Failed timing cover oil seal

[Dave K.]

I rebuilt my 66 base engine about 5 years ago. I ran the engine and car very little in preparation for flight judging that I sucessfully passed three times (two chapter and a regional). Following the Charlotte Regional in April, I decided to enjoy the car and drive it more. I have put over 100 miles on the car going through issues like Holley fuel percolation in the hot summer and a leaking Muncie countershaft that I fixed, and all was going well until I noticed some oil leaking along the bottom of the front of the crankshaft. It has gotten progressively worse and tonite, while on a lift, we were able to actually see torn pieces of the lip seal rubber protruding between the damper and seal.

When the engine was rebuilt I had to install a sleeve over the damper sealing surface because of severe wearing on the damper in the seal area. The sleeve was installed with the locktite cement and the lip seal lubed with oil. The damper has no mounting bolt on a base engine 327 but I advanced the damper to the same position as before it was removed by carefully tapping it with a hammer and block of wood. I am perplexed as to what may have caused this significant damage to the seal. The damper appears to remain tight on the cranshaft. I did paint this area with the damper on the crankshaft just like they did at Flint and you can see where the paint was worn away on the sleeve surface.

I have studied the Service Manual and it requires removal of the radiator and shroud on the 327 engine car, but the seal can be changed without removing the timing cover. I assume that you will need to pass a long bar through the grille or up and under the car to wrap the damper back on. Has anyone completed a timing cover seal replacement on a C2 small block with the engine in the car?

Kind of frustrated--
Dave Kitch

[Ray G.]

Re: Failed timing cover oil seal

Hello Dave;
Sounds like you followed the manual procedure.
Look for a very tight fit.
Could the repair sleeve have been damaged by the alignment key during installation.
A trick for installation of the damper is to cool the crankshaft(bag of ice) and heat the damper (heat gun), but not hot enough to damage the insulator(rubber)
You also need a soft sealer between the damper hub and the crankshaft.
Also check for vibration(s)
Hope that helps, Ray

[Joe R.]

Re: Failed timing cover oil seal

Hi Dave:

So sorry to hear about this problem. It sounds like you did everything right but somehow the seal got damaged.

I recently removed and replaced the timing cover and seal on my 67 300 HP. I think you will find that with the radiator and shroud removed there is enough room to swing a 5 pound sledge to "tap" the damper back on. In my case I was able to use an installation tool because I had drilled and tapped the crank for the L79-style retention bolt, so I did not actually use a hammer.

The damage to the seal is a mystery. As I recall, the nose of the damper is already partially through the seal before the interference-fit stops the damper from advancing by hand. It's hard to imagine what went wrong.

I would be uneasy about trying to install a new seal with the timing cover on the car, since there is no support to keep the cover from caving in. However, I suppose it's worth a try, since GM says it can be done that way and it saves a LOT of work. Just be sure to put some sealant on the outside perimeter of the seal to help it slip in more easily.

From what I have read, adding a sleeve to the balancer to renew the surface is a very common procedure that usually works fine. However, if you are uncertain about the sleeve, you may want to price a new balancer. The 3896903 balancer for my 67 is still available from GM and does not cost much from gmpartsdirect.com. I bought a new one.

Lastly, when you reinstall the damper, put some sealant in the keyway. Others on this board have mentioned that oil can leak out the keyway and come out the front of the damper.