Cherokee gets hot

[TGibbs13]

I have a 96 Cherokee with a 4.0 straight 6. I have a brand new radiator with 3 electric fans. Brand new thermostat, water pump, hoses, and the block has been flushed, and I have burped the system. The jeep only gets hot on the highways when I'm constantly on the gas. Up 4wheeling it does fine. I Also just installed some hood louvers to see if letting more heat escape would help. Not much difference. Is there anything else I could do? Please help.

[Jim]

Does your lower radiator hose have the metal / non-collapse insert in it. At higher RPM's the water pump can suck hard enough to suck closed the lower / intake hose - ceasing waterflow (aside from in-block flow).

A test would be to have a helper bring the RPM's up to highway speed range and watch your lower hose to see if it collapses.

Yea, yea, standard safety concerns to tend.

That's all I can think of now.

[TGibbs13]

Come to think of it, it doesn't have that. I'll have to try that tomorrow. It's worth a shot. Thank you

[Jim]

Oh, if you do the test - make sure the motor is up to temp so that the thermostat is open and trying to flow water through the lower hose.

If you don't see it collapse - just replace it. My mind doesn't know what the odds are for the interior of the hose to collapse while the outer shell of the hose still looks normal (a hose with a ply separation - something its not supposed to do).

[Chris]

Hmm, head gasket leak? Have you tried a block test? Napa #7001006 @ $25.00

It's just a test of radiator fluid added per directions that changes color if there's any combustion fluid in the cooling system.

[Hypoid]

How hot is "hot?"

[TGibbs13]

Right around 240 to 250. Hot. Lol

[Hypoid]

Did you verify the temperature readings with an IR thermometer? Has this engine always run this hot?

[TGibbs13]

I have an obd scanner that I can read while running, on dose streets it stays around 200, on highways it sticks around 245. and yeah its always been this way since I got it. It would even get relatively hot on a 30 degree day

[TGibbs13]

*side streets

[Hypoid]

You need to confirm what the temperature sender is saying. If you don't have access to an IR thermometer, I have one in Golden.

[TGibbs13]

I have one, just haven't thought of making sure the sensor is right.

[Jim]

You need to confirm what the temperature sender is saying

I agree (and it's a simple test to perform)

[Java]

My guess is that it's tied into the electric fans. Without knowing the setup I'm guessing they turn off at a certain speed or rpm? can you adjust that? maybe adding a stock mechanical fan with a clutch would fix it up too. Again, just a guess.

[Rick]

Hmm, head gasket leak?was my 1st thought too....hopefully not the issue though

[Jim]

Without knowing the setup I'm guessing they turn off at a certain speed or rpm?

Not sure for his year (newer vehicles might be more sensitive to fan needs), but in my experience, a radiator fan is only needed for speeds below about 25 or 30mph. Above that, there's enough air being forced through the front grille to cool the radiator sufficiently.

Back in the early 90's, college kid trying to shave fuel costs, I removed the mechanical fan on my V8 CJ5, in the summer, and watched my temp gauge. Long stop lights, I'd shut the motor down to avoid overheating it, but otherwise, not having the fan was never an issue. Town roads or highways - temp gauge stayed where it should.

On the flip side, if the vehicle does not have a shroud around the fan, at low motor speeds (mechanical fan), not enough air will be sucked through the radiator. A shroud is needed for a mechanical fan with a car at idle to keep cool.

[EKXJ87]

I had the same issue with my 92 new water pump,radiator,t-stat, and dual electric fans, and was running 220+ and forget climbing I/70 it would go into the red 240+. I also have a new bottom hose with spring OEM dealer part,most auto store carrier the one with out (not recommended from what I've read)
Like Hypoid stated earlier get a I/R temp gun and check inlet and outlets, T-housing cover, I did and found the temps to be below 200 degrees, so I added a aftermarket temp gauge (25.00 Autozone) and found that my OEM gauge was off by 20+ degrees.

[javaman34]

I had the same problem with my Bronco. I borrowed my father-in-laws ir thermometer and checked the hoses, thermostat housing, radiator, intake, etc... The temp gauge showed on HOT. I mean blow itself apart HOT. The highest reading I got with the ir, and this was right after running up and down I-25, was 170 degrees. My gauge is seriously messed up.

[Hypoid]

I have one, just haven't thought of making sure the sensor is right.If your water neck is all shiny after replacing the thermostat, apply a light spray of flat black paint on the water neck, or check the temperature right next to the water neck. Reflective surfaces don't always give an accurate reading with the IR.

If the temperature readings show the gauge to be wrong, try cleaning the electrical connection on the back of the instrument cluster.

[xaza]

Hey Mike what should he use to clean electrical connection? I use electrical contactor cleaner, but is there something else that works well?

[Hypoid]

I'm not sure what people do to clean the back of the instrument cluster. There are write-ups on NAXJA about cleaning there.

Most everywhere else, I use a CRC product called "QD Cleaner." QD stands for quick dry, it will not dissolve the plastic used in most connectors.

[Jim]

I'm not sure what people do to clean the back of the instrument cluster.

And I'm not sure what the back of that cluster is like, but the back of the cluster on the YJ can have contact issues. For the YJ's setup, the recommendation, once disassembled, is to use a pencil eraser to rub the contact surfaces clean.

I've done it once. I might have applied some dielectric grease to help keep oxidation at bay.

http://www.oreillyauto.com/site/c/search/Dielectric%20Grease/N0941/C0139.oap

[gm4x4lover]

Both my xj gauges are off by about 30ish degrees. I chased the same issue and finally got a ir thermometer and found it to be sitting right at 210.