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

Fox Coolant Flush & Fill - Non Running Engine

  • Thread starter Thread starter R82148V
  • Start date Start date Feb 12, 2021

R82148V

Active Member
May 26, 2020
256
59
38
.....
Feb 12, 2021
#1
  • Feb 12, 2021
  • #1
Hello!

Hope everyone is doing well and stay safe!

Just some questions about Flushing and filling the cooling system on an 87' vert. I'm probably overthinking this, but I always want to make sure and cant see to find anything concrete on the net.
I'm bringing back to life my 87 vert after sitting for 12+ years. I've owned it since 1994 and always taken extreme care of it with constant maintenance. At this time I have just about everything off and out of the engine bay for cleaning and painting, except the cooling system. The coolant is still green from what I can see taking the rad cap off... The Rad is only 3/4 filled.

Question 1 - Is it safe to flush the heater core, Rad, Engine, all separately without being able to start the engine? It'll be a long while before that.
Question 2 - Is there any way to spin the water pump to possibly simulate a running engine? like use a drill with a rubber wheel against the water pump? I dunno haha
Question 3 - is it safe or even necessary to use one of those Power flushers that use a compressor
Question 4 - again, is it safe or even necessary to use those vacuum coolant fill systems to help minimize any air pockets?

I just don't know what to do or what my options are since the engine is not running at this time.
Should I even do a flush and just top off the RAD keeping the stat out of the car until I can get the engine up and running?

Thank you everyone for all your time reading this and help!
 
Last edited: Feb 12, 2021

General karthief

wonder how much it would cost to ship you a pair
5 Year Member
Aug 25, 2016
27,844
10,520
203
polk county florida
Feb 12, 2021
#2
  • Feb 12, 2021
  • #2
Drain enough coolant (3/4 full may be enough, I'd do about half full) pull the t stat and replace it with a 190 (192 is stock) t stat and run it around town a few times (keeping eye on temp of course) and then drain/flush with water then refill with coolant (50/50?). You may find that after the first couple trips you will need to replace stuff like water pump, hoses or worse yet the heater core.
 
Reactions: Adieu

Adieu

Easy there, this ain't a dating site.
20+ Year Stangneter
Mar 7, 2002
9,531
5,187
224
Feb 12, 2021
#3
  • Feb 12, 2021
  • #3
General karthief said:
Drain enough coolant (3/4 full may be enough, I'd do about half full) pull the t stat and replace it with a 190 (192 is stock) t stat and run it around town a few times (keeping eye on temp of course) and then drain/flush with water then refill with coolant (50/50?). You may find that after the first couple trips you will need to replace stuff like water pump, hoses or worse yet the heater core.
Click to expand...

Ummm....


R82148V said:
I just don't know what to do or what my options are since the engine is not running at this time.
Should I even do a flush and just top off the RAD keeping the stat out of the car until I can get the engine up and running?
Click to expand...

My take? Get it running first, then flush it. It's a lot easier with the help of the water pump and the heat from the engine running.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,176
17,879
224
Massachusetts
Feb 12, 2021
#4
  • Feb 12, 2021
  • #4
If the engine isn't running, just flush the radiator and heater core with a garden hose through disconnected hoses. For the engine, put the hose in the radiator water neck in the intake manifold, and let it flush out the bottom radiator hose. Obviously you will need to catch the flushed water.
 
Reactions: JD1964

General karthief

wonder how much it would cost to ship you a pair
5 Year Member
Aug 25, 2016
27,844
10,520
203
polk county florida
Feb 12, 2021
#5
  • Feb 12, 2021
  • #5
MustangIIMatt said:
Ummm....




My take? Get it running first, then flush it. It's a lot easier with the help of the water pump and the heat from the engine running.
Click to expand...
WHATTT? Matt, this is what I would do, I figure getting the engine running was a given! Come on, we all know I don't always do the correct expert mechanic thing because well, I'm not a mechanic.
Do I have to post my disclaimer everytime I answer a request for an opjnion? Ok.
DISCLAIMER: The information given is an opinion and not based on any real mechanical experience.
@R82148V I'm just bust'n Matts chops only because he is a phenomenal mechanic and I'm jealous (he has all the 'cool' tools)
 
Reactions: Adieu

R82148V

Active Member
May 26, 2020
256
59
38
.....
Feb 12, 2021
#6
  • Feb 12, 2021
  • #6
General karthief said:
WHATTT? Matt, this is what I would do, I figure getting the engine running was a given! Come on, we all know I don't always do the correct expert mechanic thing because well, I'm not a mechanic.
Do I have to post my disclaimer everytime I answer a request for an opjnion? Ok.
DISCLAIMER: The information given is an opinion and not based on any real mechanical experience.
@R82148V I'm just bust'n Matts chops only because he is a phenomenal mechanic and I'm jealous (he has all the 'cool' tools)
Click to expand...
Hahah good stuff! You gotta bust some chops every now and then.

So basically, its best to wait, get the car running first before any type of coolant flush and fill.???

The Coolant has been in there for so long, I though it would a good idea and able to do it even though the car doesnt run.. I was just nervous how I would be able to circulate the regular water from the flush, out of the car without the water pump turning.. From the most part, the coolant in there doesnt look too bad. A darker Green but still green..

I know you can do a vacuum coolant fill but didnt know how well it would work to get all the air pockets out, etc....
 

R82148V

Active Member
May 26, 2020
256
59
38
.....
Feb 12, 2021
#7
  • Feb 12, 2021
  • #7
R82148V said:
Hahah good stuff! You gotta bust some chops every now and then.

So basically, its best to wait, get the car running first before any type of coolant flush and fill.???

The Coolant has been in there for so long, I though it would a good idea and able to do it even though the car doesnt run.. I was just nervous how I would be able to circulate the regular water from the flush, out of the car without the water pump turning.. From the most part, the coolant in there doesnt look too bad. A darker Green but still green..

I know you can do a vacuum coolant fill but didnt know how well it would work to get all the air pockets out, etc....
Click to expand...
was thinking of using a hand drill with a rubber wheel against the pump to simulate the car running.. pfff
 

nickyb

I gotta say i never painted my nuts, Never Ever
15 Year Member
Apr 3, 2009
2,972
1,618
153
nevada
Feb 12, 2021
#8
  • Feb 12, 2021
  • #8
When you do get her running and drain / flush coolant , it's a good idea to get one of those funnels that come with radiator caps/ adapters( got mine on Amazon )
You can fill the system and get the air out easily,and they are cheap enough. Post some pics of her.
 

R82148V

Active Member
May 26, 2020
256
59
38
.....
Feb 26, 2021
#9
  • Feb 26, 2021
  • #9
Flushing the heater core and rad separately, make sense how to do, but when you "flush" the engine, how exactly do you go by doing that? goofy question i know..

Do you just remove the t-sat, reinstall the t-sat housing, disconnect the rad hoses at the rad, put the lower rad hose in bucket, garden hose in upper rad hose and flush until clean? Once clean, just reinstall the t-sat, hoses and add either coolant / distilled water or 50 50 mix?

I dont want to attempt to remove the engine plugs since the car is an 87. I'm sure they are in there for good.

Thanks!!
 

Adieu

Easy there, this ain't a dating site.
20+ Year Stangneter
Mar 7, 2002
9,531
5,187
224
Feb 26, 2021
#10
  • Feb 26, 2021
  • #10
R82148V said:
Flushing the heater core and rad separately, make sense how to do, but when you "flush" the engine, how exactly do you go by doing that? goofy question i know..

Do you just remove the t-sat, reinstall the t-sat housing, disconnect the rad hoses at the rad, put the lower rad hose in bucket, garden hose in upper rad hose and flush until clean? Once clean, just reinstall the t-sat, hoses and add either coolant / distilled water or 50 50 mix?

I dont want to attempt to remove the engine plugs since the car is an 87. I'm sure they are in there for good.

Thanks!!
Click to expand...
I usually do this, except that I leave the radiator in the loop so that it gets flushed too unless the block is particularly rust. (Then I do them separately.)
 
You must log in or register to reply here.

Similar threads

Engine Coolant boiling in hose?
  • Teen'93stang5.0
  • Jun 3, 2026
  • Fox 5.0 Mustang Tech
Replies
7
Views
105
Fox 5.0 Mustang Tech Jun 8, 2026
Mustang5L5
S
Fox '87 GT can't get to stay running
  • spilly
  • Mar 29, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
26
Views
574
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Apr 25, 2026
CAMTWO1070
Hard to start when engine is cold
  • 86_Capri
  • Mar 11, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
31
Views
763
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Mar 21, 2026
86_Capri
C
SN95 Another Coyote swap list
  • catkiller
  • May 10, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
0
Views
82
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- May 10, 2026
catkiller
C
B
water pump installation questions
  • B0udreaux
  • Feb 5, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
38
Views
1K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Feb 28, 2026
General karthief
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
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?