Sounds like it's not a constant flow heater core if that's the proceedure. At this point I'd personally be pretty tired of doing flushes.

If you're sure you're not loosing coolant, go ahead and just monitor the fluid levels religiously over the next month or so.

It's so the coolant in the heater core will drain and not leave old coolant to contaminate the fresh coolant as soon as you open the heater valve.

Frank

roger, but some vehicles have a continous flow system and since I was hearing noise with it on both cold and hot settings I was hypothesizing that it might be a continous flow system, but then when reading the FSM, when it says to turn to hot setting before draining, that leads me to think that it isn't a continous flow system, or maybe it is a hybrid of some sort where it has a restriction valve, but it doesn't completely stop the flow so as to keep core hot in case you want heat quickly when you turn the knob, I don't know for sure yet.

in any case, yes, I am very tired of doing flushes, I have done 4 of them myself, had the dealer do two to a machine, etc.

I think the 4 hours I spent last night were well worth it, tearing it down part by part and applying garden hose pressure directly to block without t-stat in the housing (i made sure engine was not hot so as to avoiding cracking block) I also put direct pressure 3 times both ways on the heater core by itself, it would take about 10 seconds each time for the output of water to be free of air bubbles, so it seems that the core does have a lot of places to trap air.

I don't think that the water pump pushes water through the core as vigourously as my garden hose did, so I would imagine, it needs all of gravity's help along with a few times to get all or most the air out.

on a good note, just in my one trip to and from work already it sucked down a substantial amount of coolant from the overflow bottle.

I had it completely full and it sucked down about half of it. no it didn't come out the overflow, b/c it was full when it was hot and I checked again when it was hot.

I have been purposely driving it in a manner that causings engine rpms to rev a lot, I am having a very difficult time hearing the noise anymore.

sometimes I think I hear it, but after months of listening for it, maybe my mind is already starting to play tricks on me.

I think it is looking up and this is another montero cooling system saved from complete and total destruction of prevous owners just being plain dumb.

oh and lastly, don't mix orange and green coolant, unless you want to get really good and doing flushes and tearing down your cooling system for about 3-4 months.

Hi Scottie,
What presure pound age is on the Rad cap ? and change both the top and bottom hoses, that way, you know that both are new and when you refill your cooling system we over here in the UK use a 50 50 mixture of a good anti freeze and deionised water, that way, we know we wont be having any gunk in our cooling system, later on, plus the fact, the deionised water helps to let the truck run a mite cooler too
you take care and the very best of luck scottie. regards Jack.

You might be through this already but a couple of note,
The heater core in these is full flow, there is no water valve. The hose fittings are on the top tank and the core is a double pass.
This means the air will get out easily but the lower tank of the heater core is hard to flush crap out of.

I get the impression this truck ran with straight water in the cooling system at some point in its life. Makes a mess in there. I have no clue why vehicles down South get run without coolant or at least a rust inhibitor added to the system. Monteros will get rust through the water pipe under the intake pretty quick.
If all the sludge was from mixing coolant, I guess that happens at times. PITA.
When I lived in FLA we used distilled water in the systems since the city and well water is harsh on cooling systems.

I read that you filled the system with the bleeder open, closed the bleeder before placing the radiator cap on. This defeats the purpose of the bleeder. You want to close the radiator cap, start the engine and crack the bleeder open a bit to vent the high spot. If you open the bleed on a hot engine it will blow off the pressure, might get you when doing so. But during cool down the system will refill and will pressurize the next run session.
One should not open the radiator cap to take a look inside. This can at times let a gulp of air in that needs to be bled out again.
As long as the coolant bottle has fluid in it and the system is not leaking the system will be full. Even most systems with small leaks will draw from the bottle rather than drawing air back in the leak.
Yes, there are exceptions to all this.

I am not sure about pressure pound age, but I do know that the radiator cap is only a month old, I bought a brand new one direct from Mitsubishi; ordered it according to VIN to ensure it was correct.

Yes, I did use distilled water when I filled it up after I flushed it; thank you for the tip.

I have to say, the Napa anti rust and water pump lube is excellent stuff, make the coolant very 'lubricated'

it almost feels 'soapy' it is so slippery.

after driving it the past two days, it seems pressure has improved (starting to buldge out those 10 year old hoses and they are under pressure when hot you can feel it) additionally, the radiator gets much hotter; which I would assume means the heat is circulating much better now?

in any case, no more noise under the dash, lets hope it stays that way.

old colt,

thanks for all the good info,

so the bleeder bolt is supposed to worked like this:
open bleed bolt
fill up system,
put on rad cap
start engine and let it bleed out of bolt
close bleeder bolt?

I just want to ensure I under the procedure correctly.

I thought that these systems were continuous flow, b/c even the cable linkage looked like it went to an air duct not a water line.

now I will need to change my design for my heat exchanger in my SR; good to find out now rather than later.

thanks to everyone who helped on this forum not only with this issue on giving advice, but all the support from the many times before.

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Yes, that is correct, The bleeder allows getting the most air out as possible.

These heaters are hot all summer, they use a blend valve that diverts the airflow either through or around the heater core.
All of the air passes through the AC core all the time.

For a heat exchanger you want to pass though the HE first then the heater core. The other option is a parallel system which if I am correct how the rear heater is plumbed.

Good to see you have the system cleaned up an functioning before it gave you big issues this summer.

thank you for the info. based on your knowledge of how the heater core is plumbed and operates, what do you think of this setup up below:

put heat exchanger in parallel with heater core
put an inline adjusting valve between the T connector and the HE to control how hot the freshwater gets

should the inline valve be on the input of coolant to the HE or the output of coolant back to the system?

How much volume of hot water are you going to store, Is this 2 gallons or 15?