The Stovebolt Site Forums The Shop Area Engine Shop 216 rear main leak fix with stainless wiper strip

As per the title, I'm about to address the leaking rear main in the '51 216 in the 3600 in my tag line again. Bought the truck with 43k original miles back in 2014, it's now at 59k. In the past 10 years I've replaced the rear main rope seal with the Best Gasket graphite impregnated seal two times, each time the fix lasted several thousand miles then the leak reappeared. At the moment, it's to the point that clutch chatter is making starting off in second gear almost violent. 1st is even worse (T5 transmission).

I'm going to try the stainless windshield wiper reinforcement strip method of slowing or stopping the rear main leak. Many to include Jon (third post on this pageand Hotrod Lincoln (Jerry) have suggested this old school trick.

While getting ready to tackle this little job I've gathered up a couple stainless wiper strips, one is a bit over a 1/4" wide and the other is about 1/8" wide. Now for the question, anyone know how wide the grove is in the block under the rope seal that will accept the stainless strip. Hopefully I'll have one on hand when I tear things down.

Thanks,

RonR

I just measured the seal groove on a 216 block I have on an engine stand in my shop. A 235 should be the same, as they use the same rope seal for both engines. The bottom of the groove is a few thousandths over 0.150", and the top is a bit over 1/4". The 1/8" shim should work about right. The way I've done the procedure in the past is to leave the used upper seal in place, lower the crankshaft a few thousandths by loosening all the main bearing bolts a couple of turns, and grind a slight taper to the end of the shim piece. Gently tap it into the block groove behind the upper seal. I use a pair of mini vise grips as a driver, clamping onto the shim close to the block surface and tapping on the back end of the grips with a small hammer. Repeat as required to get the shim into place without bending it. Replace the lower seal rope with a new one. It will probably be necessary to sneak up on the rear main cap bolts torque a little at a time while rocking the crankshaft back and forth as the seal rope compresses.
Jerry

Thanks Jerry! Exactly what I was hoping for. Will report results when I do this little project.

RonR

Here's a good installation tool. Grind the top of the upper jaw flat to give a bit of extra clearance at the crankshaft surface.

www.ebay.com/itm/178051982327?

Jerry

Once upon a time glass setting tape was formulated so it expanded with kerosene (or even crankcase oil). You folks probably remember this. You installed your window, trimmed the tape, poured kerosene or motor oil on the rubber and overnight it would expand and lock in your window. I've been thinking about having made a rope seal which had a core of glass setting tape in the dead center so it would expand against both the crankshaft and the slot it sits in after it was introduced to oil. Makes perfect sense to me as the setting tape never went back to the original size after it expanded.

By interesting coincidence I had to replace a couple of pieces of glass recently and in my curiosity I bought setting tape from all the usual suspects. None of it expands. Not even a little bit and that includes the stuff that is rubber mixed with cork (a reasonable man would expect the cork to expand with oil). If any of you chemists or wannabe chemists know of a compound that does expand predictably when exposed to oil, please let me know. Please don't use Google and their AI answer. It will tell you nitrile rubber will be softened and expanded by oil, however I have tried both nitrile and epdm and it didn't work for me.

My next door neighbor (across a oak covered 40) was telling me that he recently bought a asbestos rope seal for the door of his wood stove that fit the description of a 216 rear main seal. I didn’t think asbestos was available in any form these days. Sadly he didn’t have any left over.

Most of the wood stove door seals that are available these days are probably some type of fiberglass, not asbestos. Chances are his supplier's nose grows every time he speaks, just like Pinnochio!
Jerry

Ya, I just replaced the seal in my mom's wood stove. It's fiberglass. It looks a lot like asbestos but it isn't.

You can buy asbestos rope in China. It is available in numerous sizes and types and the makers will be happy to send you online catalogs. There may be some difficulty getting it shipped to the USA, however. It was as I recall finally banned for good in either late 2023 or 2024, so even if you manage to get somebody to send it to you...you will not be able to sell it without getting in trouble. Sellers in China are not supposed to send it over here anymore. I actually considered buying a spool of it which was graphite impregnated to sell as rear main seals but a friend who has been involved in mesothelioma work told me he thought the ban would be final before I received the stuff.

A little asbestos never hurt anyone! same as the carbon tetrachloride. In grade school in the '60's we used to break off small bits of the steam pipe insulation in the classroom, make a spit-ball out of it and shoot it through a straw at our classmates, what ever happened to those good old days? Kids don't know how to have fun any more.

We just did "as-best-as" we could! The funny thing is going to be when today's over-protected bubble-kids are lying in bed 50 years from now, dying of NOTHING!
LOL!
Jerry