Air block, I think...
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Posting Guru
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From: Perry Georgia
Air block, I think...
I have a 1987 F250 with a 6.9 n/a and seem to have an air block somewhere. I get the truck warmed up but almost no heat. I don't have any coolant leaks that I can see. When I shut off the engine I hear gurgling from the heater area. The heater hoses are hot somtimes but not always. I have an inline heater I plug in to give the truck an easier start on cold mornings close to the front of the engine bay.Any ideas?
Logistics Pro
Joined: Sep 2007
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From: Western Mass
I'm wondering if there is something wrong with the controls, or if one of the flaps in the heater box doesn't work right. If you pull the glove box out, you should be able to get at the heater core, see if its warm, that should at least tell you if warm coolant is getting there or not.
If the heater core ISN'T getting hot (like radiator hot) when the truck is warmed up, pull it out and see if its plugged up.
If the heater core is IS hot, then you have an issue with the heat controls, the ducting or the flaps that control the air flow.
If the heater core ISN'T getting hot (like radiator hot) when the truck is warmed up, pull it out and see if its plugged up.
If the heater core is IS hot, then you have an issue with the heat controls, the ducting or the flaps that control the air flow.
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From: Perry Georgia
Sometimes the heater hoses going to and from the heater core are both hot and still very little heat. What I"m wondering about is why I hear the gurgling. There aren't any leaks I can see at least no water running fromany of the hose connections. Is there a particular way to hook the heater core up? One top the other bottom or left vs right? Like I said, sometimes we have heat, sometimes no heat and right now it's going down to mid 20's tonight.
Postmaster
Joined: Feb 2011
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the fact that you sometimes have heat and sometimes don't sure sounds like a problem in the controls. the controls are powered by vacuum, so a damaged hose could cause the heater to not do what you want it to. or a bad vacuum pump, or control unit...
Logistics Pro
Joined: Sep 2007
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From: Western Mass
Is the radiator topped off? and the coolant reservoir full? I'm wondering if the gurgling is a low coolant level.
Might also have to take the heater core out and flush it to get any accumulated crud out. And maybe the fins are all clogged up with dust, that would make a big difference.
Might also have to take the heater core out and flush it to get any accumulated crud out. And maybe the fins are all clogged up with dust, that would make a big difference.
i ain't rite
Joined: Mar 2005
Posts: 65,481
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From: Marlboro Mental Hospital.
i bet the gurgling you hear is the heater hoses on the core the wrong way. if the heater inlet is going into the top of the core, it will "fall through" the core, resulting in air pockets and only a partially full heater core, and the gurgling sound.
the proper heater hose routing is inlet to bottom of heater core, and outlet from the top of the core. this will fill the core up eliminating all air pockets.
the proper heater hose routing is inlet to bottom of heater core, and outlet from the top of the core. this will fill the core up eliminating all air pockets.
Logistics Pro
Joined: Sep 2007
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From: Western Mass
Tom thats an interesting thought!
But I'm pretty sure it wouldn't matter on the core I have in my 88, as it seems symmetric and both inlet and outlet are on the top. Not sure if an 86 is different though.
But I'm pretty sure it wouldn't matter on the core I have in my 88, as it seems symmetric and both inlet and outlet are on the top. Not sure if an 86 is different though.
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i ain't rite
Joined: Mar 2005
Posts: 65,481
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From: Marlboro Mental Hospital.
if you look at the service manual, it will tell you which line is the inlet and which is the outlet. \i want to say the inside is inlet, but am not sure. i will have to look at the manual .
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From: Perry Georgia
I've checked the radiator and parked it nose up and nose down but nothing differs as far as the level of the coolant in the rad. Both ways the level is right up to the cap. My connections are side by side so I"m planning on swapping the hoses from side to side and see if that makes any differance.
Post Fiend
Joined: Nov 2005
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From: Charles Town, W bygod Va
This is a picture from Rockauto for a 1988 F350 heater core. Every one I've ever seen is made like this. The upper tank is made in two sections, so the coolant flows down one side then back up the other, so it should not matter which way you hook the hoses up. I seem to remember a couple threads about this recently, and IIRC, one concluded it didnt matter, and the other one concluded that it did.
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