It's HOT!

[N8N_99xj]

So I was running some containers back and forth to my storage locker today... it's about 98F outside and humid, got stuck in a little backup due to a wreck, temp gauge was up around 225F! this is a bone stock '99 4.0, AW4 - nothing leaks, but cooling system is all original save for hoses and belt as far as I know.

Do you all think there's any chance that using a chemical flush will help, or is it time to bite the bullet and order a new radiator? I'm "between jobs" at the moment as they say but I don't need to screw up my vehicle by abusing it either.

I'm assuming that I should probably order a water pump, thermostat, and fan clutch at the same time if I'm going to replace the radiator?

 

[joe_peters]

Are you still running the clutch fan?

If so, that is a classic symptom of a clutch failure.

 

[N8N_99xj]

I have A/C so I have both clutch and electric... Electric is working & clutch feels tight. Do you think replacing it anyway might help? Or jump straight to "replace radiator?" I have less than 90k miles despite age.

 

[Digger87xj]

225* in stop-n-go at 98* ambient is quite normal.

 

[N8N_99xj]

That seems awful hot as it generally runs @ 210... thermostat rating is 195 I believe? It makes me nervous when engine temp is getting close to the boiling point of unpressurized coolant... I visualize popping a hose or something and the whole system flashing to steam with associated bad consequences to engine...

 

[Creeper2012]

Is the coolant still nice and bright green? I would start simple and do a flush and thermostat replacement for starters. Stick with the factory 195*. While the stat is out, shoot a garden hose through all the coolant lines and make sure the engine, radiator and heater core get thoroughly flushed until clear water comes out of everything. Put new stat and 50/50 in and see how it works. Also, make sure the fins on the radiator are clean and aren't mangled. I don't mind using a foaming HVAC coil cleaner for good measure. After that, if no success, you're probably looking at a water pump and/or radiator, unfortunately. However, it IS possible to get brand-new plastic/aluminum radiators on eBay somewhere in the $50-$60 range if push comes to shove.

 

[N8N_99xj]

Yes coolant looks pristine, cooling system was flushed by a shop right before I bought it ~1.5 years ago. Rad fins look good from behind & so do condenser fins from front. Only thing I really can't check is whether there's any dirt in between. Guess I should pull rad and look, but it's so damn hot out I can't contemplate working outside in this heat... Would I need special tools to release trans cooler lines or are they standard flare fittings?

 

[joe_peters]

Take it to a coin operated car wash.

Let it sit and cool down for 30 minutes or so.

Pull it in and shut it off. Then "backflush" the radiator from the engine side--shoot the sprayer through the radiator, engine off, and out through the a/c condenser. That should clear any buildup in the fins of both.

 

[Digger87xj]

a good wash and a new rad cap will probably help nicely. Cheap fix too.

 

[N8N_99xj]

I'll give it a try... rad cap is actually a month or two old as one day I got home from my buddy's shop and it puked all over the driveway... thought I was looking at a new rad then too but when I checked it out it was all coming out around the original rad cap! Been watertight ever since, just running warmer than I'm used to. Not sure how much flushing I can do without pulling the fan shrouds, but we'll see.

 

[joe_peters]

There are rad caps, and then there are rad caps.

Hope you didn't go cheap.

 

[Dragonslayer]

Just for laughs. Wait until it's dark. Remove the front grill and shine a bright flashlight
at the radiator fins and inspect with a magnifying glass I found all sorts of bugs, grains
of sand, glass bits, and meteorites stuck in the fins on my rad and trans oil cooler.
A free evening and a dental pick got most of them out. Flush out the fins from the rear
of the rad with a strong stream of H2O from a garden hose and put the grill back on.
Doing this dropped the needle on my temp gauge about 1/8". Cost = $0.

 

[8Mud]

Just be careful how much pressure you blow through the radiator, air or water from a pressure washer. You don't want to flatten the fins.

Air works better on dust and pollen, Water works better for the fibers and bug guts.

You can buy what they call a fin comb or fin brush, cheap and something nice to have in the bottom of the old tool box. Don't mess with the ones specifically designed for your exact fin clearances (they come in gauges). The universal model which looks like a small rake works fine.

http://www.ebay.com/bhp/ac-fin-comb

 

[8Mud]

Replacement parts may or may not be better than what you have now. New doesn't necessarily mean better.

 

[N8N_99xj]

Well today I tried to hose things out, the radiator actually looks pristine. The condenser looks like it's been beat up though, and the fins are too fine to comb with the fin rake that I have (I probably got it at HF, it's the one with the red screwdriver handle) so I did a half fast job with a mini screwdriver, we'll see what happens.

 

[8Mud]

I have no choice, I have to clean mine at least a couple of times a year. There are a whole bunch of Cottonwood trees around here and long stretches of two lane highway through farmlands (bugs).

The first time I separated the radiator from the condenser I found what looked like what you take out of the lint trap on a clothes drier. I got in the habit when I pull the aux fan and grill for a cleaning I shine a flashlight backwards (engine to front of Jeep). That Cottonwood felt (fibers) seems to get stuck between the condenser and the radiator and pretty much refuse to move, with water or air.

Do the flashlight test before you go through all the hassle of removing the top cross piece on top of the radiator.