Topic: Gas In Crankcase Cures Rear Seal Leak


JayChicago    -- 08-31-2018 @ 7:42 AM
  Do you remember a post from some time ago from a member who inadvertently filled his crankcase with gasoline instead of oil? He realized the mistake before starting the engine, and after draining and flushing with oil there were no problems. But surprisingly, there was actually an improvement: his rear main seal no longer leaked. Interesting! Can this be a so-simple fix for the rear main seal issue we all live with??

At the time, I thought it would probably be a temporary seal softening/expansion, and the seal would return to normal in short time. But I was interested to see a follow-up post on this. Don't recall seeing one. I am still curious about it. I just did a forum search with no luck; original post was probably more than 365 days ago.

Original poster, are you still here? Can you give us a follow-up report?


len47merc    -- 08-31-2018 @ 9:15 AM
  Hopefully he's still alive! Wonder what he filled the fuel tank with...

Steve


CharlieStephens    -- 08-31-2018 @ 9:21 AM
  Jay,

You can search for more than 365 days by going to the word "All" at the top of the list. It sure would have made sense if it was at the bottom of the list below 365.

Charlie Stephens


JayChicago    -- 08-31-2018 @ 11:13 AM
  Charlie, thanks for that educating me on the "ALL" search option. With that, I was able to find the original post. It was posted by Silverchief. And he didn't fill the crankcase with gasoline as I said, it got in there by the electric fuel pump running all night and overcoming the carb's float valve.

His last post from back then said: " My oil pan is starting to show the first very faint traces of oil. It's been about three weeks."

Silverchief, I'm curious about the longer-term effect. How's the rear seal holding now?


TomO    -- 09-01-2018 @ 8:09 AM
  Jay, I hope that you are not contemplating adding gas to your oil pan to fix the rear main seal leak.

Besides being dangerous, it will have no effect on the rear main seal on your original 1940 Ford engine.

Your engine uses a "slinger" type seal for the rear main. This is a thin steel plate fixed to the crankshaft that rides in a "V" grooved pot metal piece. The theory is that the slinger will direct excess oil from the main bearing back toward the oil pan.

Tom


JayChicago    -- 09-01-2018 @ 5:14 PM
  Thanks for that info Tom! I had no knowledge of the slinger seal. I thought my engine had the rope seal.

No, was not planning on doing it, at least not any time soon. My car does not have enough leakage to bother me, and I would want to hear from others' experiences before trying anything new. I was just intriqued by that original post. I'm still curious to know if there is any validity to the idea that the rear seal could be improved by filling the crankcase with a solvent.

This message was edited by JayChicago on 9-1-18 @ 9:58 PM


silverchief    -- 09-02-2018 @ 10:05 AM
  For your information guys - the leak is now back just as before. Didn't take long - a few weeks.


JayChicago    -- 09-03-2018 @ 8:33 AM
  Well, there's the answer! Now I can put this crazy idea behind and move on.


supereal    -- 09-05-2018 @ 10:46 AM
  If the rear crank seal leaks, it is either worn, or was installed incorrectly. The seal rope must be soaked in oil well before installation. We keep seals in a closed container filled with oil for future use. Another cause is by trimming the ropes to make them fit the groove. They should be left as provided , since replacing the oil pan pushes them into place and also swells them for a better fit. A dab of RTV on the ends of the seals is a good idea. In any case, some seepage is normal, and the cotter pin in the bottom of the clutch housing allows oil to escape before it lubes the clutch. Gas in the oil, if not completely drained, likely washed the oil from the seal surface. The seepage will probably, overtime, re oil the seal.


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