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

Engine 1990 car overheating at idle and rad staying cold

  • Thread starter Thread starter 5.0Mitch
  • Start date Start date Apr 26, 2018
5

5.0Mitch

New Member
Nov 26, 2013
1
0
2
Apr 26, 2018
#1
  • Apr 26, 2018
  • #1
put my car away for the winter and it was running fine but had a small oil leak out of the timing cover so when i brought it out of storage i pulled the timing cover and replaced the gasket and also put on a new water pump on because mine had a water stain out of the weep hole.
when i went to run the car to get the air out of the cooling system it took about 10-15 minutes to get to the temp it was running at before but it kept climbing. i shut the car off when the temp got to 3/4 of the way on the gauge and then felt the rad and it was still completely cold. i have now removed the thermostat housing because i thought that i might have put the thermostat in backwards when i reassembled but it was in the correct way and i can push it open with my fingers so i know its not siezed. also take into account that this is a brand new water pump, new rad a year ago, all new hoses a year ago and the thermostat is only a year old as well. just wondering if anyone has some insight into what the problem could be. only thing i can think of is maybe the thermostat will open by pushing it open but wont from the heat of the coolant. i am about to go and test it in some boiling water
 

mikestang63

SN Certified Technician
Aug 27, 2012
11,606
8,859
214
In the garage
Apr 26, 2018
#2
  • Apr 26, 2018
  • #2
test the thermostat in boiling water
make sure all the air is burped
make sure the lower hose isnr collapsing
 

jrichker

StangNet's favorite TOOL
In Remembrance. Thank you for your contributions
Mar 10, 2000
27,512
2,813
234
Dublin GA
Apr 26, 2018
#3
  • Apr 26, 2018
  • #3
Depending on which rotation water pump and belt routing you have, you might be turning the water pump in the reverse direction. Look at the belt routing diagram on the brace across the top of the radiator for the belt routing diagram.
 
Reactions: RangerJoe
You must log in or register to reply here.

Similar threads

Engine 1986 GT Overheating issues
  • 86 5O GT
  • Jan 25, 2026
  • Fox 5.0 Mustang Tech
Replies
18
Views
663
Fox 5.0 Mustang Tech Jan 29, 2026
86 5O GT
Engine Themostat
  • Mindseye007
  • Jan 30, 2026
  • Fox 5.0 Mustang Tech
  • 2
Replies
21
Views
752
Fox 5.0 Mustang Tech Feb 1, 2026
86HO5.0
8
K
86 GT Water Pump
  • Kade5114
  • May 11, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
3
Views
100
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- May 11, 2026
nickyb
M
Resolved 1988 Foxbody - Overheating Summer
  • MDrisc
  • Oct 26, 2025
  • Fox 5.0 Mustang Tech
Replies
16
Views
694
Fox 5.0 Mustang Tech Jul 17, 2026
fasterthangas
F
S
Fuel ‘88 GT Runs Rich Cold — Fixes Itself When I Unplug Sensors (ECT, MAF, O2, etc.)
  • Sufarry
  • Nov 6, 2025
  • Fox 5.0 Mustang Tech
Replies
12
Views
864
Fox 5.0 Mustang Tech Nov 9, 2025
Mustang5L5
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?