BK N 66

yahoo

after chasing a oil leak for 5 years i finally found out where my oil
leak was coming from. i checked everything i could think of for a
small oil drip for 5 years and could not find my oil leak.
it was not coming from valve cover gaskets and not coming from
rear main seal. not from fuel pump. not from oil pan drain plug.

The leak was coming from around the oil pan gasket where it goes
around the rear main bearing. where the semi circle is at the front
of the oil pan. apparently it has been leaking here for a very long
time. i guess the silicone seal around the front of the oil pan just
wore off and it started leaking.

Not looking forward to pulling my oil pan off and redoing it but i know
it is a must if i want to stop this annoying oil leak that i have been
chasing for 5 years.

anything else i should look at or replace once i get my oil pan off?

i know i will need all new gaskets. i just hope i can put the new
gaskets on and seal it back up hopefully with no more oil leaks??

thanks for any help and information.

mrg

The one-piece oil pan gasket seems to get the nod fo oil leak containment. .. Haven't tried one yet, though. With the oil pan removed it might be good to pull a couple of main and rod caps to check general bearing condition. Possibly replace the rear main seal with an elastomer 2_piece if not already installed.
John

Tampa Jerry

I would also replace the rear main seal as long as you are there. I just did this on my 66. I used a one piece oil pan gasket and a Fel Pro rear seal. I have a lift, so the job was not difficult at all. Jerry

Frankie the Fink

That's what I'm thinking, I wouldn't want to guarantee that your seemingly oil pan gasket leak is not, in some part, a rear main seal leak..

Bluestripe67

Make sure the pan rail is straight without dimples and don't put the gorilla arm on the bolts. Dennis

dkleather

You should be aware that the service replacement oil pans (1975 & later) have a different front radius and use a thicker gasket than original small block oil pans. An original pan has a 2-1/4" radius and gasket thickness is 0.22", while replacements have 2-3/8" radius, gasket thickness increased to 0.41". Thus, using the OEM style/size front gasket with a replacement oil pan will result in a serious leaker & you'll get to do it all over again.
(Copied here from a previous thread)

ejboyd5

This is simply inviting trouble. Remember, if ii ain't broke . . .

GTOguy

I pulled the main caps and a couple of rod caps because I had to on my '67 GTO a few years back in order to lift the crank up to replace the rear main. But I'm the guy who built the engine, and have experience building engines. For a layman to start pulling rod and main caps, if not necessary in order to replace the rear main seal is, as ejboyd said, inviting trouble. Unless you are experienced in this area, you are much better off not messing with the bearings.

SDVette

Huh?? Front or rear???

If it's the front... read dkleather's post (#6) above.. If rear, nevermind!

MikeM

Kinda' my first impression but I kept quiet until now.

Lot's of main seals get replaced because of ?????????????????????

BK N 66

jerry
i do not have a lift so i will probably pay to have it done.
my question is once the oil pan is removed how hard is it to replace the
rear main seal? does the transmission have to be removed?
i might as well have it all done at the same time? however, i guess it
is going to cost me some big bucks $$$? i will try and be prepared.

thank you for your help and insight. i hate oil leaks. to me an oil leak
no matter how small is the worst thing in the world. i just keep chasing
these dam oil leaks and i just cant seem to get em fixed? it just has
been so frustrating for me that sometimes i just want to replace my
engine with one that does not leak oil. sorry for my rambling.
take care and have a nice New Year.

frankie

dkleather

Just make sure that your mechanic measures and determines what oil pan you have so the correct gasket is used or you will be paying for it to be done again. If you know for sure it's an original pan, I'd get the gasket before taking it to be done. Likewise if you know it's a 1975 or later pan. Dave

Tampa Jerry

First thing to do is remove the negative battery cable.Drain the oil for about an hour. To replace the rear main seal, remove the idler arm and push the steering linkage forward. This will give you the room to remove the oil pan. Once removed, drop the two oil pump bolts and remove the pump. Remove the rear main bearing, also two bolts. The lower half of the seal will be in the bearing case. the upper seal can be removed with a wooden dowel pin. I used a plane on the dowel pin to a chisel point to remove the upper seal. Don't use a brass or steel punch, you could scratch the crank. when replacing the seal, offset it on top by about 3/8". Do the same on the bottom. I add a little oil to the seal where the crank rests. Lastly, put a little ATV cement on the edges of the block and the bearing. Replace the bearing and torque to 75/80 ft. lbs. Do the same with the oil pump bolts. Replace the pan gasket with the new bolts in the Fel Pro kit. Fill with fresh oil. Test engine. Reconnect the suspension. There are a few good You Tube videos on the subject. Lastly, you do not have to remove the transmission or starter to do this job. I have done this without a lift, but I was younger . Good luck. Jerry

champs65

Here's a pic I saved....probably courtesy of JohnZ

tbarb

I feel your pain, I don't think I have seen a S/B that did not leak oil somewhere. If it's not that bad, considering what a shop would charge to do the job, I would leave it because it may not come back any better.

Along with the suggestions above, the crankshaft surfaces should be inspected as well and this is best done during a overhaul and we don't want to go there.

Frankie the Fink

My 'go-to' mechanic guy said $320 for a rear main seal in my '63. I just got a price on a whim but wound up doing it myself...no more leaks... It'd been prob 45 years since I had done one. It is IMPERATIVE you get the right seal...

If you get that fixed and solve any possible valve cover leaks you'd be surprised how leak-free these engines can be. My '63 doesn't leak noticeably and my '61 sheds about a dime size drop under it after two weeks of sitting...

Unless you have low oil pressure or a high-mileage engine I wouldn't start dicking around with the bearings...

MikeM

Your diagnosis is confusing to me. Maybe not to others? No silicone sealer to "wear off". Leaking around the rear main bearing......at the front of the pan?

I'd look carefully at the seal in the timing cover that wraps the harmonic balancer while I was under the car.

I've always used the standard Fel Pro or Victor pan gasket set. Not the one piece that many like to use. Follow the directions on the package about the dabs of sealer to use and the location of the four places the rubber/cork junctions.

Make sure the pan rail is flat and DON'T overtorque the bolts.

With proper assembly, there's no good reason for a SBC to leak oil to the point of dripping. Especially if you have a working OEM PCV system.

cardo0

Well what are you ready for and willing to do. Something like this can really snowball and your cruiser can easily become a garage project/restoration. I'll just say I've learned my lessons the hard way and in your case I'd park the car over a drip pan (like my camaro is now) until the car needs some major work. Oil pan gasket can turn into a new oil pan, replace RMS, replace main bearings, then rod bearings, then full overhaul. Not that much fun. I'd rather be driving the car that replacing the motor.

A large leak like enough to reduce the oil level between changes - ya time to change that gasket. But just a few drops each week - fix it with a $13 drip pan from AutoZone.

Good luck with whatever you choose.

BK N 66

thanks cardo for your information. however i do have a aluminum
drip pan in my garage that i park my corvette over.

i just get tired of looking at and wiping up the oil that is in the drip pan. every day when i go out to garage there is oil in the drip pan.

i wipe it up with a rag and the next morning the same thing happens.
another oil drip in the pan? everyday its the same old thing more oil
in the drip pan. it just gets frustrating. thanks

6T5RUSH

BK N 66,

Just to add to Tampa Jerry's step by step to get at the rear main seal, before you get started rotate the engine so the harmonic balancer index line is at 5 o'clock (thank you JohnZ). Doing this first will allow the pan to clear all the counterweights (they'll be up high).



Jim
In God We Trust!