Hi Guys,

I got a 1978 300 inline. Just changed the oil pan gasket, and that damn thing is leaking where the bell housing and engine meet. Painted everthing and scrubbed the crap out of it. Now it leaks just as bad as before.

The gasket for these things is a peice of work, i'm not going to spend all day re-doing it. I wonder if it's a rear main seal. Where is it and could it be the problem?

Are there any tricks out there for this problem?

 

i see there are lots of veiws on this thread but no responses.

I guess what i want to know is where the rear main seal is and could this be the problem instead of a leaking pan?

 

Rear main seal is forward of the flywheel, inside the block. If the oil is coming from behind the oil pan and leaking from the bottom of the clutch-or-flywheel housing it is probably a rear main unless it's the tranny with a bad front seal. Whichever one is loosing oil is where it's coming from. If the oil is dripping down the rear of the pan, your pan-gasket isn't sealing the crankcase. Haven't changed a rear main on the I-6, because never had one before, but did change one years ago on either a flathead V8 or newer V8 (or maybe even a Jeep 4-banger or old Chevy I-6) by simply taking off the pan, unbolting the mains, lowering the crank a tad and slithering a new seal up and around the groove (seal was made in two halves, one for upper and one for lower... or, did I cut it in half? Too long ago to be sure). Can't even remember what model it was on, or what else was involved, but was probably a Ford. Seems there was some kind of little stiff but flexible cable that helped drag the seal up and around. This was really a day or two ago, maybe even 18,650 days ago........... ;-) Good Luck.

 

I replaced the rear main seal on my 300I6, twice. The first time when I replaced the clutch the first time. The second time was when I rebuilt the motor. This rear main seal is a one piece unit. Yes, you guessed it. You have to pull the tranny, clutch assy and flywheel. When you replace the flywheel use some type of thread sealer with the bolts the fasten the flywheel to the end of the crank. The fricken threaded holes in the crank run all the way thru to the inside side of the engine. Oil will pass the threads and oil your flywheel and clutch assy. I will say I love my second clutch assy, a Centerforce, big bucks, so hope fully I don't have to screw with it for a long, long time.

 

Just a thought..... I just finished rebuilding my 300ci, and found the pan gasket to be a pain, to put it lightly. Here is what I found worked best for me: 3M weather strip adhesive, just a small dab to hold the gasket in place, a little engine silicone in the front and rear corners to seal the pieces together. By using that combination I was able to not only keep the gasket in place, but work at my own pace and keep everything in place while putting the pan on. However, do not use the weather strip adhesive on the rubber ends, just the cork pieces.

As far as the rear main seal.... I use Sili-Glide it is a lubricating compound that will allow the rubber portion of the seal to slide onto the crankshaft without binding. If the seal goes on dry it can cause the lip of the seal to seat unevenly and cause a big leak. The Sili-Glide also makes installation easier, since the seal slides on the crank easily. I did not have a seal installer, so I used a small, very small mallet and a piece of angle iron to spread the impact from the hammer evenly on the seal. If you try hitting the seal to hard it will dent the outer case and warp the inner seal, and again cause a leak. The above listed method worked for me, and hopefully it will work for you. I found Sili-glide at Knecht's Auto parts; however Napa or Shucks should be able to get it. Hope this helps, good luck!

 

Note: the rear main seal is a one piece, and transmission will have to come out.