1quickTransAm

iTrader: (4)

I just finished my first engine build with my 383 LT1 and fired it up last week (more on the build later in another post). The engine fired right up and runs great, but I noticed that a good amount of oil was leaking from the low/rear engine/trans area when parked, and it was accumulating in the bellhousing and trans and leaking out of every mating surface or bolt hole (I hope too much didn't get onto my clutch too!).

It was either the RMS or the low/rear oil pan gasket so I started off with the easy one and lowered the oil pan a bit in the car, cleaned up the surfaces, and put a little RTV around the back to see if that would solve the issue. Unfortunately it didn't fix the leak so I pulled the transmission tonight to inspect the RMS.

Sure enough, the RMS was oily, but more concerning was that it is pretty clear that the rear main seal is not concentric with the crank end. In the pics below you can see a small gap at the bottom of the RMS and there was matching compression at the top.

Any idea why this issue is here or how to resolve it? I have read that align honing can do this, any idea how far the crank centerline could have drifted during machining? I did measure the diameter of the end of the crank and it matched OEM. I am a bit concerned because I don't want to do this several times and keep having the same issue, and am really ready for this project to be done by now.

Catmaigne

iTrader: (6)

There is movement in the RMS adapter for that specific reason. You have to center it yourself, it is not an exact fit.

guppymech

iTrader: (7)

You could try the Felpro Teflon RMS p/n BS 40626. It has a bigger sealing lip than the rubber RMS and may work better if the CL of the crank and RMS carrier are off. White ring in pic is a supplied installation guide. Any issues with the front crank seal?

1quickTransAm

iTrader: (4)

No the front is dry.

1quickTransAm

iTrader: (4)

Would it make sense to put the flywheel and bell housing on after the new RMS is on, run it for 15 min like that (no trans) and then pull the flywheel off to check for leaks before bolting everything back on? Think that would show a leak if there was one?

guppymech

iTrader: (7)

Try re-centering the RMS housing like Catmainge said first. Sure run it with just the FW, no need for the bellhousing. Then just look behind the FW for signs of a leak, why make extra work? I cut the top of the FW inspection cover off that goes around the top of the starter so I could remove it without removing the starter or FW, it still works fine and makes things easier.