The Stovebolt Site Forums The Shop Area Engine Shop Rear main leak

I have just completed a rebuild of my 1950 216, with a lot of help from folks on this forum. I have the engine on a stand so I could run it before it goes into the truck. I have a bit of an oil leak, appears to be the rear main seal. I used the rope seal that came with the Fel-Pro gasket set. I did not use any type of sealant at the mating point for the two seal pieces. Would it be worth trying to add a sealant at this point?
The amount leaking is not tremendous(8-10 drops after running 10-15 minutes) but more than I like.

Now is the time to fix it to your liking. It's out and easily accessible. Get it the way you want before you proceed.

JackieC,

8-10 drops might be a little too much

You most likely followed the procedures described in the Shop Manual (and used a new seal):
http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0617.htm
http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0627.htm

This Tech Tip suggests not to cut the seal ends flush on the block-side - leave them a little "proud" (1/64" protruding at each end).

Wait to see advice from other posters. Maybe Pre '68 Dave will post opinions/suggestions.

Yep, I cut the ends flush

Run it some more and see if the leak stops or reduces dramatically. It needs some run-in time to swell and get a good running fit with the crankshaft.

Unfortunately, the rope seals made recently without asbestos don't seem to work as well as the OEM seals from 50 years ago. Doesn't a company called "Best Gasket" make a rope seal that's a lot better at stopping leaks? I don't have any hands-on experience with that brand, but it's been highly recommended here on the forum frequently.

Edit:
We used to soak the seal ropes in motor oil for several hours prior to installing them. That seemed to make them leak-free a lot sooner than installing them dry.
Jerry

Best Gasket - part number 6100

http://www.bestgasket.com/distributors.asp

Jim Carter, Chevs of the 40s, American Classic do not list it by the Best Gasket part number, so you might want to call them.

Ecklers seems to have the best price/shipping.

In my mind, Best Gasket is the only way to go.
They do recommend pinning the seal in the instructions to keep it from moving, but I have never done that and would not.

I just installed a FelPro, soaking overnight seemed to wash away a lot of black (graphite??)that was on it.

I too second Best Gasket. Two thumbs up!!!!! And if you are unsure, just give them a call. What a great bunch of folks and extremely helpful.

I have used the Best Gasket seal and it is the only one that I will use. It is a woven product. On these 216s, I try and get the clearance on the main bearings down to the minimum when I am installing a rear main seal. I have found that if the bearings are on the loose side, the seal no matter what style, will leak after about 200 miles. Also, I don't pin them.

I went ahead and bit the bullet! I ordered
This From The Filling Station . Can this be changed without the crank being completely removed?

Yes, but it can be somewhat of a challenge. Lisle sells a tool known as a "Sneaky Pete" that is very useful for getting the top seal installed. It's a braided cable "Chinese handcuff" tool that grips the end of the seal and helps pull it over the crank. Loosen all the main cap bolts several turns so the crank can drop away from the seal, pull the old one out with the tool that looks like a big wood screw with a finger ring, and snake the new seal in. It goes in a lot better if it's oil-soaked, at least the ones I've been installing for 50-something years.

http://cdn1.bigcommerce.com/server4...0__06357__00962.1360953669.1280.1280.JPG

Jerry

Yes,I changed mine in my 50 pickup years ago. You may have to loosen another main to make it a little easier. I used what I called a Chinese noose to pull it around the crank. I've heard of other ways....but yes, it can be done...or should I say its done all the time.

Chinese Finger Oil Seal Remover/Installer
KD 492

Sneaky Pete Oil Seal Remover/Installer
Lisle (LIS27000)

Removes seals with engine in place
Removes and installs upper rear main seals without dropping crankshaft.

Thanks for all the input....I ordered a Sneaky Pete as well!!
2 steps forward and 1 back is still progress!!

Be sure to follow the directions to the letter using the Best seal. I had a Pontiac lock up solid from heat at the rear seal because I packed the seal in a little tight and didn't oil it as I should have. Best is the only rear seal to use, and to this day I haven't had one leak yet, even the incorrectly installed one didn't leak!

Joe

I found that all the other seals sold give you about 1/4" extra in the length. If you put a noose on one of them there isn't enough extra seal to remove the tool. the best seal gives you almost 2" extra in length.

I pull the transmission back and lower the crankshaft about 1/4" at the back and not as much at the front. That is also hard on the front seal. I use picture hanging wire to pull mine in. If you do drop the crank a bit, don't cut off the ends until you bring the crank up in place. That is because the seal will seat up into the groove when the crank is pulled up and the extra length will diminish some. I found this summer that it took a lot of patience. I used the thick Lucas oil product to lubricate the seal. Once the seal started to move in it went really smoothly.

I have some Lucas assembly lube left over it is very slippery!

Pre '68 Dave,
Do you install the Best Seal using RTV silicone instead of their pinning method or do you install it like a normal seal?

Thanks,
Jackie

I use nothing, just a small path of Permatex from the seal over to the pan end gasket area. this prevents wicking between the cap and block.

Truck is back on the road after 1 3/4 years with lots of help from this forum!
I installed the Best Gasket rear main while the engine was on a stand following the advice gathered from this post. I have driven maybe 50 miles since "Completing" the build. Today I found what appears to be a rear main leak (looks very minor). I removed the flywheel cover and found a drip hanging from the rear cap.
How long does it take for the rope seal to become fully saturated with oil? I am not worried just curious about others experiences.


Jackie

Give it a few miles. Even if the leak doesn't go away completely, it should remain as a very slow drip at worst. Stovebolts with rope seals tend to mark their territory a little.
Jerry

I don't think your seal will improve with time. I have found that the best results were achieved by adjusting the main bearings to the minimum clearances. If the bearings are on the loose side the seal will be pounded flat and the leak will increase. For me this happened around 200 miles. I replaced and adjusted my main bearings, installed a new Best seal and it has been very successful. A few drops out of these seals is not an unusual situation.