• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

normal operating temp issue???

  • Thread starter Thread starter apex827
  • Start date Start date Feb 17, 2009

apex827

New Member
Dec 14, 2008
14
0
1
Florida
Feb 17, 2009
#1
  • Feb 17, 2009
  • #1
ok so my engine only ever heats up to about 165 to 175 range, maybe 180 but not any higher. Its not reaching 200 and im not sure why. i just replaced the thermostat last week (old one was stuck open) and i know i put this one in facing the proper way, so im not sure whats up.

is there any other reason that it might not be reaching operating temp?
 

1991notchbackLX

Active Member
Dec 25, 2007
1,483
47
48
New York
Feb 17, 2009
#2
  • Feb 17, 2009
  • #2
did you happen to put a 180* thermostat in it or an even lower one by mistake? a lot of guys read crap online about the lower the temperature your car runs at the better, and therefore get tricked into buying lower temp thermostats, the fact of the matter is the optimum operating temperature for our cars is higher, closer to 195*
 

apex827

New Member
Dec 14, 2008
14
0
1
Florida
Feb 17, 2009
#3
  • Feb 17, 2009
  • #3
no, me and my dad put in an OEM rated one, i believe its a 195 thermostat from NAPA.

we also replaced the electric fan controller cus my other one fried last week. And its adjustable so i can control when the fan comes on. I adjusted it, Im not sure what temp its adjusted to, but its higher than 175-180 cus thats as high as the car gets and the fan wont turn on. so idk

ive have no clue why its not heating up.
how long should it take for it to reach normal operating temp?
 

Blandnuts

I don't swallow; I only swoosh
Founding Member
Aug 21, 2000
1,172
124
124
FloorDuh
Feb 17, 2009
#4
  • Feb 17, 2009
  • #4
What gauge are you getting your temp rating from?
 

apex827

New Member
Dec 14, 2008
14
0
1
Florida
Feb 17, 2009
#5
  • Feb 17, 2009
  • #5
the stock temp gauge and a handheld laser thermometer thing
 

parrish5o

New Member
Dec 22, 2008
2
0
0
Dirty South
Feb 17, 2009
#6
  • Feb 17, 2009
  • #6
An aftermarket gauge would not be a bad idea, the stock ones are vague at best.
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Feb 17, 2009
#7
  • Feb 17, 2009
  • #7
Also, if it's cold where you're at, you can keep it right on the edge of the opening threshold of the stat. If your fan controller is set too low, even while idling you can keep it right on that threshold.

FWIW, my stock temp gauge read 35*F too cool at 190*F. I/R thermo's are good for relative comparisons but not an absolute comparison with a temp sender in the liquid medium.
 

apex827

New Member
Dec 14, 2008
14
0
1
Florida
Feb 18, 2009
#8
  • Feb 18, 2009
  • #8
Today the car heated up to about 200 on the stock gauge, but it did not maintain it for very long. It seems to want to sit around 170-180. So i still dont know whats up with it, ive been adjusting the fan to help it warm up to normal operating temp, but it never gets there.

Also yesterday i noticed my "low coolant" light was on, so i checked the rad and the coolant tank and it was a bit low in the tank so i filled it up. then i went to class today and the light was still on, i checked once again and both were full. im not sure why its saying its low. Any ideas?
 

apex827

New Member
Dec 14, 2008
14
0
1
Florida
Feb 18, 2009
#9
  • Feb 18, 2009
  • #9
I also am probably gonna eventually get an aftermarket gauge like you guys suggested. And i was looking at LMR and i saw this

THERMOCAP RADIATOR CAP, 16 PSI, SILVER TRIM ALL

Anyone have experience with these? Are they good for reading temp or are they just junk?

Thanks for the help guys
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Feb 18, 2009
#10
  • Feb 18, 2009
  • #10
apex827 said:
Today the car heated up to about 200 on the stock gauge, but it did not maintain it for very long. It seems to want to sit around 170-180. So i still dont know whats up with it, ive been adjusting the fan to help it warm up to normal operating temp, but it never gets there.

Also yesterday i noticed my "low coolant" light was on, so i checked the rad and the coolant tank and it was a bit low in the tank so i filled it up. then i went to class today and the light was still on, i checked once again and both were full. im not sure why its saying its low. Any ideas?
Click to expand...

Again, the stock gauge has too much built-in hysteresis to be used for diagnostics or setting of a fan controller.

Clean the prongs on the low-coolant sensor and the light should go out. When they get dirty, the light comes on.
 

1991notchbackLX

Active Member
Dec 25, 2007
1,483
47
48
New York
Feb 18, 2009
#11
  • Feb 18, 2009
  • #11
apex827 said:
I also am probably gonna eventually get an aftermarket gauge like you guys suggested. And i was looking at LMR and i saw this

THERMOCAP RADIATOR CAP, 16 PSI, SILVER TRIM ALL

Anyone have experience with these? Are they good for reading temp or are they just junk?

Thanks for the help guys
Click to expand...

you could probably take the $26 for that thing plus the $15 flat rate shipping LMR charges and light a cigar with it and be better off... put that money towards an autometer temp gauge so you'll have the right tool to diagnose what the problem really is... also, don't have 100% faith in a brand new thermostat, i've had two that were bad on me right out of the box, just a suggestion for troubleshooting
 

apex827

New Member
Dec 14, 2008
14
0
1
Florida
Feb 18, 2009
#12
  • Feb 18, 2009
  • #12
yea i figured as much for the cap. prolly better off shelling out the money for the gauge, i already have an air/fuel ratio gauge that i need to install so now i guess ill have to install two gauges lol.

i know what you mean i went about the faulty thermostat. i went through 3 in one day once. the first time they gave me the wrong one, then the next was faulty, and finally got a working one on the 3rd try. Of course thts the one that was stuck open and replaced last week. The new one was working, hopefully it didnt crap out too.

Thanks HISSIN50 for the low-coolant sensor tip, i cleaned it up an now the light went off.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,265
17,952
224
Massachusetts
Feb 18, 2009
#13
  • Feb 18, 2009
  • #13
apex827 said:
yea i figured as much for the cap. prolly better off shelling out the money for the gauge, i already have an air/fuel ratio gauge that i need to install so now i guess ill have to install two gauges lol.
Click to expand...


If there was ever a worthless gauge to install...it's an air/fuel gauge.


Seriously, if you are going to install only 2 gauges, it should be oil pressure and water temp.

Air fuel gauge is a light show really.
 

apex827

New Member
Dec 14, 2008
14
0
1
Florida
Feb 18, 2009
#14
  • Feb 18, 2009
  • #14
lol, light show. yea tht prolly sums it up right. ive had one lying around so i was prolly eventually gonna just install it.

what i would like to do if i had the spare cash is get the Florida5.0 gauge cluster with all new Autometer gauges. that would be nice, but for now until i get some cash idk
 

Bottomlesspit

I started the longest tech thread in the known uni
Founding Member
Jan 1, 1999
2,636
2
48
Del Rio, TX
Feb 18, 2009
#15
  • Feb 18, 2009
  • #15
I am in the same boat as you..so to speak. I installed a new thermostat months ago and I can't get the temp over 160*...even on a 100* day! Yes, I have an autometer temp guage installed. Looks like I'm going to have to wrestle with that darn heater bypass hose again!
BTW, this was supposed to me a 195* stat, best one they had in stock...go figure?
Ken
 
You must log in or register to reply here.

Similar threads

Resolved Got Too Hot!!!
  • PonyGTrider
  • Apr 27, 2025
  • Fox 5.0 Mustang Tech
Replies
7
Views
600
Fox 5.0 Mustang Tech May 6, 2025
PonyGTrider
M
Resolved 1988 Foxbody - Overheating Summer
  • MDrisc
  • Oct 26, 2025
  • Fox 5.0 Mustang Tech
Replies
16
Views
717
Fox 5.0 Mustang Tech Jul 17, 2026
fasterthangas
F
W
High Cylinder Head Temp - Not Overheating?
  • wtfwork12
  • Jun 26, 2025
  • 2005 - 2014 S-197 Mustang -General/Talk-
Replies
9
Views
2K
2005 - 2014 S-197 Mustang -General/Talk- Jul 1, 2025
wtfwork12
W
8
Engine Rough idle and aggressive sputtering when accelerating
  • 88vertible
  • Aug 13, 2025
  • Fox 5.0 Mustang Tech
Replies
4
Views
1K
Fox 5.0 Mustang Tech Dec 13, 2025
Jarhead67
J
D
2004 v6 mustang strange issue with coolant system...heat in cabin comes and goes...
  • daveinfl33777
  • Jun 3, 2024
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
13
Views
1K
1996 - 2004 SN95 Mustang -General/Talk- Jun 3, 2024
daveinfl33777
D
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?