DodgeTalk Forum banner

Status
Not open for further replies.
1 - 4 of 4 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
I've read through so many posts on overheating issues and have no idea where to start looking for my solution. Here's what I have going- my 2007 4.7 begins to overheat ie. gives check gauges warning signal while driving on surface streets. If I dump heat by turning on heater, temp gauge drops to just above mid point on gauge. This occurs regardless of outside temperature. When driving on highway, the temp stays just above normal without heater being turned on. I have checked the fan clutch by rotating when off as well as trying to slow while it's running. I have coolant at appropriate level and mix. When I touch radiator cap after driving, the system is under pressure, but the cap is not hot. I also noticed the top half of radiator is not hot. I'm not sure where to start trying to fix this thing. Any help is greatly appreciated.
 

·
Premium Member
Joined
·
30,924 Posts
Welcome to DT!

What you're describing sounds like a bad fan clutch; I'd replace it. Just to be safe and because the cap is pretty cheap, I'd replace it as well. I've had problems with the off the shelf brands of radiator caps. The ones from the dealer cost a-little more but personally, that where I get mine. Here's a post from early 2000-n-something and it's written for the older model vehicles because today's vehicle, the coolant moves though the heater core all the time. It doesn't sound like you need the old post because you've checked most of it already but there may be something in there that will help. And remember, you cannot mix the older green anti-freeze with the orange HOAT. Again, it may be $14-bucks a gallon but I only get my HOAT from the dealer.

If you're hearing water running though your heater core, you have air in the cooling system. You need to park the truck in the driveway with the nose sitting higher than the rest of the truck. While the trucks engine is cold, get under the hood and remove the cap. Start the truck and put the heater on high-heat. Double check the level in the degas-bottle and fill it up to the cold mark. Now just let the truck idle while it warms-up slowly. You need to be careful here because if the system has an air pocket, it could flash-boil on you. If it does that, it’ll push coolant out like “Old Faithful”; so be careful. As a safety measure, you can put the cap on but leave it loose. That way if it flash-boils, it won’t hose you down with hot coolant; not fun! As the coolant flows though the bottle, you can feel when the thermostat opens. You need the thermostat to stay open a number of times because it the only way to get the air out of the system. Check the gauge on the dash from time-to-time and when you’re sure the coolant is hot, the thermostat has open-n-closed effort times, and the level in the bottle is full to the hot fill line, you can bet the air is out of the system now. Tighten the cap. Turn the heater off and you’re done purging air from the coolant system. There’s a purge tap on top of the engine but if the bottle is sitting higher, using the bottle is the better choice. I’ve never be able to use the bleeder tap without getting hot coolant all over me and the whole engine. That and I hate the feel of coolant on my arms and hands.

Now you can check the cooling fan. Nothing is harder on the cooling system than the time the vehicle is sitting still with no air-flow though the front of the vehicle. When you first start the truck, you won’t hear the fan after the first few seconds. But as the truck just sits there, the air flow though the radiator gets hotter, and the fan clutch begins to get a little heat into it, the clutch will began to lock-up. You should be able to hear the fan pulling air though the radiator. Keep checking the gauge on the dash and watch where it peaks. Where does the gauge set as you drive down the road? That’s about where the needle should be now as your truck just sits with the engine idling. If the trucks temperature keeps climbing, you could very well have a bad fan clutch.

Move you hand across the face of the radiator. Check for cold spots or areas that seem much hotter than the rest of the surface. If the temperature isn’t uniform, you could have a plugged radiator core. Stop leak products have a bad habit of plugging good and bad areas within the core.

Check your EGR valve. If it's disconnected or plugged, it can cause heating problems. And then after checking all of this, the system just seem to be running too hot; you could have a thermostat that’s not opening fully. Checking or testing it will take more time than the thing is worth. They’re pretty cheap so just replace it. If you’re going to take the time to replace it, you need to make a choice? Do I flush the cooling system or use the old coolant. And since you think there maybe stop leak in the system, you need make a choice about using an acid flush though the system. The acid flush should clean that crud out of the system. If you use the acid flush, you need to remember to open up the heat core as well.


:dtrocks:
 

·
Premium Member
Joined
·
30,924 Posts
Keep us in the loop what you're doing and what you find, okay?


.
 
1 - 4 of 4 Posts
Status
Not open for further replies.
Top