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Running hot... really hot.

17K views 92 replies 20 participants last post by  Bos-R/T 
#1 ·
Ok, so I realise it's a 9 year old truck with 90,000 miles on it, but it's also been well maintained. Even the coolant was changed last year, well before the interval.

Tonight when I got home from driving to and from Branson to SPFD, 1 hour each way, and towing my boat a total of 6 miles, and running the ac, the truck was literally on it's last leg. It's like it had run a marathon after smoking a pack of cigs. I opened the hood, and although there was no steam, every surface under the hood was hot. Obvoulsly hot engine = less power.
You would think with the heat extractor hood, fairly new coolant, and running at highway speeds that the truck wouldn't be running so hot.

Should I add a 180 degree thermostat to the truck, would that be of any benefit? :huh: Could the coolant have "failed" should I have that checked?

Can I trust the factory temp gauge? It didn't read over straight up.

( There's no way this could be connected to recently installed 4.10 gears? My RPm's aren't that much higher...)
 
#4 ·
Red Hot, Red Hot
To the top, we are Red hot
http://www.youtube.com/watch?v=qZN5h8mQmoo

I had the same problem you're describing...

My truck was running hot and would overheat with the a/c on, I flushed the radiator and switched to an electric fan from a 2000 windstar Im running both fans at top speed and I can open the hood or touch the fenders without burning myself

before doing both these things I had heat from the engine coming into the cab and I'd actually start sweating by standing near the front wheel wells with my truck running from the excessive heat it was producing,

my engine probably has over 200k miles on it and was completely rebuilt a month ago, I'm running it without a t-stat but I'm going to make time to put one in

factory temp gauge (before t-stat and e-fan) at operating temperature normally shows around 212F, if it goes over that it means there could be a problem, don't trust that gauge though, try some aftermarket gauges for proper readings
 
#5 ·
Engine bay temperature is no indication of an engine running hot or not. If the temp gauge never went over halfway, the coolant isn't boiling, it has never overheated before then I think that you can trust the temp gauge. There are some engine components that are alot hotter than the engines coolant temp, that along with a nice warm day and the demand that you were placing on the truck at the time would make for one hot engine bay.

Did the truck just seem a little sluggish or what????
 
#6 ·
Yeah if it's hot it'll sound like a toilet flushing; because your coolent will boil into the overflow tank.
If it sounds like a jet engine and feels sluggish, welcome to summer baby:jester:, the fan clutch engages and sucks juice and hot air is less dense then cold air thus bringing in less fuel and making less power.
 
#7 ·
Yeah, never past 12 o'clock on the gauge isn't that hot. I wouldn't worry about it.

I was hauling my trailer with the RZR and two other quads last weekend (total weight 3-3300lb)...came across a windy ass long hill. Probably a mile and a half up, 25mph tops in 2nd gear. Shortly before the top, the gauge creeped over 12 o-clock and the trans started locking the TC in 2nd which means trans temp over 240 and/or coolant temp over 244.

If I hauled this weight often, I'd look into doing something with the cooling system. But, I think it fared pretty well given that the TC generates a ton of heat when unlocked and I wasn't moving fast enough to get much air flow...never mind the restrictive SS inserts.
 
#8 ·
Sounds about right. Did you mix the coolant 50-50 MAX? Less is actually slightly better, you could also add Redline Water Wetter or a similar product to help heat transfer.

The under hood temps sounds right though, hot day and towing = heat :)

Though power shouldn't have decreased that much.
 
#9 ·
You may have a catcon that is getting hot and melting down causing the sluggishness.
Flush the cooling system, INCLUDING backflushing the heater core. Coolant always flows through it and contributes to coolant capacity.
If you have only a single row radiator, you need at double row for towing.
A friend had a 90s Ram van, 318. Always overheated in the summer. It had a single row rad, once it got old and dirty it wasn't enough to cool the engine.
A new double row unit cured it.
 
#12 ·
yup, got a little redline in mine too
 
#13 ·
If your cooling system is working properly, Water Wetter, etc won't do you a bit of good.
Guess what closes when the temp drops?

If you have lower than a 192 t-stat and you still run hot you have a mechanical problem.
If you have the 192 and it runs hot and you aren't in the desert, you still have a problem.
 
#14 ·
I'm having a similar problem. Every now and then in city driving, mine will creep above 12 o'clock. Oddly, mine hovers right around 180 for a long time, but then it'll start creeping up fairly quickly. I've flushed coolant twice and burped several times. I suspect my radiator is clogged. I'm going to replace it with a 2 core rad and upgrade my e-fan at the same time.
 
#22 ·
I didn't say the stat was the problem if it is overheating.
I said if it is overheating REGARDLESS OF THE THERMOSTAT RATING there is a problem that needs to be corrected.

Using the heater core is the same as adding another radiator, which I said needs to be done if the radiator is maxed out.

What was said was WW will make an engine run cooler if it is overheating..
My point is the mechanical problem needs to be fixed. If the radiator is the correct size and there is nothing mechanically wrong WW just drains your wallet, like snake oil and "vortex generators" and the like.

A correctly sized and operating cooling system will keep an engine in the correct operating temperature range.
Additives like WW cannot make a radiator transfer more heat to the air flowing through it if it is operating at its physical limits.
 
#26 ·
Well, an interesting development, my driver side rotor locked up. I'm wondering if it has been partially locked up for a while, and I just didn't notice it after upgrading to 4.10's.

I'm still probably going to change the thermostat and do the efan thing...
 
#27 ·
I finally got my gauges working, average temperature seems to be around 150-180 at the most

This is my truck without a t-stat and a dual 2000 Windstar e-fan setup running at top speed constantly.

unless I'm heavy on the gas it stays around 150-160, a/c running gets it to around 170, never creeps near 210F.

Its over 100F outside everyday so, keeping the truck cool is a good idea, especially since I overheated it a month ago
 
#30 ·
why would you run no thermostat? kinda stupid. the truck needs to get to operating temperatures or it will stays in open loop (180* it goes into closed loop) 195* is stock, why not put that in? or if u wanna stay cool put in a 180. but with all ur fans and wetting water stuff why not just run a 195?



just put in a t-stat and run it.
 
#29 ·
The brake calipers were defective on many of the 01's, I have had to replace both of mine.

You already have an efan :) They come stock. The stock efan is more than capable of cooling our trucks if the cooling system is in good shape - as an example, I use only the stock efan (have from day 1) on my 01 QC 5.9 4X4 and don't overheat even when pulling a 11,000-12,000 (total - truck n trailer) load whether through the mountains of WV or in South Florida during the summer.
This is with a stock thermostat and stock cooling system minus the crank driven fan.

I don't rec. boiling of the rad, if it is restricted just replace with a new HD version. I've seen to many fail not long afterwards over the years.
 
#31 · (Edited)
I'm not running a t-stat not because I think I shouldn't run one but because I've been too lazy to put it in, its actually sitting in my glove box

its also common practice here to remove the t-stat here in may and put it back in late october-november to prevent overheating, don't ask me why, everyone insists on not running a t-stat in the summer, so at my engine rebuild the guys decided to take it out and not tell me until the job was done
 
#33 ·
Normally an engine will overheat if the thermo is out because the thermo monitors the flow so the coolant stays longer in the radiator. If theres no thermo the coolant just flows at maximum not cooling down. If you can run no thermo in the 115 degree heat with high humidity then my hats off to you. Not everybody can. Depends on the climate and how long you are in stop and go traffic. My truck in this Alabama heat is a prime example.
And thats true too about it staying in open loop. It needs to be in closed loop.
 
#39 ·
"You are extremely lucky. I wish my truck would run that cool with just the factory efan. My truck will get in the 220's without the fan clutch. And not to be in any way at all but you are wrong on the fan clutch engaging because 230 degrees is way to hot to be waiting on the fan clutch to engage. You can here mine engage and its about 200 or 205 on the gauge. The factory efan cuts on at 215 if I remember right. Now thats stock.
Reply With Quote"

Different years viscous clutch engage at different temps, on my 01 it didn't fully lock until about 230, it STARTS to engage way before that. On the 99 it was much earlier. The fan itself is much larger and heavier on the 99 vs. 01.

I would have to check using the DRB3, but I thought my fan kicked on at about 215 and off at 205 or something like that. That is not hot and there is very little to be gained overall by running engines cool in normal street driving. 220 isn't that hot, I don't sweat it until over 250+ in all honesty.

But sitting still with your a/c off, the stock efan should cool your engine enough to cycle the efan on and off - even in 90 deg. days with high humidity.

One big thing is, antifreeze is only really good for 2-4 yrs. even the long life stuff - which does not impress me at all :)
 
#43 ·
50/50 aantifreeze/water boils at 223 degrees. You add a 15 PSI cap on there and, I think, it will raise it to around 250. I honestly will not allow my truck to get past 220. But thats just me. The a/c sucks at those engine temps too. I have a 180 thermo and am happy with my truck sitting at 200 in heavy traffic with the a/c blasting.
 
#40 ·
Oh and the no thermostat part is false if you are using that as a blanket statement.
Since the ASE only deals with stock factory setups, then their point is true - to a degree.

A restrictor can and will let cooling take place as well as a thermostat does. Without a restriction "some" but not all engines will run hotter than with a thermostat (which is a restrictor) under certain conditions.

A thermostat is nothing more than a variable restriction to adjust flow to maintain coolant temp. over a wide range of operating conditions.
 
#42 ·
ASE testing is multiple choice and very tricky at times because three of the answers could be right but one answer will have both of the other two answers in the one. If that makes sense to you. If I remember right the question is like " a car comes in and is overheating only during heavy traffic." And the answer would be something like "technician A says it has a bad water pump. Technician B says it has a stuck open thermostat. Technician C says it has a faulty cooling fan. Which one is right? Tech A? Tech B? Tech C? or Tech B&C?" The answer would be D= Tech B&C. Because both could be right. If you would have just answered C then it would have been wrong since B&C are both right.
You cant run without a thermo where im from in stop and go traffic. I have owned my shop for the past 17 years and have had tons of customers with a stuck wide open thermo complain of overheating in traffic. My 17 year old daughter blew a head gasket last year because she overheated it while sitting in 45 minutes of traffic stuck on 85 in Atlanta Ga. Guess what we found when we took the thermo out....? A stuck open thermo. Thats the only thing we replaced. The radiator and water pump had been replaced in the past.
The thermo will make an engine run cooler at highway speeds BUT will EVENTUALLY get more hot in traffic and not cool as good til you start getting down the road. I stand behind that and always will. Simply because I have seen it ALOT..:drive:
 
#45 ·
I set mine up to run hot, a 180 cost me driveability and mpg with no upside - but our weather is different than yours most of the year.

Not sure how a stuck open thermostat will overheat a stock auto - esp. since most are fully open at 195-200 deg. and most efans shut off before that point. Since that occurs, the thermostat would never close under those conditions.
Stuck closed will do it every time but I've never seen a stuck open (normal hot position) do it.
After all, the thermostat is by design fully open above the set point.

I'm not saying it can't or doesn't happen.

15 psi with pure water is about 250 depending on elevation.

Antifreeze doesn't do a whole lot for boiling point, it is mainly for low temp and anti corrosion.

Yea the a/c sucks with the higher temps but that is due to the lack of a bypass on the heater core.

The only thing I don't like about running hotter is the higher pressure, I personally would like a setup that will run 220 with no pressure :)
 
#47 ·
Well my truck is running at 210 and creeps above that when in stop and go traffic, already replaced the t-stat (180), raditor back in march, and still running above 210... Have a viper fan running on low at all times since my A/C is always on .. what should i look into next?

I was thinking about switching the wires on the fan controler to run high during the summer.. what do you guys think?
 
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