I'm COLD. NEED HEAT. GOING MAD

[PGSigns]

If you had the core out and cleaned it did the water flow through it good? If it did the core is fine. If not core is plugged. That pipe setup for the 3/4" hose could be an issue if it is restricted. A good temperature gauge is almost a must. The one on the dash wont tell you if you are running 150 or a 190. Just that you are between the lines. In you last pick of the air cleaner there is a hole in the fire wall that used to have a plug in it about 1 1/2" around. I can tell you that it will push a lot of cold air in to the cab. Been there done that.
Jimmy

[SS317]

another thought, just a thought, make sure you have the correct heater core in there. I had a smaller one and the air would go around it. A small piece of foam will force the airflow through the core and not around it if that happens to be the case. Just a thought.

[KJSR]

Originally Posted by SS317

another thought, just a thought, make sure you have the correct heater core in there. I had a smaller one and the air would go around it. A small piece of foam will force the airflow through the core and not around it if that happens to be the case. Just a thought.

That's a great point. The smaller cores are MUCH smaller.

Maybe take the top cover off the heater box exposing the core and take a picture?? Pretty easy check.....

[Figuarus]

sorry guys, I've been out of town.

the core doesn't have a seal on it, but is correct for the size of the opening.

I will take a picture later this evening.

When I flushed it, the water going in, was flowing pretty well, and in both directions.

[jtrichard]

strange??????

[Figuarus]

Originally Posted by jtrichard

strange??????

Yeah, now you have an inkling of what i'm feeling...

[CRGRS 66]

worn waterpump, or blockage somewhere

[Bare64]

Take that valve out next to the water pump on the 3/4" hose, it could be clogged or broken, it looks like a galvanized 1/2" T one would by from Ace Hardware with something stuck in it. Hook hose back up to water pump, see what happens.

[jtrichard]

That is a temp sender what its doing there is anybody guess (maybe its there to tell you if the heater is over heating LOL ) .....the nipples on either end of that "T" could have rust build up i would pull the hose and at-least clean them out... also depends how long that sender is it may have the "T" plugged off

[Figuarus]

Ok, got some updates

I managed to get ahold of a laser thermometer.

These temps were all taken after having driven the truck for a while, and was left idling for about 5 minutes.

The block, intake and cylinder heads are hovering around 150.
The radiator upper, was about 125, the lower around 110

the 5/8 hose was around 110, the 3/4 was closer to 90 degrees

the air coming out of the vents was about 65-75 degrees

The outside ambient temp is hovering right about 34 degrees

Im thinking about taking the cover off the airbox, and seeing if bringing in air from underhood will help matters some.

[Figuarus]

that sending unit is for the gauge at the panel. it's not deep enough to cause any blockage. I have pulled the hose there, but there isn't much buildup.

I have yet to pull the fitting on the manifold, but from what I could see, there isn't much going on there either.

[chevy_mike]

If those numbers are correct, you are not going to get much heat if any into the cab. Upper radiator hose should be in the 180+ range. It sounds like the heater is working but the input water temp is too low (like when an engine is cold, you get no heat). In my wagon, if the water temp is below 140* range, the air out of the vents is lukewarm at best. Once over that temp, it starts to feel warm and at running temp (180*) it feels hot. The temp of the heater hose coming from the water pump should be higher (match what the lower radiator hose temp should be).

Since your outside temps are low, there is just not enough heat in the water to raise it higher. Basically your engine is running too cold.

[Figuarus]

So then what would be the best course of action? Are we talking about changing the thermostat again?

So if the case is that perhaps the 180 thermostat is too low, and the 195 thermostat I used to have in there is too high, what should i do? Block off the radiator?

I'm at a loss as to what to do from this point on.

[61K10]

I had a 69 chevy 3/4t with a 350. In the winter i put a piece of cardboard that covered half of the rad to get any heat out of the heater. just try it and see if it helps.

[PGSigns]

First thing I would do is put a good quality mechanical gauge in the truck so you know what the water temperature really is. Trouble with the way you are measuring it is the surface temperature of what you are measuring is all you are getting and that is being affected by the air off the fan and the outside air temperature. Once you know what the true water temp is it will be much easier to figure out what is going on. You need to get the reading from the intake if possible since it will be measuring what the thermostat is seeing or the factory spot in the cylinder head.
Jimmy

[awbrown]

At 90 on the heater core exit , you will never get heat out of that , like i said hot pipes near the heater core should be scorchin to the touch ,and that is both of them , i would use a 195 thermostat and like others have said , get a gauge and put it in the correct place by the thermostat...

[CRGRS 66]

I retract my water pump blockage suggestion, it does seem that your engine is running cool.

[KJSR]

Buy a GOOD quality thermostat (not mr gasket) like a stant or Napa gold. I run a 180 and the heater works just fine............in fact too good.

[jtrichard]

ONE thing you did wrong is testing temps after it had been idling for 5 min. drive it around and check as soon as you stop..... you are in UTAH in JANUARY NOT palm springs CA in JULY 5 min. loses a lot of heat at idle

[Figuarus]

So a quick update. I put some cardboard in front of the radiator and covered about 1/2 of the core. The other side has a trans cooler in front of the radiator.

I drove it on the freeway this morning, and i am still only getting about 55-60 degrees of air temp coming from the
vents in the dash. So, I'm gonna try a few things

I'm gonna get a 180 and 195 thermostat this afternoon. I'll start with the 195 degree, and hopefully that fixes this situation. Who knows? Maybe the last one I had was defective or something...

I'm gonna make a gasket for the airbox and re-seal it. hopefully that will also help some.

[donthekawguy]

The temp wont go down no matter what the temp is. When its full temp it is at full temp. The thermostat will keep it at whatever temp the thermostat is. If anything it will be warmer idling without cold air blowing through the radiator.

[scottofksu]

I've encountered an alarming number of defective "new" thermostats lately... As such, I now test all of them in a pan of water in the oven at a temp slightly above (10-15F) the advertised opening temp for the thermostat... Remember, you want to make sure it opens AND closes (once the water begins to cool on the counter).

[awbrown]

if you can confirm that the engine is running at 195 after changing the thermostat and you still have no heat , replace the heater core ....

[Figuarus]

don, I agree with you. I've wondered why there is such a huge variation in temp if the thermostat is designed to keep the engine at a certain temp.

I will have to try that oven trick.

if you can confirm that the engine is running at 195 after changing the thermostat and you still have no heat , replace the heater core ....

dammit. I was hoping to avoid doing that...

[awbrown]

at least they are easy to change (at least the deluxe heater ) I had mine all a part because it had the typical rats nest in it ,so I blasted it and painted it .... my core is the original one with the built in valve , but my valve has always been stuck open ...