How to Replace Rear Main Seal??

[devildog78brat]

My rear main is leaking so when my gasket comes in on friday ill start it but before that i was wondering if theres a how to or if anyone has any tips. its a 78 brat. i know from looking ill have to drain and remove the radiator, unbolt the motor and unbolt it from the tranny and slide it forward, then remove the old gasket and put the new one on. that sounds easy but will it really be easy? is there any special tools i might need or any techniques anyone has learned from doing it?

 

any info will help.

 

by the way my carb works great now it blew something out of it ha. i got a new air filter today for 99 at autozone it was on sale, did an oil change and replaced all my front lights. :banana:

[Snowman]

You may very well have to disconnect your exhaust from the heads to rock the engine forward (I've always just pulled the engine to do this so I'm not sure, but others here would know), which necessitates buying new exhaust gaskets as well, FYI. It's also a good idea to soak the mounting studs with penetrating oil for several days beforehand.

 

Also, are you planning on doing a cluch while you're in there? Unless it's nearly new, it's definitely worth it to replace the clutch, as it all has to come off anyway. If you're not doing the clutch, you'll need to find a clutch disk alignment tool for reassembling it (one comes with a new clutch kit, so no worries if you're doing that).

 

Since you're taking the radiator hoses loose, this is a good time to replace them if they're old (on an EA71, they probably are).

 

Not positive about the EA71 engine, but on all the other EAs I've worked on, the flywheel bolts that go into the crank are tapped all the way into the oil galley, so they need to have RTV or pipe sealant applied to them during installation, or they may leak oil all over your clutch.

[idosubaru]

rear main seals are tricky, you want plenty of room to work with so it seats and installs properly or you'll be doing it again the following week. it's not a "gasket" as you mention which are typically more forgiving. a seal needs to be pseudo-pressed in (i usuallly use the old seal) and seated properly. take note of the old seal deptth and install the new one to the same depth. and make sure it seats and installs flush and even.

[RenaissanceMan]

its usually easier to install the rear main onto the bellhousing and then install the bellhousing onto the block. Gives you a chance to reseal around that area at the same time. (as well as motivation to replace that leaky oil pan gasket)

 

Best advice I can give you either way, and this has worked for me every time... Silicone the ouside and grease the inside. The silicone on the outside acts as a lubricant when you're installing it. -so nicely that you literally push the seal in with your thumbs. (makes it easy to adjust it where you want it too) Once the silicone sets up, then its function is a little extra sealant for any scratches that may have been put in the bore.

 

The grease on the inside is to keep the rubber from "sealing dry". Exposing the rubber to friction without any lubricant in there will harden the sealing edge of the rubber and sometimes will "cut" into the crankshaft.