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XJ too cold?????

B

bugout

NAXJA Forum User
Location
Florida EVERYDAYS forcast: Hot and humid with a 50
Heres my story. Bought a 96 XJ Country with 200k plus on the 4 liter and the AW4. It has a new head, valve train, oem radiator and water pump with 15k on them. The motrr was worked on and maintained by a father/son combo that run a reputable performance shop (mostly 5.0 mustang drag cars). They purchased it from a teen that managed to crack the head. The motor runs fine. No leaks. The temp needle stayed at 210 on the road and 220 plus in a drive thru. The water pump started to weep so I decide to replace it and the fan clutch with oem equipment from NAPA. Now with a 70/30 coolant/distilled water mix and no A/C running it stays between the 210 mark in the middle and the mark to the left which is 180 I guess. This is far from the norm according to all the other posts I've read. I don't have an IR gun to check the temp. I did unplug the sending unit and spray it out with NAPA electronics cleaner. I know it works because when I was burping the system it climed to 240 for about a minute then came back to 210 or lower. The coolant bottle is not overflowing at anytime either. The day I bought it, I changed the oil. I used and oversized NAPA gold filter and some Rotella 15w-40. I live in SW Fla. Everyday has been in the mid 90s with 100% humidity. ANY speculation is welcome!!! No, dut to time restraints I did not change the thermostat.
 
my guess is the coolant flush got some crud in the thermostat, causing it to stick. or something along those lines. Please use normal font.
 
My question though is this too cold? I know I may be opening up a huge can of worms thats been discussed a thousand times before. The exhaust still smells the same so I don't think I'm running particularly rich or lean. How hot does the oil have to get to do it's job efectively/properly? Is it possible that the previous owner put a 180 thermostat in it being performance minded and this is the result between the new water pump, fan clutch and Rotella 15w-40???
 
Sounds like you have a 180 in there, I have one and mine runs at the first mark before 100C (Canadian eh) and runs hotter (~100C/210F) when in traffic and going slow, but for the most part stays on the high side of that 180 mark. But that's where I wanted it to be in my case. Originally I was trying to save a failing 0331 head without doing too much ancilliary damage. then it cracked and I just stuck with it.
 
212ish

Hotter.is better for mileage

Get the cooling sys working right, and the oil temp will work itself out. Thse arent aircooled motors
 
The factory specified thermostat is 195*. "Normal" operating temperatures for an XJ 4.0L are about 195-210*. 215-220* can be experienced under heavy use or off-road.

Gas mpg's are most greatly affected by your driving style, regular maintenance, and proper tire pressures.

Oil is oil. In hotter climates one might consider using a higher viscosity oil.
 
Been my experience the 4.0 likes it a little hotter than some other motors. I've always been told for longevity, right around 80C is optimum and what most motors were designed to run at.. Synthetic motor oils are generally more forgiving, the viscosity doesn't vary as much as dino oils.

I swapped out my OEM thermostat the other day and found it in three pieces. I normally use OEM thermostats because they have a built in air vent and the OEM gasket is far superior to anything after market I've seen. And they are what the motor was programmed for.

You never can fully trust any gauge or gauge sender in any XJ I've ever owned.

The sender and gauge actually tell you what the temperature is plus or minus in the very small area (2 cubic inches maybe) right around the sender and are basically indicators and not instruments.
 
bugout said:
OK....but where is it suppose to be as far as the oil is concerned??? I know oil that is too cold is just as usless as oil that is too hot as far as engine wear is concerned.
Click to expand...

Your oil is going to be hotter than your coolant, but it takes about 15-20 mins normal driving to reach proper oil temperature.
 
Well, since nobody has told me this is bad for the motor.....I think I'll leave it alone until I get it off road and romp on it a little bit.

Im just not sure why everybody has issues with their XJs running so hot and shooting for where mine is running right now.

It's actually a little encouraging because I was hoping to completely revamp the entire cooling system in a few months when I can afford for the rig to be off the road for a little while. I'm talking hoodvents, CFS 3row radiator, Hesco water pump, hesco 180 thermostat, hesco thermostat housing, 272310 NAPA fan clutch...the whole shabang!!!! Now I can spend that money elsewhere!!!!!!!
 
OK, I'll tell you that running a cooler engine temp is detrimental. An engine-specific board I used to frequent, had a member cite an ASE study on engine operating temperature and wear. The study concluded that cylinder wear increased with a drop in operating temperature. It will take some time to find that post.

I also question when the ECU goes into closed loop mode. I had a RENIX Jeep that would not pass Colorado Emissions because of a faulty sender. Eflores hooked up his scanner and found the ECU never saw above 165*F because of that sender. Thus, the ECU was running in open loop mode the entire time.
 
Hypoid said:
OK, I'll tell you that running a cooler engine temp is detrimental. An engine-specific board I used to frequent, had a member cite an ASE study on engine operating temperature and wear. The study concluded that cylinder wear increased with a drop in operating temperature. It will take some time to find that post.

I also question when the ECU goes into closed loop mode. I had a RENIX Jeep that would not pass Colorado Emissions because of a faulty sender. Eflores hooked up his scanner and found the ECU never saw above 165*F because of that sender. Thus, the ECU was running in open loop mode the entire time.
Click to expand...

yeah but we are talking about engine temps above 180F, low but high enough to boil off moisture and allow proper warmup. And not low enough to get into poor oilling issues.
Sure the system is designed for 195F but it won't spontaneously explode or wear out at 180F

Hell, I've had my 180F thermo in since 142,000kms ... I'm now at 234,000kms ... sure, I plan to swap it out eventually. But, since I'm still hitting 22-23mpg on the highway so I'm in no rush (and that's with the overly rich Neon injectors in, and yes my speedo was recalibrated and checked against GPS). Winter warmups are only about 5 mins slower than with a 195F Thermo.
Point being it's not the "holy crap it'll blow up your motor" gloom and doom speak I keep hearing.
 
Found it, from 2004:

Torque1st said:
The SAE ran baseline engine and fuel consumption tests. They are published in SAE manuals that you can buy for $$$. I was lucky enuf to have access to them at a place I worked. There is one manual I would dearly like to have if anyone has a spare $400 that they want to give me... Anyway- The baseline for engine wear was picked to be 180°F for the SAE tests. For every 10°F under that temp engine wear doubled. So at 160°F the engine is wearing at 4 times the rate as it would a 180°F. The paper did not go into higher temp applications but it follows that engine wear is probably halved at 190°F. This wear rate is caused by a chemical reaction that occurs at the cylinder wall that erodes the cast iron surface. The resulting particles of cast iron that are released also abrade the cylinder walls. The rings, bearings, and other engine components also wear more rapidly due to these particles carried in the oil. An oil filter only removes a certain % of the particles on each pass (called a beta ratio by filtration Engineers). So the more particles produced the more circulate in the oil. Each particle abrades all of the surfaces it comes in contact with and produces more particles. This wear mechanism does not have anything to do with the oil film. The fuel consumption per brake HP also increased at temperatures under 180°F but I can not remember those figures. You can see the effects of engine coolant induced wear rates on many inline-6 engines where the #1 cylinder has a much higher wear rate than the rest of the cylinders. Check a few of those engines in the junkyard and feel the ridge on #1 and compare it to #4,5, or 6... Increased engine temps are just one of the reason we see higher engine life from newer engines. Even higher engine temps get into other problems with material breakdown and degradation.
Click to expand...
So the paper did not cover temperatures above 180*. The guy who cited the study made his own extrapolation, based on those observations.
 
Devilfrog said:
Point being it's not the "holy crap it'll blow up your motor" gloom and doom speak I keep hearing.
Click to expand...
I appreciate all that. I'm still not convinced that a clean, adequate cooling system needs the earlier opening temp.
 
Never said it needs it, doesn't really, but if you have it (like the OP suspects) it's not like the motor will blow up anytime tomorrow so to say. I put mine in on purpose a while back and have just been lazy swapping it out ... my reasoning was to do with the 0331 head issue and when it started to run hot I had time before hitting the critical danger zone. Which it did, and I caught it before I had coolant mixing.
That being said ... it's on the list.

FYI - even with the 180 in place the engine will still run up to temp in stop and go traffic in the city but doesn't go past just left of 210/100 (that's with new fan clutch, new rad, new water pump and hoses) there are no issues wrong with my cooling system ... but the low temp point is now 180 as opposed to 195.
 
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