i think i would take it in and have the cooling system, checked out by a pro.

I can't afford to, but I may not have any other options.
I did get some free info from a pro and did some checking.
From a cold start I let it sit and come up to normal temp.
And it just sat there idling and stayed at normal temp.
I backed out of the driveway and took off up the road.
The temp guage started climbing. I turned around and came back.
By the time I pulled into the drive way the guage was at max.
And the check guage light came on. I let it sit in the
driveway and idle and the guage came down a bit. And then
the check guage light went out. But it was still higher than
normal operating temperature. I turned on the heater.
Heat came out the vents and the guage dropped almost to normal.
And that is where it stayed until I shut off the engine.

So apparently the water pump and thermostat are working.
The professional I talked to said sometimes a multicore
radiator gets one of the core sections stopped up and
since coolant isn't flowing thru the whole radiator it will
sit and idle with no problem but while driving it not enough
coolant can flow thru the radiator to be cooled.

Normally with that diagnoses I would say a good flush and
refill would fix it. But how can I flush the whole radiator.
If I just push water thru it won't it just go around the
obstruction. So how can I flush it ALL out.

And it still would be a good idea to change the thermostat.
It's been in there for 9 years so it is way overdue.

So my question now is how do I flush a multicore radiator.

Thanks.

Pooh Bear

Just imagine a career where dealing with a problem like this is common. That's what you are actually paying for when you take your car to a pro to have it repaired. Your NOT just paying for a thermostat (Which while the most common part guessed is not likely to actually be the problem). Your not paying for a radiator, (Remotely possible, but unless the cooling system has been grossly neglected, not likely either). Your not just paying for a water pump and coolant. (There are reasons that this could be the right direction, but undiagnosed accurately should not have parts just thrown at it).

My routine for similar reports of trouble is to first ensure that the coolant is full. That may mean removing a heater hose or some other component high on the engine to allow any air collected to get out, or maybe even be forced out with my pressure tester. Then I road test the vehicle with a scan tool connected. That way I can monitor the engine temperature with not only the gage, but with the sending unit that the PCM uses to control the fuel injection. If they both agree and the engine is running hot, then that directs my next step. If there is a discrepancy between the two temperature readings I need to find out why.

If both sensors are reporting higher than normal temperatures, I watch to see how much engine load plays a role in both the creation of engine heat, as well as dissipation of the heat once created. I will often stop alongside the road and use my infrared thermometer to measure radiator surface temperatures. This shows me if the coolant in the radiator is flowing smoothly, or if there are restrictions. The temperature of the air going through the radiator also shows me if I might be dealing with restricted airflow. Engine surface temperatures, are also checked to see if the entire engine is evenly heated. Internal restrictions to coolant flow inside an engine can occur. Did you know that leaving a thermostat out completely can in fact leave the temperature gage low, while a portion of an engine badly overheats? I can't tell you how many times I have had to throw away a piece of cardboard that someone stuck between the radiator and the condensor so that they got heat in the winter, and then they forgot to remove it themselves come summer. Of course the reason they do that is the normal failure often associated with a bad thermostat, stuck open, FWIW, they can stick closed, or partially open but it's rare, like one out of fifty. People in a town like Erie Pa. that have a lot of cottonwood poplar trees have to watch for that cotton building up in the condensor cores, which results in limited airflow, and a similar report of overheating. Camaro's, and Firebirds of the 80's and 90's often had plastic ductwork come loose behind the bumper that was supposed to direct air through the radiator. At highway speeds, this would allow the ductwork to deform, and actually block airflow instead of forcing it through the radiator. Even the air dam below the radiator support is an important and often overlooked as a cause of engine overheating on the highway.

The most likely cause of your vehicles problem right now is a coolant leak, and you probably have air stuck behind the thermostat. Replacing the stat, people opften then fill the system correctly, and the falsely think they fixed the car, only to have it act up in a week or two (or less).

If you really think you cannot afford a pro to fix this, just wait till you blow a head gasket from actually overheating this a few times. If this is the Single Overhead Cam V-6 with two timing chains like mine, the special tool kit that ONLY WORKS ON THAT ENGINE, to set the timing chains is $500. You will find that only the top shops, and dealerships have invested in owning that tool kit.

That's what your actually paying for.

Yep, it's that old "It's not which screw I turn, it's the
knowledge of which screw to turn that you are paying for."

That's why I'm here asking.
How do I flush the system out properly.
Especially how do I flush a multicore radiator.

Pooh Bear

I fixed it. Put a new thermostat in it.
Drove it around for a while and up some steep hills.
Temp guage never went above normal operating temperature.

Right now I have a mixture of Prestone Super Radiator
Cleaner and distilled water in the system.
The instructions say leave it in for 6 hours driving time.
Then rinse it out and refill with regular coolant.

But it works. And it wasn't hard to change at all.

Pooh Bear

Here is a link that might be useful: Prestone Super Radiator Cleaner

2003 Ford Explorer...I think the seal on the water pump went a few months ago...I've had to add antifreeze/water to the overflow for the last few months...up until a couple of weeks ago I could get away with adding antifreeze/water once a week depending on my distance driven...over the last week I've had to add antifreeze/water every 80 miles...a few days ago the heat stopped working (blows out cold) and the truck over heats within 8 miles of driving...today I filled up the resevoir, drove 10 miles...stopped...waited a couple of hours...filled the resevoir (it took just over a gallon) and got home but it started overheating within 8 miles and still blowing out cold air...here's my question: in your opinion, is it the water pumpo and the thermostat?...or do you think a leak in the radiator...that seems like a lot of water to go within 8 miles...btw, when I looked after driving I saw no water leaking from hoses (the overflow was steaming and hissing for a while)...I've changed the tstat before and that's easy...how hard is the water pump to change if in fact you think that's what it is...I KNOW I shouldnt have waited this long but right now I really need some expert opiniopns on how to proceed...thank you in advance for your advice...Chris

Chris, You should have started a new thread. This thread is almost 6 years old. Anyway if the water pump is leaking you will see anti-freeze on the ground. If there is no fluid on the ground then it is using up anti-freeze internally. The problem could be blown head gaskets, cracked heads, intake gaskets, or the intake itself. As far as blowing cold air. The reason for that is because there is not enough anti-freeze in the block to circulate thru the heater core. No hot fluid going thru heater core Means no heat and cold air.

Anyway Good Luck

Bob