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Rear main seal replacement advice

20K views 23 replies 16 participants last post by  4DoorSS 
#1 ·
well time has come to change this seal, so was hoping you guys can offer some helpful tips

so far i know i can drop the tranny and go in from there,

so any advice guys, im all ears

thanks
 
#2 ·
Haven't done one yet, but did look into it sometime ago. Pretty straight forward, the seal housing has pry tabs on it, so you can pry it out. When installing tap evenly around the edge, make sure you lube up the inner portion that mates to the crank, so it will slide on easier. This pic may help
 
#3 ·
That couldnt of been done any better Mike.
 
#4 ·
a tool like this http://www.myaston.com/k/?view=item...ore+LT1+5+7L+Rear+Main+Seal+Installer+J+35621

makes the job VERY easy. I did not use the KM one, IIRC it was a "matco" one i borrowed from a friend but works the same. bolts to back of crank and you just screw in the center bolt/handle on tool to press it in.

As mike said you can tap it in evenly without a tool but if you can find a tool cheap/free than use it.

Grease inner lip of seal before install. My $02 is go with the 'rubber" FelPro (not teflon) rear main seal.
 
#6 ·
I used the felpro rubber one as well. So far no leaks. As Roger said, use the tool if you can borrow one. If not, I used a small piece of wood to tap mine in. It is only a 3 minute job --- once you get the tranny out!
 
#7 ·
lol thanks guys, if i can i'll see about that tool, but this tranny drop is gonna blow!! more then likely i'll be doing this in my driveway(hoping not the street) and if i'm lucky my bro can give me a hand, since hes dropped his before
 
#12 ·
Rear Main Seal leak?

Guys just got my new LT1 Motor bk in my 95 SS and everything looks and runs great just one problem. I have noticed a very small oil leak although not constant coming from around the rear main seal. The motor has less than 50 miles on it, so are there any chances that it may seal up on its own and stop? Im using Mobil 1 Clean 5000 5w 30. I was told I shouldnt use synthetic until it has some miles on it so is there a chance this small leak may stop or should I be thinking about having it fixed already? Thx Steve
 
#13 ·
I guess it is possible that it might seal on its own. Might give it a few days to see. Also, before you pull the trans to replace the rear main seal, make certain that your leak is not at the rear of the intake manifold (that is a common place for these motors to leak).
 
#15 · (Edited)
Give it a few good runs Oklahoma, let her get good and hot.
Don't over heat it, but getting hot may help the seal "cure", for lack of a better word.

Just thought of this.
Try a quart of 10W-40 in your next oil change.
So 4 qts. 5w-30 and one 10w-40. May thicken things up just enough to not leak.

I've got to replace both of my main seals at some point.
And probibly front cover seals.
Mabey valve covers. I know the front oil seal on the bike leaks.
Dam, I've got s^#t leaking all over the place.
 
#18 ·
Rear Main Seal Installed without the special tool

Changed mine out Saturday. It took two of us about 6 hours with lunch and a mid afternoon break to run out for more beverages. We had the car up on a two post lift and we had a transmission jack. I have a TKO-600 five speed and we installed a new front seal in it at the same time.

Bought the FelPro teflon rear main because that is what AZ had in stock. It comes with a nifty plastic sleeve that helps seat the teflon inner seal without damage. Similar to the water pump seal tool except its thin. Note the teflon seal is installed dry.

With the transmission and flywheel removed, the old seal pops out with a screwdriver. No need to remove the flange holding the seal. Wiped the crank hub and outer flange clean using some brake fluid and used some compressed air to dry it out.

Started the new seal with finger pressure and then put the old seal on top of it and gently tapped it into place with a plastic hammer. After the inner seal is over the edge of the crank you can just pull the plastic liner out the back and finish seating the seal by tapping around the crank in a circle, many times. It worked best using light taps and just continuing round and round until the seal was flush.

Drove it about 40 miles and no drips on the garage floor the next morning or oil on the bell housing so for now it looks like its fixed.
 
#19 ·
Changed mine out Saturday. It took two of us about 6 hours with lunch and a mid afternoon break to run out for more beverages. We had the car up on a two post lift and we had a transmission jack. I have a TKO-600 five speed and we installed a new front seal in it at the same time.

Bought the FelPro teflon rear main because that is what AZ had in stock. It comes with a nifty plastic sleeve that helps seat the teflon inner seal without damage. Similar to the water pump seal tool except its thin. Note the teflon seal is installed dry.

With the transmission and flywheel removed, the old seal pops out with a screwdriver. No need to remove the flange holding the seal. Wiped the crank hub and outer flange clean using some brake fluid and used some compressed air to dry it out.

Started the new seal with finger pressure and then put the old seal on top of it and gently tapped it into place with a plastic hammer. After the inner seal is over the edge of the crank you can just pull the plastic liner out the back and finish seating the seal by tapping around the crank in a circle, many times. It worked best using light taps and just continuing round and round until the seal was flush.

Drove it about 40 miles and no drips on the garage floor the next morning or oil on the bell housing so for now it looks like its fixed.
Nice! I will be installing mine today. I don't have a special tool for the install, so using the old seal as a guide will help. Thanks for the tip!
 
#21 ·
"X" pipe exhaust, for me, does not interfere with droping the tranny

Pogo posted a link to the "tool" to use for RMS ( one in my link died) although as mentioned the rear seal often does come with a olastic sleeve to help slide it over crank. Using the Teflon seal, which does install DRY, will go on better if using the plastic sleeve or the "kent Moore" exploding wallet tool. Then just use a wood block to cover and tap in or gently tap in in circle steps using a mallet

I will note before replaceing the RMS, REALLY confirm it is in fact leaking. It is way more common for rear intake gasket, oil filter adapter to leak before RMS. The oil migrates down from the leak source and "appears" to be coming from RMS. IIRC on the TC cover there is a slot to look up and see...been 7 years since I had an automatic :)
 
#22 ·
reading more and more im starting to think if it really is the rear seal that is leaking. where is the rear seal exactly located? I noticed my leak is comming from the front of the crank. i removed water pump, opti and balancer. water pump and opti seals were replaced. i did not see a trail comming from the front crank seal. maybe if I post how my leak began somone will have a different suggestion.
I've always had a slow leak like one drop per hour. I installed the supercharger and thats when my leak began to drip constantly. I would leave a trail of oil as i drove. im thinking that since i already had a slow leak, by adding the extra belt, that made one of the seals loose and caused a constant leak. constant leak only happens when i turn the car and noticed that its comming from where the red circle is located and drips all the way down to where the tow hooks are. can it still be the rear seal?




 
#24 ·
No, what is pictured is the front of the engine. What you have circled in RED is the front of the OilPan gasket. If that is where your leak is, then time for a new pan gasket.

Tow hooks? Never seen them as a factory option on a b-body before.
 
#23 ·
if its not the front crank seal it could be the timing cover.
 
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