How to replace rear main seal?

[MalcolmV8]

Seems the rear main seal on my truck has let go. I'm getting a lot of oil on the ground from between the engine and tranny. About a 6" diameter puddle in an hour.
I know I'll have to pull the tranny which sucks because it means removing the radius arms to squeeze out the 4r70w but once I get there what's involved? It's been so long since I've replaced a rear main seal I remember nothing about it. Can I do it from under the truck with the motor in?

Thanks
Malcolm

[94stranger]

when my motor was out I replaced the rear main. you have to remove the flywheel and plates to get to it when you do use a really small thin screwdriver, push it in gently all around the seal(make sure not to force it or put scratches or dings in the metal suface),take your time. slow pop the old seal out by using the little rubber fins on the seal, and it should come out. when putting your new one in use some silicon put it over the rubber part with the fins all around the seal put it in place push in gently, use old seal put it up to the new seal and use it to tap it in evenly.

I hope this helps Malcom since I have only ever done one or two seals, as for doing it in the truck I don't have an answear for that.

[Bazowak]

Malcom,

The last time I did one on my Turbo Ranger I did it in the truck and it wasn't too bad. This is just my suggestion.

I read this right from a repair manual and it worked great. Once the trans, flywheel, and intermediate plate have been removed you will have full access to the seal. Use a drill w/ an 1/8 inch bit and drill 2 holes on either side. Then thread in 1 coarse thread screw into each hole. Just make sure that the screws you use are 1 to 2 times bigger than holes you just drilled. After you have the screws in you can use a tool of your choice to gently pry the old seal out. I used a short wonder bar. I know it sounds like the wonder bar is a bit of overkill but it work very well and did not distort the old seal upon removal. Then like someone said before me, use the old seal to aide in the install process. Just be sure to use a light coat of engine oil on the I.D. of the seal prior to install so that it doesn't have a dry start. Then you get to have the fun of the install again. If you have any other questions please let me know. I PM'ed you with my contact info if you would like any more info on how I did it.

Sorry, I don't have any projects to tinker with anymore so I get my hotrod fix through you guys now. If you use this process, let me know what you think and how it worked for you.

[MalcolmV8]

Thanks for the tips guys. I noticed last night the driver's side valve cover is leaking really bad. So I'm going to get the valve cover gaskets replaced this weekend (and probably use some silicon too this time) and then I'll see what's leaking from there. Right now there's so much oil messed all over the motor and tranny from that valve cover it's hard to tell if anything else is really leaking.

Thanks
Malcolm

[cjcnomor4]

check the rear seal on the intake manifold. they can push out and dump oil down the top of the trans.

[MalcolmV8]

Good call. I will check that when I get the upper plenum off this weekend. I tired looking back there last night with a flash light but it's just to cramped to see anything.

[plowboy34]

cjc beat me to it. I was going to say make sure and check that intake first. It is a very common mistake I have seen several times. Be a bummer to do all that work and it's not the rear main. The way you say it just started I seriously doubt it is the rear main. They just don't suddenly start leaking like that. As far as replacing the seal it is just like doing any other seal. If you want to spend the cash I recommend getting a seal installer, makes it much easier and much more sure that you don't ruin seal putting it in. Again a lot of work to just have it still leak. Just my thoughts.

[MalcolmV8]

Thanks guys. I will tackle the valve covers this weekend first and while the upper plenum is off I'll check the rear lower intake seal too.

[MalcolmV8]

Well I got the driver's side valve cover gasket changed out today. I used silicon on the new gasket so hopefully it doesn't leak horribly like the old one.
While I had things apart I checked on the rear of the lower intake and that area was all clean so that gasket is just fine. I'll give it a few days and see if any additional leaks show up.
It looks like the remote filter hoses are leaking right where they connect to the block adapter on the engine. I power washed it all today and will check in a few days for where the leaks are. I will probably have to drop the power steering gear box and pull those remote filter hoses and re-seal them next weekend.

Later
Malcolm

[cjcnomor4]

are your lines leaking or is the filter adapter leaking? I sent L&L an email looking to see if I could buy a replacement o-ring 2 weeks ago and havent heard anything yet.

[MalcolmV8]

I think it's the lines, right where they attach to the adapter. I'm going to pull them and try and find some local replacement o-rings and probably put some teflon tape and and some silicon in there too because these leaks are very annoying.

[cgrey8]

I put my couplings on the remote adapter end and they leaked right on install. I had to put silicone gasket on the threads and let it sit for an hour or so to get it to not leak. I put silicone on the threads and didn't wait long enough before cranking it and the pressure just pushed the silicone out of the way. Give it time to set before cranking and fill the threads with silicone and that should take care of it. It's done the job for me.