idea to replace your thermostat. Your hoses as well if you have a lot of miles or age on them. Also have you had the need to add coolant? Check your water pump as well.
08-29-2016, 01:27 PM
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Thanks Tachdriver.
It's a 92 F150 Std Cab 4.9L I6, sorry for not mentioning from the start.
I just bought the thing, foolishly, without much due diligence. I just replaced the upper rad hose on account of it bursting, so I'm sure at minimum the lower hose needs replacing as well (looks old).
I was told the water pump is solid (though the source is questionable). I do think I need to add more coolant; perhaps that is my main problem. I filled to top of radiator, then ran until warm. What I didn't do was let it cool down and top-off again.
Having a mechanic give it a twice-over tomorrow and will likely have him replace the stat. I started the job over the weekend but the housing bolts are rusted and I'm scared I'll snap them.
It's a 92 F150 Std Cab 4.9L I6, sorry for not mentioning from the start.
I just bought the thing, foolishly, without much due diligence. I just replaced the upper rad hose on account of it bursting, so I'm sure at minimum the lower hose needs replacing as well (looks old).
I was told the water pump is solid (though the source is questionable). I do think I need to add more coolant; perhaps that is my main problem. I filled to top of radiator, then ran until warm. What I didn't do was let it cool down and top-off again.
Having a mechanic give it a twice-over tomorrow and will likely have him replace the stat. I started the job over the weekend but the housing bolts are rusted and I'm scared I'll snap them.
08-29-2016, 01:57 PM
#4
Mark
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water pump blades could be worn out..
08-31-2016, 11:23 PM
#5
Martin
So after sitting still and temp starts to creep up, if you where to rev the motor up does the fan sound like a helicopter taking off? That's full lock on the fan clutch. Id bet yours has leaked the fluid out that makes the clutch engage. If the fan clutch is not working properly our trucks can over heat pretty quick at idle.
