International Full Size Jeep Association
Home Forums Reader's Rigs Tech Library Trail Stories FSJ-List
International Full Size Jeep Association  

Go Back   International Full Size Jeep Association > Tire Kickin' > General Chit-Chat

View Poll Results: Will an engine over heat without a thermostat?
Nope! It will never reach operating temp 15 88.24%
Yes! Don't do it! You will over heat! 2 11.76%
Voters: 17. You may not vote on this poll

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 02-19-2021, 12:10 PM
rang-a-stang's Avatar
rang-a-stang rang-a-stang is offline
Administrator
 
Join Date: Oct 31, 2016
Location: Camarillo, CA
Posts: 4,068
Will an engine over heat without a thermostat? Vote here!

If you spend any time surfing the web, there are two schools of thought here:
1) if you remove your thermostat, the engine will never reach operating temp. Coolant will flow through the radiator and always be cold. This prevents the engine from running at the temp it is supposed to, increasing wear, fuel consumption, smog, etc. ALWAYS RUN A T-STAT because it is bad for your engine since it will never reach operating temp!

2) If you remove your thermostat, the engine will take a long time to warm up, but then will keep going and overheat because the coolant does not have time to exchange it's heat in the radiator. The Thermostat slows the coolant flow down in the radiator to help cool it down and let the engine run at normal temps. ALWAYS RUN A T-STAT because you will overheat your engine!

SO! I have the ability to record my engine temp, RPM, Speed, and run time, and graph them together. So let's do it! Let's see what happens! For the record, I have a bent toward the school of thought #1 above.

Test configuration:
1979 Jeep Cherokee, 401 (.030 over), mild cam, iron heads, TBI ontop of a Edelbroke performer, Hedman Headers to a single 3" exhaust, BJs Crossflow Radiator with electric fan (fan only comes on below 25MPH) and shroud, about a 60% Distilled water to 40% universal coolant mix, TH400, QT in 2WD front hubs unlocked, 3.55 gears, 33.2" tall tires, heater will remain off for the entirety of the test and the temperature mix switch will be in the cold position.
Test route:
I will drive my truck to work on my normal route (about 18 miles, no freeway, mostly 2 lane, 55mph, flat road with some lights and some street driving). I will start data recording before I start my truck and stop recording when I get to my destination.

Control test:
Monday 22 Feb, I will drive my truck to work in the morning, then home in stock configuration with a 195 degree T-Stat. I will log data both ways and show the graph on here. Weather guessers are saying 80 degrees and sunny in Camarillo for Monday and I work in Port Hueneme which they say is 72 and sunny on Monday.

So... will it overheat? or will it never reach operating temp? Vote here! Let's see what happens!
__________________
79 Cherokee Chief (passed CA smog check Sept 2020)
(Cherokee Build Thread)
11 Nissan Pathfinder Silver Edition 4x4
09 Mazdaspeed3 Grand Touring

Last edited by rang-a-stang : 02-20-2021 at 01:36 AM.
Reply With Quote
  #2  
Old 02-19-2021, 01:03 PM
iapexl8r's Avatar
iapexl8r iapexl8r is offline
232 I6
 
Join Date: Jul 06, 2018
Location: Nort Idaho
Posts: 66
The jeep IMO will not overheat. but running without a thermostat will let the motor swing in temp with airflow, rpm and OAT. This will effect fuel economy and possibly the operation of the heater. could it be a factor in overheating yes I think it could overheat given the right circumstances.


My jeep had the waterpump bypass hose ran from the upper connection of the water pump to the radiator (basically bypassing the thermostat), in the summer warm weather this was fine although I did notice larger than normal temp swings. But when I drove it into cold temps the engine did not run right and the heater blew cold air,I had to put cardboard infront of radiator to get the motor to run at 160f.


I did not vote because there is no other box to check or even a yes to both never reaching operating temp and overheat.
__________________
1976 Cherokee chief
1970 AMC rebel THE MACHINE
1969 AMX
1965 mustang fastback
1972 international travelette
Yes I have a problem that’s why Iam here

Last edited by iapexl8r : 02-19-2021 at 01:28 PM.
Reply With Quote
  #3  
Old 02-19-2021, 02:10 PM
Heep-J4000's Avatar
Heep-J4000 Heep-J4000 is offline
258 I6
 
Join Date: Feb 09, 2014
Location: Schoorl ,the Nederlands
Posts: 316
No a engine Wil not overheat!

It takes more time to get on a higher temperature ,but would not get at the correct working temperature.

I did have a stuck open thermostat in my dodge 2500 with Cummins 24 valve engine two weeks ago , and along the drive in the morning i did recognise that there was something not like it should. (Stuck thermostat or low coolant niveau)
The heater did not blow warm and the temperature gauge didn't get at the number it normally does.

The engine sounded normal as always and the truck did drive as it does everyday ,so it was not a big problem.
But checked and replaced the thermostat later that day.

btw , the thermostat came from Rockauto and it was the second thermostat in two years that broke down.
FYI it was the cheapest thermostat available.

And about a electric or manual fan ,I say the manual fan is the best for cooling but the fan shroud needs to be there and also match the fan.
Together they do wat they are developed for.
I'm not a fan of a electric fan , have seen enough overheating problems with them.
(Most were builds and or project cars and after putting a manual fan back on with a shroud cooling worked spotless.)
__________________
Jeep "because mother nature hates flat roads to"

http://www.ifsja.org/forums/vb/showthread.php?t=180974

99' Dodge ram 2500 4x4 crew cab 5.9 Cummins ,backup work truck for now
73' Jeep J4000 (named Heep or Desert Dragon) amc 360 V8 converted to LPG with T15/D20 (was my daily work truck for thirteen years and is going to have major overhaul
80' Jeep cj5 350 V8 Chevy/ms420/D300 (a slow ongoing never finished project)

Trucks/car's from the past:
85' Volkswagen caddy mk1 1.6 diesel.
83 Toyota land cruiser BJ42 3.4 diesel.
Reply With Quote
  #4  
Old 02-19-2021, 04:40 PM
SJTD SJTD is offline
304 AMC
 
Join Date: Apr 26, 2012
Location: Lompoc and Sunland, CA
Posts: 1,618
Someone will want to say it will run hotter because the water passes through the radiator to fast to loose heat completely ignoring that IF that were true it would also be flowing too fast through the engine to pick up heat.
__________________
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.
Reply With Quote
  #5  
Old 02-19-2021, 08:22 PM
jeepman42 jeepman42 is offline
232 I6
 
Join Date: Mar 13, 2019
Location: porter tx.
Posts: 57
To heck with the jeep temp;I'm impressed with the temp prediction of 72-80 degrees Mon. No wonder my brother lives in Long Beach and not in Texas anymore- especially after this last week! Cheers to warm weather!!
__________________
Easy doesn't do it!!
Reply With Quote
  #6  
Old 02-20-2021, 11:24 PM
MysticRob MysticRob is offline
327 Rambler
 
Join Date: Nov 26, 2019
Location: Boise, ID
Posts: 519
I voted that it won't overheat. Might take forever to warm up in colder temps but with coolant constantly circulating with no thermostat, I don't see how it could possibly overheat.
__________________
--Rob--
1988 Jeep Grand Wagoneer / Baltic Blue & Tan
2008 BMW 535xi Wagon / Deep Sea Blue & Tan

My build thread:
https://ifsja.org/forums/vb/showthread.php?t=189245
My Howell TBI Install How-To:
https://ifsja.org/forums/vb/showthread.php?t=189877
Reply With Quote
  #7  
Old 02-24-2021, 08:52 AM
Ristow Ristow is offline
 
Join Date: Jan 20, 2006
Location: The Great Googley Moogley Midwest.
Posts: 17,268
if your cooling system can keep the engine cool with a thermostat,it will keep it cool without.

if it were not so,your engine temps would continue to climb anythime the thermostat opened under engine load. right? it aint brain surgery.
__________________
Quote:
Originally Posted by Hankrod
Ristows right.................again,




Quote:
Originally Posted by Fasts79Chief
... like the little 'you know what's' that you are.




Quote:
Originally Posted by Fasts79Chief
I LOVE how Ristow has stolen my comment about him ... "Quoted" it ... and made himself famous for being an ***hole to people. Hahahahahahahahahha!


→ Where the kids hang out...

fsjbuilder.org come for the mindless chat,stay for the hand drawn emoticons.

It's like you're unraveling a big cable-knit sweater that someone keeps knitting...and knitting...and knitting...and knitting...
Reply With Quote
  #8  
Old 02-24-2021, 12:13 PM
SJTD SJTD is offline
304 AMC
 
Join Date: Apr 26, 2012
Location: Lompoc and Sunland, CA
Posts: 1,618
It took a while but someone said it.

Heat transfer is a funcfuncfunction of several things, one of them being the Reynolds number which is dependent on the flow velocity. If velocity increases, Re increases and heat transfer increases.
__________________
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.
Reply With Quote
  #9  
Old 02-24-2021, 01:31 PM
fulsizjeep's Avatar
fulsizjeep fulsizjeep is offline
Señor Jackhead
 
Join Date: Aug 21, 2002
Location: Jubilee Jeeps.SWCO
Posts: 22,461
Quote:
Originally Posted by Ristow
if your cooling system can keep the engine cool with a thermostat,it will keep it cool without.

if it were not so,your engine temps would continue to climb anythime the thermostat opened under engine load. right? it aint brain surgery.
That's really good because if you have a QuadraTrac, you already have your frickin hands full.
__________________
Flint
Ran when parked.
http://jubileejeeps.org/quadratrac
88 GW, 401/727/208, 5" lift, D44s/4.10s/locked up, 35s with a few Evil Twin & TT's Fabworks mods
76 401 Wag, 77 401 Wag, 77 401 J20
http://eviltwinfab.com http://www.ttsfabworks.com
Reply With Quote
  #10  
Old 03-03-2021, 02:24 PM
J20 project's Avatar
J20 project J20 project is online now
304 AMC
 
Join Date: Dec 27, 2000
Location: Nevada
Posts: 2,478
"If velocity increases, Re increases and heat transfer increases." Not sure I fully agree w/ this....Residence time is important.


J20
__________________
BP Drivetrain...........

Driveshafts for all Jeeps, Constant velocity rebuilds, Replacement, Repair
775-537-7918

https://www.facebook.com/BPShafts/

Putting this back up. "Someone is gonna have to crawl under the rig"
Reply With Quote
  #11  
Old 03-03-2021, 03:07 PM
rang-a-stang's Avatar
rang-a-stang rang-a-stang is offline
Administrator
 
Join Date: Oct 31, 2016
Location: Camarillo, CA
Posts: 4,068
Countdown starts. TStat will be removed on 22 March.
__________________
79 Cherokee Chief (passed CA smog check Sept 2020)
(Cherokee Build Thread)
11 Nissan Pathfinder Silver Edition 4x4
09 Mazdaspeed3 Grand Touring
Reply With Quote
  #12  
Old 03-03-2021, 09:12 PM
SJTD SJTD is offline
304 AMC
 
Join Date: Apr 26, 2012
Location: Lompoc and Sunland, CA
Posts: 1,618
Quote:
Originally Posted by J20 project
"If velocity increases, Re increases and heat transfer increases." Not sure I fully agree w/ this....Residence time is important.
J20

You're only looking at half the system. If you stop the flow the water in the rad will get nice and cool but the objective isn't to cool the water it's to cool the engine.

Gotta look at the whole system.
__________________
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.
Reply With Quote
  #13  
Old 03-07-2021, 10:18 AM
RamJetFSJ RamJetFSJ is offline
350 Buick
 
Join Date: Jul 18, 2001
Location: Carpinteria, CA
Posts: 892
Agreed. If you remove the t-stat, you may also need a restrictor in its place to slow down the flow. The coolant can pass through too fast to transfer the heat.
__________________
Ben
1980 Wagoneer - Ram Jet 350, 700R4, NP208, 4" lift, 33x10.5 tires.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Engine build ( a learning thread) Chief Gunner General FSJ Discussion 12 11-20-2012 06:01 PM
termostat help Poley General FSJ Tech 4 05-11-2004 04:54 PM
Need Expert Advice On Engine Rebuild!! Rompn General FSJ Tech 7 12-31-2003 09:45 AM
Help please Dan G General FSJ Tech 36 09-02-2002 08:47 AM
Thermostat Puslinch Engine 0 08-14-2000 06:27 AM


All times are GMT -6. The time now is 02:41 PM.


Powered by vBulletin Version 3.5.4
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
corner corner