Ok I finally broke down and took my 98 to the shop and had the intake gaskets replaced and thermostat, drove home and now I have no heat blowing out of the heater , worked fine before fix. Hose going into firewall gets hot the return not to hot, air stays cold , vaccum line ok. Can it get air locked ?? or ?????

 

It is possible that they did not get all of the air out of the system and the core is air locked. You could try running the truck with the cap off and the front end elevated as high as you possibly can get it with the passenger side just slightly higher than the driver.

 

I've also been having intermittent heat problems in my '99, and I notice on acceleration there's a gurgling noise coming from the dashboard, like someone blowing bubbles in a glass of soda. I can't imagine anything else back there besides the heater core that could produce such a noise. Would this be the same problem?

 

Sort of, but not quite. This is typically due to a restriction on the core along with an air entrapment issue. You should flush the core and then bleed the system as noted. If you continue to have the noise and intermittent heat output, let us know.

 

I just did the intake gasket too, I had to burp my system like 3 times to get it working right. Could be sludge in the core too if they did not clean up after themselves. $5.00 flush kit and a garden hose should take care of that.

Swartlkk has the perfect method. Try that and maybe a few burps, (letting the cap off the radiator) and that should do it. Also check your fluid levels, make sure the radiator is full when the car is off and cooled.

 

After having intake gaskets replaced, I had to disconnect return heater hose, run the engine till I got a flow then shove it back on the fitting while engine still running, now I finally got heat , ( I flushed it out before and it would'nt heat up )

 

I had to back flush my core after doing the intake gasket 3&1/2 years ago.
Flushed it into a container and found mostly pieces if rust I had dislodged.

Had to do it again the next fall. Been good ever since. I hope it says that way as I do not what to pull the dash to change it.

Blazeme

 

Right then, I'll give that a try. Thanks for the response.

(It's going to need an intake manifold gasket in the not too distant future, so I'll probably have to do it again then, judging by the others in this thread...)

 

heater worked great for a day , then went cool had to back flush again to get air out , working hot now , how long ???

 

drove for about 15 miles and the heater air locked again, what's the deal ????