Dodge RAM 1500, 4.7 L V8, 70,000 miles.
Runs warm (235) when around town. Runs Hot (250+) when going up hills or pulling a light trailer. (1000 Lbs)
The dealer replaced the Thermostat and Water Pump, ran all the cooling system checks and found nothing. (checked temp guage too)

Any Ideas?

Many Thanks!!!

(Thank God I have a warranty!)

Klanker

seeping head gasket.plugged cat or muffler,bent exhaust pipe,plugged radiator fins or core plugging up.these are just a few of what i can think of off the top of my head but have seen all happen to fairly new cars and trucks.oh and if it has been up to 235 it probably does have a blown head gasket.especially if it is an aluminum engine

Open the high end and install baffles, that should help !


Albert

If it is getting hot while under a load, or driving on the expressway, you might have a restricted radiator. Another sign of the radiator being the problem is if it stays at it's normal operating temperature during city driving. This is because while under a load the engine produces more heat. This requires more cooling. If the radiator is restricted it can't handle the extra heat. Driving around the city doesn't create as much heat, so a restricted radiator may have provide enough cooling during those conditions. If you have an infared temp gun you can check for cool spots on your radiator. Where you have a cool spot, is where it's restricted or plugged. In most cases you will need to replace the radiator. Sometimes flushing it will work, but that depends on how plugged it is.

Put the gear selector in 2nd gear and drive down the interstate right behind a large semi at 75mph till the engine gets so hot it locks up. Go to dealer where warranty was purchased and get new engine...... simple. BTW ask them to replace the radiator just for peace of mind. If that doesn't work, try it in 1st gear.

BF

Originally Posted by as722

Open the high end and install baffles, that should help !


Albert

that would be great but the computer on new cars remembers speed,rpm and a lot more,even in rental cars- don't ask me how i know this but they shut down at 105 mph

Are you using the Orange cooling fluid in the radiator? They had problems with that stuff causing blockage in the cooling lines.

Originally Posted by 3ddd

that would be great but the computer on new cars remembers speed,rpm and a lot more,even in rental cars- don't ask me how i know this but they shut down at 105 mph

^^^^^Only some cars come with speed limiters, most domestic(US) cars do. The ones that have it are set at different speeds for different makes and models of cars, my '97 chevy shuts off at 100mph.

If your problem is in the exhaust (espeacially if the catalytic converters are clogged) you can check if this your problem by matting the gas from a stop and if the car sputters or maybe even wants to cut off instead of going like its supposed to the exhaust is your problem.

Here's something else you can try. It's the factory service manual: http://www.hemitruckclub.com/

Left hand frame, maybe halfway down. You could use that to see if it's throwing any codes. On my '03 2500 you cycle the key 3 times without actually starting the engine and the codes show up on the dash. That should tell you if your cat is clogged.

If the water pump, the thermostat (the correct one), and other extenal equipment such as fans, fan sensor, hoses external leaks, new fluid etc..have been verified, I would flow test the radiator. Be careful here though. Not everyone who is a qualified radiator mechanic knows what he's doing, and may not know what good flow looks like. An example of what one should see is the flow of water should "GUSH" out on the suction side. Not pour, but "GUSH" The suction side is the bottom port.

The cooling system is a very simple system. There are only a few components that can cause overheating disregarding the strange, and unusual like a cracked block, water jacket, or some other internal leak. Internal leaks are typically idenified by zero radiator pressure, water loss, but not to the outside environment.

Verifiying the thermostat is opening is easy to check. Leave the cap off, start the engine, let it warm up, and witness the flow of coolant through the opening. It will go from zero flow, to flowing. DOn't concern yourself with the rate of flow. this increase, and decreases with engine rpm. But you should see a change. That means that the thermostat is working. To see if the system is holding pressure, cap on, get the engine up to opertaing temperature, and squeeze the top hose. It should get hard, and stay that way even after the engine has been shut down for a time.

70,000 mile is a lot of mileage if the cooling system is neglected. But even with a properly maintained system, the radiator can still become restricted.



Question: Is the radiator aluminum?

Aluminum radiator have a greater risk for corrosion than brass.

He is another consideration.100% Radiator fluid by itself is poorer at removing heat than water. One should typcally run a 50-50 solution for best heat transfer, but check with the owners manual for details, some newer systems may reqiure different solutions.

Originally Posted by LawnJockey

Are you using the Orange cooling fluid in the radiator? They had problems with that stuff causing blockage in the cooling lines.

Bruce hit the nail on the head!! It's called "Dex-Cool" completely worthless!!! It gels up and plugs all kinds of critical water passages. Get rid of it and flush it real good. Have you checked the fan clutch to see if it freewheels when cold and is locked up when it's hot? Pretty common problem. New radiators are fairly cheap, just buy a new one rather than try to fix the old one (plastic tanks) And don't buy it from the dealer, any good radiator shop should have one for it or can get it.

Tom

Many thanks for all the advice gang. The Dodge dealer will have it this week. Gotta get it ready for The DOGS!

Klank

Look mate picking a plugged radiator is dead set easy. Just go for a drive until the engine gets good and warm, hot if you like. Pull over, kill the engine and lift the hood. Carefully touch the hot (Inlet side of the radiator with your hand. Now touch the outlet side. Not sure if yours is crossflow or vertical. Anyway it makes no difference. If the outlet (return to the water pump) is way way cooler than the inlet the cores blocked internally. ( Flow is too slow thus it over cools but the flow is not enough to keep your engine cool) If it hot both sides then the core is blocked externally, waters passing through fast enough but not cooling down. (Lack of air flow). Get it MATE!!! Us old farts in wheel chairs and lap blankets are not dumb you know.

Now young whipper snapper all this comes to pass with a little thing called DeltaT. A good radiator will have a cross core drop in temp of between 5 and 14 degrees C. Do not ask me for F as you guys can work that out your self.

The inlet/outlet temps were checked and while the engine was at 225F, the inlet temp was 195 and the outlet temp was 165. How does that sound?