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

Engine Leaking water pump. Can I use RTV on the back cover?

  • Thread starter Thread starter evintho
  • Start date Start date Jan 18, 2023
  • 1
  • 2
Next
1 of 2 Next Last

evintho

20+ Year Stangneter
Nov 12, 2003
683
245
73
Santa Rosa, CA.
Jan 18, 2023
#1
  • Jan 18, 2023
  • #1
Like the title says, it's leaking from the bottom of the rear cover plate. I already pulled the water pump. It's a new Ford Racing M-8501, non reverse rotation cuz I have an early timing cover on the motor. I installed a FelPro gasket on the rear cover and it leaks. Would I be better off just smearing a coat of RTV black onto the back of the pump, then slapping the rear cover on?
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,181
21,349
234
Box behind Walmart
Jan 18, 2023
#2
  • Jan 18, 2023
  • #2
I would not and have not hesitated to put Black Gasket Maker like [The Right Stuff] on those gaskets. A thin coat on each side will do. I've also replaced gaskets with the same stuff.

Don't overdue it. Whatever squishes out from beneath the surface goes inside too.

Extra Note: Let it fully cure before running the engine. Full 24 hours if it's inside. Longer if not.
 

evintho

20+ Year Stangneter
Nov 12, 2003
683
245
73
Santa Rosa, CA.
Jan 18, 2023
#3
  • Jan 18, 2023
  • #3
Thanks for the confirmation! I'll attack it tomorrow.
 

evintho

20+ Year Stangneter
Nov 12, 2003
683
245
73
Santa Rosa, CA.
Feb 2, 2023
#4
  • Feb 2, 2023
  • #4
UPDATE:
Water pump still leaks! Again, it seems to be coming from the back cover plate just to the side of the weep hole. I used no gaskets. Nothing but RTV Ultra Black 82180 on both the back cover and W/P to timing chain cover. Both the cover and W/P are new. Both surfaces impeccably clean. Smeared a light coating on all surfaces. Tightened the bolts in a crisscross pattern. Once installed, I let it sit for 2 days before I fired it up. The only thing I can think of......does the RTV need to tack up for any length of time before installation?
I've pulled the pump again and cleaned all surfaces thoroughly and waiting for any replies before I reinstall the pump. I don't want to do this again!
 

OldManRiver

Active Member
Feb 14, 2015
238
131
53
Central Wisconsin
Feb 2, 2023
#5
  • Feb 2, 2023
  • #5
Are the bolts holding the rear cover in place low profile hex heads?
If regular hex bolts are used the heads will contact the timing cover preventing the water pump from seating properly.
 

evintho

20+ Year Stangneter
Nov 12, 2003
683
245
73
Santa Rosa, CA.
Feb 2, 2023
#6
  • Feb 2, 2023
  • #6
OldManRiver said:
Are the bolts holding the rear cover in place low profile hex heads?
If regular hex bolts are used the heads will contact the timing cover preventing the water pump from seating properly.
Click to expand...
Yeah, there's 2 of 'em and they're the stock low profile bolts.
 

96pushrod

I think they're a little easier to get off
5 Year Member
May 15, 2018
1,530
871
133
Savannah
Feb 2, 2023
#7
  • Feb 2, 2023
  • #7
evintho said:
UPDATE:
Water pump still leaks! Again, it seems to be coming from the back cover plate just to the side of the weep hole. I used no gaskets. Nothing but RTV Ultra Black 82180 on both the back cover and W/P to timing chain cover. Both the cover and W/P are new. Both surfaces impeccably clean. Smeared a light coating on all surfaces. Tightened the bolts in a crisscross pattern. Once installed, I let it sit for 2 days before I fired it up. The only thing I can think of......does the RTV need to tack up for any length of time before installation?
I've pulled the pump again and cleaned all surfaces thoroughly and waiting for any replies before I reinstall the pump. I don't want to do this again!
Click to expand...
I’ve never really let it tack up. Usually I’ll just put rtv on, barely tighten and let it sit for a few mins, then torque everything down. I do usually use a gasket and rtv on the water pump, but I’ve put thermostat housings on with just black rtv this way.

I also always pull the back cover plate off and put a thin coat of rtv on the back gasket. Never had one leak.
 

90sickfox

Wasn't a pretty sight...and I've got big hands
SN Certified Technician
Mar 2, 2015
6,945
5,816
213
Feb 2, 2023
#8
  • Feb 2, 2023
  • #8
In the shops there's no time to let it tack up smear it on, tighten up, and let it roll. Back in the customers hands as fast as you can get it out.
 

AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,967
4,080
183
Claremore, OK
Feb 2, 2023
#9
  • Feb 2, 2023
  • #9
Runs straight edge across the back of the water pump and see if there is any high/low on the sealing surface. Do the same thing on the timing chain cover.

The plate between the pump and cover should be flat but a little warp is okay.

I use gaskets and RTV every time but not a lot of RTV.
 

mikestang63

SN Certified Technician
Aug 27, 2012
11,606
8,859
214
In the garage
Feb 3, 2023
#10
  • Feb 3, 2023
  • #10
right stuff
 

91GTstroked

15 Year Member
Jun 14, 2007
504
282
93
Feb 6, 2023
#11
  • Feb 6, 2023
  • #11
Are you referring to the back plate on the WP? So it's leaking at the bottom between the WP and the back plate?

If so, I had this problem on both my 90 coupe and 93 lx hatch after replacing the WP. I would get a slow drip when car was running. It would stop once the car was off.

I would put permatex form a gasket. And blue loc tite on the back plate bolts.

Honestly it drove me nuts, but after a few heat cycles both stopped leaking.
 

evintho

20+ Year Stangneter
Nov 12, 2003
683
245
73
Santa Rosa, CA.
Feb 8, 2023
#12
  • Feb 8, 2023
  • #12
FINAL UPDATE:
Installed the pump with new FelPro gaskets and a thin coating of RTV. Fired it up and it leaks worse than before!!
Walked away and completed some other tasks on the car I had to do. The next day I pulled the pump again (this is getting old)! Cleaned everything up and put a straightedge on the rear cover. There was a gap on each end.......





So I chucked it in my vise and straightened it. This time I decided to go without gaskets and ran a fairly good bead of RTV on all surfaces. Put it back together and let it sit for 36 hours. Fired it up, brought it up to temperature and no leaks! Not a drop! Finally I think I'm done.
Also, just sitting in the shop idling with the fan on, my SW gauge reads 200*. Is that about normal? I have a 192* thermostat. That's kinda scary for me as my roadster never gets above 180*.
 

AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,967
4,080
183
Claremore, OK
Feb 8, 2023
#13
  • Feb 8, 2023
  • #13
That T-stat is not going to start coming off its seat until 192 deg F so full open will be warmer than that. The other thing you need to take into account is that even though it is stamped 192 deg F doesn't necessary mean it will open at that temperature. I have seen the parts store brand units vary +/- 5 degrees on the regular over the years. I run a Robertshaw in both of my cars and have had zero issues and they open at the rated temperature.

Also, the car will run warmer not moving unless you have an electric fan that is worth a crap (Mark VIII, Contour, etc.). You can put a heavy duty clutch on a stock fan and it will help but make sure you have the shroud and you also have the deflectors on either side of the radiator.

Mustang Radiator Side Air Deflector Pair (79-93) E4ZZ-8310

Replace those rotted out radiator side air deflectors on your 1979-1993 Mustang with these direct replacements from 5.0 Resto!
lmr.com
 

evintho

20+ Year Stangneter
Nov 12, 2003
683
245
73
Santa Rosa, CA.
Feb 8, 2023
#14
  • Feb 8, 2023
  • #14
I was looking for a Robert Shaw and couldn't find one. Guess I wasn't looking hard enough!
I have an 1100 cfm SPAL fan (the only one that'd fit) and I'm using the Mustang radiator and shroud, no deflectors though. Just wondering if I should drop to a 180* or 185* thermostat?

 

90sickfox

Wasn't a pretty sight...and I've got big hands
SN Certified Technician
Mar 2, 2015
6,945
5,816
213
Feb 8, 2023
#15
  • Feb 8, 2023
  • #15
200° is where the factory wanted our cars to run. I used to use 2000 jeep cherokee wlectric fans im my mustangs. They'd trim pretty easy and install inside the factory shroud with a few bolts and washers. Now, I run Ford Contour fans. My turbo car likes to be around 203°. I run a 192 thermostat. Cruising temps drop to about 196°. My car never goes above 213°
 
Reactions: General karthief

mikestang63

SN Certified Technician
Aug 27, 2012
11,606
8,859
214
In the garage
Feb 8, 2023
#16
  • Feb 8, 2023
  • #16
1100 cfm will not keep that cool.
 

evintho

20+ Year Stangneter
Nov 12, 2003
683
245
73
Santa Rosa, CA.
Feb 8, 2023
#17
  • Feb 8, 2023
  • #17
mikestang63 said:
1100 cfm will not keep that cool.
Click to expand...
Well that sucks! Any idea what the CFM rating was on the factory fan?
 

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,957
10,600
203
polk county florida
Feb 8, 2023
#18
  • Feb 8, 2023
  • #18
From what I have gleaned from the experts here, I think it would take about 2500 to 3000 cfm to kool us on an average day even with AC.
you can find the info in the tech/tips forum for the contour fans or search out for one of many builds here that use a couple different wiring setups.
 

mikestang63

SN Certified Technician
Aug 27, 2012
11,606
8,859
214
In the garage
Feb 10, 2023
#19
  • Feb 10, 2023
  • #19
go to the JY and get a Contour dual fan, an SN95, or a Taurus fan from a V6. They are OEM, cheap, easily replaceable and pull well over 3000CFM. Couple that with a FAL33165 controller and you are set. Been done 10000 times and multiple write ups here and on the Corral.
 
Reactions: General karthief

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,181
21,349
234
Box behind Walmart
Feb 10, 2023
#20
  • Feb 10, 2023
  • #20
evintho said:
I was looking for a Robert Shaw and couldn't find one. Guess I wasn't looking hard enough!
I have an 1100 cfm SPAL fan (the only one that'd fit) and I'm using the Mustang radiator and shroud, no deflectors though. Just wondering if I should drop to a 180* or 185* thermostat?

Click to expand...
That is a pretty vivid image. What did you take this pic with? I'm guessing that it's [not] a cell phone (even tho the flash is a wash).
 
  • 1
  • 2
Next
1 of 2 Next Last
You must log in or register to reply here.

Similar threads

D
Engine Water pump back plate bolts touching timing cover?
  • dqureshi06
  • Oct 27, 2024
  • Fox 5.0 Mustang Tech
Replies
14
Views
1K
Fox 5.0 Mustang Tech Oct 29, 2024
limp
B
water pump installation questions
  • B0udreaux
  • Feb 5, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
38
Views
2K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Feb 28, 2026
General karthief
2
Electrical mayhem
  • 2000ElectricGreen
  • Mar 13, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
2
Views
287
1996 - 2004 SN95 Mustang -General/Talk- Mar 24, 2026
2000ElectricGreen
2
6
Hey all,I’m putting together a 302 for my 1968 Mustang and wanted to post the combo + some questions to make sure I’m not missing crucial
  • 68_Disgustang
  • Feb 22, 2026
  • 1965 - 1973 Classic Mustangs -General/Talk-
Replies
4
Views
976
1965 - 1973 Classic Mustangs -General/Talk- Jun 20, 2026
gray owl
G
S
Drivetrain 8.8 Pinion and 302 rear main seal leaks after replacing. 93 5.0 with t-5
  • Steigy4827
  • Jun 23, 2025
  • Fox 5.0 Mustang Tech
Replies
10
Views
687
Fox 5.0 Mustang Tech Apr 1, 2026
Steigy4827
S
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?