Motor Has To Come Out >???>bad Rear Main ???

agro1 · #1 (**permalink**) 09-06-2002, 09:45 AM

...so we dyed my motor and traced the oil leak to the rear main seal, which has already been replaced once. It's a 2 piece. Now it turns out that the back of the cam may possibly be egg shaped or not completely flat, allowing oil behind it and at every start up it pushes it out the rear main. I am being told 2 things:

1. The motor has to be pulled, torn down, a 1 piece spring loaded rear main put in and then the motor put back together and dropped back in. (would this be considered a rebuild??)

2. Second option (maybe) is to use some sort of sleeve or tool that takes the 2 piece main seal out (without pulling the motor) and replaces it with a one piece. This alternative sounds like the best way to go with the least amount of trouble and cost. But, I want it to be done right. Has anyone ever heard of this and if so, does it work ??

Everything else has been perfect with the motor and it runs like a bat outta hell, CHP builds very nice stuff - I just don't understand why a 1 piece main seal wasn't used from the get go...

Any thoughts, suggestions would be greatly appreciated.

Mr.Fixit · #2 (**permalink**) 09-06-2002, 10:18 AM

To put a one piece rear main seal in an early windsor block, one needs to cut the back of the block and the rear main cap to accept the seal, while the block is mounted in the line honing machine. This is labor intensive, not to mention that many shops forgo the line hone to begin with.

Jeb · #3 (**permalink**) 09-06-2002, 10:21 AM

who is telling you this?

you should be able to change the rear main by loosening the motor mounts, jacking the engine up slightly, and using an awl-type tool to push the seal around and out, or just pull it out. I'm not clear on your particular situation and exactly what kind of seal is in there, if there's a ton o' epoxy in there, or what, but it shouldn't necessitate complete removal of the engine. Unless there's more they're not telling you. Do they want to do a cam change too?

EDIT: didn't realize this wasn't an FE, but a Windsor. Sorry. From a 289 site:

Quote:

Replacing the Rear Main Seal
If your car had the rope type seal, replace it with the newer neoprene seal. Note that if the car had a rope type seal in it before, it will have a small pin (like a nail) sticking into the seal cavity in the main cap. It must be driven or ground out before the new seal can be installed. Seals really aren't that hard to install, especially on a 289 Mustang. Unbolt the idler arm and push steering linkage away. Remove the starter. Drain and unbolt pan and remove it. Loosen all the main cap bolts a couple of turns. Remove rear cap. The old seal will usually slide around so you can grab it and pull it out if you rotate the crank by hand in the direction you pull the seal. If it won't come, there are inexpensive tools that thread into the old seal to pull it out. BE CAREFUL NOT TO NICK THE CRANK. Install the new seal by carefully pushing it in place while rotating the crank in the same direction as the push. Lube the seal with oil and go easy as the sharp edges of the block will try to shave off pieces of the seal. Leave one end sticking out of the block 3/8" and match the one in the cap to it. Lube the lower seal and install the cap with a small bit of RTV near the rear of the parting surface of the cap. Torque all the mains and reinstall the pan. Don't use a gasket, just RTV Ultra Black, thick where the end seals went and thin on the flange. Everything must be cleaned with lacquer thinner first to get a good bond. Torque the pan tight to the block while the RTV is wet and it will never leak again.

agro1 · #4 (**permalink**) 09-06-2002, 10:47 AM

FIXIT - my block is a 1979 Windsor block - would this matter ? They are telling me that they have a tool that will take the 2 piece out and put a 1 piece in since it is a late model Windsor block. ???????

Great Asp · #5 (**permalink**) 09-06-2002, 11:28 AM

Argo1,

Sorry to hear about your motor. It is disappointing to get the car of your dreams, and not be able to drive it. Much less the worry that goes with the unknown.

Hope it all goes well, and your back on the road soon!

Eric Brown

Mr.Fixit · #6 (**permalink**) 09-06-2002, 11:49 AM

I haven't heard of such a tool before, may work great for all I know. How much do they have to tear down to do this? Can the crank and pistons stay in? It's a piece of cake to replace a 2 piece jobber by only removing the oil pan and rear main cap. Problem is you still have a 2 PIECE SEAL and this only fixes the leak about half the time. If the builder wanted a 1 piece rear main seal, he would have modifyed the block and main cap before building the motor.

427sharpe · #7 (**permalink**) 09-06-2002, 11:54 AM

FoMoCo makes a tool for this purpose. I dont see why they want to go this route though! A 2 pc seal will work just as well if installed correctly....Did he tell you if the seal he used (the 2 pc) was a rope type or a rubber? The rope type must have a pin left in the block to pinch it into place. It will leak if that is missing. As far as the cam story, I think that is a load of crap. If the rear journal of the cam were out of round, you would get instability in the valvetrain. And exactly how oil is supposed to gather behind the cam and push out the rear main is a mystery!
Having never seen your Windsor, I would bet that the wrong type of 2 pc seal is being used, or it is being installed incorrectly.
The lips of the 2 pc seal should NOT be parallel to the edges of the cap, and there should be a small bead of sealer on the edges of the cap. About a 1/16" wide in the corners or the rear main register and coming up to the edge of the oil slinger. Do the same on the cap, stopping just short of the seal. Also, make sure that the seal is installed in the correct orientation.

agro1 · #8 (**permalink**) 09-06-2002, 12:38 PM

427SHARPE - for some reason the 2 piece is not working and the guys (House of Cobras) who replaced it the first time know what they are doing...they said the Crank may be egg shaped in the rear allowing oil to get to the main seal. The cam is fine...I'm being told that it has to have a 1 piece seal. Jesus, all this over a $30 part !!! Am I missing something ???

Jack21 · #9 (**permalink**) 09-06-2002, 03:00 PM

Not adding up to me either. 2 pc seal installed per above should work fine. If it's leaking now, it was installed wrong. Nix the 1 pc seal at this stage of the game.

agro1 · #10 (**permalink**) 09-06-2002, 03:05 PM

The motor is being pulled and going back to the builder - so we shall see. They have been great up to this point and they said they would make it right. We shall see.

427sharpe · #11 (**permalink**) 09-06-2002, 03:12 PM

Agro: Things are starting to add up a little! in your first post, you said 'cam' was egg shaped. In the second, 'crank'. If they are saying the crank is out of round, than they did one crap job of machine work! NO WAY this should have been overlooked. A machinists job is to check EVERYTHING....twice! If the crank is out of round, no seal on earth is gonna seal it. Maybe this is why they want you to pull the motor...to repace a crank. I still hold to the conviction that a 2 pc seal, installed correctly, is as good as a 1 pc. I admire your conviction that they know what they are doing, after 2 rear main failures on a new motor! I just wish some of the customers I used to deal with in my shops were so understanding!

agro1 · #12 (**permalink**) 09-06-2002, 08:12 PM

427Sharpe - "...But Sir ?!?! He saw the Big Board !!!" Probably the greatest ever...

or..."Hail !!! Sorry Mr. President...."

LOL

RE: the motor - they will get it figured out. CHP, and especially Tim has been great to deal with. Very apologetic for my inconvience and promised to have it straightened out before the end of next week (barring any unforseen problems like parts out of stock).

427sharpe · #13 (**permalink**) 09-06-2002, 08:24 PM

Agro; Good! I hope they do you well so you can have some fun!
About the line...I wish I could make the abomb ride my avatar!

YEEEEEEEHAAAAAAAA!

427sharpe · #14 (**permalink**) 09-06-2002, 08:50 PM

Self portrait???

Art · #15 (**permalink**) 09-06-2002, 09:48 PM

My first post, be gentle....

My experience from re-occuring rear main seal leaks are caused by the following; (1). Not enough crankcase venting. Guys buzz motors up to 7K with a PCV valve and a vented oil cap.... Popped out intake gaskets and leaky rear mains! Crankcase pressure has to go somewhere....Doooh! (2). Not enough lube on the seal at start-up... Dry start-ups will pour oil instantly, but slow enough to leave a 6" diameter of 20W50 on the floor after a romp! Use plenty of Moly assembly lube on the rear seal. (3). Not the seal at all, but a leaky intake gasket, block plug or rear camshaft plug, Flywheel bolts should be sealed, on factory SB motors, the holes for the flywheel bolts go all the way through into the crankcase.

Respectfully disagree with the previous poster concerning a 2 piece seal "as good as" a one piece... No way, Jose'! IMO, one piece seal is far superior than a two piece split seal. I believe 1980 and newer Windsor and 5 Liter engines carried the better one piece rear main seal.

Steve R · #16 (**permalink**) 09-07-2002, 01:18 PM

Had a similar problem on a 318 Chys eng. turned out, the dipstick was not accurate, causing me to overfill the engine with oil. once I recalibrated the dipstick, I have not had a problem since........Just a thought...
Steven

eric hinderberg · #17 (**permalink**) 09-08-2002, 08:27 AM

ARGO 1 I have been down this road many many times. Does the crank have a smooth surface that the rear seal rides on? If so,you may never get a two pc. seal to work. The way we do all our blocks is to cut it for the far superior one pc. type. If you want we made a tool to put the factory lined finish on the seal area,that you are welcome to use. This is the only way we could get the old style seal to work on the stroker cranks that are sold in the aftermarket today. The nice thing about the tool is the motor can stay together, and in the car. Call me if you have any questions. Eric at Performance Engineering (513) 738-5001

Great Asp · #18 (**permalink**) 09-08-2002, 08:51 AM

Hey Eric H! ("E")

Good to see you post!

My killer 418 you build has no leaks! Last night it waxed a supercharged Firebird. Got him by a car out of the hole, and walked away from him after that! Guy said he is pushing 600 HP and over 500 ft# torque. If he's right, it was a good match up.

Love the motor!

Eric

khall · #19 (**permalink**) 09-08-2002, 07:13 PM

Hey Art,

I have a 351/393 that pops the breather cover off every time it revs above 5000 rpm. A PCV screw-in on the pass side (3/8" hose) and a vented cap on the oil fill tube. What type of ventilation should we have on these strokers?

Art · #20 (**permalink**) 09-08-2002, 08:11 PM

I have a 1 1/2" aluminum tube TIG welded to the front of each valve cover directly over the oil baffle. On the tube, I have a K&N breather. (Easier to wipe a little oil mist off the valve cover than replace a rear main seal). I have the tall Ford Motorsport covers.

PCV valve? I don't have no steenking PCV valve!!

BTW, I have a 392 also...Love it!