YAOT (yet another overheating thread)

01 XJ, new-to-me 01 motor (unknown mileage), 6mo old flowkooler water pump, 3day old CSF 3row radiator, 3day old Stant premium 195* tstat, 3day old Stant radiator cap, original hoses (still firm, no collapsing), unknown age fan clutch, 1600cfm 10" e-fan, lebaron vents, original A/C condenser (fins look good).

In 90* ambient temps, temp rose to and held at 215 in 5 minutes of surface roads, and dropped to 210 once on the highway. Drove 8 minutes at highway speeds, then exited back onto surface roads. Temp slowly climbed to 220 and peaked at 230 sitting at a redlight. Dropped to 225 on a faster road, and dropped back down to 220 after 5 minutes on the highway, but that was all. Wouldn't drop any lower. All temps approximate, shown on both dash gauge and scangauge.

I believe the fan clutch needs to be replaced (marginal resistance when hot) and the e-fan is sub-optimal, but that doesn't make any sense as to why it's not cooling at speed. Both the upper and lower hoses are hot, so I'd assume the water pump is working.

The only thing that makes sense is that the engine is simply running hot (lean?). How can I confirm that? It's possible the original 02 sensors are worn out and not giving correct readings.

Couple of things:

The fan clutch should still be turning the fan at 30 percent of shaft speed even when disengaged. If the clutch has failed you have lost that much pulling of air, even at highway speeds. While we all like to say straight air flow is enough at highway speeds, I think we take for granted that the fan is pulling a little.

(An interesting experiment would be a highway run with a good standard fan clutch, then a second highway run with the fan removed--using an electric fan to get you onto the highway w/o overheating totally.)

Next, what is your coolant mixture? If 50/50 cut it to 30/70--30 ethylene glycol and 70 distilled water. Ethylene glycol is a good anti-freeze and a lousy cooling agent.

Now, all that said, what HEAD is on that engine? Looking at your posts you probably have seen the discussions on the 0331 casting.

I'm sure that puny e-fan won't pull enough air to keep it from blowing up, it's just a bandaid until I can figure out how to mount a stock e-fan without it getting chewed up by the PS pulley. I do have a new stock clutch ready to go in, but was considering taking it back to swap for the ZJ clutch.

50/50, keep forgetting to pick up some distilled water.

It's the cursed 0331 head, I don't think it's cracked yet, guy I bought the motor from said it was pulled from a wrecked XJ with no problems. Oil pressure is good, 40-60psi idle/power. No signs of oil in the coolant or coolant in oil (unlike the motor this one replaced).

So, I just finished jumping the hoops on an iverheat issue. Put in the ZJ fan clutch (interesting whistle...), no help. Flushed the bejeezus out of it (interesting that it drained out BLACK), no help. Today, I replaced the radiator with a bright shiny new one. Problem solved. Just for gits and shiggles, I opened up the factory radiator and it was essentially totally plugged. I would hae been running flush chemicals for the next three years to get that junk ou...

o-gauge-steamer said:

So, I just finished jumping the hoops on an iverheat issue. Put in the ZJ fan clutch (interesting whistle...), no help. Flushed the bejeezus out of it (interesting that it drained out BLACK), no help. Today, I replaced the radiator with a bright shiny new one. Problem solved. Just for gits and shiggles, I opened up the factory radiator and it was essentially totally plugged. I would hae been running flush chemicals for the next three years to get that junk ou...

Click to expand...

Old radiator weigh a little bit more than the new one?

FYI--I use the 15 minute flush on even years and the 3-6 hour cleaners on odd years as routine maintenance. I change the coolant on the odd years, just save and reuse it on the even years.

joe_peters said:

Old radiator weigh a little bit more than the new one?

FYI--I use the 15 minute flush on even years and the 3-6 hour cleaners on odd years as routine maintenance. I change the coolant on the odd years, just save and reuse it on the even years.

Click to expand...

Geez, even to me that sounds odd.

Yeah, but I when I scope my radiator--which appears to be OEM factory (I'm second owner)--the tubes still look good.

I would rank overheating engines up their with guns that won't shoot and lousy drivers as some of my worst peeves.

Plus, I'm anal retentive!

joe_peters said:

Yeah, but I when I scope my radiator--which appears to be OEM factory (I'm second owner)--the tubes still look good.

I would rank overheating engines up their with guns that won't shoot and lousy drivers as some of my worst peeves.

Plus, I'm anal retentive!

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Anal Retentive ?????

Sheesh ... whats that make me ???

I even throw the radiator away at about 5-6 yrs unless it checks out 100%.

Ever have any "overheating issues" because of your attention to detail, anal retentativeness/OCD condition, joe_peters ??? ...

I havent ....

No, other than personally overheating at the pool--bikinis!

Given that the XJ is notorious for radiators going south, Adding an annual or bi-annual flush is not that baad an idea. Coolant does not last forever and needs to be changed anyway. I'm going along with joe_peters on this one. Yah, I'm an old guy too... Easiear to flush than change a rad.

X3 on the anal retentive, old dude connection. I am pretty conspicuous on my maintenance. If the rad is in question, flush. If it's still a problem change coolant to 70-30. I just think that regular maintenance on fluids, and other (maybe not necessary) stuff will always prevent problems down the road. That's why I have a 20 year old Jeep with 230K on the clock that still passes CA smog like the day it was born.

I'm with the old dudes.

cruiser54 said:

Geez, even to me that sounds odd.

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That was supposed to be a play on words.:yelclap:

installed the stock-spec fan clutch and went for another test drive. Temp stayed much lower, but the ambient temperatures was 20* lower than the previous trips thanks to a cold front that just brought in a nice storm. Temp was holding at 209 on the local roads and dropped to 206-207 once at speed (55-60), under extra load (slight upgrade and accelerating to 70) the temp went up to 211, but dropped as soon as the load decreased.

Back on local roads, temp was holding around 210. Stopped in a parking lot and sat for 10 minutes, temp climbed to 220 but start dropping on the local roads. Back on the highway and dropped to 207 again.

So, looks like airflow is a significant factor! I am wondering if the hood vents could be hurting the airflow... I'll try to rig up blocking plates for them. That and see about finding a stronger electric fan.

Will also try removing the thermostat and see how it performs then. If the temp stays under 211 even at idle, I'll probably get a 180* thermostat to replace the 195* one I have now. A bandaid, I know... but I want to keep it cool until I can figure out what else is wrong. Maybe try this tomorrow before going to work. Will repeat the above test drive first, since the weather forecast is calling for more heat again.

One thing to note, I don't have a shroud for the clutch fan. It won't fit between the fan and the CSF radiator. I think I can trim off a bit of the bottom to make it fit, though. I'll try that tomorrow as well before doing the test drive.

Second note, I could see heat pouring out of the hood vents when parked. I couldn't see that the other day. Proof that the new fan clutch is working a lot better!

Yeah, you lose a lot of efficiency without a shroud.

Changing the thermostat really doesn't help. If the system is going to reach 210, then that is where it is headed even without a thermostat.

ok ok.. this thread is a year old, I know. But I finally fixed the overheating issue recently and seeing the other cooling threads being started and bumped reminded me about this. Maybe my troubles will help somebody else.

The Flowkooler pump turned out to be bad. It blew up a couple weeks after the original post. Replaced it under warranty and the new one has been working fine for the past year. Replaced the thermostat with a 180* version at the same time. Temps were fine over the winter, but when the ambient temps started getting into the upper 80s, the engine temp started getting higher... creeping up over 220 when not moving. Even hit 240 once when I left it idling in my driveway. Ooops. Would only get down to 210-215 range with the A/C off and cruising around 40mph, but it would take a while.

So, time to revisit the auxiliary fan! As posted above, I was using a 10" electric fan similar to the one Dirtbound Offroad uses in their kit. However, the airflow was minimal compared to a stock fan. I went to a junkyard and picked up a stock XJ fan and squeezed it into my XJ. Plugged it in, dead. Grumble... So I picked up a new aftermarket fan from Quadratec, opened the box at the warehouse to confirm it had the s-blade 10 fan setup and left the box there. (The local parts stores don't carry the 10 blade fan) Got home, and it doesn't fit. The aftermarket stock type fans are a little thicker than an OEM fan. I had run into an issue with this before, the fan was rubbing on the power steering pulley. I guess due to an aftermarket fender being a little bit shorter?

So, I looked behind me in the driveway and went inside to grab my brothers XJ keys off the shelf. Opened the hood, removed his circa-2000 fan and replaced it with the Quadratec fan (fits fine) and stick his fan in my XJ. Fits, but just barely. More importantly... it works! Temps since then have been up into the upper 90s and I believe hit 100 a couple times. Even with the A/C on, the highest engine temp my XJ has seen is 214*. Usually down closer to 204, down in the 190s with the A/C off.

The "works for me" configuration... CSF 3-row radiator (copper/steel), Flowkooler water pump, 180* Stant Superstat, pep boys fan clutch, oem fan (no shroud), oem aux. fan. roughly 40/60 coolant/water mix, lebaron hood vents. The hood vents have eliminated the heat-soak problem I had before after adding the Banks header.

All engine temps per my ScanGuageII reading the ECU, not guessing from the dash guage.

I want to add that I was very tempted to get the 3-fan with shroud kit from DirtBound, but figured I would try replacing the auxiliary fan first since it would be faster than waiting for shipping from the west coast. I'm still very curious to see how their kit would work for me, but since it's fixed... I don't have a real need to tear it apart again.