temperature
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temperature
I recently bought a stepside f100 registered as a '77 although the door jam says '79. The engine was replaced with a 460 yet the temparature seems to be very eratic.
What is the normal operating temp?
It goes from 190 to 230, sometimes higher back and forth. I replaced the thermostat, flushed the cooling system, will soon change the fan clutch. The waterpump doesn't appear to be leaking therefore I'am assuming it's working OK. Could it be that the temp gauge is faulty?
Thanks for your advice.
What is the normal operating temp?
It goes from 190 to 230, sometimes higher back and forth. I replaced the thermostat, flushed the cooling system, will soon change the fan clutch. The waterpump doesn't appear to be leaking therefore I'am assuming it's working OK. Could it be that the temp gauge is faulty?
Thanks for your advice.
Posting Legend
Joined: Sep 2001
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Keep the fan clutch. Check it annualy for wobble and cracks in the blades.
I have seen many instances over the years in this forum where those flex fans failed to keep the engine cool. I have also seen some nasty flex fan failures that made a mess of an engine compartment.
I have seen many instances over the years in this forum where those flex fans failed to keep the engine cool. I have also seen some nasty flex fan failures that made a mess of an engine compartment.
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Joined: Feb 2002
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From: East Bend, Carolina, U.S
You didn't say if the engine was actually boiling over, so I am assuming your engine may not actually be running hot. Sounds exactly like the wiring problem I had on my truck once.
My 76 had the same problem when I first got it. The engine was not obviously hot, but I wasn't going to risk overheating the engine. After replacing everything that has to do with the engine temperature regulating and measuring, the problem remained. Then I finally noticed the cab to engine ground needed some attention, so I replaced it with a new one. I would have never guessed that this simple wire would cause such strange readings on the temperature gauge. But it does make sense because the temperature sending unit is a source for a ground and the accessories in the cab were using (at least partly) the ground wire to the sending unit.
I would check this first since it is possible to waste lots of time and money swapping out the other parts in vain.
My 76 had the same problem when I first got it. The engine was not obviously hot, but I wasn't going to risk overheating the engine. After replacing everything that has to do with the engine temperature regulating and measuring, the problem remained. Then I finally noticed the cab to engine ground needed some attention, so I replaced it with a new one. I would have never guessed that this simple wire would cause such strange readings on the temperature gauge. But it does make sense because the temperature sending unit is a source for a ground and the accessories in the cab were using (at least partly) the ground wire to the sending unit.
I would check this first since it is possible to waste lots of time and money swapping out the other parts in vain.
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Originally posted by Torque1st
Do you have a fan shroud?
Do you have a fan shroud?
Thanks for your answer.
Actually there is no shroud.
By the way do you know what the normal temp should be?
Could it be that the water pump is intermittent, at present it doesn't leak which is how I thought you could tell if a pump is inop.
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Don't go by the factory gauges,they have a habit of going bad..
First you have to determine what the EXACT temp is using the best method.
With rad cap off, start & run engine until peak operating temp,take a candy or meat thermometer and take a reading of the temp of the coolant.
Most operate at about 208*F..
With 180*/195*F thermostats : they open when they reach that temp,obviously the engine runs hotter than that.
First you have to determine what the EXACT temp is using the best method.
With rad cap off, start & run engine until peak operating temp,take a candy or meat thermometer and take a reading of the temp of the coolant.
Most operate at about 208*F..
With 180*/195*F thermostats : they open when they reach that temp,obviously the engine runs hotter than that.
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Joined: Dec 2001
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From: Louisville,Ky.
Try to find a shroud if possible, they make a big difference.
195 is the normal temp, depending on the thermostat installed.
To check the waterpump, start the truck cold with the radiator cap off. Let it run until it gets around 180 degrees, then start watching the coolant in the radiator. (some may run over as it heats up, this is normal) As it hits close to 195, you should see the water start to flow thru the radiator. It if appears to be flowing pretty good, the rev it up a little bit and make sure that the water speeds up too. If so, then the pump is probably ok.
If you do not have a shroud, then it will probably run around 190 while driving down the road and start heating up at slow speeds and idling. The fan can't pull air thru the radiator as well without the shroud encasing the blades.
Jimmy
195 is the normal temp, depending on the thermostat installed.
To check the waterpump, start the truck cold with the radiator cap off. Let it run until it gets around 180 degrees, then start watching the coolant in the radiator. (some may run over as it heats up, this is normal) As it hits close to 195, you should see the water start to flow thru the radiator. It if appears to be flowing pretty good, the rev it up a little bit and make sure that the water speeds up too. If so, then the pump is probably ok.
If you do not have a shroud, then it will probably run around 190 while driving down the road and start heating up at slow speeds and idling. The fan can't pull air thru the radiator as well without the shroud encasing the blades.
Jimmy
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Vacillating back and forth can be caused by the lack of a fan shroud. When the truck sits still it overheats from lack of airflow and the temp climbs. When the truck gets up to 30 mph airflow thru the radiator increases and the temp starts to go down. Moving thru traffic can make the temp gage go crazy.
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Thanks for the info, it seems however that this happens at various speeds going down the Hwy, without any traffic. It'll hover at 190 and jump to 230+ on to 260 and finally come back down. All this pretty regurlarly. Also this seems to occur more in the 1st 20mn of running the truck after which it tends to stabilize but will peg upward some but not as regularly. Someone suggested buying a candy thermometer to verify the temp. I 'll do that over the week-end.
Thanks again
monte54
Thanks again
monte54
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If you are missing the baffles around the radiator support you can get strange fluctuations also. The baffles are left out after many engine swaps by people that do not know what they are for so they toss them. Ford didn't put any "extra" parts on these trucks just for fun.