Won't warm up!!

[mhicks]

I have installed 2 new thermostats in my '73 350 and it will not warm up. The temp stays at the first mark on my temp gauge and the heater blows cold air or just a little warm. Any clues?

[Captkaos]

Well, this is just guessing since I know know the history, but it is possible that the sending unit to the guage isn't working and the Heater core is stopped up at the same time? If you still have the t-stat you can check it by putting it in water brought up to the specified temp.

[Russell]

My guess would be that your thermostat is stuck open. That happens to me all the time, at least twice a year, but thats due to the fact that I always buy the cheap Napa ones, lol

[mhicks]

Well, I have had them stick open before too and that is why I gave 10.99 for mine. I used to buy the cheaper ones and they stick open too so I started buying the more expensive ones. Maybe I need to take this one back and get the mid priced one because there is nothing else it could be. Right?

[86 GMG]

what type motor is is b/c if the heater hose is located at the water pump instead of the radiator or visa versa (sp?) sbc is what im talking about one of the hoses goes to the intake the other can go to the pump or rad. you might swop this hose around and see if that helps just a thought. and will someone else chime in on this topic that knows more than me on a logicall explaination on the diffrences on why it make it work diffrence on some motors

[TrainD5115]

I just had this problem yesterday after installing a new t-stat. On my end it appears that I had alot of water in my system which translated into ice blocking the lines and heater core. After a lengthy warm up and a complete flush and refill with quality anti-freeze, I have good heat again.

[Captkaos]

You can check the t-stat like I listed above before returning it and see if it is sticking.

[MylilBowTie]

Carboard in front of the radiator? Might help if everything else is okay and working.

[bodydropped]

my 78 only goes to the first mark to but it blows really really hot air i sometimes have to turn the vent on

[marvxyz1]

Check to see if you've got thermostat in backwards. The spring goes toward the motor.

[marvxyz1]

Check to see if you might have the thermostat in backwards.. The spring goes toward the motor.

[SSC's76]

What temp t-stat did you get? Like mentioned a plugged heater core or improper mix of antifreeze will contribute to heat loss. I use to have a real good heater until I needed a new heater core. Some of these aftermarket junk HC's dont work quite as well as OEM.

[mhicks]

I have the spring down, towards the motor. Still has the original heater core. I put a new crate motor in back in the summer and haven't used the heater much until now. I have noticed that the temp control for heater will not slide all of the way to heat. I'm thinking that the gauge is supposed to stay at the first mark when engine is warmed up but I was thining it should be half-way. I think I will dig in to the dash and find out why the temp control doesn't slide all the way to heat. Maybe it has something to do with that. It likes about 3/4 of an inch to going all the way to the right.
Thanks Guys,
Mike

[Bishops Trucks]

Sounds like the cable is binding on something. The temp guage in my truck goes up about a 1/4 of the way and stays there. I have great heat. I'm not asking this to make you sound bad but do you have the heater hoses on right. If thats not the problem then it sounds like the heater core is stopped up.

[79BIG10]

Also how do you have your heater lines ran? When you installed the motor you have have swapped some lines to or from the heater.

[mhicks]

No, I think I have them right. The big hose comes off of the waterpump and goes to the top input at the firewall and the small hose comes off of the intake and goes to the bottom input on the firewall. I am beginning to think the heater door isn't closing all the way because of a problem with the cable. Will probably check that tonight.

[79BIG10]

I think you have the problem there. Mine come off the intake to the heater core and the other from the heater core goes to the radiator on the passenger side by the cap.

[Bishops Trucks]

Mine is 3/4 hose on the bottom going to the intake and the 5/8 hose on the top going to the waterpump. It gets hot in my truck to where I have to open the back window. What year truck are we talking about anyway?

[79BIG10]

Originally Posted by Bishops Trucks

Mine is 3/4 hose on the bottom going to the intake and the 5/8 hose on the top going to the waterpump. It gets hot in my truck to where I have to open the back window. What year truck are we talking about anyway?

It's a 73. The one thing that's different on BB and SB is the port on the water pump. SB have it plugged off and BB have the port open to the intake right above it.

[C&C Chevy]

hicks, did you ever find out what happened? Mine is doing the same thing. Just wonderin'.

[mhicks]

No, I haven't had a chance to check it out anymore. It does seem to be blowing a little air out the defrost while in the heater position. I think I'm going to have to tear into the dash again.

[86 GMG]

m hicks before you start changing stuff swap your hose from your waterpump to the port on the radiator i almost garantee its the problem if you will look at my first post i mentioned this.

[mhicks]

If I do that then I would have to change the size of nipples coming out of my intake and waterpump. I know when I swap the motor that I put the correct nipples in the correct spots. I got it from my dad a couple of years ago and he bought it new and I don't think that would have been messed with.

[86 GMG]

i,m not saying anything about you not have it done right just the fact that i have been in your shoes and this was my problem. as far as the items being in the right place either set-up is "correct" except the fact that some motors ? require one way and others the other way ?????? can't explain it but would hate to see you drive a cold trip where ever you go just because a couple hoses needed to be moved along with the nipples best luck keep us updated and tellus what was wrong when you get it fixed.