I would think putting it on cold would stop the flow, but it makes the noise no matter what position, hot or cold.

The prestone stuff is ok for routine maintenance, not serious cleaning. Try MAC's #1400. It's available from NAPA. It comes in a small blue bottle and it's like a dehydrated acid. Serious pro stuff. I've had excellent results with it.

is it safe for montero's cooling system? I don't want to do any further damage either.

see, the thing I don't get is:

I had my 97 SR serviced at this dealership, they did t-belt and the like; well they also did a cooling system flush and changed t-stat and all hoses..............no problems with air in system or noise

now this 99 montero comes along and is a pita.........same dealer can't get that noise to go away, that is why I think it might be something other than just air........why would a 97 be so easy with no prob and now the 99 is being impossible? as far as I know, they are the same systems in 99 and 97 monteros right?

Some of the things I've dealt with on the the wife's 98 are clearly indicative to me of PPPO- piss poor prior owner. (You know the PMs we've traded.) I am convinced hers now has bad kharma that it is inflicting on us undeservedly. Sounds like you might be in the same boat... <img src="/forums/images/graemlins/cheers.gif" alt="" />

I've followed this post, and after reading about how gunked up the inside of the block might be, you may have severe blockage in one of the water passages, that's preventing all of the air, and corrosion, to escape.
The gurgleing sound should be gone, after all the flushes, and your previous posts about the heater core itself.
If you've only removed one of the block drains, and not the other, you'll have a difficult time getting all of the corrosion out.
You need to start again, and focus on the drains being cleared.

Oh, also, I have a slow coolant leak in the 95. Ever since it started, I have been getting the gurgling as well. I know some systems have an air purging process. Haven't dug into ours yet as I need to deal with the source of the leak first. I thought though that our t-stats with the hole-flapper-thingy was supposed to vent the air back to the rad to circulate it out...?

Yes, it's safe. So long as you follow the destructions.

<img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> I say that <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" />

Scottie, from what you say about getting sound with or without the heat on and therefore with or without coolant flow through the heater core is weird. May be there's a pin hole in the core and it's sucking air in. Check under your carpets for signs of a small leak. I agree that the block drain plugs need to come out (if you can). With the block drain plugs out flush the whole system with the garden hose for a while (thermostat out too). May be the heavy duty cleaner that Hazy suggested will break it all up.

Oh and you can get the system pressure tested, if you're worried about head gaskets, at a good rad shop.

You could also install the 29 cent heater core bypass gadget.
But then you would not have heat.