318 rear main seal replacement

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7dswinger

7dswinger

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Rear seal's started leaking :/. Going to go ahead and guess that I have to remove the steering linkage to get the pan to clear to wiggle out. Never done this though so anything is helpful haha
 
It could be the lower and/ or the upper seal that requires lowering the crankshaft.

I'm not entirely sure you have the clearance at the front of the pan, between the K member and the engine block and crank to get the pan low enough to take out, but you'll still need to remove the crank/ trans from the crank and engine to get it down, for the upper.

I think your best bet is going to be to pull the engine out or at least divorce the transmission, slide it back and lift the engine from the mounts at the K member, high enough to remove the entire pan, if you don't feel like taking it out and taking everything off.
 
I think the least amount of work would be to remove the starter, trans to engine bolts and the two vertical transmission bolts from the tailshaft mount, exhaust from the heads, mount bolts at the member, carb, lift the engine with a carb plate.

That way, you can slide the trans back enough for the torque converter to clear the flex plate and crank and lift the engine enough for the pan to clear the K member.

You will have to keep track of the main cap bearings and get the crank down far enough to fish the upper seal and little blocks on either side out, but it can be done in the car this way.

Come to think of it, you may have to also remove the water pump, harmonic and timing cover, but it can still be done. Good time to check the chain and replace the pan gasket.
 
Do you have an engine hoist? I'm getting to the point now where I want to pull my motor every couple of years to put all new gaskets and seals on. I hate leaks and if you want to get serious about fighting them then keeping all your gaskets in seals in good shape is key. I have never changed a rear main seal with the motor in the car though so I can't help ya:(
 
I could acquire one but I really don't want to rip the engine out of the car. I believe it's the bottom seal that's causing the problem. As long as I can get the pan out, which by removing the cross link in the steering it looks like I can get it out I should gain access to it. All I have to do is remove the rear main cap and pull the top and bottom seal out and put new one's in right?
I think if I unbolt the engine and jack it up some and put wood under it to support it that might gain me some clearance as well.
 
Some cars, the pan will come out without lifting the engine, you have to rotate the crank counter-weight out of the way,, others I lift the engine just high enuff to place a 1/2 drive socket between each of the mounts and pads, for clearance, and that allows you to rotate the crank as you coach the seals in and out..,

The book says 3.3 hrs to replace lower 1/2 of seal,, and 4 hrs to do them both, add 6.4 hrs to R&R engine if you feel the need..

hope it helps..
 
hhmm crank counterweight? I've never delved into this area of an engine so this is new haha.
Is there any special things I need to do when replacing the seals?
 
It's alot easier to replace a rear main seal when the engine is out of the car than with it in...
 
It's all straight forward till it comes to getting the top seal out,, you didn't mention year,, if you've got a rope seal,, that can be challenging,, but by your avatar,, the seal should be rubber,, so if you look closely at the ends of the seal,, you'll see a "wire"'' on your old one,, push on the wire, as you rotate the crank in the same direction,, it'll come out enuff to grab with pliers etc,, install it reverse,, making sure the seals "lip" is facing into engine,, refer to old seals direction..

Use weatherstrip glue, or rubber cement to hold the gskts in place,, with a dab of RTV silicone at the corners,, use a hammer to straighten the pans sealing surface, tapping out the mushrooms the bolts tend to make..

hope it helps.. cheers

I'd get laughed outta my own shop if I yanked the engine to do a rear main..lol

and explaining the extra 6 odd hrs. to a customer is outta the question.. lol
 
You could prob get one from Napa or who-ever,,

Fel-pro or a brand name will prob be cheaper,, get pan gskt, RTV and glue (3M weatherstrip adhesive/gorilla snot lol) there too..

P.S. Also be aware, if you jack the engine up too far,, the dist cap can interfere with the firewall.. perhaps loosen cap if you get close.. and the fan may hit the shroud..
 
The upper seal was rope on my '73. I replaced it with the rubber one. I can almost guarantee that yours is rope, too. They are no more difficult to replace than rubber, but having a rope upper and rubber lower might be tricky to seal. You could try RTV at that junction, but I don't know that the rope being saturated in oil will ever take the RTV completely. It might slow the leak down significantly, though.

Either way, just taking the rear main cap off won't do anything to get to the upper, because it's above the crank, in the block, itself, along with the rubber blocks that seal the main cap to the block and the lower, within the main cap.

The issue with the pan isn't what is under the pan, it's what is inside the pan, down below the bolt/ gasket line that will make your life hell, with the engine in place. You have to get the pan down far enough to clear the crank at the very front, but even if you rotate the crank so that the counterweight for the 1/2 piston journal is up and out of the way, you still have to move it around the pickup in the sump.

You shouldn't have to take the engine out, or the water pump/ timing cover if the rear main lower seal is what is leaking.

Do you know what your timing chain looks like, or how long ago it was changed?

The reason I ask is that if you've got the car apart down there and the car is out of commission, it would probably be a good idea to change the chain. A rear main seal leak is usually not the only part of the bottom end that needs maintenance, when it goes, unless it's a fluke.

I think it would be wise to do upper and lower seals, or just wait on it, save some cash and pull the engine to clean up and put new gaskets on everything, with a new chain, all at once.
 
If it still has a rope seal,, replace it with a rubber one as you posted,,

To remove the rope seal, use a medium self tapping screw, and screw it into the end of the rope as far as u can, avoiding any contact with the crank,, .

I use a piece of mechanics wire attached to the screw,, to pull on it as I rotate the crank.. The screw expands the rope and wedges it against the crank,, and when you turn the crank,, it drags the rope out with it.. the only problem I've ever had, is not putting the screw in far enuff the first time,, and essentially "stripping" it..

A little patience,, you'll get it done..

hope it helps,,

P.S... be absolutely sure it's not a valve cover, distributor, or most common, the oil pressure sender that's leaking,, or all your work will be for nothing..
 
First thing I checked was the oil sender unit but there's no oil coming out of it. I noticed the leak after I cranked the engine over a few times as I'm getting the car back on the road. No leak on the floor before crank and then a enough that it's more than just a drop but a good leak.
I can see oil pooling on a lip of a gasket protruding out between the pan and the block behind the trans dusk cover so I when straight to rear main seal.
 
Be sure it's oil that you see, coming from behind the dust cover and not dark trans fluid.
 
It's oil all right, no doubt about. Here's a crappy pick I just took haha
IMG_0811_zps0adccf5b.jpg
 
Giant orange thing is oil pan and black ring in the center of the picture is where the oil is dripping off of, rubber seal poking out.
 
I gotta be honest with you,, were I you,, I'd clean the begeebees outta the whole area with brake clean,, then run it,, oil leaks are elusive as hell,, .. I took it for granted it was the rear main,, a few times,, then I learned to clean and look very carefully,.. you're likely right,, buttt,, that's no small task you're taking on,,, just my .02..
 
I sprayed to whole area with degreaser, going to keep cleaning it tomorrow.
That is the rear main that's poking out there though right, not the pan gasket.
 
That's the rear pan gskt/seal,, that black rubber thing..

Oil could be coming outta the front and running down the top of the pan,, to the rear.. just a thought..
 
I'd be surprised, I just cranked it over 3 times, never fired it up or drove it, just cranked it and it leaked haha

So that's not the rear main seal then? Cause that's where the oil is coming from or seeming too, rather replace that first then delve into the main seal ordeal. I'll check other area's when I get off work and I clean it a bit more.

I may stick a video camera under there and crank if and see if I can see what's going on, did it before with a trans leak and it worked great!
 
sounds good will do, hopefully it's just the pan gasket not the main seal, but knowing my luck ahah, thanks for the help, post back tomorrow what I find.
 
where in cali are you? i have loads of extra gaskets and what not, if you are near me i will give a hand or what ever.
 
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