Skull34

99 Jeep Grand Cherokee Laredo 4.7 it runs at 222 to 230 I replaced water pump thermostat radiator cap flushed motor and flushed radiator and new clutch fan is that a normal running temperature

rgr4475

That's too warm. My 4.7 never goes over 210. I would test the temperature using a infrared thermometer. The gauge could be off.

97grand4.0

A good way to read engine temp is with a scan tool that has real time data, find them on ebay for under 50.
That will tell you the temp that the engine management system is seeing, via the coolant temperature sensor.

dave1123

On 99 and newer jeeps, the temp sensor sends data to the PCM which interprets it and sends a signal to the gauge for the readout. The sensor is NOT hooked directly to the gauge. Therefore a scan tool should agree with the gauge. Or should.

What I found amusing was with the engine at operating temp of 210* the IAT was showing 158* at idle with an outside air temp of 65*. Not exactly cool, if you know what I mean. I hope it's cooler at highway speed.

IStoleIt

Heat soak is a fickle *****! Heat wrap the intake and exhaust components to lessen the soak. You can also vent the hood to promote more air flow higher speeds, but generally the manufacturers do a pretty good job of designing them properly.

IStoleIt

As others had said, there are many different ways to diagnose, and the first step is to verify your factory gauge is accurate with a know good gauge. Cheapest way would be to hack a cheap radiator hose in half, add an inline ANALOG temp gauge, and compare. With the gauge on the dash being PCM controlled there are many things that could cause a bad reading/signal to the gauge. Could be a bad Earth Ground under the dash, at the firewall, or the frame(unibody). Also could be corroded wires, and with corrosion the electrical resistance rises and could cause all sorts of odd signals. Good luck.

Skull34

So far I've replaced everything but the radiator right now I'm running radiator cleaner through it for about 3 hours now and still running at 240 on the highway when I'm sitting at an idle the temperature starts dropping I just can't figure it out my radiator is clear I can see right through it there's no obstruction the temperature is 80 degrees today so it is running hot never tried it with the air conditioning on yet I think it would completely overheat

Skull34

I forgot to say the faster I go to the hotter it gets it don't make no sense

fb97xj1

If the temp drops at idle id say the fans are doing thier job. Looking thru the radiator from the outside wont tell you if the internal passages are clear so the radiator is still a possibilty. When it is hot, whats the engine temp? Point an IR thermometer at it (wherever the temp sensor is for your year) to see what the temp actually is.

The faster you go the hotter it gets? Makes perfect sense to me. The greater the rpm, the greater the friction. The greater the friction, the greater the temps. The cooling system can only do much. You say it still hits 240 on the highway. How hot does it get around town, at lower speeds?

IStoleIt

I agree ^^ if the RAD is the only thing you havent swapped, just do it. I spent an extra $40 over the OEM quality and got a 3 row welded end-tank aluminum RAD and havent even hit 210F yet.(AMAZON-like 2 years ago.)

As a short term helper(NOT A REMEDY) you could get some Water Wetter from the parts store. It is pretty good about lowering the coolant temps 10-20degree. But I would never call this a fix, It's a chemical change that has nothing to do with your existing cooling issues.

rgr4475

Did you burp it correctly using the screw on the top of the rad?

JimmyBo1313

Didn't see any of this till I started striping it out. The air conditioning condenser in the front and the fan and fan shroud in the back hid it pretty well...I think my first gander at my problem was when I took the body metal off the top of the radiator.

IStoleIt

Well... aint that a sight! While bent fins are not helping the cooling, it should still work. That dirt that fell onto the cardboard is impressive. If only all of our cooling issues could be as simple as a blocked RAD.

JimmyBo1313

That's not just a blocked rad, that dust IS the rad! Look close and you might find a glimmer of my tactical flash light trying to come through.