The Stovebolt Site Forums The Shop Area Engine Shop Rear Main Seal Leak?????????

Installed a new rear main seal about a year ago and now it seems to be leaking some dripping from the lower flywheel cover. Is there a good product on the market to add to the oil to stop the leak?? Thanks!!!

Marv.

No,all the products for that are for rubber seals.

Pete

being that you have a rotating shaft and a stationary stuffing box so to speak, where the seal sits in the groove which is nothing more than valve/pump packing it's going to leak to some extent. if it didnt it would burn up and completely fail. the thing is how much is it leaking. i have two 270's with new seals in them. the one in the ashton leaks slightly more than the one in my 40. they were installed by two different people which the one in the 40 is from "best gasket" and i like the way its made. i know from reading thier installation instructions using the proper tools to seat the packing in the groove and where you cut off the excess is critical for good performane. as for my leaks compared to how they leaked before engine replacement they are acceptable to me. if it took a year for the oil to go from the shaft to the drain hole then i wouldnt worry. remove the cover and wipe it clean and see how long it takes to drip back out.

I needed to install new mains bearings on the crank, was able to lower the crank enough to insert the new bearings and replace the rear main seal. My big concern is that the new clutch would get wet. The dripping and adding some oil once in a while does not bother me much but I was hoping not to drop the pan to replace the seal again. Do I have to worry about that or not????????? Thanks!!!

Marv.

51 ashton makes an interesting point. If the seal ran completely dry it would toast itself. I have personally used both rope and 1 and 2 piece rubber seals and so far none has been 100% drip free after a few years, but no clutch problems have resulted either.

It is not easy to find rope seals any more. In my amateur opinion they are less fragile and if stuffed into their grooves tightly and cut off perfectly flush with the block seem indestructable. Stufffing the upper half of a rope seal really tightly into its groove with the crankshaft in place seems like an impossible assignment. A "slim jim" will pull it into place helped by rotating the crankshaft as you pull but that stretches the rope, the opposite of stuffing it.

The rubber seals have the advantage that you can rotate them slightly in the groove so their ends don't exactly coincide with the parting line between the main cap and block.

I was never able to fit the little wire basket on the puller, onto the seal. I used a piece of picture hanging wire to pull it through. The last seal I put in has remained dry. It was an NOS seal and I installed new mains. I adjusted the mains to the limit and I think it did the trick. Before I installed new mains, I had two seals that lasted about 100 miles.

If you are looking for an original type seal, try contacting "Gasket City". I think he has some.

Good point about main bearing clearance. If the crankshaft is bouncing up and down with excessive clearance, it will hammer the seal away from the shaft and allow leakage. The rubber lip seal might work better with some wobble at the shaft, but it's more prone to wear a groove into the sealing surface. The rope seal, installed properly with a minimum-clearance main bearing is my first choice.
Jerry

Thanks!!! for all your time and input but my second question was not answered yet. What about the clutch getting wet???

Marv.

I`ve had the same problem with my 1952 IHC L-130, which is powered by a 220 "Silver-Diamond".

After replacing the seal the 2nd time, I followed the advice of a farmer friend of mine.

His theory; since the trucks set in the barns, except during harvest time, and have usually been serviced with "multi-grade oil", the seals tend to dry out and the lower viscosity multi-weights seep through.

I changed to a straight weight 30. The seal hasn`t leaked yet.
Still don`t know whether I might just have had a better "seal installation", or the differance in oil solved the problem?

Unless the leak is pretty severe, it's not very likely that the clutch will be affected. The oil will run down the rear surface of the oil pan and/or the front of the flywheel, but unless enough oil slings off to saturate the area inside the bellhousing, it will be difficult for it to find its way onto the area where the clutch meets the flywheel.

My 59 model 3800 flatbed came to me after a "rebuild" by the PO, who left one flywheel bolt out. Those bolt holes bypass the rear main seal, so there was a massive leak. The clutch began to slip within a couple of weeks, but the engine was leaking about a quart of oil to every tank of gas, and it was leaving big puddles everywhere I parked it. Unless you've got that kind of leak, I doubt if your clutch will be in danger.
Jerry

To be honest I don't remember if the rear main seal was rope or rubber come to think of it. The overhaul kit was a Fel-Pro, would it hurt to add some stop leak anyway and what type would you guys recommend????????? Thanks again!!!!!!!!!

Marv.

My two cents would be, don't use an additive.

If you want to save money by adding an additive to stop a seal leak...just don't buy the additive and drain the oil.