Heater question
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Elder User
Joined: Oct 2004
Posts: 813
Likes: 1
From: Auburn, Il
Heater question
My heater doesn't seem to be working. I dont see any leaks on the floor board and the blower is working but its blowing cold air out. I have a thermostat in and you can see its working, once it hits 190 it drops back down around 170-ish so I'm at a loss on what to do.
Lead Driver
Joined: Dec 2000
Posts: 6,298
Likes: 47
From: South central, Minnesota
Check your heater hoses under the hood by the firewall for a valve. I believe there should be one that was originally operated by a cable. It allows you to shut off the flow of coolant to the heater core. I'm guessing you have one and it's closed.
If you don't have one my 2nd guess would be your heater core could be plugged up so it's getting no coolant flow thru it.
If you don't have one my 2nd guess would be your heater core could be plugged up so it's getting no coolant flow thru it.
Thread Starter
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Elder User
Joined: Oct 2004
Posts: 813
Likes: 1
From: Auburn, Il
Check your heater hoses under the hood by the firewall for a valve. I believe there should be one that was originally operated by a cable. It allows you to shut off the flow of coolant to the heater core. I'm guessing you have one and it's closed.
If you don't have one my 2nd guess would be your heater core could be plugged up so it's getting no coolant flow thru it.
If you don't have one my 2nd guess would be your heater core could be plugged up so it's getting no coolant flow thru it.
Lead Driver
Joined: Dec 2000
Posts: 6,298
Likes: 47
From: South central, Minnesota
It's been a while since I messed with any of the stock heaters. I don't remember if any of them had any kind of selector door/flap to control the air flow in the heater box. If it does that could be shut to block the heater core from the air flow.
You might want to check into that first and if it's not that then pull the hoses and check the heater core for blockages. You could also check the heater hoses while the engine is running and warmed up and see if either are warm/cool. That would at least tell you if the coolant is getting to the heater core.
You might want to check into that first and if it's not that then pull the hoses and check the heater core for blockages. You could also check the heater hoses while the engine is running and warmed up and see if either are warm/cool. That would at least tell you if the coolant is getting to the heater core.
Post Fiend
Joined: May 2008
Posts: 7,641
Likes: 21
From: Poway, Ca.
Don't try flushing the heater with the garden hose, you'll blow up the core.
Start the truck and warm it up. Hold the heater hoses in your hand. They should both be warm. If not, you either have them hooked up in the wrong places, or the nipples coming out of the outlet or going to the inlet is plugged up.
Your heater hose should run off the nipple coming off the intake manifold to the lower heater inlet. It comes out the upper tube then goes back to the 1/2 inch tube extending out from the water pump on the passenger side.
If you didn't replace those two tubes when you rebuilt your 289, then chances are they are rusted up. Again check both of these tubes for a shut off. Normally it's the one on the intake manifold and it will have a little butterfly type twist on the top to open and close the valve.
If when you hold the heater hoses they are both warm, then the core is heated up, you just have a temperature door closed or the controls are frozen/not connected properly.
Start the truck and warm it up. Hold the heater hoses in your hand. They should both be warm. If not, you either have them hooked up in the wrong places, or the nipples coming out of the outlet or going to the inlet is plugged up.
Your heater hose should run off the nipple coming off the intake manifold to the lower heater inlet. It comes out the upper tube then goes back to the 1/2 inch tube extending out from the water pump on the passenger side.
If you didn't replace those two tubes when you rebuilt your 289, then chances are they are rusted up. Again check both of these tubes for a shut off. Normally it's the one on the intake manifold and it will have a little butterfly type twist on the top to open and close the valve.
If when you hold the heater hoses they are both warm, then the core is heated up, you just have a temperature door closed or the controls are frozen/not connected properly.
Thread Starter
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Elder User
Joined: Oct 2004
Posts: 813
Likes: 1
From: Auburn, Il
Don't try flushing the heater with the garden hose, you'll blow up the core.
Start the truck and warm it up. Hold the heater hoses in your hand. They should both be warm. If not, you either have them hooked up in the wrong places, or the nipples coming out of the outlet or going to the inlet is plugged up.
Your heater hose should run off the nipple coming off the intake manifold to the lower heater inlet. It comes out the upper tube then goes back to the 1/2 inch tube extending out from the water pump on the passenger side.
If you didn't replace those two tubes when you rebuilt your 289, then chances are they are rusted up. Again check both of these tubes for a shut off. Normally it's the one on the intake manifold and it will have a little butterfly type twist on the top to open and close the valve.
If when you hold the heater hoses they are both warm, then the core is heated up, you just have a temperature door closed or the controls are frozen/not connected properly.
Start the truck and warm it up. Hold the heater hoses in your hand. They should both be warm. If not, you either have them hooked up in the wrong places, or the nipples coming out of the outlet or going to the inlet is plugged up.
Your heater hose should run off the nipple coming off the intake manifold to the lower heater inlet. It comes out the upper tube then goes back to the 1/2 inch tube extending out from the water pump on the passenger side.
If you didn't replace those two tubes when you rebuilt your 289, then chances are they are rusted up. Again check both of these tubes for a shut off. Normally it's the one on the intake manifold and it will have a little butterfly type twist on the top to open and close the valve.
If when you hold the heater hoses they are both warm, then the core is heated up, you just have a temperature door closed or the controls are frozen/not connected properly.
Thread Starter
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Elder User
Joined: Oct 2004
Posts: 813
Likes: 1
From: Auburn, Il
Oh by the way Julie, do you have a diagram for the heater switch, I want to make sure the 3 wires that go to the back of the switch are hooked up correct.
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Fleet Mechanic
Joined: Dec 2005
Posts: 1,603
Likes: 44
An old saying
My father pounded in my head his old saying in relation to heater hoses.
"bottom to top and top to bottom" just remember that.
If confusing > the bottom of the heater core goes to the top of the
engine (usually the head) and the top of the heater core goes to the
bottom (usuall the water pump) and also on some systems its a real
pita to get an air pocket out. Symtoms usually are no heat, a high rise
in engine temp until the thermostat opens, then a little heat, then it
goes to cold. My family ran a bus fleet in the fiftys. Lets say we are
to replace the water pump. (engine in rear) 20min for a new pump and
2Hrs to bleed the heaters. These buses as well a school buses with
3 heaters they usually have bleeders on the cores. So you will have to
crack a heater line with the engine running Just a little so you dont get
burnt. If this does not work=then the core is blocked, 100% of the
time its due to over the years/and stop leak. To me stop leak is like
snake oil its a heater core killer.
"bottom to top and top to bottom" just remember that.
If confusing > the bottom of the heater core goes to the top of the
engine (usually the head) and the top of the heater core goes to the
bottom (usuall the water pump) and also on some systems its a real
pita to get an air pocket out. Symtoms usually are no heat, a high rise
in engine temp until the thermostat opens, then a little heat, then it
goes to cold. My family ran a bus fleet in the fiftys. Lets say we are
to replace the water pump. (engine in rear) 20min for a new pump and
2Hrs to bleed the heaters. These buses as well a school buses with
3 heaters they usually have bleeders on the cores. So you will have to
crack a heater line with the engine running Just a little so you dont get
burnt. If this does not work=then the core is blocked, 100% of the
time its due to over the years/and stop leak. To me stop leak is like
snake oil its a heater core killer.
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Thread Starter
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Elder User
Joined: Oct 2004
Posts: 813
Likes: 1
From: Auburn, Il
My father pounded in my head his old saying in relation to heater hoses.
"bottom to top and top to bottom" just remember that.
If confusing > the bottom of the heater core goes to the top of the
engine (usually the head) and the top of the heater core goes to the
bottom (usuall the water pump) and also on some systems its a real
pita to get an air pocket out. Symtoms usually are no heat, a high rise
in engine temp until the thermostat opens, then a little heat, then it
goes to cold. My family ran a bus fleet in the fiftys. Lets say we are
to replace the water pump. (engine in rear) 20min for a new pump and
2Hrs to bleed the heaters. These buses as well a school buses with
3 heaters they usually have bleeders on the cores. So you will have to
crack a heater line with the engine running Just a little so you dont get
burnt. If this does not work=then the core is blocked, 100% of the
time its due to over the years/and stop leak. To me stop leak is like
snake oil its a heater core killer.
"bottom to top and top to bottom" just remember that.
If confusing > the bottom of the heater core goes to the top of the
engine (usually the head) and the top of the heater core goes to the
bottom (usuall the water pump) and also on some systems its a real
pita to get an air pocket out. Symtoms usually are no heat, a high rise
in engine temp until the thermostat opens, then a little heat, then it
goes to cold. My family ran a bus fleet in the fiftys. Lets say we are
to replace the water pump. (engine in rear) 20min for a new pump and
2Hrs to bleed the heaters. These buses as well a school buses with
3 heaters they usually have bleeders on the cores. So you will have to
crack a heater line with the engine running Just a little so you dont get
burnt. If this does not work=then the core is blocked, 100% of the
time its due to over the years/and stop leak. To me stop leak is like
snake oil its a heater core killer.
Post Fiend
Joined: May 2008
Posts: 7,641
Likes: 21
From: Poway, Ca.
Honestly, my feeble brain doesn't remember my 289. And I'm not sure why you have two outlets coming from the water pump, but I would say yes they are not hooked up right. But, I'll get into my book to see.
Look on the top of your intake manifold in front of the carb and slightly to the right (pass) side. There should be a place to screw in a nipple - it might be plugged at the moment. Pic:
That's where the coolant should be coming from for the heater. And as mentioned, that should go to the lower heater tube. The outlet hose should go to the water pump - the upper one you have on there now, and the other inlet on the water pump plugged.
So, yes I'd say you need to hook them up differently!
On your heater switch, if you have the two position pull type, one of the terminals should have a "B" next to it. Power goes in there. The other two wires can go in either of the remaining terminals.
Look on the top of your intake manifold in front of the carb and slightly to the right (pass) side. There should be a place to screw in a nipple - it might be plugged at the moment. Pic:
That's where the coolant should be coming from for the heater. And as mentioned, that should go to the lower heater tube. The outlet hose should go to the water pump - the upper one you have on there now, and the other inlet on the water pump plugged.
So, yes I'd say you need to hook them up differently!
On your heater switch, if you have the two position pull type, one of the terminals should have a "B" next to it. Power goes in there. The other two wires can go in either of the remaining terminals.
Fleet Owner
Joined: Jul 2004
Posts: 27,297
Likes: 1,059
From: NM
You know, I recall 289's being different; take a look at his setup. It doesn't have the usual annoying bypass line (90-deg elbow) between the intake and WP. I can't think what else the two lines on the WP would be for.
Cargo Master
Joined: Jun 2001
Posts: 2,571
Likes: 22
From: Oxford, Indiana
You've definitely got them hooked up wrong. The upper of the two barbs on the water pump is supposed to have a short 90 degree bypass hose going to a small barb on the thermostat housing. As you've got it, both heater hoses are seeing suction from the water pump and there is no flow through the core. You need to get a bypass hose on it and hook the other hose up to the intake manifold at the port right behind the thermostat housing.
Thread Starter
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Elder User
Joined: Oct 2004
Posts: 813
Likes: 1
From: Auburn, Il
You've definitely got them hooked up wrong. The upper of the two barbs on the water pump is supposed to have a short 90 degree bypass hose going to a small barb on the thermostat housing. As you've got it, both heater hoses are seeing suction from the water pump and there is no flow through the core. You need to get a bypass hose on it and hook the other hose up to the intake manifold at the port right behind the thermostat housing.
Post Fiend
Joined: May 2008
Posts: 7,641
Likes: 21
From: Poway, Ca.
I don't remember the by pass arrangement on my 289 - maybe someone could take a pic for you - there's none of it in the Manual. On the 390 it comes in straight off the manifold forward to the back of the water pump (which is connected only on the wings not the entire face)
On your set-up as it is, all you need to do is remove the top hose going into the water pump and connect it to the outlet on the intake manifold just behind the thermostat housing (make sure that hose is on the top one of the two heater tubes as it shows in the diagram I posted). Then your heater hook up is ok.
But as Joe mentioned, you need to plumb your bypass then!
On your set-up as it is, all you need to do is remove the top hose going into the water pump and connect it to the outlet on the intake manifold just behind the thermostat housing (make sure that hose is on the top one of the two heater tubes as it shows in the diagram I posted). Then your heater hook up is ok.
But as Joe mentioned, you need to plumb your bypass then!
Thread Starter
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Elder User
Joined: Oct 2004
Posts: 813
Likes: 1
From: Auburn, Il
Julie in your diagram on the thermostat housing I have a place to put a barb or hose hook up. Can I put it there, its not blocked by the thermostat or does it have to be on the intake?