heater doesnt work

[Brunoboy]

Hey guys, I pulled my motor, put another in, now the heater doesnt wanna blow hot. The temp gauge reads normal. but If i shut the heater off, wait a few minutes turn it on, it blows HOT for 30 secs and then back to cold. can someone tell me what it is? Maybe something is clogged? The car sat for 4 months before i decided to put this motor in. Thanks
-Shane

 

[Barnes]

Most likely the core is clogged. You can try back flushing it. Sometimes it works. Take off the coolant hoses, then hook up a relatively low pressure source for water. Like a garden hose turned down a bit. Hook the flush line to the connection on the heater core that normally connects to the hose coming from the radiator pipe (not the line from the t-stat housing). You will probably see gunk coming out as you do this. Be careful not build up too much pressure. I don't think these things handle much heat.

If that doesn't work, new heater core time. /ubbthreads/images/graemlins/frown.gif

 

[fivestardsm]

Di you happen to change the thermostat? I had something similar happen to me, and there actually wasnt even a thermostat in the housing. The engine was previously used in a corn field figure-8 car.

 

[gvr4ever]

If you're just going by the gauge, it's horribly wrong. My t-stat went bad last winter and I didn't know it till I took a trip out of town. It was a long cold drive back.

Anyway, the gauge looked a little cool, but not cold. It wasn't till I plugged the logger in that I could really tell what the problem was.

 

[Brunoboy]

Thanks guys, thermostat was replaced in April, but the car sat after July til now because of the motor, now I'm driving it and it reads normal temp but no heat, well heat if I first turn it on then cold and right now my coolant hoses are kind of dirty =\ maybe rust in the pipes?
-Shane

 

[Romanova]

Mine never really worked worth a sh*t. I flushed the heater core using water and vinegar... still didn't really work worth a sh*t.