Overheating at low speed (new coolant, new tstat, new fan clutch)

[winkosmosis]

The temp sensor is what my Scangauge is getting its readings from though isn't it?

I think turning on the AC drops the temperature about 5 degrees. WTF? I thought they stopped linking the AC and efan around 1997.

Today when I got out to open the gate, I felt in front of the grill. The coolant temp was at least 220F, probably 225F. On the right side air was flowing in, but on the left side hot air was coming out. Then a few seconds later the efan turned on and started sucking air in just like the other side. Shouldn't the efan have been spinning the whole time?

 

[winkosmosis]

Here's the pic of my fan shroud. Is it supposed to be enclosed only at the top like this?



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[MoFo]

You need to replace that fan shroud, it is broken.
If you decide to replace your fan clutch, you may want to use a ZJ clutch. the ZJ clutch has been discussed a few times on here. Do a search, so you know which ZJ clutch to get. Since that clutch spins the fan quicker, be warned as it will make more noise

 

[ehall]

210-220 at highway speed is way too hot. You don't have a problem with fans (they aren't needed at highway), you have a blockage somewhere that is limiting the ability to transfer heat out of the engine. Could be something in the radiator limiting heat transfer (my last time was from rubber particles in the coolant from a hose that was rotting on the inside). Could also be blocked cat converter limiting exhaust flow, although you'd probably notice loss of power too. My advice is dump the coolant and do a bunch of flushes. Make sure to drain through multiple locations, and to bring the engine to full temperature with each flush.

 

[winkosmosis]

You need to replace that fan shroud, it is broken.
If you decide to replace your fan clutch, you may want to use a ZJ clutch. the ZJ clutch has been discussed a few times on here. Do a search, so you know which ZJ clutch to get. Since that clutch spins the fan quicker, be warned as it will make more noise

It looks like someone cut it really cleanly with a hot blade or something. I don't understand how or why... Maybe someone thought that was easier than unscrewing the shroud??

I had Sears replace the clutch the new one really seems to be bad too... Now that the original clutch is out, the bolts should be easy to remove myself so I can upgrade to the ZJ clutch.

 

[winkosmosis]

210-220 at highway speed is way too hot. You don't have a problem with fans (they aren't needed at highway), you have a blockage somewhere that is limiting the ability to transfer heat out of the engine. Could be something in the radiator limiting heat transfer (my last time was from rubber particles in the coolant from a hose that was rotting on the inside). Could also be blocked cat converter limiting exhaust flow, although you'd probably notice loss of power too. My advice is dump the coolant and do a bunch of flushes. Make sure to drain through multiple locations, and to bring the engine to full temperature with each flush.

Well highway speeds on Maui top out at 55mph. Yesterday at 55 It was about 205. Then when I got to a light the temp would rise. Around 35-45 it hovers around 210-215.

I guess for a blockage I'd have to find a shop that actually flushes, or get a whole new radiator and hoses right?

 

[ehall]

just break up the gunk or get it out of the coolant... when I first got my beater and flushed it, a chunk of dried yellow coolant came out the heater lines, looked like a clump of straw

now I disconnect everything and run tap water through every orifice I can find

 

[winkosmosis]

just break up the gunk or get it out of the coolant... when I first got my beater and flushed it, a chunk of dried yellow coolant came out the heater lines, looked like a clump of straw

now I disconnect everything and run tap water through every orifice I can find

I wish I could do that.

BTW the old coolant was red. The new stuff Sears put in is green. That's the right stuff isn't it? Could the red have cause corrosion?

 

[ehall]

red might be dexcool, which is usually orange. that is sold as a "long-life" coolant since it's supposedly good for ~5 years instead of ~3 years like the green stuff. however it tends to turn into a brown wax after a while so it can cause some problems if its not maintained. if it's just a couple years old then I'd dump it and switch back to the green stuff, keep a maintenance diary and you won't need anything else

 

[winkosmosis]

I don't think the orange stuff was that old, probably 2 years old. My dad was telling me the previous owner had just changed the water pump himself when I bought it 2 years ago. I forgot about that, but now that I know it's pretty new I'm guessing the pump is fine.

My brother thinks it's a blockage too. He's a Ford tech but he lives in TX so he can't look at it himself. He did say that the water pump either works or it doesn't.

 

[winkosmosis]

I wish the Scangauge could function as a data logger. I'd love to make some graphs comparing speed with temp, rpm with temp, etc.

 

[winkosmosis]

OK, I think we can rule out airflow being a problem. I drove to the upcountry today, which includes a long straight stretch of 55mph highway uphill. I was at 230F all the way up. Going back down (steep enough to require zero throttle) I was at 205F. So it does sound like a clog or something other than airflow is causing poor cooling efficiency.

 

[spat70]

I know it might of been covered. But Down here in FL it gets really hot out. Every XJ I get my hands on I put in a new water pump, tstat, Hoses, fan clutch and flush the heater core out really good.

I use the 2 core all copper ones from Advance ($150). After doing all of this I cant get the temp over 210, that is with the a/c on and the fan disconnected.

We all know that heat kills the 4.0, one good overheating can crack the head.
I take no chances, so far so good! (AFTER I LEARNED MY LESSON)

I have done all of the above with the cheap aluminum single core radiator and had it run hot in traffic, so never again. ONLY GET 2 CORE)!
The parts house will have it listed as "Extreme Duty"

Maybe you should just do the entire cooling system if you plan on keeping this XJ alive for a while.

 

[winkosmosis]

OK, I'll get a copper if I replace the radiator. NAPA sells one with metal tanks. Their aluminum one has plastic tanks.

Maybe I would have just replaced the whole cooling system if I knew it was so hard to diagnose. I've spent about $300 so far and a lot of that will have to be redone if I get the rad and hoses and heater core and whatever else replaced.

I wish vehicles were still air cooled, this liquid system is a mess.

Man, an 11 year old XJ is expensive. I just spent $800 on the rear main seal and timing belt. Now because it's impossible to diagnose my overheating without tearing the whole thing apart, at which point everything might as well be replaced, for another $1000? Better pull more money out of my IRA!

 

[winkosmosis]

According to the FSM, running hot while in slow traffic or uphill is normal. I guess this doesn't apply to me because it was at 230F going uphill at 55mph, but it shows that they really did intentionally give the XJ a crappy cooling system.

 

[winkosmosis]

I'm starting to think it's airflow again. Like I said it will reach 230F going 55mph up a slight grade... But intake air temp is also high every time it gets that hot.


Hmmm. Maybe I need to powerwash the hell out of my radiator.

 

[Digger87xj]

I'm having the same problems with my '93. I am a 25 year veteran tech and this problem is dogging me like a komodo dragon on a water buffalo.

New everything, and a ZJ fan clutch. better, but still gets HOT uphill

Heading into changing the head gasket next... steam ports must be clogged not allowing enough flow through the engine.

 

[joe_peters]

I'm having the same problems with my '93. I am a 25 year veteran tech and this problem is dogging me like a komodo dragon on a water buffalo.

New everything, and a ZJ fan clutch. better, but still gets HOT uphill

Heading into changing the head gasket next... steam ports must be clogged not allowing enough flow through the engine.

Have you tried running a commercial grade flush--the 500 mile kind?

 

[Digger87xj]

no I have not. the engine has over 230K... I'm thinking it's time for a new one anyhoo...

Also... afraid that a chemical flush may open up other cans of worms...namely the heater core. Not looking forward to that one, as it has the rockhard internal cage.

 

[joe_peters]

no I have not. the engine has over 230K... I'm thinking it's time for a new one anyhoo...

Also... afraid that a chemical flush may open up other cans of worms...namely the heater core. Not looking forward to that one, as it has the rockhard internal cage.

Rig a bypass hose so the flush doesn't go through the heater core.