427 rear main seal

Good Morning,If I may suggest,to have your new mechanic to check valve cover bolts,and the spot where the oil pressure sensor is connected.The oil pressure sensor,in most to all cases on Vettes, is on the side of block just above the oil filter location. I have found that most mechanics state the oil leak is a rear main seal ( more money to repair)than checking the pan bolts,valve cover bolts,and sensor area.In any event glad to hear it may be the pan and not the rear main seal..Have a great day..   Sal C 

Thanks for the information. I will ask him about those areas on the engine.  Bobby

The '69 should have a brass oil pressure line fitting in the block, with a metal line going up to a junction fitting in a bracket. From there, it should have a plastic line into the interior for the gauge.You could certainly have an oil leak at any of the junctions for the oil pressure lines.
I'd be leaning to it being the pan gasket, tho....especially if someone thought it was the rear main leaking to begin with. Prolly leaking from one of the corners of the pan back there.



|UPDATED|10/2/2014 9:52:57 AM (AZT)|/UPDATED|

Thank you for the information and diagram. The bottom of the pan is bent in , probably damaged when the engine was reinstalled in the car.  I want to keep the original pan and hopefully get it repaired. 

 It was determined that between the damaged oil pan and the original muncie 4 speed leaking that we finally found the oil leaks .  I am happy to know where they coming from. Now I can get these two things fixed.  This will be a good winter project. I want to save the orginal oil pan and have it repaired, and then have the muncie gone through completely

The only place a Muncie could leak up front is the countershaft, where it fits(snuggly) into the case bore. That area should have a thin layer of silicon spread around on it to keep it from leaking. Originally, just the tight fit kept seepage to a minimum, but over time, the case bore distorts, and it will start leaking some. The silicon will prevent that from becoming an issue. The input shaft has NO seal at all on it....and it rarely leaks. The only way for it to leak up that high is if the oil level is too high. Also, a leak from the input shaft will get gear lube onto the clutch...not a good thing....

Hope they got the engine oil leaks fixed, anyway....

Hello All, and congrats on them finding the leaks and your plan on sealing up the culprits. Joel is right about the leak between trans and bell housing etc..I wanted to ask if your Muncie trans is aluminum or like the Saginaw trans( Oh yes Muncie did have some cast iron cases) .. I have a Aluminum  Muncie "Rock Crusher" in my '68 Camaro for over 20 years and have never had a leak,however I have had friend with a cast iron trans who also had a small leak and repaired just like Joel recommended..Again Great finding the problems and good luck on the repairs.  Sal C

Pic- Oil pan leak

(modified life-size image to link-aapple)


|UPDATED|10/13/2014 7:51:50 PM (AZT)|/UPDATED|

I believe it is aluminum