Diagnosing heater problems

[fj40openair]

Hi All,
I did a bit of searching but couldn’t find info on diagnosing my heater problem, or potential fixes without replacement. I have a ‘78 FJ40.

I don’t want to buy a new one ideally.

No heat, but fan works fine. Rear heater works great.

Is there a way to rehab or fix a heating element? I assume that is what would be creating the heat but I am new to all this.

Thanks!

 

[3_puppies]

either the outside of the heater core is plugged up or the inside of the heater core is plugged up
need a bit more info
is this a new rig to you?
is this a new issue?
do the pipes/hoses going into and out of the front heater core get hot?
if the front heater is on vent, do you get good air flow out the top louvers?
remove the duct between the fan and heater box and look inside, is it full of gunk?

 

[Living in the Past]

The air is coming out the bottom of the heater not the top? You know about the three position damper arm on the driver's side? Joining just a few days ago might might be new to your cruiser and not familiar how it works. Does the heater just below the plastic top fill warm when engine running and the back is working?

 

[Mike Shull]

The heat only comes out the bottom floor vent and through the defrost vents, which is what @Living in the Past is mentioning. The top vent on the heater is ambient air.

If you don’t have heat coming out of your floor vent then I would remove your hoses and flush the heater core with water. Also check your hoses for proper flow to the heater. Any radiator shop should be able to do a deeper flush and repair if necessary.

 

[pb4ugo]

either the outside of the heater core is plugged up or the inside of the heater core is plugged up
need a bit more info
is this a new rig to you?
is this a new issue?
do the pipes/hoses going into and out of the front heater core get hot?
if the front heater is on vent, do you get good air flow out the top louvers?
remove the duct between the fan and heater box and look inside, is it full of gunk?

^^^^^^^this^^^^^^^

Remove the plastic heater duct. There's only 2 screws and look in side the heater box. I found the foam had disintegrated from the flap and was laying on top of the heater core, blocking air flow. You can vacuum it out, or rebuild the unit. I pulled the unit and hosed it out. I'll eventually rebuild it. You can use the search function, using a something like "heater restoration ". I also found this thread .

FJ40 Heater box and blower replacement gasket review

not affiliated in any means but figured I'd put it up for anyone looking in the future. I purchased this set off eBay (PartsPuzzle) from the Netherlands. I'll go through the set as I applied them. Here is the blower gasket along the firewall. first compared to the original and then on the unit...

forum.ih8mud.com

 

[B y r o n]

Here is a thread on how to rebuild your heater. There are minor variations based on year but for the most part the internals are nearly the same.

 

[Living in the Past]

^^^^^^^this^^^^^^^

Remove the plastic heater duct. There's only 2 screws and look in side the heater box. I found the foam had disintegrated from the flap and was laying on top of the heater core, blocking air flow. You can vacuum it out, or rebuild the unit. I pulled the unit and hosed it out. I'll eventually rebuild it. You can use the search function, using a something like "heater restoration ". I also found this thread .

FJ40 Heater box and blower replacement gasket review

not affiliated in any means but figured I'd put it up for anyone looking in the future. I purchased this set off eBay (PartsPuzzle) from the Netherlands. I'll go through the set as I applied them. Here is the blower gasket along the firewall. first compared to the original and then on the unit...

forum.ih8mud.com

This why I asked where the air was coming out of the heater. Mentioned have good air flow. If the damper is set to come out the bottom doubt the fins are plugs. Low air flow would move less air but air would actually be hotter having more time for heat transfer. If there is good air flow out the bottom but it not warm then they is most likely a plug in the coolant line after Tee on the flow in and before the Tee in the return line.

 

[charliemeyer007]

My guess is a "stop leak" plugged up core from PO actions. Might be a good time to check your entire cooling system.

Air bubble in the heater core or hose. Drive up on a steep incline. Park. Open radiator. Make sure its full. Let engine run until you see the coolant surging several times, indicating the thermostat is cycling. Your heat control valve on the engine/fire wall should be fully open. Take a big pair of hemostats and clamp off the feed line to rear heater - all fluid flow will be forced threw the front heater - give it a few minutes. Move clamp the front heater feed hose. Give it a few minutes for a few thermostat cycles. Put the cap on and go for a drive.

 

[pb4ugo]

This why I asked where the air was coming out of the heater. Mentioned have good air flow. If the damper is set to come out the bottom doubt the fins are plugs. Low air flow would move less air but air would actually be hotter having more time for heat transfer. If there is good air flow out the bottom but it not warm then they is most likely a plug in the coolant line after Tee on the flow in and before the Tee in the return line.

My guess is a "stop leak" plugged up core from PO actions. Might be a good time to check your entire cooling system.

Air bubble in the heater core or hose. Drive up on a steep incline. Park. Open radiator. Make sure its full. Let engine run until you see the coolant surging several times, indicating the thermostat is cycling. Your heat control valve on the engine/fire wall should be fully open. Take a big pair of hemostats and clamp off the feed line to rear heater - all fluid flow will be forced threw the front heater - give it a few minutes. Move clamp the front heater feed hose. Give it a few minutes for a few thermostat cycles. Put the cap on and go for a drive.

The OP says his rear heater "works great".

 

[charliemeyer007]

Stop leak can go anywhere or not. Restrictions for whatever reason are easier to plug. My 72 didn't get a rear heater until like 84. The front heater core and radiator are original.

 

[3_puppies]

to throw another WAG out there
new rig and the PO installed a 55 series blower motor and squirrel cage, bolts right in but the squirrel cage is opposite direction for what a 40 needs and doesn't move any air. the fan will sound good but not move much air.

answers to some questions above will help alot

 

[TemboTusk]

Before going crazy ... check that the heater hose valve at the engine is open. In older 40s there is a valve to isolate coolant from entering the heater core and it is located on the carburetor side of the engine. Location of valve may vary. Good luck!

 

[3_puppies]

Before going crazy ... check that the heater hose valve at the engine is open. In older 40s there is a valve to isolate coolant from entering the heater core and it is located on the carburetor side of the engine. Location of valve may vary. Good luck!

he stated the rear is working and IIRC the front and rear are tied together, 1978 should have 1 valve on the firewall controlled by a pull cable