Sorry for crap grammar or typos. I am having a couple drinks out of frustration and need to vent it out

Ok, I think I have read every single overheating thread on here and naxja... haha
Ill start with what I have: 1996 XJ 4.0L Auto Transmission 111,000 miles

Living in Las Vegas when I purchased this XJ and it had overheating problems and I got a good deal for it! So I figure I would learn and fix!
Boy has that been a trip..!
First trip out I pushed her to hard and had trans fluids leaking. Temps that day where 115 and I was driving 75 80.
Took it to a shop verified everything was fine and I had stopped in time before anything bad happen.
Ended up installing a trans cooler for it and have had no problems with leaking or trans fluid overheating (pink foam)

Next step check all parts of cooling system.

Waterpump: New (not sure of model came with XJ)
Radiator: Mishimoto (came with XJ)
Thermostat: New installed 180 Mishimoto
Installed new Radiator Top hose and over flow hose.
Fan Clutch: I upgraded it to ZJ with new fan shroud
Hood vents: I installed
Hood Spacers: I installed (K suspensions spacers)
Electric fan: 100% working
I ended up installing a wire switch for it to control myself and has been amazing! I can trail 4 low and keep it around 200 with no AC on. (100+ weather)
Compression Test: Passed, super great!
Full system Flush and cleaned by a mechanic after I installed everything

Issue now is driving and turning the AC on because it is 115 to 120 degrees outside, it will start overheating. Between 0 and 70 mphs.
Starts fine then 15 mins later 220 to 240. I will always shut it off by 240 and let it fall back to 210-230.
After that it is always at 220, maybe on a good day it will fall back to 210 but the first hill I come to back up to 220.
I never turn the AC back on after that. I have never seen any coolant leak or steam.

Its so hot and I would love to be able to drive home with some AC on

I am going out to check on the lower hose to see if anything looks wrong but that is my last idea..
Anyone have anything else I can check!??
THANK YOU FOR ANY RESPONSE!

Attached is a photo of my POS! I love it





Random ending thought.. Anyone watch Matt's Off Road Recovery? He said he fixed his Ac problem by adding an aux cooler in his heatcore line.
6mins in

 

New Mopar radiator cap.

I'm in the northeast and while not nearly as hot as where you are, we had a good stretch of what was considered "really hot" around here. 90+ and humid.

I had some overheating when running A/C, mostly when idling but ran fine while driving (also, it's a manual, so there's no tranny heat load for the engine cooling system to contend with), figured fan clutch despite it being only a couple years old and a reputable brand. Sure enough, wetness around the shaft. It was warrantied so I grabbed a new part for no cost. I had a Mopar T-stat I'd been sitting on for some time and figured, well, might as well put it in while I'm in there. Also, since I'd be draining the cooling system and taking the belt off, might as well throw a new water pump on there as well. Stumbled across a new Mopar e-fan (I'm trying to refresh all electrical stuff with new Mopar just in fear of future scarcity) and at a great price, so I grabbed that.

I did all this stuff and it seemed better... better, but I'd still occasionally get the temp creeping past 210 and would hit 220 before either the e-fan started bringing it down, or I wasn't willing to risk running hot.

I figured I'm looking at a serious flush due to cooling passages being blocked (the coolant has been flushed not too long ago and was never very dirty) and/or a new radiator. I figured I might as well replace the cap despite it "looking" reaaaaaalllly good and seemingly firm when I pushed by hand.

Got a new Mopar cap and I kid you not - it completely stopped the overheating. If anything, my gauge is solidly lower than I'd like typically. It was very very clearly a difference from flaky, jumpy temps that swung well into the 200's to a steady, solid and idle safe spec temp. And I idle A LOT and for long periods sometimes.

Regardless of whether you have the same issue and will see the same results, for the price and ease of slapping a new Mopar cap (Under $20 through RockAuto using the part number search/Mopar brand) on it, there doesn't seem any reason not to do it. Worst case you've eliminated one of the possible root causes and have a dependable cap for the next several years.

 

I am no expert on the subject, but my thoughts are check lower radiator hose is not collapsing and just confirm the radiator fluid is correct since it comes two ways, pre-mixed and concentrated. A coolant tester is $5 at the auto parts store.

 

Good points.

If the moral of my story wasn't obvious, I'd consider:

- Buy a new cap, preferably Mopar
- flushing to correct any scale/rust buildup

Then -- as the previous caller said -- also do the lower hose (which is pretty much draining the current fluid by definition) and make sure you're refilling with new, properly mixed standard green anti-freeze available at any place that sells motor oil. Where I am there's the "cheap" grocery store and not only do they sell both full strength and pre-mix, it's half the price Walmart charges for store brand. So there's no contest when it comes to where I go for antifreeze...lolol.

 

Do you happen to have the Mopar part number? I don't see it listed on Rockauto and although my cap is new I'd like to have a Mopar on hand.

 

I believe Matt's Offroad Recovery also put a high flow water pump and a high flow thermostat housing in it. I want to know what axles and ratio he's running. I think somewhere Blazer was mentioned. Did Blazer have a driver's side diff drive? He also complained about the AW4 not staying locked in 1st like he'd like it to. The hood louvers he's running are from a Corvair rear deck lid flipped upside down. I've watched every one of his videos at least once and taken notes! He said most of the time he's offroad, it's in low range. That would keep the fan running at a high speed with less load on the engine, I would think. He's currently running 35" Patagonia tires at 8 to 10 psi when offroad.

 

Thanks for the info! Ill buy a new cap now and keep you posted!

 

I would love to know all that as well! Love that guys channel! Im really interested in how he route his heatcore hose into an Aux fan.

 

I checked the lower hose with a buddy. He had the RPMS around 2-3 and I looked everywhere for something collapsing....nothing looked wrong.
I also did make sure the temp was hot enough for coolant to pass through. I did not do that the first time oops...

 

I would assume he just hung another heater core in the hose with a fan in front of it. If I did it, I would face it downward over the starter with the fan blowing out the bottom. Knowing him, I would suspect he got the parts from a wrecked RZR.

 

Well it turns out that the Mishimoto Rad cap is not universal, so I will have to buy the same cap from them..
Which is a 19lbs pressure. And the OEM one is 16lbs. I wonder how much of a difference that would make.

 

I'm going to second that. Had the same problem and lower hose didn't have a spring in it and was collapsing because it is right up against the power steering lines. Got a stock lower hose with the spring in it, and I also cut about 1/2 inch off the end of it to give it a little more clearance around the ps lines. Has been running cool ever since.