Did a full coolant flush and now have no heat!

[Josh83]

I did the full coolant flush per the FAQ. Ran water until it came out clear, then ran it some more. Now the truck heats up(according to the gauge) but the heater blows COLD(front and back). I already checked the heater control valve and it is operating. What did I screw up?

 

[Romer]

Probably got some crap stuck in the thermostat. Get a new one and the gaskets, because when you take it apart to clean it out, you have done all the work to replace it.

 

[Josh83]

How could it be the thermostat if the truck heats up? It gets up mid way on the guage just like normal.

 

[CruisenSurfin]

You probably just have an air bubble in the system. Remove your radiator cap and let the truck run for a while. This usually gets the air our of the heater core. If not it will eventually work itself(bubble) out of the system.

Good Luck

Jesse

 

[Romer]

I am going by what you said, you did a flush and now it doesn't work. If it is stuck open, it will allow fluid to run through the radiator at start up keeping the coolant colder for the heat core. So the temp gauge goes to the same spot as before? I'll go check the FSM and see where the sensor is located and where the heat core taps off the fluid.

 

[Landpimp]

both heaters on full blast, cap off, front end of the Cruiser elevated a bit(like a hill) let it run.......

helps to rev it up now and then

 

[Romer]

That sounds a lot easier than a thermostat. Hopefully your out trying it now. Let us know.

Good luck

 

[Romer]

I did a google search and another potential cause is that the heater core plumbing could be restricted. That is similar to the bubble in the core theory above.

 

[Josh83]

Well, let it run for 30 minutes or so while I cleaned up the tools and stuff. Seems to have gotten MUCH better. Still not like it should be, but some driving should take care of the rest of it.

EDIT: Thanks guys...this place rocks.

 

[Romer]

Glad it is working better. Now you and I both learned something new. I hadn't heard of the air bubble before.

 

[e9999]

Glad it is working better. Now you and I both learned something new. I hadn't heard of the air bubble before.

there is lot of expertise about that here because a lot of the guys on this forum are expert at *hot air*...

not the ones who posted, of course...

E

 

[best4x4xfar]

Here is a very nice tool for cooling system flushes. One you have finished flushing the system, you attach this to the overflow tank, and attach a compressed air line. It creates a vacuum in the cooling system (Removing air), and draws coolant in from the bottom up until the entire system is full, and no more need to burp out air bubbles!! I don’t know what it costs, but I’ve seen it used, very cool! Check it out here:

http://www.mityvac.com/coolingsystem.html

 

[PHAEDRUS]

or you can do the easy mechanics way of burping hte system for air bubbles. start the engine, point the nose up hill and take off hte radiator cap. grab the upper rad hose and squeeze it a few times. this should solve it.
the other possibility is that there is some blockage at the heater bypass valve. My old 87 mini truck had this problem. I removed it form the system. cleaned it out and then it worked great.
Chances are there is some crud constricting the flow of collant inot the core though I would look there first.
Dave

 

[turbocruiser]

Okay, so here's a question...assuming that after the flush the heaters work fine ( no air bubble maybe? ) how long more or less will it take for the antifreeze/water mixture to completely mix? In other words after dumping a gallon of antifreeze in, followed by a gallon of water, etc, how long will it take for the mixture to be mixed? I'm asking in general, this isn't one of those "exactly how fast can I go with my lockers locked" questions! Just in general...ten minutes idling, twenty, ten miles driving, twenty, whatever in general seems safe. Thanks Dudes.

 

[Landpimp]

I have to think it mixes pretty fast(10 min?). I dump a full gallon of red and water in, then pre mix the next 2 gallons.

Okay, so here's a question...assuming that after the flush the heaters work fine ( no air bubble maybe? ) how long more or less will it take for the antifreeze/water mixture to completely mix? In other words after dumping a gallon of antifreeze in, followed by a gallon of water, etc, how long will it take for the mixture to be mixed? I'm asking in general, this isn't one of those "exactly how fast can I go with my lockers locked" questions! Just in general...ten minutes idling, twenty, ten miles driving, twenty, whatever in general seems safe. Thanks Dudes.