Rear Main Seal Advice

4barrel · 04-15-2007, 11:59 PM

I'm building a street/strip 347 from a production 302 roller block with a Coast High Performance kit. I'm thinking the block is a later 5.0 piece, so it should get a 1 piece seal, right? I'm just wondering what brand and material is the rear main seal you guys use or recommend.

USMC302 · 04-16-2007, 04:30 PM

Fel-pro and Mr gasket sell both the 2 pieces and 1 pieces just to name a couple.

~The Jester~ · 04-17-2007, 07:27 AM

If it's a later block, it's gonna be a 1 piece which seals WAY better. It's metal coated in a rubber polymer, typical round seal. Spring goes towards the oil. USMC nailed it, go FelPro or Mr. Gasket. You can get a FelPro at your local Autozone, Advance, etc etc.

If you do find out you need a 2 piece, DO NOT put the gaps in line with the block/oil pan flange. Rotate it almost 45* so the seams are up in the block, and down in the oil pan.

4barrel · 04-17-2007, 11:39 AM

I also hear NAPA Teflon rear seals are good, but I think the two you fellers listed sounds like more reputable names. Thanks for the help.

sleeperstang · 04-23-2007, 09:52 AM

Did you really mean 45*, Jester? If it is, that's a bit of advice I've been wanting to hear. I've replaced the main seal twice in the last year, and the leak doesn't seem to go away. I don't line up the two pieces witht he flange, but I only offset it between 10*-15*. If that's the case, I may need to go under the car again, because I just did that deal 4 weeks ago, and it seems I have the drip still.

Dark_5.0 · 04-24-2007, 02:59 PM

Everytime someone tells me that their rear main seal is leaking I find a valve cover leak.

~The Jester~ · 05-01-2007, 03:45 PM

You're both right. If you have oil on the ground, find the HIGHEST place it can come from, and work your way down. Eliminate intake, valve covers, etc etc. Work your way down, just like gravity does. Make sure it's not the rear of the intake, cuz that'll run down your bellhousing and LOOK like a rear main. Pan gasket? Valve covers? Do yourself a favor and start with the easy crap first.

And YES, I mean 45* on the seams. Kind of a PITA, but it's worth it. Have to pay CLOSE attention during assembly.

04-15-2007, 11:59 PM	#1
4barrel Mustang Rookie Join Date: Apr 2005 Location: Lexington Kentucky Posts: 98	Rear Main Seal Advice I'm building a street/strip 347 from a production 302 roller block with a Coast High Performance kit. I'm thinking the block is a later 5.0 piece, so it should get a 1 piece seal, right? I'm just wondering what brand and material is the rear main seal you guys use or recommend. __________________ 1989 Mustang GT aka Hailey http://www.cardomain.com/ride/822269

04-16-2007, 04:30 PM	#2
USMC302 Registered Member Join Date: Apr 2001 Location: Gallatin, Tn Posts: 1,326	Re: Rear Main Seal Advice Fel-pro and Mr gasket sell both the 2 pieces and 1 pieces just to name a couple. __________________

04-17-2007, 07:27 AM	#3
~The Jester~ Rat Killer Join Date: Aug 2002 Location: Cold ass Ohio Posts: 1,143	Re: Rear Main Seal Advice If it's a later block, it's gonna be a 1 piece which seals WAY better. It's metal coated in a rubber polymer, typical round seal. Spring goes towards the oil. USMC nailed it, go FelPro or Mr. Gasket. You can get a FelPro at your local Autozone, Advance, etc etc. If you do find out you need a 2 piece, DO NOT put the gaps in line with the block/oil pan flange. Rotate it almost 45* so the seams are up in the block, and down in the oil pan. __________________ d-Con Racing "Nothing fancy, just 347 inches of RAT POISON!" MICE need not apply.....

04-17-2007, 11:39 AM	#4
4barrel Mustang Rookie Join Date: Apr 2005 Location: Lexington Kentucky Posts: 98	Re: Rear Main Seal Advice I also hear NAPA Teflon rear seals are good, but I think the two you fellers listed sounds like more reputable names. Thanks for the help. __________________ 1989 Mustang GT aka Hailey http://www.cardomain.com/ride/822269

04-23-2007, 09:52 AM	#5
sleeperstang Registered Member Join Date: Jun 2001 Location: Lynwood, CA, U.S.A. Posts: 82	Re: Rear Main Seal Advice Did you really mean 45, Jester? If it is, that's a bit of advice I've been wanting to hear. I've replaced the main seal twice in the last year, and the leak doesn't seem to go away. I don't line up the two pieces witht he flange, but I only offset it between 10-15. If that's the case, I may need to go under the car again, because I just did that deal 4 weeks ago, and it seems I have the drip still. __________________ 65 Mustang Coupe...Comp Cams 262 Xtreme Energy, T-5 conversion, Romac Balancer, 620 Front Springs-4.5 Mid-eye rear springs.......work in progress Last edited by sleeperstang; 04-23-2007 at 11:40 PM..*

04-24-2007, 02:59 PM	#6
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	Re: Rear Main Seal Advice Everytime someone tells me that their rear main seal is leaking I find a valve cover leak. __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

05-01-2007, 03:45 PM	#7
~The Jester~ Rat Killer Join Date: Aug 2002 Location: Cold ass Ohio Posts: 1,143	Re: Rear Main Seal Advice You're both right. If you have oil on the ground, find the HIGHEST place it can come from, and work your way down. Eliminate intake, valve covers, etc etc. Work your way down, just like gravity does. Make sure it's not the rear of the intake, cuz that'll run down your bellhousing and LOOK like a rear main. Pan gasket? Valve covers? Do yourself a favor and start with the easy crap first. And YES, I mean 45* on the seams. Kind of a PITA, but it's worth it. Have to pay CLOSE attention during assembly. __________________ d-Con Racing "Nothing fancy, just 347 inches of RAT POISON!" MICE need not apply.....

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
rear main seal	racerx0071	Windsor Power	1	02-19-2003 02:18 AM
how do i put a rear main seal in	302crew	Windsor Power	3	09-23-2002 11:36 AM
advice on rear main seal	Conman	Windsor Power	7	07-25-2002 09:15 PM
Rear main seal on 87 2.3L	Radon	Small Ponies	1	02-20-2001 03:08 PM
rear main seal	66fastback	Classic Mustangs	2	07-04-1999 10:08 PM