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2000xj running hot

cherokeefan_1

NAXJA Forum User
Location
North idaho
2000 xj running hot. I have done a Spectra radiator from Napa, original was leaking. 2 coolant flushes that yielded nothing. Even the block behind water pump has no rust or scale, same with head. I installed a dealer water pump, dealer fan clutch, dealer thermostat, dealer radiator cap. I have tested for exhaust gases in cooling system 3 times. Pressure tested cooling system. Pressure tested radiator cap. Tried an 18 lbs cap and 16 lbs cap. I have now also tried the Napa 4 cylinder xj fan clutch. Also has a new belt. In slow traffic, stop n go, or sitting the temp creeps to 220 then the aux fan kicks on and brings it down to 214. With a/c on it goes up to 224 before I call it quits and turn heat on.

Now, with the 4 cylinder fan clutch the temp won't drop below 210 keeping a high idle, hood open, with heat on. At least with the dealer clutch I could get the temp down to 200 with just heat/high idle.

What I have noticed is the factory electric fan pulls more air through the front of the radiator than either of the clutch fans, at idle.

Oh, and this is a bone stock xj with 230k in super nice shape. Was well taken care of. I will try my factory 91 xj 3 core copper/brass radiator next as it did an ok job of cooling my 91.
 
We've owned this for 3 years but it didn't get driven much as we lived in the city and it's not lifted. Was a replacement for my lifted 91 that was t-boned by a semi that blew a red. But this thing is not worthy of off-road like my 91 was.
 
Have you put a scanner on it, specially with data logging? How about a Mopar temp sensor?
 
Have not data logged. What am I looking for if I do? I've read the Mopar temp sensor is n/a and I have no clue if the one on it is. O2 seams to react fast but is always pulling fuel, reading a negative 1.6 to positive .8 at idle. Long term trim is negative 6
 
The radiator that was leaking is the exact same Spectra I put in from Napa. Not sure about the running hot before as we didn't drive it much, especially when it was 90+
 
Maybe next weekend I will swap the radiator out of my wrecked 91. That or the head is cracked but not pushing exhaust into the coolant at detectable levels
 
The block test (exhaust gasses in coolant) won't always detect a bad head gasket or crack. I know it sounds weird, but I've ran into that at least 3 times.

1) Grand Am with a 3.3 v6
2) Mazda 3, 2.3
3) old school bus with a 6.9 diesel

Sounds like you've done some decent diagnosis and have a brand new cooling system. It's frustrating, but you probably have to pull the head.
 
Have not data logged. What am I looking for if I do? I've read the Mopar temp sensor is n/a and I have no clue if the one on it is. O2 seams to react fast but is always pulling fuel, reading a negative 1.6 to positive .8 at idle. Long term trim is negative 6

That's the kind of things you need to know, you very well may have intake/exhaust leak. You don't even have hot ambient temps!
 
Yeah, I know about exhaust gas in the coolant not always being good. On big trucks they rarely work unless there is a massive issue. Same with equipment. I don't lose coolant or gain oil so I figured the head/gasket was good.

Maybe I will buy a intake gasket and redo it. It has the cast exhaust with dual down pipes 6:2:1 style instead of the tubular stainless 6:1. Never seen that before but not familiar with these late model Cherokees.

I just know it's the head, somehow. I really don't want to support china with an aftermarket and don't see the point of Edelbrock unless I rebuild which is not happening now.

So, need to find a good used tippy.
 
The 4.0 in my 91 ran strong, only leaked oil. And I beat on it for 170k. Did the head gasket at about 50k and it had a big score in #4 but had good compression and decent leakdown. Was a rebuild at some point with around 50k on it when I got it. So it's just over 200k now. Lots of piston rattle. But fires right up with no knocking or smoke, even after sitting for a year.
 
Is the fan facing the correct direction?
 
2000 and 01 had cast manifolds. I've heard they're less prone to cracks than the 99 and earlier, so hang on to them.

Grab yourself a head from the JY and just take it to a machine shop. It might cost a couple hundred bucks, but you'll have a verified good head (and you'll be buying an American head from an American JY and taking it to an American machine shop)
 
Is it possible to put it on backwards? Lol. Yes, it's on correct.

Hows your catalytic converter?

I had an overheating problem on my 94 that was due to a clogged cat.
 
Clogged cats also equal reduced power. This thing has no lack of power and will lay rubber for a block or until the stupid lack of first gear hold kicks in.

Finding a junkyard head that accepts the cool over plug design will be the same crack prone 0331 unless I can find a tuppy which is near impossible and there are no u-pull it type yards anywhere near where I live.
 
I don't see any mention of the heater core? It plays a significant role in cooling.
 
You sound like you can be creative. Make a couple mounting straps for the coil rail. That way you can use a non-COP head, which doesn't crack and supposedly flows better.

(Not my picture. I found it in a Google search)

218827d1383539237t-2000-xj-head-swap-advice-needed-image-755695245.jpg
 
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