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

Brand new 347 has rear main leak!!

  • Thread starter Thread starter Spook302
  • Start date Start date Jul 9, 2007
Prev
  • 1
  • 2
First Prev 2 of 2

4G-KDMP

10 Year Member
Jul 23, 2005
935
19
39
36
CA
Jul 10, 2007
#21
  • Jul 10, 2007
  • #21
if it leaks replace it !

maybe it wasn't the rms then?
 
S

Spook302

Member
Jun 21, 2005
109
2
18
Durango CO.
Jul 10, 2007
#22
  • Jul 10, 2007
  • #22
No the rms was clearly leaking and bent. I clean the area went in the house for a while and came back to it. I Then replace the rms, clean the area went in the house and came back ready to put everything back together and I noticed the pan gasket leaking as well.
 

4G-KDMP

10 Year Member
Jul 23, 2005
935
19
39
36
CA
Jul 10, 2007
#23
  • Jul 10, 2007
  • #23
sorry i didn't read where you had said that the rms was bent and leaking, but you were able to get and install the teflon rms right?
 
S

Spook302

Member
Jun 21, 2005
109
2
18
Durango CO.
Jul 10, 2007
#24
  • Jul 10, 2007
  • #24
Yeah, I had the tool and I used a thick plastic cup that i had that just happen to fit perfectly around the seal. I used some royal purple i had lying around.
 

ShortThrow50

Member
Oct 22, 2006
923
2
16
50
Pa
Jul 10, 2007
#25
  • Jul 10, 2007
  • #25
you dont need silicone for the oil pan gasket. It helps keep the gasket in place if you are installing it with the engine right side up. The only way i install them is with my engine on a stand and upside down, so it stays in place anyway. Never had a leak
 
S

Spook302

Member
Jun 21, 2005
109
2
18
Durango CO.
Jul 10, 2007
#26
  • Jul 10, 2007
  • #26
That really sucks it is leaking there. Brand new gasket, brand new block, and a brand new pan as well. I tried backing off the oil pan bolts and resetting the gasket and tightning them back up, I cleaned the area came back to it a half hour later and it is still building up at the edges and falling to the middle of the back of the pan.
 

maxine-70

20+ Year Stangneter
Mar 27, 2003
273
1
18
50
louisville, ky
Jul 11, 2007
#27
  • Jul 11, 2007
  • #27
another fine new stangnet member....:Zip2:


the last thing a guy with a new motor thats got something wrong with it needs is some dumbass telling him to stop crying about it. the forums are here to pool our knowledge and so people can learn things from each other. he was asking for possible explanations....
 

Rick 91GT

Mustang Master
Nov 29, 1999
9,692
95
99
49
PA
www.rnhperformance.com
Jul 11, 2007
#28
  • Jul 11, 2007
  • #28
Coming from a builder "**** happens" the rear main seal is an art on the Fords, I have them down and haven;t had one of those leak in a long time but it happens. One reason I tend to leave them out if the person has the ability to put them in, if the motor sits the small amount of oil I put on the crank will not prevent the seal from sticking and ripping.

The trick I have found is to put a thin coating of Permatex on the outside of the seal, then slip it in...never had one leak.

Even with the one piece oil pan gaskets I put a bead across the front and rear, at all 4 corners and a thin layer on the block surface. Fel-Pro OS34508R

As far as the flywheel/flexplate goes, use Loctite (Blue) on those bolts, the Permatex or silicone will not give you a true tq reading, you can use liquid teflon as well.

The leak on Daggers car drove me insane, it was nice that Fel-Pro changed the MLS head gasket to eliminate the tabs towards the intake with out any warning or tech bullet...
 
S

Spook302

Member
Jun 21, 2005
109
2
18
Durango CO.
Jul 11, 2007
#29
  • Jul 11, 2007
  • #29
Thanks for that info.
 
Prev
  • 1
  • 2
First Prev 2 of 2
You must log in or register to reply here.

Similar threads

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
677
Fox 5.0 Mustang Tech Apr 1, 2026
Steigy4827
S
C
New mustang owner
  • CPH89LX
  • Apr 26, 2026
  • The Welcome Wagon
Replies
3
Views
138
The Welcome Wagon Apr 27, 2026
91AOD5.0LX
J
MEED HELP!! 86 mustang
  • Jacob0121
  • Jan 23, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
6
Views
351
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Apr 25, 2026
CAMTWO1070
Engine New Oil Leak Help.
  • Slo5Oh89
  • Mar 14, 2025
  • Fox 5.0 Mustang Tech
Replies
8
Views
611
Fox 5.0 Mustang Tech Mar 19, 2025
Slo5Oh89
R
What's it Worth? 1997 Cobra, a ton of mods and restoration
  • riored97snake
  • Jun 18, 2026
  • What is it Worth?!?!?
Replies
2
Views
181
What is it Worth?!?!? Jun 21, 2026
riored97snake
R
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?