coolant temp
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More Turbo
Joined: Jul 2009
Posts: 705
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From: Taxachusetts
coolant temp
first, before I changed my fan to the severe duty one, my temps were normal, ect 190ish* eot 195ish*. after the fan change my ect creeps up 188* then drops to 180* I assume because the tstat opens. the delta is 5-7*.
I noticed today that once at operating temp, while coasting for a long time the air temp coming out of the vents slowly cools (it's still warm just not hot), as soon as I touch the throttle bringing up the rpms to 1200 the air would get hot again in about 3 seconds. the ect doesn't change stays 180ish*.
my thought is the coolant is not flowing thru the heater core while coasting causing the cabin heat air temp to cool. I don't know if because the the tstat stays closed most of the time the coolant is flowing thru the heater core or the water pump is just not circulating. is the coolant flow controlled by vacuum so that when I'm coasting vacuum bleeds off?
I noticed today that once at operating temp, while coasting for a long time the air temp coming out of the vents slowly cools (it's still warm just not hot), as soon as I touch the throttle bringing up the rpms to 1200 the air would get hot again in about 3 seconds. the ect doesn't change stays 180ish*.
my thought is the coolant is not flowing thru the heater core while coasting causing the cabin heat air temp to cool. I don't know if because the the tstat stays closed most of the time the coolant is flowing thru the heater core or the water pump is just not circulating. is the coolant flow controlled by vacuum so that when I'm coasting vacuum bleeds off?
Hotshot
Joined: Jul 2005
Posts: 13,834
Likes: 25
From: Middle Tn.
Vacum has nothing to do with engine speed. You have an electric vacum pump. I personally think your t-stat is hanging up. I would replace it. You'r now running too cold for optimum engine efdficiency and mpg. T-stat is the easiest and cheapest item to remedy first.
Token Redneck
Joined: Jun 2007
Posts: 9,332
Likes: 341
From: Breckenridge, TX
Well, let me caveat that real fast^^^. Check the cold soak temp spread between the ECT and EOT sensors to make sure this isn't just the senors going 3% out in opposite ways. 180* by itself isn't 100% a bad t-stat, you could have a sensor that's 4* low and a t-stat thats 4* cold and swapping either part might not get you all the way there. Some t-stats apparently run cold out of the box, so a replacement might not do anything. But if the temp split on the sensors is correct, then once it's getting into the high 170s or not going over 180*, it might be time for a new t-stat.
What year? Earlier trucks did have a smaller water pump, but later years got a larger one that's a fairly low-failure part
Vacuum DOES control the heater control valve, directly under the rear cowling on the passenger side behind and to the right of the oil fill cap. Make sure the vac line is correctly plugged in and the valve is functioning correctly.
It's the black circular thing right behind and to the right the yellow oil fill cap, and the grey vac line is incorrectly unplugged in this picture:
What year? Earlier trucks did have a smaller water pump, but later years got a larger one that's a fairly low-failure part
Vacuum DOES control the heater control valve, directly under the rear cowling on the passenger side behind and to the right of the oil fill cap. Make sure the vac line is correctly plugged in and the valve is functioning correctly.
It's the black circular thing right behind and to the right the yellow oil fill cap, and the grey vac line is incorrectly unplugged in this picture:
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More Turbo
Joined: Jul 2009
Posts: 705
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From: Taxachusetts
it's a late 04. the tstat is a 6month old motorcraft.
before I changed the fan my temps and delta were normal 190-195* unless I had the plow on, then temps would stay at 200+*, which is why I put the severe duty fan on. I didnt notice the coasting only warm air thing till yesterday.
My cold soak temps are within 5* of each other. the ect and eot sensors are less than a year old I suspect the connectors need to be replaced as the clips that hold them tight are broken off. the iat is not new.
how do I check the vacuum pump?
before I changed the fan my temps and delta were normal 190-195* unless I had the plow on, then temps would stay at 200+*, which is why I put the severe duty fan on. I didnt notice the coasting only warm air thing till yesterday.
My cold soak temps are within 5* of each other. the ect and eot sensors are less than a year old I suspect the connectors need to be replaced as the clips that hold them tight are broken off. the iat is not new.
how do I check the vacuum pump?
Hotshot
Joined: Jul 2005
Posts: 13,834
Likes: 25
From: Middle Tn.
[quote=samsdad02;13070488]it's a late 04. the tstat is a 6month old motorcraft.
before I changed the fan my temps and delta were normal 190-195* unless I had the plow on, then temps would stay at 200+*, which is why I put the severe duty fan on. I didnt notice the coasting only warm air thing till yesterday.
My cold soak temps are within 5* of each other. the ect and eot sensors are less than a year old I suspect the connectors need to be replaced as the clips that hold them tight are broken off. the iat is not new.
how do I check the vacuum pump?[/quote]
Turn your ignition on and go to the vacum pump on the passenger side wheel well. Unplug the vacum lines and block the pump nipples off. The pump should stop. If not replace it.
before I changed the fan my temps and delta were normal 190-195* unless I had the plow on, then temps would stay at 200+*, which is why I put the severe duty fan on. I didnt notice the coasting only warm air thing till yesterday.
My cold soak temps are within 5* of each other. the ect and eot sensors are less than a year old I suspect the connectors need to be replaced as the clips that hold them tight are broken off. the iat is not new.
how do I check the vacuum pump?[/quote]
Turn your ignition on and go to the vacum pump on the passenger side wheel well. Unplug the vacum lines and block the pump nipples off. The pump should stop. If not replace it.
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