94 pickup running hot need help
05-21-2014, 11:50 AM
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94 pickup running hot need help
Basically my pickup has had the thermostat replaced, the radiator flushed, the fan clutch replaced, and a brand new head installed (with new gasket) and its still running hot, but its weird, I can leave it idling forever with the a/c on and it won't get hot but once I'm driving then it creeps up. And it creeps super slow, I'll have to drive like 15miles before it gets above half on the gauge. It has never been in the red, nor do I have a cel. Is it my water pump? Do I just need a new radiator? Please help. The picture attached shows where it'll get and usually stay. Before I get scared and turn it off.
05-21-2014, 01:40 PM
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Why do you think it's a problem for the gauge to run there? The gauges aren't that accurate in the first place. As long as it stays put at that point, just assume that's its "happy spot."
If you're not boiling off coolant you're not overheating the engine or damaging it in any way.
If you're not boiling off coolant you're not overheating the engine or damaging it in any way.
05-21-2014, 01:50 PM
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Why do you think it's a problem for the gauge to run there? The gauges aren't that accurate in the first place. As long as it stays put at that point, just assume that's its "happy spot."
If you're not boiling off coolant you're not overheating the engine or damaging it in any way.
If you're not boiling off coolant you're not overheating the engine or damaging it in any way.
05-21-2014, 02:13 PM
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That's not particularly surprising. At 60mph, you're burning between 3 and 4 gallons of gasoline per hour. At idle, probably less than 1/2 gallon per hour. Huge difference in the amount of heat generated. As long as the radiator is clean and the engine fan is in good shape, it will easily stay cool at idle.
There are several things that happen to increase cooling when the engine is working harder, burning more fuel, and thus creating more heat.
- the thermostat opens further to allow more coolant through the radiator. Once it's opened fully, that part of the equation is maxed out.
- Higher engine speed pumps more water through the block and radiator, providing more heat transfer.
- Higher engine speed and/or vehicle speed forces more air through the radiator, increasing radiator cooling capacity.
- Coolant temperature increases, which increases the amount of heat that can be dumped to the atmosphere. (heat transfer in the radiator is proportional to the difference between air temp and coolant temp, all other factors being equal).
The last one is important, and is the reason the coolant temps go up somewhat when the engine is working harder. Perfectly normal and nothing to worry about, unless the coolant temperature continues to rise to the boiling point. If that happens it means you've maxed out all of the methods listed above and cooling is still inadequate.
There are several things that happen to increase cooling when the engine is working harder, burning more fuel, and thus creating more heat.
- the thermostat opens further to allow more coolant through the radiator. Once it's opened fully, that part of the equation is maxed out.
- Higher engine speed pumps more water through the block and radiator, providing more heat transfer.
- Higher engine speed and/or vehicle speed forces more air through the radiator, increasing radiator cooling capacity.
- Coolant temperature increases, which increases the amount of heat that can be dumped to the atmosphere. (heat transfer in the radiator is proportional to the difference between air temp and coolant temp, all other factors being equal).
The last one is important, and is the reason the coolant temps go up somewhat when the engine is working harder. Perfectly normal and nothing to worry about, unless the coolant temperature continues to rise to the boiling point. If that happens it means you've maxed out all of the methods listed above and cooling is still inadequate.
05-21-2014, 02:17 PM
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That's not particularly surprising. At 60mph, you're burning between 3 and 4 gallons of gasoline per hour. At idle, probably less than 1/2 gallon per hour. Huge difference in the amount of heat generated. As long as the radiator is clean and the engine fan is in good shape, it will easily stay cool at idle.
There are several things that happen to increase cooling when the engine is working harder, burning more fuel, and thus creating more heat.
- the thermostat opens further to allow more coolant through the radiator. Once it's opened fully, that part of the equation is maxed out.
- Higher engine speed pumps more water through the block and radiator, providing more heat transfer.
- Higher engine speed and/or vehicle speed forces more air through the radiator, increasing radiator cooling capacity.
- Coolant temperature increases, which increases the amount of heat that can be dumped to the atmosphere. (heat transfer in the radiator is proportional to the difference between air temp and coolant temp, all other factors being equal).
The last one is important, and is the reason the coolant temps go up somewhat when the engine is working harder. Perfectly normal and nothing to worry about, unless the coolant temperature continues to rise to the boiling point. If that happens it means you've maxed out all of the methods listed above and cooling is still inadequate.
There are several things that happen to increase cooling when the engine is working harder, burning more fuel, and thus creating more heat.
- the thermostat opens further to allow more coolant through the radiator. Once it's opened fully, that part of the equation is maxed out.
- Higher engine speed pumps more water through the block and radiator, providing more heat transfer.
- Higher engine speed and/or vehicle speed forces more air through the radiator, increasing radiator cooling capacity.
- Coolant temperature increases, which increases the amount of heat that can be dumped to the atmosphere. (heat transfer in the radiator is proportional to the difference between air temp and coolant temp, all other factors being equal).
The last one is important, and is the reason the coolant temps go up somewhat when the engine is working harder. Perfectly normal and nothing to worry about, unless the coolant temperature continues to rise to the boiling point. If that happens it means you've maxed out all of the methods listed above and cooling is still inadequate.
05-21-2014, 02:36 PM
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What do you mean by "didn't want to turn back on"? No activity from the starter? Starter cranked the engine fine but it wouldn't fire? Engine fired intermittently and seemed like it would try to start, but never would fully "catch" and get going?
How long after shutdown did you wait when you first (unsuccessfully) tried to start it? How long did you have to wait before it would actually start?
How long after shutdown did you wait when you first (unsuccessfully) tried to start it? How long did you have to wait before it would actually start?
05-21-2014, 02:47 PM
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What do you mean by "didn't want to turn back on"? No activity from the starter? Starter cranked the engine fine but it wouldn't fire? Engine fired intermittently and seemed like it would try to start, but never would fully "catch" and get going?
How long after shutdown did you wait when you first (unsuccessfully) tried to start it? How long did you have to wait before it would actually start?
How long after shutdown did you wait when you first (unsuccessfully) tried to start it? How long did you have to wait before it would actually start?
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05-21-2014, 03:21 PM
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So, my original point was that, just based on your gauge readings, your engine temperature doesn't seem abnormal. As I said though, those gauges aren't particularly accurate. You may want to try to get an independent temp reading of the coolant somehow.
Since you have spark, your starting problem is likely either too much fuel or not enough. Do you smell fuel when it won't start? Try holding the accelerator all the way open while cranking the starter. That will give it extra air, and it will likely start if the problem is too much fuel. I've seen this situation on my son-in-law's '97 4runner. I suspect in his case that somehow a sensor is telling the ECU that the engine is cool and needs a rich mixture when in reality it's still hot and needs leaner.
On the other hand, if the problem is not enough fuel, holding the accelerator open will not help it start. In this case I would agree you would want to check the fuel pressure.
Since you have spark, your starting problem is likely either too much fuel or not enough. Do you smell fuel when it won't start? Try holding the accelerator all the way open while cranking the starter. That will give it extra air, and it will likely start if the problem is too much fuel. I've seen this situation on my son-in-law's '97 4runner. I suspect in his case that somehow a sensor is telling the ECU that the engine is cool and needs a rich mixture when in reality it's still hot and needs leaner.
On the other hand, if the problem is not enough fuel, holding the accelerator open will not help it start. In this case I would agree you would want to check the fuel pressure.
05-21-2014, 03:25 PM
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UOTE=RJR;52197438]So, my original point was that, just based on your gauge readings, your engine temperature doesn't seem abnormal. As I said though, those gauges aren't particularly accurate. You may want to try to get an independent temp reading of the coolant somehow.
Since you have spark, your starting problem is likely either too much fuel or not enough. Do you smell fuel when it won't start? Try holding the accelerator all the way open while cranking the starter. That will give it extra air, and it will likely start if the problem is too much fuel. I've seen this situation on my son-in-law's '97 4runner. I suspect in his case that somehow a sensor is telling the ECU that the engine is cool and needs a rich mixture when in reality it's still hot and needs leaner.
On the other hand, if the problem is not enough fuel, holding the accelerator open will not help it start. In this case I would agree you would want to check the fuel pressure.[/QUOTE]
Thanks for all your help, I will try to get some sort of temp reading. As far as the temp goes for now I won't worry unless it gets in the red. I'll try your suggestions for starting once I am near it again. Hopefully its good.
I'm trying to take it on a road trip in a month
Since you have spark, your starting problem is likely either too much fuel or not enough. Do you smell fuel when it won't start? Try holding the accelerator all the way open while cranking the starter. That will give it extra air, and it will likely start if the problem is too much fuel. I've seen this situation on my son-in-law's '97 4runner. I suspect in his case that somehow a sensor is telling the ECU that the engine is cool and needs a rich mixture when in reality it's still hot and needs leaner.
On the other hand, if the problem is not enough fuel, holding the accelerator open will not help it start. In this case I would agree you would want to check the fuel pressure.[/QUOTE]
Thanks for all your help, I will try to get some sort of temp reading. As far as the temp goes for now I won't worry unless it gets in the red. I'll try your suggestions for starting once I am near it again. Hopefully its good.
I'm trying to take it on a road trip in a month
05-21-2014, 04:18 PM
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How old is the radiator cap?
Pull the temp sensor and clean the scale off the probe. The scale can cause wacky readings.
Where was the needle sitting before you did the work in post #1? New coolant mix was put in when rad was replaced?
Pull the temp sensor and clean the scale off the probe. The scale can cause wacky readings.
Where was the needle sitting before you did the work in post #1? New coolant mix was put in when rad was replaced?
05-21-2014, 04:25 PM
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I will check out that idea about the sensor. Also the rad wasn't replaced only flushed and before all the work it would be in the same spot. Once I turn the heat on though it goes down. And yes for new coolant
05-22-2014, 08:17 AM
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So, my original point was that, just based on your gauge readings, your engine temperature doesn't seem abnormal. As I said though, those gauges aren't particularly accurate. You may want to try to get an independent temp reading of the coolant somehow.
Since you have spark, your starting problem is likely either too much fuel or not enough. Do you smell fuel when it won't start? Try holding the accelerator all the way open while cranking the starter. That will give it extra air, and it will likely start if the problem is too much fuel. I've seen this situation on my son-in-law's '97 4runner. I suspect in his case that somehow a sensor is telling the ECU that the engine is cool and needs a rich mixture when in reality it's still hot and needs leaner.
On the other hand, if the problem is not enough fuel, holding the accelerator open will not help it start. In this case I would agree you would want to check the fuel pressure.
Since you have spark, your starting problem is likely either too much fuel or not enough. Do you smell fuel when it won't start? Try holding the accelerator all the way open while cranking the starter. That will give it extra air, and it will likely start if the problem is too much fuel. I've seen this situation on my son-in-law's '97 4runner. I suspect in his case that somehow a sensor is telling the ECU that the engine is cool and needs a rich mixture when in reality it's still hot and needs leaner.
On the other hand, if the problem is not enough fuel, holding the accelerator open will not help it start. In this case I would agree you would want to check the fuel pressure.
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