Cooling fan trick

[firemedic2714]

I was told by a mechanic that condensation in motor oil really doesn't start evaporating until temps hit 200° so, if the thermostat doesn't open until 220°, that sounds about right.

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[Stan H]

That is where I was going with the first comment. Back then engines ran cooler by design than they do now. While sure, plenty of well maintained engines did go over 100k, plenty of engines also failed or had major problems too. I worked as an automotive machinist in the 80s. I remember for awhile it was common to get those late 70's pontiac 301 V8s needing a top end rebuild by 75-80K because the oil in the top end had turned to sludge. You couldn't even see the valve springs or pushrods.
They were nasty.

And that was pretty much due to No one really used synthetics and the detergent packages in oils in the 70's and 80's sucked. I think that better oils have lent themselves to cleaner internals.

 

[ShadowsPapa]

I was told by a mechanic that condensation in motor oil really doesn't start evaporating until temps hit 200° so, if the thermostat doesn't open until 220°, that sounds about right.

Thermostats begin to open at the rated temperatures.
(years of testing and replacing and fixing cooling systems)
A 190 stat just begins to open - there's a spec of 0.xxx" at the spec'd temperature.
It would be fully open, depending on the thermostat, at 220, or even 224 for some stats and engines.
I've got the specs for some of the various stats used in the past in TSMs.
We tested them on a gas burner we used to heat up soldering coppers. A pan of water, thermometer, stat in the pan. You watched for it to hit the magic number stamped on the stat and see if it had opened the required fractions of an inch.
And then you took it up to the top temp where it should be fully open.
Some defective stats started to open at the required temp - but then never went all the way open, so you had to check it all the way through the range.
OR - just replace the damned thing! LOL

Yeah, it's around 200 where you start to get the moisture out. Doesn't need to "boil", but it DOES need to stay at that temperature for a while to finish the job. Hit a higher temp, you burn out the moisture faster. Get it up to 200 on a commute to work, then 2 minutes later park it, you aren't getting the job done.

Back then engines ran cooler by design than they do now.

Many engines in the late 60s through the 1970s - stat starts to open at 190. Doesn't fully open until about 225 or so. Then of course all of the emissions "crap" hung on engines in the 80s caused changes all over the place -50 feet of vacuum lines, different operating temperatures, EGR, lowered compression, it got crazy. The 80s was my least favorite decade for engines.

The bugger in all of this is that back then, you had a gauge with red at the top, green at the bottom, and no degree markings. A lot of assuming was done - hey, water boils at 212, my engine is running WAY too hot!

 

[NC_Overland]

I just read through all of this. I noticed when stuck in bad traffic the other day that it was hitting 220 degrees and the fan wasn’t coming on. It never went past 221-222. Is it really true that the fan doesn’t come on till 225? It runs 190-195 going down the hwy. I guess that’s normal?
Those transmission and oil temps ok?

2020 Overland with factory tow so it has the HD cooling.

 

[JohnWick]

The temps are fine.

This whole "200-220 is too hot" sentiment needs to die. It isn't too hot. Modern vehicles seldom run at 180 now.

 

[ShadowsPapa]

I just read through all of this. I noticed when stuck in bad traffic the other day that it was hitting 220 degrees and the fan wasn’t coming on. It never went past 221-222. Is it really true that the fan doesn’t come on till 225? It runs 190-195 going down the hwy. I guess that’s normal?
Those transmission and oil temps ok?

2020 Overland with factory tow so it has the HD cooling.

The @#$% thermostat doesn't even fully open until around 220.
It begins to open at over 200 degrees. (most say the rating for the factory stat is 203 - so far I've not seen anyone counter that)

EDIT:
I'm going to "second guess" that myself, I guess..........
I believe the real "just starts to open is ~195
Legacy stats have similar ranges, often 195 start to 225 fully open.
In this case, recalling my JT's temp swings and then on a trip back from a dentist this am, watching and the thing hovered around 195 - depending on hills, torque load on the engine, speed and other factors, but the number that kept sticking out was 195 And I believe someone in these forums said that long ago the stat range was 195 to 223 or there-abouts.

From a tech page - starts to open at ~195°F and is fully open by ~221°F

Edit of the edit - further digging found that "replacements that match factory specs" start to open at ~195 and that matches actual observation over the years.

IMO, your oil and transmission temps are plenty low.
We're talking modern fluids and a good oil handles a lot more heat than things from the 1980s.

The temps are fine.

This whole "200-220 is too hot" sentiment needs to die. It isn't too hot. Modern vehicles seldom run at 180 now.

Amen.
people are stuck in the past, or, not having seen actual temperature numbers before do some internet digging and find stuff that is just wrong or OLD.
You should see what AMSOIL says their oil will handle without flinching.
Others aren't far behind.

 

[Stan H]

The temps are fine.

This whole "200-220 is too hot" sentiment needs to die. It isn't too hot. Modern vehicles seldom run at 180 now.

Well said
Oh and P.S. I really liked your movies .

 

[NC_Overland]

The @#$% thermostat doesn't even fully open until around 220.
It begins to open at over 200 degrees. (most say the rating for the factory stat is 203 - so far I've not seen anyone counter that)
IMO, your oil and transmission temps are plenty low.
We're talking modern fluids and a good oil handles a lot more heat than things from the 1980s.

Is it true that the fan doesn’t come on till 225? I think mine might be malfunctioning because I leave it in auto year round with the AC on and I never see it come on and it should be on with the AC.

 

[JohnWick]

Well said
Oh and P.S. I really liked your movies .

On IG? What is your handle?

 

[JohnWick]

Is it true that the fan doesn’t come on till 225? I think mine might be malfunctioning because I leave it in auto year round with the AC on and I never see it come on and it should be on with the AC.

It may or may not come on with the AC.

Usually the fan will get a command to come on when the high side pressure rises to a certain threshold, if you are going down the road with airflow to the condenser then it might never come on.

Also this is just a general guess as I do not know the specific A/C fan control logic of the Gladiator.

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