Topic Options
#2451518 - 02/13/18 10:31 PM Small block w/ automatic rear main seal question
OLD318 Offline
super stock

Registered: 02/02/04
Posts: 910
hey guys,

Can you replace an LA small block rear main seal with both the
engine and trans installed in the car..

If so, do I need any special tools, tips etc?

IF any one on here has done this job please chime in
Thanks

Top
#2451529 - 02/13/18 10:51 PM Re: Small block w/ automatic rear main seal question [Re: OLD318]
70AARcuda Offline
master

Registered: 01/20/03
Posts: 9681
Loc: las vegas
yes...Done it in a couple of pickup trucks last year.

no special tool..just need to push upper half of neoprene seal out...

lubed the new one and pushed it into upper half...
_________________________
Tony

70 AARCuda Vitamin C
71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield)
71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas)
71 Duster 360 (10.641 @ 124.17 9/16/16 Bakersfield)

Top
#2451534 - 02/13/18 11:08 PM Re: Small block w/ automatic rear main seal question [Re: OLD318]
kcarfanatic Offline
member

Registered: 02/03/18
Posts: 34
Loc: new haven ct
Not quite so easy if it's a rope seal.Get yourself one of those corkscrew type seal remover tools. Might even help if you carefully loosen the #4 main cap a bit.

Top
#2451536 - 02/13/18 11:10 PM Re: Small block w/ automatic rear main seal question [Re: kcarfanatic]
kcarfanatic Offline
member

Registered: 02/03/18
Posts: 34
Loc: new haven ct
I believe Lisle Tools has the seal removal tool.


https://www.ebay.com/i/282433611363?chn=ps




Edited by kcarfanatic (02/13/18 11:14 PM)

Top
#2451567 - 02/14/18 02:46 AM Re: Small block w/ automatic rear main seal question [Re: OLD318]
Cab_Burge Offline
I Win

Registered: 08/23/03
Posts: 31046
Loc: Bend,OR USA
Have you made sure that the main seal is leaking and not something else?
I've seen more than one car have the rear main seal replaced several times when it wasn't leaking to start with shock
Does the flexplate or flywheel flange have oil slung out on the surface that faces forwards? scope
If not it is not the main seal leaking shruggy
The rear cam bearing plug or the rear oil galley plugs can leak and look a lot like a rear main seal leak shruggy
Good luck either way thumbs
I have loosen all five main caps with the engine and tranny in the car to replace the rear main seal on BB and early hemi motors, not sure if I have done that on a LA SB realcrazy
_________________________
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Top
#2451570 - 02/14/18 03:43 AM Re: Small block w/ automatic rear main seal question [Re: OLD318]
PurpleBeeper Offline
super stock

Registered: 07/05/11
Posts: 752
Loc: Chicago
I just replaced a rear main seal on a big block a month ago and this is what I learned. Most if not all of this applies to small blocks too.

1. You can change it with motor/trans in place. You will need to break loose the pitman arm & idler arm to lower the center/drag link enough to get the pan off. Leave the tie rods alone & you won't mess up your alignment.
2. Oil galley plugs & rear cam seal (looks like freeze plug) can leak, but that is very rare.
3. There are 2 types of seals, 1-piece rope seal and 2-piece seal. Rope seals better but is MUCH harder to install remove. You need a "Chinese finger lock" tool to install it and a screw-in tool to remove it. Loosening the #5 main bearing cap (or all of the main bearings) might help. If using a 2-piece seal, it is stiff, so you can slide the top half up/around the top of the crank without loosening any bearings. TRIPLE check which way the lip of a 2-piece seal goes on both halves...the lip faces the engine, not the trans like is "seems" (ask me how I know)
4. For either seal, lube well with assembly lube.
5. For a 2-piece seal, make sure to offset the two halves about 1/8" so the break between the two halves doesn't line up with the break in the rear seal cap.
6. Make SURE your cap is clean & free of debris.
7. Use a single drop of special Loctite seals (check online for which one) where the two halves of the seal butt up against each other.
8. Use about 2 drops of RTV on the rear main cap surface where it butts up against the block, no more.
9. Tighten the rear seal cap slowly and make sure it goes in even.
10. Almost forgot, lube the side seals of the rear seal cap too.
11. Buy the good silicone 2-piece main seal & side seals, not the Felpro ones.

Hppe most of this helps & good luck.... and MAKE SURE it's the main seal & not the back of a valve cover or something else leaking first. Hughes Engines site has some very helpful information too.


Edited by PurpleBeeper (02/14/18 03:46 AM)
_________________________
70 Roadrunner convt. street car 440+6, NOS, 4-spd, SS springs '96 Mustang GT convt. street car '04 4.6 SOHC, NOS, auto, lowered "Officer, that button is for short on-ramps"

Top
#2451943 - 02/14/18 09:44 PM Re: Small block w/ automatic rear main seal question [Re: OLD318]
OLD318 Offline
super stock

Registered: 02/02/04
Posts: 910
Hey guys, THANKS for all the responses! The parts book lists a 2 piece seal....Is there a particular brand that you used or recommend? I'm also thinking while I'm at it - upgrade from a stock oil pump to a high volume Melling oil pump...anyone done this/recommend it? thanks for all the feedback

Top
#2451954 - 02/14/18 10:01 PM Re: Small block w/ automatic rear main seal question [Re: OLD318]
moper Offline
I Live Here

Registered: 02/03/03
Posts: 12667
Loc: Columbia, CT
If it was rope it wouldn't be leaking... My advice would be to pull it and install the rope. Do it right and it will never leak. The lip seals will.
Rope seals are two piece but they are a snug fit (hence the never leaking) and need to be trimmed to fit - so slipping one in is not as easy.
_________________________
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.

Top
#2452001 - 02/15/18 12:32 AM Re: Small block w/ automatic rear main seal question [Re: moper]
Cab_Burge Offline
I Win

Registered: 08/23/03
Posts: 31046
Loc: Bend,OR USA
Originally Posted By moper
If it was rope it wouldn't be leaking... My advice would be to pull it and install the rope. Do it right and it will never leak. The lip seals will.

I use to work in several different service station near a Marine base back in the early 1960s when rope seals where stock OEM in all new Mopar motors, I saw more than one rear main seal leak back then shruggy
I've rebuilt motors and had to use the OEM style rope seals, once the new style rubber and later Neopreme came out and now the newest Viton seals sold today I haven't had a rear main seal leak in over twenty years, I have had the old side seals leak on BB Mopars years ago but not anymore boogie
If the factory can make the stock rear main seals not leak then we should be able to get the same results, no matter which type or material used work
The old technology and parts where invented years ago, they are not as good as the modern ones used today twocents work


Edited by Cab_Burge (02/15/18 12:34 AM)
_________________________
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Top

Advertisement
Forum Stats
25,425 Registered Members
32 Forums
191,767 Topics
2,236,751 Posts

Most users ever online: 1,424 @ 06/20/18 07:18 PM
Moparts Newest Topics
1978 Dodge , north Central Minn , $5000 D-200
by bigdad
08/14/18 01:38 PM
1976 Dodge D-200 north central Minn $5850
by bigdad
08/14/18 01:35 PM
What spark plug are you using in your stroked Hemi
by davesmopars
08/14/18 01:23 PM
need clarification: 68 4 speed a-bodies black carpet only?
by copperSwinger
08/14/18 12:36 PM