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CC Advertisers
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View Poll Results: Does your SB rear main seal leak oil?
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My one piece rear main seal leaks.
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9 |
20.93% |
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My two piece rear main seal leaks.
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5 |
11.63% |
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1 to 2 drops when I park the car
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5 |
11.63% |
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3 to 4 drops when I park the car
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4 |
9.30% |
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5+ drops when I park the car.
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5 |
11.63% |
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My rear main seal doesn't leak a drop of oil.
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27 |
62.79% |
03-22-2009, 10:30 AM
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CC Member
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Join Date: Oct 2007
Location: Livermore,
CA
Cobra Make, Engine: SPF 2168, 418, TKO 600
Posts: 203
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Not Ranked
Does your SB rear main seal leak oil?
Does your small block Ford rear main seal leak oil?
I'm trying to get an idea of how common this problem is. |
03-22-2009, 10:36 AM
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Senior Club Cobra Member
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Join Date: Feb 2004
Cobra Make, Engine:
Posts: 1,226
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Not Ranked
Not a drop. I hope I didn't just jinx myself.
Jim
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03-22-2009, 10:45 AM
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Senior Club Cobra Member
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Join Date: Oct 2006
Location: Santa Cruz,
CA
Cobra Make, Engine: SPF 2613 Titanium w/Black, Roush 402SR
Posts: 4,097
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Not Ranked
Quote:
Originally Posted by ou812545
Does your small block Ford rear main seal leak oil?
I'm trying to get an idea of how common this problem is. |
Are you sure it's your rear main seal that's leaking? Drips that accumulate at the bell housing could be coming from other sources and look like the rear seal.
__________________
Doug
No stop signs, speed limit - Nobody's gonna slow me down - Like a wheel, gonna spin it
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03-22-2009, 11:10 AM
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CC Member
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Join Date: May 2001
Location: California,
Ca
Cobra Make, Engine: NAF 289 Slabside Early Comp Car with 289 Webers and all the goodies. Cancelling the efforts of several Priuses
Posts: 6,592
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Not Ranked
As GTB above has stated, other leak sources can prevail but sometimes the front corners leak where the pan and the front cover meet and the road draft will carry the oil along the pan rail and collect at the rear. The seam on an oil filter can leak. Another spot to check is the lower rear corners of the valve covers, and rear most edge of the intake manifold. Good assembly practices with good sealants will minimize this annoying condition. A product to check out is called "The Right Stuff" it is made by Permatex and comes in a small aerosol can like "Cheeze Whiz". It is far superior to silicone for preventing oil leaks. It does not "Flow" like silicone does and has some very good binders in it, allowing it to bite into irregular surfaces much better than silicone. It's a little pricey but well worth investigating.
Good luck.
__________________
Rick
As you slide down the Banister of Life, may the splinters never be pointing the wrong way 
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03-22-2009, 11:11 AM
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CC Member
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Join Date: Feb 2007
Location: Colorado Springs,
CO
Cobra Make, Engine: Backdraft, supercharged Coyote
Posts: 2,448
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Not Ranked
Any oil leak anywhere on the engine always shows up on the backing plate. Even a fuel pump boss leak. That makes everyone think the RMS is leaking, when it really isn't. |
03-22-2009, 11:40 AM
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Senior Club Cobra Member
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Join Date: Jan 1999
Location: MARKSVILLE,LA.,,
Posts: 3,235
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Not Ranked
I guess I've been lucky, the 351-W I built in the early 90's hasn't leak a drop, two piece old style rear main seal.......
Race car motor is built on a 1970 302 block, old style two peice seal, 3 season of hard racing and no leaks.......
Be very careful when installing the seal and make sure everything is really, really clean and use a small dab of sealant on the ends....
David
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DAVID GAGNARD
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01-20-2014, 07:53 PM
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CC Member
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Join Date: Aug 2012
Location: Grand Rapids, MI,
MI
Cobra Make, Engine: StreetBeasts, 331 Stroker
Posts: 149
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Not Ranked
David, I know this post is some years old, but I'm wondering about the dab of sealant you're referencing putting on the ends of the rear main seal. I've heard some people say put RTV silicon on the block side and motor oil on the crank side, others motor oil both sides, others dry on block and oil on crank...... so I'm really wondering. I need to redo my rear main seal after about 1000 miles so something is incorrect, but I'm wondering if I should use a sealant in the installation. |
01-20-2014, 09:21 PM
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Senior Club Cobra Member
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Join Date: Jan 1999
Location: MARKSVILLE,LA.,,
Posts: 3,235
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Not Ranked
Quote:
Originally Posted by RedEye
David, I know this post is some years old, but I'm wondering about the dab of sealant you're referencing putting on the ends of the rear main seal. I've heard some people say put RTV silicon on the block side and motor oil on the crank side, others motor oil both sides, others dry on block and oil on crank...... so I'm really wondering. I need to redo my rear main seal after about 1000 miles so something is incorrect, but I'm wondering if I should use a sealant in the installation.
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When I'm ready to install the rear cap,make double sure everything is super clean,make sure you have put some engine oil on the seal lip itself,never install a seal dry.....
then where the ends of the 2-piece seal end on the block side, I put a small dab and I mean small dab of RTV on each end of the seal itself (the part that fits in the groove in the block), then install the cap..... you may or may not see a little RTV "squish" out of the ends of the cap, depends on how much RTV you put on the end of the seal.....
if you put RTV on one side and engine oil on the other,you are defeating the purpose of the RTV as it will not seal up....the RTV is to seal any imperfection in the seal ends as they are pulled together when you torque down the cap.....
One thing I ALWAYS DO is when I install any crankshaft and have all the cpas torqued down, I put a dial indicator on the end of the crank and rotate it over a number of times to see if it is true in the block........if it is not true in the block, you WILL have a rear main seal leak.......
One machinest told me if it is out .002, it will leak, if it is out .005,it will pour oil out of the back side......
__________________
DAVID GAGNARD
Last edited by DAVID GAGNARD; 01-20-2014 at 09:27 PM..
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01-20-2014, 10:04 PM
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Full Blown Member
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Join Date: Sep 2008
Cobra Make, Engine: KMP 427 S/C, Twin Paxton 511 FE
Posts: 2,594
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Not Ranked
I had 2 small blocks (351/402 Roush in a SPF and a 302 in an AC Autokraft) and neither leaked at the rear main.
In fact, the 302 didn't leak at all and the Roush only at the rear VCs (easy enough fix).
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rodneym
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01-21-2014, 01:41 AM
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CC Member
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Join Date: Feb 2006
Location: Gore. New Zealand.,
SI
Cobra Make, Engine: DIY Coupe, F/T ,MkIV.
Posts: 808
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Not Ranked
When you fit the two seal halves in the block/cap fit them one up/one down by about 1/4" so that they DO NOT line up with the block/cap parting line, this helps align seal ends, also check that the old peg from rear main cap that was reqd with fabric seals has been removed/ surface around that area checked for any damage from peg removal and filled with sealant. 'Right Stuff' on seal ends & cap/block parting line around seal area and grease on crank seal surface rather than oil to prevent seal from 'grabbing' crank prior to startup if its going to sit for a while, when refitting rear main cap snug down bolts/nuts very gradually & equally to avoid twisting the cap on the block & possibly distorting the seal as a result.
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Jac Mac
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01-21-2014, 05:39 AM
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CC Member
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Join Date: Jun 2005
Cobra Make, Engine:
Posts: 3,077
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Not Ranked
I can honestly say i have never had one leak on the 4 sbf i have owned. one time i thought one was leaking but it was the pushpin connector on the oil gauge fitting. to be honest i have had zero oil leaks on any of my engines (SBF) and I did not build them.
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02-02-2014, 11:28 AM
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CC Member
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Join Date: Jul 2006
Location: Sulphur Springs,
Tx
Cobra Make, Engine: Hurricane Motorsports #1121 427W
Posts: 105
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Not Ranked
My KC 427W would leave a puddle of oil after a 10 min. run . I took brake cleaner and
cleaned the rear pan area very good and found the leak from the corner of the pan .
I can say that I am a Ford guy from way back and I never had a leak from the rear main
on an engine I built lol.........my first engine for my Cobra was from Cheecago and it
leaked and thrashed , I love my KC engine 533 hp with a 'mild' thumper . I hope like hell
to make the Texas Cobra meet this year ! Oh by the way I have overhauled aircraft
engines too.......at least Ford got away from the rope seal :-) The aircraft engine reference
is to the fact if that puppy quits you can't pull to the side of the road . I love SBF and
you can keep your ole FE's ......(ok a side oiler at 7K rpm is one a beautiful sound indeed lol.
Last edited by FuzzyDiceRide; 02-02-2014 at 11:32 AM..
Reason: blah blah added
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