Well, sounds like Air in the system still. you should keep track of what you put in, and what teh capacity is. I really need to track down my manual, as I want to do a A/F swap this fall.
Youve replaced everything else. T-stat is seemingly working, and the pump. So, it really leans only to air in the system. Especially if by tank, you're refering to the left and right of the radiator, and not the cowl that houses the washer fluid/overflow. Is your overflow tank dry?

 

When was the last time you had your fluid checked? there is a tool you can get cheap that will test the fluid and tell you if it has enough of the chemical in anti-freeze coolant.

If its old it wont work well.

Check the center of the Rad, if its a different temp than the rest then it could be clogged.. Rad flush yet? Have you checked this yet? basically what your describing is not enough cooling power of the Radiator.

Either 1. Fan is not pulling enough air through because its weak or not turning at proper RPM.
1.1 Fan is not pulling enough air through because of blockage of the actual fins of the radiator
2. Coolant is not being cooled down because of blockage in the radiator so would cause a decrease in cooling ability.


Example.. My truck (318 w/ fan clutch.) did the same thing in traffic and idling.. my fan clutch was not kicking in, however even with the new clutch it still will climb up to 210ish but never over now.. but once i give it the slightest of gas it will come down minute if only for a breif time (stop/go traffic)

I put in a 180 stat (Again) and in combination.. it climbs up to like 192-195 which is normal temps from factory.. so its cool..

Just an example..

 

Thanks for the quick replies; here are the answers to your questions.

@DakMan6704

Is your overflow tank dry? No, the overflow tank is full.

Also, you are correct when referring to the right or left side radiator tanks. Standing in front of the truck looking towards the motor; the right side tank which is the "out" for the water pump and the left side tank is thermo side. The right side tank stays at ambient temp even when the truck overheats.

@jondakotaguy

I had the system flushed and the thermostat replaced about 3 to 4 months ago. The condenser fan which is mounted on the back side of the radiator kicks on when the truck reaches operating temperature (thermostat temp) which should assist the new radiator fan / clutch I installed at the same time as the condenser fan (2 weeks ago). The truck cooled fine with these two new parts; however the overheating did not start until the radiator was replaced. Also, new coolant was added to replace what was lost when changing out parts.

I have been suspicious of the new radiator, even more so since I have replaced everything else. So I agree with you that it could be that the radiator is not providing sufficient cooling capacity.

BTW, the truck overheats parked @ idle and the heater on. I took the truck to the shop and they couldn't bleed it either because it boils over through the bleeder valve.

I am working with the local shop, where I ordered the radiator, to replace it. I will install the replacement and then post an update.

Thanks again for your support!

 

i am having the same issues but i beleive mine is the radiator, i bought the truck used with 107,000 miles and i dont believe it was taken care of, but i think it is scaled up so bad, so check your coolant if it comes out discolored or looks like mud thats your problem, if you guys think it is your radiators i found a site that sales quality new oe radiators at good prices.
www.andysautosport.com

 

My 2004 Dodge Dakota is doing same thing - runs only warm when I'm at idle. It's been doing this for about a week. There are no leaks. I just topped off my coolant. The temp gage runs to about the mid point but no further and I can hear the fan come on. With our temps in 60's, I thought this to be odd for it to be running this warm and causing the fan to come on. I plan to get it checked this weekend with my mechanic. Is it still safe to drive til then? I have no other alternative for a vehicle. The temp goes down when I'm driving...just when I'm at idle does it start to run warm. I just don't want to make the issue worse.

 

I don't think it would jibe with overheating at idle but not at highway speeds, but anyway, here's another frequently overlooked cause of overheating. It's the lower rad hose. If it is old and flabby, the water pump can actually suck it closed or partially closed, preventing coolant circulation.

 

My AC compressor just quit on me and it stopped both my overheating issue and my oil pressure guage working intermittently. So my truck was just showing hot. My AC compressor was drawing too much power and screwing up the power wires coming through the firewall

 

I'm currently having this same issue. The truck won't go all the way to red, but does get hot enough to trigger the warning light. Holding the engine at 1500 RPMs keeps the temp low enough to avoid this. Any idea what I could be looking at? Oil Pressure doesn't change and the top hose has coolant moving through it

 

You may want to start your own thread and give more details about what you have already checked and what truck you have. I'm currently assuming you have a 2004 Dakota.

Your electric fan comes on correct? It should come on automatically when the temp gets about halfway up the gauge.. And then the engine still stays too hot?

​​​If this IS the case my initial thought is you have a flow problem.. Reason is because even with the mechanical clutch fan removed in the past, I've had my 4.7s stay cool enough with the electric fan alone cycling itself.
When I have both fans installed the mechanical fan keeps up all alone most of the time. And when the electric fan does come on it gets the temps down in a hurry.

What does the coolant look like? Is it full? Obviously it needs to be full to work right. If it's nasty you could have a restriction.
How old is your thermostat? It may not be opening all the way causing a restriction.
When you raise the engine RPM's you push the coolant harder through a restricted area and cool the motor down. The mechanical fan also moves faster helping cool the motor more (assuming it works right).
You should hear the mechanical fan clutch start engaging/moving more air when the engine temp rises above it's typical range.
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General cooling notes from my experience:

Overheating at idle and running normal at speed is, 9 times out of 10, an airflow issue.

Water pumps can fail internally. The impeller blades can actually wear out, and not catch enough water per revolution to cool the engine. Running faster than idle "solves" the problem by letting the impeller take more whacks per minute at pushing coolant through. If the fan clutch is locking and it's still overheating, but revving the engine brings it down, replace the water pump. Dodge water pumps look as though half the pump is the front face of the block, unlike the Chevy engines I'm used to, so you can examine the impeller directly when you pull it.

I've had a new out of the box Autozone radiator that had half the tubes crimped. Apparently the radiator didn't pass their leak test and their fix was to cut and bend the tubes over, not replace them, and there was apparently no max number of crimped tubes allowed. That vehicle (with a new engine, mind you) was overheating out of the box, and when I shut the engine down and felt the radiator the top of the radiator was too hot to touch, the bottom was ice cold.

My mother lives on a road frequented by Tyson chicken trucks, as she lives near the heart of the Tyson protein empire. On her last truck, a 93 GMC, every 2 years I had to pull the radiator out to clean chicken feathers from between the radiator and condenser. We'd know it was time when she started overheating at idle. Her current truck, a 2001 Silverado, has no such problems. When I replaced the engine in her truck last year, after having driven the truck for several years, there wasn't a single feather in there. Point here is, junk between the rad and condenser can cause overheating, and it can't really be seen from the outside. Having someone shine a flashlight through the shroud should show this though, if you can't see the light from the grill then the radiator's backed up with junk.

I too have had thermostats, and rad caps, bad out of the box. Drilling a 5/16 hole in the thermostat allows coolant to circulate, and will help heat the thermostat up faster to get it to open sooner.