93 Full-size Blazer - gurgling noise in dash

I have a FUll-size 93 Blazer. Lately it has been making some gurgling noises that seem to come from behind the dash on the passenger side. I presumed this had something to do with coolant and began checking the system. I found the radiator cap needed to be replaced (the gasket was bad) and the line to the overflow reservoir was clogged. I replaced the cap and cleaned out the reservoir and the line to it. None of this has stopped the noise. It is some sort of gurgling/slurping/bubbling noise that sort of sounds like someone squirting water inside the dash. Any thoughts on the cause(s) and how to fix it would be greatly appreciated.

Sounds like maybe a heater core going bad.. Do you smell coolent in the cab at all?

I have the same problem on my 94 p/u and I read in a post in this forum (don't remember which one) the fix. It was something like a rubber washer in the heater core were the hoses connect. It said to remove the washer and just leave it out. I have not had time to try but that's suppose to be the fix. The washer is only in one of the connections, I don't remember which one. You might want to do a search on the forum-it's hear somewhere.

Haven't smelled any coolant to date.
Sounds like maybe a heater core going bad.. Do you smell coolent in the cab at all?

I forgot to mention, that the noise tends to be during acceleration.

You do not neccesarly smell the coolant until the outer shell begins to leak. The noise is usually airbubbles passing through the system. If the noise is coming from under the dash that would indicate that is where the preasure is being released. i.e. sucking air. It could also be that the cooling system is getting hot enought to boil. Is the noise apparent when the engine is cold or both when cold and hot? It could be something as simple as the radiator cap as well.

On my 96 s10 i have the same problem, It is the heater core, though mine is probably caused by the former owner mixing the green and orange coolent which caused rust in the cooling system. We have been flushed it 4 times, and flushed just the heater core all to no avail.


You do not neccesarly smell the coolant until the outer shell begins to leak. The noise is usually airbubbles passing through the system. If the noise is coming from under the dash that would indicate that is where the preasure is being released. i.e. sucking air. It could also be that the cooling system is getting hot enought to boil. Is the noise apparent when the engine is cold or both when cold and hot? It could be something as simple as the radiator cap as well.