360 rear main

[Rowdy Bars]

I'd check the block before ordering anything.

I'd check the block before ordering anything.

I know it’s a 360

 

[Rowdy Bars]

Another question I have is my crank has been turned it’s 20 under is there a chance they messed up and cut the seal surface for the rear main

 

[Rowdy Bars]

I know it’s a 360

 

[Icetech]

Another question I have is my crank has been turned it’s 20 under is there a chance they messed up and cut the seal surface for the rear main

Anything is possible but it would have to be the worlds worst machine shop to do that.... higher chance the seal was put in backwards

 

[Rowdy Bars]

Anything is possible but it would have to be the world’s worst machine shop to do that.... higher chance the seal was put in backwards

I double checked i put it in the right way

 

[Icetech]

I double checked i put it in the right way

Not to sound silly.. but there's like 5 places the back of a block can leak and it would go right into the bell housing.. have you stuck a scope up there to make sure it's not the cam plug or anything else leaking? Saw a video of a guy the other day that pulled his oilpain to do the seal and it was the back of the intake leaking down...

 

[Rowdy Bars]

Not to sound silly.. but there's like 5 places the back of a block can leak and it would go right into the bell housing.. have you stuck a scope up there to make sure it's not the cam plug or anything else leaking? Saw a video of a guy the other day that pulled his oilpain to do the seal and it was the back of the intake leaking down...

I know it’s not the intake oil sender or valve covers I checked those it could be the cam plug but I feel like it would leak bad all the time not just out on the highway

 

[Killer6]

I just posted this in another rear main leak thread, from the '79 B-series van FSM, look at the cap diameters....per Prof Fate......

 

[Professor Fate]

Another question I have is my crank has been turned it’s 20 under is there a chance they messed up and cut the seal surface for the rear main

HIGHLY unlikely.
If you've got a 318 pan on a 360, that's where your leak is. Period. Heck, you'd darn near be able to poke your finger in past the rear pan seal. That's why it leaks under acceleration or on the highway- all the oil is being pushed towards the back of the pan, and it just goes right on out past the rear pan seal. Not as noticeable when stationary or parked.

 

[Rowdy Bars]

See that makes sense I’m gonna pull the motor back out tonight see what I can find

 

[tonysrt]

Also check the crank where the seal sits, you may have grooves in it which is good for the rope seal but no good for the rubber seal. The grooves cut up the rubber seal.

 

[Rowdy Bars]

Also check the crank where the seal sits, you may have grooves in it which is good for the rope seal but no good for the rubber seal. The grooves cut up the rubber seal.

I checked late time I put a seal in and it looked fine

 

[Desoto291hemi]

HIGHLY unlikely.
If you've got a 318 pan on a 360, that's where your leak is. Period. Heck, you'd darn near be able to poke your finger in past the rear pan seal. That's why it leaks under acceleration or on the highway- all the oil is being pushed towards the back of the pan, and it just goes right on out past the rear pan seal. Not as noticeable when stationary or parked.

Thank the Lord that someone reads all the posts and then comprehends what it means .
The Op clearly knows his engine is a 360,,,,and he stated that he used a 318 pan .
The old 318-340 pans will have a very large gap at the rear of a 360 block main cap .
Just the way it is .

Tommy

 

[Locomotion]

A 360 rear seal can also leak if the channel wall that the rear seal fits into is damaged. I've seen a few small blocks where that seal channel on the rear main cap was chipped because somebody set it down on the concrete on that edge with the main caps installed.

 

[tonysrt]

The grooves I mentioned were done in the making of the crank. They are many parallel lines at a 45* degree angle. The factory back then used the rope seal so those grooves were that for a reason.

 

[Ironmike]

I think this is gonna end with the 318 pan on a 360. No reason to investigate anything until that issue is cleared up. GEEZ LOUISE! Ask us for help before you start crankin bolts.

Measure twice, cut once.

 

[James Clews]

Are you sure that it is leaking from the main seal? My 318 had a serious leak and I knew it was coming from the rear of the inlet manifold! You could idle it all day long and there was not a drop of oil but you take it for a run down the highway and there was oil everywhere!
I took the manifold off and resealed it and now it is perfect!