Hey - I have a B2600 with carb (did they come EFI?)

I didn't pay a lot for the truck, so I didn't pay a lot of attention to what worked and what didn't work either.

Anway...

The engine is not getting warmed up, and therefore I am not getting any heat in the cab. I already replaced the thermostat, and that didn't help. The heater blower works, but only tepid air comes out. The temp gauge on the dash moves only slightly from a cold start to operating temp.

Any help on what might be the problem would be greatly appreciated. I really don't want to spend a lot on this truck, so I am hoping it is something simple.

Thanks

 

After the engine warms up, does the upper radiator hose get hot? Generally, if you can only hold the hose for about 2-3 seconds, its about 180 degrees. If you can grab it and hold on for a long period of time, it is about 120-130 degees. If it is hot, are your heater hoses getting hot on both sides? What degree thermostat did you go with, and what brand? Just asking because i put an Autozone thermostat in my 323 and it opened way to early and same problem no heat. So I went to put in a Stant brand, and I had heat.

 

I will have to check the brand. I bought it at NAPA.

The top hose gets hot. I can only touch it for about a second. I will check the heater hoses. I guess I better get a Chiltons because I don't know where they are or what they look like.

thanks so far.

 

Sounds like the engine is at normal operating temp. It could possibly be a bad heater control valve or a plugged heater core itself. I have also seen people bypass the heater core if it leaks also. Never know what you will find with a used car!

 

is it true that the heater core is buried under the dash? Thats going to suck if it is true.... I don't know if I have the time or hutspa to deal with that.

Do you know where the gauge sensor unit is in relation to the heater core? I guess what is puzzling me is that the engine does seem to get hot, but the gauge only moves slightly. I am wondering if the sensor is somewhere closer to the heater core where it might be behind the blockage????

 

The heater core is located in the air handler box behind the dash. IF the heater core is blocked, what I have done is to remove the heater hoses and connect a garden hose to clear it out.

Do you mean the sensor for the temp gauge? I just didn't quite undertand most of the last paragraph, and what you were trying to ask. The temp sensor is on the cylinder head near the thermostat housing. Should have a one wire connector and be about a 14mm wrench size. As far as a possible blockage, I speak of inside the heater core itself. If you have never seen a heater core, it looks like a miniature radiator. can become plugged internally. I would be sure to check the heater control valve which is inline of the heater hoses.

 

Hey bkey71 - I appreciate your trying to help out. I am giving up and will be taking it to a shop... I don't have the time or knowledge to deal with this one.

I will post afterwards and let you know what all it ended up being.

 

I guess being in the great northwest you want to get it fixed soon! Winter is just around the corner.

 

the easiet way is to take it to a gararge to get it fixed, you don't want to mess up the truck worse then it is

 

Factory manual does no list any such heater control valve and I have never heard of any vehicle older than perhaps about a 98 having such a devise. Most cars coolant constantly flows through the heater core and hot or cold air is directed using a series of flaps. These flaps are prone to fail in Mazda trucks, my dad and I have owned 3 so far that has had this problem, heater core was fine but when you put in into heat the flaps where stuck in the vent position.

Either way though its probably best for an inexperienced person to just take it to a shop.