I pulled the motor on my '71 350ci to replace the clutch and rear main seal. The engine is now nicely hanging on the engine stand.

I'm planning to replace the seal this week, but I'm wondering what's involved? From what I've read, it's a two piece rubber seal. I'm assuming the pan will need to come off so I can get to the rear main cap.

Once the cap is off, how do I replace the half that's under the crank?

Also, from what I've read, I should use a one-piece felpro gasket for the pan. I'm going to replace the timing cover gasket and front seal too.

Am I on the right track here? With the engine out, it's a great opportunity to fix some things like oil leaks. Are there any other gaskets I'm not thinking of? I was planning to leave the top-end alone since it doesn't have any leaks.

Any tips and suggestions would be greatly appreciated...

 

On SB's, you'll have to remove the oil pump to get a clear shot at the bearing cap.
To remove the upper half of that seal, just push on it with something. A small punch works well to get it started, then grab the opposite protruding end with pliers and PULL! Be sure the new seal is facing the correct way when you install, and use the plastic "shoe horn" provided to install the new seal. A dab of high temp RTV at the two corners where the two seal ends meet is a good idea too.
Now's a great time to detail the engine compartment, and paint the block!!!
Good Luck
Eddie

 

Offset the seal ends so they're not flush with bearing cap/block. I replaced my seal three times in one week and each time leaked, but not anymore once I learned of that trick.

 

Make sure you don't nick the crank when removeing the seal. Be slow and steady with whatever you use to get the seal started out. one nick on the crank and then you will see an oil leak. And don't forget a new oil pump drive sleeve they are plastic and it will break when you remove the oil pump.
Also use rtv lightly between the cap and block and use a torque wrench to tighten the rear bearing cap.

 

One piece oil pan gaskets:
If you have GM OE 71 pan ... use Felpro P/N OS34509T.
If you have an aftermaket pan, or if the pan is GM OE from a 75 thru 85 ... use FelPro P/N OS34510T.

OS34509T has THIN front seal-section for 74 and OLDER sbc.
OS34510T has THICK front seal-section for 75 thru 85 sbc.

The difference is in how the pan itself is configured for the front seal-section ... the pan's front lip is higher on the older models; lower on the newer models.

Most (but not all) aftermarket pans are configured for the later THICK front seal-section.

Check both the front damper snout and rear journal of crank ... where the seals run. Over time, seals tend to wear a slight groove into the metal. Simply putting a new seal on a grooved surface may work ok for a while ... but will leak prematurely. If there's a groove in the damper's snout, your local parts house has a thin-wall metal "Redi-Sleeve" that you tamp onto snout ... reconditions snout ... works very well. If you have a groove in crank journal ... your local parts house has a rear main seal with a slightly "offset lip" ... seal lip rides on slightly different, fresh section of journal ... works very well. Both seal solutions are quite inexpensive.

 

A lot of good info posted all ready but a few things i can think of:

To prevent moving the oil pick up on rear main cap use just a little tack weld to hold it in place on the pump, if it hasn't been moved - clearance to bottom of oil pan is critical. U can check clearance with modeling clay if needed.

A light coat of Hylomar on main cap to block surface needed (prior to torquing) as that is a metal to metal boundry to atmosphere. Permetex II will work also there.

Don't know which type of seal u will use.
I have installed rope seals before with success by pre torquing cap with new rope seal inside then trimming closely with sharp razor blade.
The rubber type should be rotated off the mn cap to block break line and a dab of Permetex II placed just on the meeting ends before bolting on cap. If u install a rubber type seal wet it with oil before closing it up to prevent dry rub on start-up/break-in. Seals started dry have been known to leak right away from some type of galling.
Yes its confusing to use sealer on the ends and oil too on the bearing side surfaces but once u look it over i think u will understand this.

Man i wish they had the 1 piece pan seals out last time i replaced mine - would have saved me a lot of sealer and sealed-up hair.
Good idea to replace the t-cover gasket too - any that don't are asking for leaks.

BTW i buy LUK clutches from Northern Auto Parts. Great clutch for the price - most trans shops wish they could buy them mail order but can't do business waiting for the shipment. U can spend 2x or 3x more for big name hi-po clutches but only maybe 5% better clutch (if at all).

Good luck and lets us know of any problems. cardo0

 

Not sure what numbers you are using. These are the numbers I have for Fel-Pro one piece seals:

Part No. 1880 -- Left Hand Dipstick with Thick Front Seal
Part No. 1881 -- Right Hand Dipstick with Thick Front Seal
Part No. 1882 -- Straight Rail with Thick Front Seal
Part No. 1885 -- Left Hand Dipstick with Thin Front Seal

By the way I have a 1885 for sale if any one is interested. I bought and then discovered my pan takes the thick seal. Actually I'll give it away if someone is willing to pay the shipping.

 

First, the 188X numbers are ALL race gaskets ... usually not so readily available at local parts store ... often kinda pricey ... and race op gaskets are not necessary for most apps. Your list is incomplete; it does not include the many fp 1-piece op gaskets that are not tagged as race.

Second, I have personally installed a bunch of OS34510T ... several in real race cars ... a bunch of fellow builders / racers doing likewise ... they work great, readily available, good price.

You might not find OS34510T in hardcopy summit catalog & other boyracer rags ... but look it up at summit online (it's there). Better yet, visit your local "real" parts store and ask for it by P/N ... see for yourself.

BTW, if your 85 has a 2-piece rear main seal (probably does), OS34510T will fit your 85 ... the gasket has a thick front section AND it has provision for BOTH Left or Right ds. It even comes with ALL new op bolts & washers ... thick gasket needs slightly longer bolts ... probably buy it locally for about $25.

No, I did not invent the numbers ... I offer the info as an aide ... your choice: file it away ... or ... disregard.