Cold Operating Temp/No heat
02-03-2012, 05:51 PM
#11
Not so much "sucked" but pushed. If the o-ring and housing flange isn't holding the thermostat down and seated into the intake manifold it will (mine did) 'float' when forced up by the coolant stream. If the thermostat 'floats' the gap around the edge becomes a 1/8" thermostat bypass. That is if our systems are not reverse flow systems which I believe they are not.
Have you taken a temperature reading at the top of the thermostat housing? Amazon.com has the laser pointed temp guns for $18-$89 and I opted for a $27 one and it is remarkably accurate for being low priced and Chinese.
If you are getting a housing temp anywhere near what I'm getting I'd say that your heater core has a restriction.
Without going back and reading this entire thread.... have you determined that you have 100% flow through your heater core by disconnecting the in/out lines and flowing water through the core? I made up hose barbs to garden hose adapters years ago for heater core flushes.
I DID replace the gauge sending unit with a Motorcraft unit from Ford and at $12 it was a cheap way to determine if the old one was faulty but I still only get 35% up the temp zone on my gauge. So it is apparently in agreement with my 167 degree operating temp at the thermostat housing.
Maybe I just have an overly efficient cooling system? But..... I always thought that the thermostat determined the final, high operating temperature.
I've not swapped the housing yet nor have I changed the current 195 thermostat out with a Motorcraft unit but that will probably be my next attempt to elevate the operating temp. The current thermostat was purchased from Advance Auto when I flushed the system and they did not have the "BEST" quality Robert Shaw thermostat in stock so maybe, just maybe a 195 Motorcraft thermostat will make a difference.....
I'm also going to check the coolant for hydrocarbons but I don't have any dropping coolant level issues or surging coolant on start up nor would I think that a head gasket leak would be evidenced by a consistant 167 degree operating temp. I've seen overheating symptoms with a blown head gasket but not consistant low temps.
P.S....... I searched for thermostats with a higher temp than 195 and there are none. Probably a good thing. I remember running a '99 4.6 Expedition from Phoenix to Michigan towing an MGB on a trailer in July and we flushed and changed coolant and installed a new 195 thermostat and with the a/c blasting at ambient temps of 85 - 115 the gauge never went past the 50% mark..... So a properly operating 4.6 is apparently fine with a 195 stat at a very wide ambient operating temperature and that makes sense as Ford engineers no doubt designed the 4.6 to operate at very wide ambient operating temperatures with the 195 stat...
Let me know if you determine : 1. Housing temp 2. 100% heater core flow. 3. Thermostat seated properly in manifold.
Good thing it's been a mild winter... Or are you north of International Falls MN? Hope not..........
Have you taken a temperature reading at the top of the thermostat housing? Amazon.com has the laser pointed temp guns for $18-$89 and I opted for a $27 one and it is remarkably accurate for being low priced and Chinese.
If you are getting a housing temp anywhere near what I'm getting I'd say that your heater core has a restriction.
Without going back and reading this entire thread.... have you determined that you have 100% flow through your heater core by disconnecting the in/out lines and flowing water through the core? I made up hose barbs to garden hose adapters years ago for heater core flushes.
I DID replace the gauge sending unit with a Motorcraft unit from Ford and at $12 it was a cheap way to determine if the old one was faulty but I still only get 35% up the temp zone on my gauge. So it is apparently in agreement with my 167 degree operating temp at the thermostat housing.
Maybe I just have an overly efficient cooling system? But..... I always thought that the thermostat determined the final, high operating temperature.
I've not swapped the housing yet nor have I changed the current 195 thermostat out with a Motorcraft unit but that will probably be my next attempt to elevate the operating temp. The current thermostat was purchased from Advance Auto when I flushed the system and they did not have the "BEST" quality Robert Shaw thermostat in stock so maybe, just maybe a 195 Motorcraft thermostat will make a difference.....
I'm also going to check the coolant for hydrocarbons but I don't have any dropping coolant level issues or surging coolant on start up nor would I think that a head gasket leak would be evidenced by a consistant 167 degree operating temp. I've seen overheating symptoms with a blown head gasket but not consistant low temps.
P.S....... I searched for thermostats with a higher temp than 195 and there are none. Probably a good thing. I remember running a '99 4.6 Expedition from Phoenix to Michigan towing an MGB on a trailer in July and we flushed and changed coolant and installed a new 195 thermostat and with the a/c blasting at ambient temps of 85 - 115 the gauge never went past the 50% mark..... So a properly operating 4.6 is apparently fine with a 195 stat at a very wide ambient operating temperature and that makes sense as Ford engineers no doubt designed the 4.6 to operate at very wide ambient operating temperatures with the 195 stat...
Let me know if you determine : 1. Housing temp 2. 100% heater core flow. 3. Thermostat seated properly in manifold.
Good thing it's been a mild winter... Or are you north of International Falls MN? Hope not..........
02-03-2012, 10:52 PM
#12
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Must be thousands of these truck engine configurations doing the same thing as ours... I'm amazed that there are not more references to this problem. Your thermostat housing is within 10 degrees of mine. Also, you radiator, hose and manifold temps are nearly the same as mine. One odd thing I noticed when I checked the temp of the exhaust manifolds was a nearly 100 degree difference in temps. Not sure but I think that the passenger side was the cooler of the two.
Interesting that you found a 210 thermostat. I searched on-line with no luck but based on your info (thank you) mI won't bother with that.
This is quite maddening in that we both have the same problem and there is no way (?) that coolant could be getting to the radiator for extra cooling unless there is a connection in the intake manifold or via an unknown hose that is allowing a thermostat bypass condition.
I'll try to look for a cooling system diagram in my factory service manuals tomorrow. If I find any suspected means of bypassing I'll let you know.
Wish I knew a Ford mechanic with gray hair who has probably seen this condition.... would be a cheaper and surer way of getting to the bottom of this than shoveling $ into a dealer's pockets.
This is nutz.
Interesting that you found a 210 thermostat. I searched on-line with no luck but based on your info (thank you) mI won't bother with that.
This is quite maddening in that we both have the same problem and there is no way (?) that coolant could be getting to the radiator for extra cooling unless there is a connection in the intake manifold or via an unknown hose that is allowing a thermostat bypass condition.
I'll try to look for a cooling system diagram in my factory service manuals tomorrow. If I find any suspected means of bypassing I'll let you know.
Wish I knew a Ford mechanic with gray hair who has probably seen this condition.... would be a cheaper and surer way of getting to the bottom of this than shoveling $ into a dealer's pockets.
This is nutz.
02-03-2012, 10:57 PM
#13
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Was just thinking... in order for coolant to bypass the thermostat there would have to be an additional hose running from the engine (other than the upper and lower hoses) to the radiator or coolant resevoir. That would be the only way that the engine could be bypassing the t stat.
Sheesh...
This should not happen.
Sheesh...
This should not happen.
02-03-2012, 11:13 PM
#14
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I wish that folks that are clueless would stay away from their computers when offering their opinions....
But I DID glean a few nuggets...
If the PCM sees an improper value from the coolant sensor (not temp gauge sender) it could cause the engine to run in an open loop condition which would be a rich fuel mixture condition.
I did find very different exhaust manifold temps, I've had a P153 code twice (O2 sensor) which could be cuased by a rich mixture...
A rich mixture would / could cause the engine to run cold as well (well?)
My fuel mileage has been bad as well...
So... what the heck... Maybe I'll buy a new coolant temp sensor at Ford tomorrow....
But I DID glean a few nuggets...
If the PCM sees an improper value from the coolant sensor (not temp gauge sender) it could cause the engine to run in an open loop condition which would be a rich fuel mixture condition.
I did find very different exhaust manifold temps, I've had a P153 code twice (O2 sensor) which could be cuased by a rich mixture...
A rich mixture would / could cause the engine to run cold as well (well?)
My fuel mileage has been bad as well...
So... what the heck... Maybe I'll buy a new coolant temp sensor at Ford tomorrow....
02-03-2012, 11:14 PM
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Some clueless but a few nuggets of infor that may help us...
http://www.google.com/search?num=50&...0l78l152l2l2l0
http://www.google.com/search?num=50&...0l78l152l2l2l0
02-04-2012, 10:45 AM
#16
I know that the low temp will cause an open loop running condition. But I don't think that the system in open loop would cause the engine to run cool. Now if the thermostat is operating correctly, the only other thing I can think of would be the fan clutch being constantly engaged. The thing is there is really only 2 things that control the temperature from getting too hot beyond the design of the cooling system. The fan and the thermostat. I can't think of any other part that would "overcool" the engine.
02-04-2012, 11:07 AM
#17
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Thanks for distilling to simplest terms.... A lot can be said (in my case at least) for sleep and coffee as far as clarity of thought. Been on standby all week and had multiple calls in middle of night. Utilities never sleep.
I'll just meter the sensor and check it against specs.
Yes.... only two things could 'overcool' the engine. And that is what's so maddening.
1) My fan clutch, upon starting sounds locked for the 1st 45 seconds (with a lot of air noise) then gets progressively quieter (less air noise) over the next minute or so. That would seem to indicate that the clutch is unlocking and the fan is free wheeling in a cold condition.... So, my fan clutch is okay.... Right?
2) You and I have been down thermostat road a lot and it always comes back to the thermostat NOT being able to do it's job. The only thing that would prevent a known good thermostat (and even a 210 t stat) from regulating the engine operating temp to the thermostat's design temp would be........ bypassing.
Right?
I have found a lot of complaints on cold running 4.6 engines in Mustangs, Crown Vics and F trucks but of those I've found that 90% of the replies stop at "replace the thermostat".
I'll just meter the sensor and check it against specs.
Yes.... only two things could 'overcool' the engine. And that is what's so maddening.
1) My fan clutch, upon starting sounds locked for the 1st 45 seconds (with a lot of air noise) then gets progressively quieter (less air noise) over the next minute or so. That would seem to indicate that the clutch is unlocking and the fan is free wheeling in a cold condition.... So, my fan clutch is okay.... Right?
2) You and I have been down thermostat road a lot and it always comes back to the thermostat NOT being able to do it's job. The only thing that would prevent a known good thermostat (and even a 210 t stat) from regulating the engine operating temp to the thermostat's design temp would be........ bypassing.
Right?
I have found a lot of complaints on cold running 4.6 engines in Mustangs, Crown Vics and F trucks but of those I've found that 90% of the replies stop at "replace the thermostat".
02-05-2012, 08:26 AM
#18
I would think that even without a thermostat at all I would run hotter than 155° F.
Also I think that my thermostat is working properly. I can here the truck go out of the open loop mode into the closed loop mode after it first warms up. I hear the rpms drop and then I have good heat for about 2-3 minutes max then this running cold. its almost like the thermostat can not re close to regulate the temp.
Also took so temperature reading of the vents. I was at 81° after a hour of running around town.
Do you think that this makes any sense? If so I have an idea to run by you. Sorta thermostat test procedure if I can find the time to get good results out of it.
Also I think that my thermostat is working properly. I can here the truck go out of the open loop mode into the closed loop mode after it first warms up. I hear the rpms drop and then I have good heat for about 2-3 minutes max then this running cold. its almost like the thermostat can not re close to regulate the temp.
Also took so temperature reading of the vents. I was at 81° after a hour of running around town.
Do you think that this makes any sense? If so I have an idea to run by you. Sorta thermostat test procedure if I can find the time to get good results out of it.
02-05-2012, 09:39 AM
#19
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A thermostat test?
Like a pan of water on the stove right?
Starting to wonder if there are bad thermostats out of the box. Bought a Purolator fuel filter that fell apart internally and plugged a Carter AFB. So a bad thermostat out of the box might be possible.
What's really wierd is that you are only getting 81 degrees out of the heater outlets. I'm getting 121 which is acceptable if the ambient temp is above 25 degrees.
My truck also goes from open to closed loop. The hottest area around the thermostat is just below the upper edge of the hole in the manifold and slightly behind the driver's side mounting bolt which is 176 degrees after a 15 mile blast down the highway and back.
The fan clutch temp was 67 at an ambient of 39 and freewheels in an engine stopped condition.... for what it's worth.....
Like a pan of water on the stove right?
Starting to wonder if there are bad thermostats out of the box. Bought a Purolator fuel filter that fell apart internally and plugged a Carter AFB. So a bad thermostat out of the box might be possible.
What's really wierd is that you are only getting 81 degrees out of the heater outlets. I'm getting 121 which is acceptable if the ambient temp is above 25 degrees.
My truck also goes from open to closed loop. The hottest area around the thermostat is just below the upper edge of the hole in the manifold and slightly behind the driver's side mounting bolt which is 176 degrees after a 15 mile blast down the highway and back.
The fan clutch temp was 67 at an ambient of 39 and freewheels in an engine stopped condition.... for what it's worth.....
02-05-2012, 01:51 PM
#20
No the test I was thinking of was going to be to make some plates to put in place of the thermostat. i would drill the plate with different size hole to "meter" the coolant flow. Blocking it off should make the engine over heat. I figure anything that is not totally blocking it should cool the engine some. start with one 1/8th" hole in it and see if the engine over heats or if it holds a good temperature.