Wants to overheat in extreme cold weather?

[MarkinWMich]

Coming home from work last night. Wind chill well below zero, wind howling, blinding snow. Highway driving, but only at a steady 40mph. In 4HI, driving just fine, then I notice the coolant temp. guage climbing about 3/4 the way up...something it has never done. I put a new thermostat in it a few months ago, flushed and refilled the coolant, the old coolant was clean and the aluminum inside the radiator and intake appeared shiny and clean, no pitting. The fluid level appears normal in the reservoir. The engine oil is full and clean. The drivetrain was regreased and diff. fluids topped off about 6 weeks ago....although there is a slow drip from the front left differential seal...but not enough to drain all the fluid...I don't think.

So, here's the deal. I turn up the heater fan to max. and take it out of 4HI and put it in 2HI...the coolant temp. drops back down to normal. I get off the highway, close to home,...roads not plowed. Put it back in 4HI, no issues, drives just fine.

Anyone have any "wierd" behavior like this before? Is this a prediction of future problems with the coolant pump? Could low front diff. fluid cause enough resistance to cause the engine to overheat...but still drive just fine? No apparent noises, growling, howling, etc. that I could tell. With the extreme cold, I am getting a bit of a "screach" from the engine for a split second, or so upon initial start up first thing in the morning...later on, it doesn't do it.

 

[my92t4r]

fan clutch? therrmostat @ 6 oclock? air bubbles in system and why would you, "Wants to overheat in extreme cold weather?"

 

[MarkinWMich]

Fan clutch...probably my "screach" when I start the engine? The thermostat and coolant have been in the engine for a while without any issues, plus the heater seems to work well,...so I am leaning away from trapped air or a sticky thermostat,...but I'll keep an open mind until I get it sorted out.

The engine has 126K on it. It's about due to start having problems with the coolant pump,...and fan clutch...thanks.

 

[radlynx]

it will overheat if the thermostat don't open to let the coolant flow to the radiator. it could be that during that very cold weather, it got stuck and did not open rightaway.. at this temperature, even if you have a malfunctioning fan clutch, it will still cool down your engine. does it make sense? give it a test a couple more time and see if you get the same problem

 

[preacher35]

Any liquid cooled motor can overheat in sub-freezing temperatures if there is not a consistent flow of coolant. Your random/sporadic overheating issue could be indicative of a bad thermostat (even a newly installed, aftermarket one). However, you still may be low on coolant, REGARDLESS of what you see in the "reservoir". When a contemporary, liquid cooled motor over heats, coolant blows back (from pressure), into the reservoir, giving the "appearance" that you have plenty in there. Do not wonder or experiment as you do NOT want your motor to overheat again as you could create other issues (like laying the foundation for your head gasket blowing) or causing the transmission to overheat and get damaged (yes, it can happen). Get it checked out as soon as possible.

 

[BlackWorksInc]

Radiator iced over maybe? I know truckers restrict airflow to the radiator in cold weather for some reason, I always assumed it was to help keep the engine at operating temperature.

 

[RPS13]

Classic symptom of low coolant. I bet you've got a coolant leak, check it when cold and I bet it's low.

Also betting it's a weeping water pump. Look for traces of your color (hopefully pink) coolant coming out from the bottom snout of the water pump.

 

[RPS13]

BTW, on many cars turning on the heater will cool down the coolant circulating around the temp sensor, but NOT cool down the engine much more when the coolant is low. If you've got an aftermarket gauge on the coolant outlet, this is very apparent if this happens to you.

 

[MarkinWMich]

Fan Clutch

I checked everything out this morning. Cold coolant level...full. No evidence of leaking around the pump, hoses, etc. Fan clutch spins easily when cold, no evidence of loose bearings at the pump or clutch. Take it out for a drive in 4HI, heater on low. Get it up to operating temp., heater blows hot, temp. guage reading normal. Drive it around town for a few more miles, stop in a parking lot, engine running, pop the hood, no excess temp., no smell of coolant, pulleys quiet. Turn off the engine, and check the fan clutch...still spinning easily...it didn't tighten up once it warmed up.

Good news is that I drove it home without any evidence of overheating. Got in the driveway, sat in park, revved the engine at 2000, 2500, and 3000 rpm for about 5 min....no overheating. Popped the hood, turn off the engine, fan spins easily, but it would appear that the rest of the cooling system is working normally.

So, Rockauto has got an OEM fan clutch for $90. Should be an easy swap.

 

[RPS13]

That would do it too, but odd it's completely loose. Been known to happen though.

You should hear the fan spin up on a cold start then the fan clutch still start to slip and the fan will quiet down.

 

[MarkinWMich]

That would do it too, but odd it's completely loose. Been known to happen though.

You should hear the fan spin up on a cold start then the fan clutch still start to slip and the fan will quiet down.

Mine appears to be slipping all the time, regardless of temp. Sure, there is enough resistance to spin the fan, and it seems to spin just fine upon visual inspection when at idle. My Toyota repair manual says when it is cold, the fan should spin freely...well, there is a little bit of resistance, but it spins easily with a flick of a finger. When the engine is hot, some resistance should be felt. If it turns easily, replace the fan clutch. There was no change, at all, with mine...it didn't tighten up to make the fan turn faster.

So, low speed, short distance driving around town,...probably not enough to load the engine and test the cooling system. Probably why it was overlooked. It wasn't until it was loaded with caked on ice and snow, 4WD, going up against a head wind, that the engine got hot enough warrant a higher fan speed...and failed.

 

[beefed88]

Get an antifreeze tester. My bet is you had a frozen hose and there was no circulation. How did you mix the coolant when you did the thermostat? I had the same thing happen in Texas because I had mixed the coolant a tad light and we had below normal temps.

 

[MarkinWMich]

Prestone 50/50 w/ Hyper-lube coolant additive.

 

[ebg18t]

Prestone 50/50 w/ Hyper-lube coolant additive.

Why did you chose that over the OEM Antifreeze?

I am not 100% convinced it is the fan clutch.

Several years back I had my wife's coolant system flushed 'profesionally'. It turned out they used a premixed coolant, the wrong coolant (separate issue) that in super cold weather would freeze/start to freeze. It damaged the electronic thermostat and ended up icing which caused a clog and led to overheating.

Based on your temps up there I suspect some freezing/clogging in the hoses. Especially since you were ok during the summer.

 

[MarkinWMich]

Using my Prestone tester, the needle was reading -45F/-43C...basically the lowest available reading.

The new Prestone 50/50 mix with their "Cor-Guard" additive meets or exceeds all manufacturers requirements and will not void any warranties. Using the Hy-Per lube coolant additive further enhances the lubrication and surfactant activities to promote better heat transfer.

http://youtu.be/1MtFKlrmOgs
New Prestone with Cor-guard Inhibitors

hyperlube.com
Hy-Per Lube Super Coolant

At any rate, there is no need for a "this product is better than that" pissing match. I've used Prestone in it since 2008. The dealership said nothing to me, ever. I've used Prestone in all my vehicles since the mid-1980's without issue. I really do not think the coolant had anything to do with the situation, since I've already found the problem with the fan clutch.

Thanks for your thoughts. Peace...

 

[Jeremy556]

Going 40mph, the fan clutch doesn't matter. My vote goes to crap replacement thermostat or air bubble(s).