ok, I just spent the past 4 hours doing the following:

1. drained radiator
2. put in napa rad flush mac something recommended above
3. ran it for 30 mins with water in it and the flush
4. let cool
5. drained and disconnected ALL hoses
6. remove t-stat
7. directly flushed and back flushed each section with garden hose pressure
8. put everything back together
9. elevated front of vehicle
10. opened bleed bolt
11. filled slowly with coolant distilled water and napa anti rust and water pump lube
12. closed bleed bolt
13. started and let idle hot for 30 minutes to work the air out with no rad cap on it
14. topped off and put rad cap on
15. filled clean overflow tank
16. test drove


there is still just a slight noise; I am confident that I did all I could

any further recommendations?

I will see how it sounds over the next few days of driving it.

I did notice that one of the heater hose clamps on the engine side was slightly loose, not sure of that could have been letting air in????

other than that, I am tired and wife is mad at me for not spending time with her.

The destructions for the cleaner say to run the for only 30 mins? The cleaner I used said 6 hours. It does sound like it has improved. The loose clamp may allow air in during cooling, but I would also think it would allow coolant out when hot since the system is under pressure.

Ha, mad wife hey?! <img src="/forums/images/graemlins/shiner.gif" alt="" /> I bet she'd be madder if she got stuck on the side of the road because you didn't bother to fix the truck <img src="/forums/images/graemlins/lol.gif" alt="" /> Ah, such is married life <img src="/forums/images/graemlins/kewl.gif" alt="" />

Although I work on a different line of trucks, we get a stubborn amount of air trapped in a heater core from time to time on several models with the Nippondenso heater system. We use this trick to help speed up the process. Elevate the front of the truck quite a bit by putting it on jack stands. This way, your expansion tank/overflow bottle is much higher than the heater core, and greatly increases the chances of the air being moved out of the core and up towards the overflow bottle. Run the engine at 1500 RPMs, then idle it for a minute, then rev it up again. Usually only takes one or two times of doing this for a 5 or 10 minute period to work the air out. Japanese heater core systems do seem to get the air trapped in them easier than you'd expect.
We use our drive-on service lifts at work to accomplish the same thing as the jack stands, but you get the idea.

Depending on the amount of crap you got out, I'd do that flush again. Then call it done.



As far as that goes, why is your wife not out there helping? That's her fault IMHO. My wife looks forward to shop time because I can't escape her if I want to get stuff done on my truck. Plus she makes food for all the guys at the shop as well as clean the shop owners house.

got it on the front being elevated, I will see how it sounds over today and tomorrow, if needed, I will 'get her high' over the weekend and do it again.

at some point, if this never does get resolved, I may take on the huge task of replacing heater core myself.........I wish someone knew out there if the gen II and gen II.5 systems were continuous flow or had a valve inline with the heater hoses operated by the temp control knob. like I said, the sound doesn't go away when it is on cold which leads me to believe:

1. the valve is damaged or broken and that is where the noise is coming from
2. it is a continuous flow system that always allows coolant to flow through core; heat is controled by re-directing the air flow, not the coolant.


input?

They are newly married. Give it 10 years and she will say "go do something out in the garage" <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/patriot.gif" alt="" />

oh and btw, when the dealer had it and did some work on it, I think they lost the little rubber seal out of the temp sensor electrical connector on the front of the coolant outlet fitting. it is a two pin plug and I am pretty sure it is supposed to have a rubber seal inside the plug that makes it water tight to keep the terminals dry if the engine got wet. not a huge deal, but I am a perfectionist and want that seal; dealers can't order that part by itself, so if anyone is going to a part yard and sees a gen II or gen II.5 montero and the engine still has that wiring harness on it, see what it will cost to cut off that connector or just carefully pull the seal out of the connector. I will pay whatever the yard charges plus your time and effort. I can take a pic if required, but it is the coolant temp sensor (two pin) right at the front top of the engine mounted on the coolant outlet fitting (right next to engine oil fill cap).

TIA for anyone who can swipe this little bugger.

Been married 13 years. But yes, we're still newlyweds <img src="/forums/images/graemlins/kewl.gif" alt="" />

I don't have my Montero service books in front of me, but from your complaint of air/gurgling from the heater core at all times, it does sound like a continous flow system with air being blended or shut off for temp. control.
I've never had to study that portion of my Monty, cause it always just works. <img src="/forums/images/graemlins/notooth.gif" alt="" /> I've changed the evaporator for the usual A/C leakage, but that's as far as I've had to venture into the dash other than the yearly removal of the blower motor to pull small leaves out of the blower cage after Fall has passed and we're into Winter.
While I HAVE changed a heater core assembly on a Land Rover/Disco 2 for air/waterfall sound that no one could get rid of, I doubt you'll have to go to that extreme of a measure.
Remember, we have it easy compared to a front radiator/rear engine set-up vehicle like an old MR2 or Vanagon. I've seen the bleeding procedures for them, it's REAL complicated, with moving of one end of the vehicle up high, then the other end to help with air bleeding.

well, to be honest, if this noise doesn't go away, the heat works great and I will just turn the radio up higher LOL, it just isn't worth it in time to me to take that dash apart b/c of an occasional squirting noise.

but all that aside, I will over the next few days elevate the front end, take off rad cap, let it get hot and idle to try and work the air out.

if this is a continuous flow system, my setup for heat exchanger will have to change, but before I venture into that project, if anyone can verify that would be great.

the reason I am not so sure either way is b/c in the FSM, it tells you to turn heater on full before draining coolant, which leads me to believe that it has some effect on coolant flow through the hoses.............can anyone explain?