Rear main seal question

[Huicho417]

I just finished replacing the oil gasket and pan. Before that the rear main seal. This is the third time I replace the pan and gasket and it leaked again. No leak with just the car idling, but once I get it over 2000 rpm it leaks. I am using the Milodon 4 piece gasket with a summit racing pan. The leak only happens at the rear and looks like it’s from the rubber seal. Not sure that this pan is fitting properly. I am going to clean my original pan and see if that is the issue.

Is the rear main seal placed correctly on the images attached. The main cap also seems to sit proud of the engine block. I removed it to see if I could push it back but it only goes in that way when I tighten the bolts. Not sure if this is an issue.

Also, are the ears that stick out past the cap supposed to be cut?

 

[493 Mike]

I generally cut those nubs off with a razor blade and apply a bead of silicone sealant to the junction between the block and the main cap.
Mike

 

[BeepBeepRR]

Another way to do the rear main is to offset the 2 halves and don't line them up with the main cap and block. just kind of rotate them 45 degrees.

 

[pnora]

Three times. Maybe the rear main or pan is not your leak. I would start looking elsewhere. Common thing on a leak it always drips from the bottom.

 

[snakeoil24]

Did you check cam bearing end at back of block for leaks?

 

[PurpleBeeper]

Also, check to make sure some of your oil pan bolts aren't bottomed out (need washers) and not sealing the pan gasket. Happened to me....took a year to figure it out

 

[RemCharger]

Another way to do the rear main is to offset the 2 halves and don't line them up with the main cap and block. just kind of rotate them 45 degrees.

On a big block

 

[R413]

Another way to do the rear main is to offset the 2 halves and don't line them up with the main cap and block. just kind of rotate them 45 degrees.

LOOK at the seal, you cannot rotate it on A small block Mopar.

and the rotation is not why it is leaking anyway.

the factory built how many thousands of BB mopars and they never rotated the rear main seal. They didn’t leak.

 

[Huicho417]

Did you check cam bearing end at back of block for leaks?

I have not checked it. I did some work on the engine about two years ago and it looked good, so I left it alone. Maybe I should have changed it, but nothing was leaking at the time so I did not think it should be changed. Attached is a picture during that work. What looks like oil around the camshaft plug is aviation sealant. I also added that sealant to the galley plugs which I did replace. I will see if I can find a small camera that I can snake up there to see if its leaking. If it is, can it be removed from the rear, after removing the transmission?

 

[pnora]

I have not checked it. I did some work on the engine about two years ago and it looked good, so I left it alone. Maybe I should have changed it, but nothing was leaking at the time so I did not think it should be changed. Attached is a picture during that work. What looks like oil around the camshaft plug is aviation sealant. I also added that sealant to the galley plugs which I did replace. I will see if I can find a small camera that I can snake up there to see if its leaking. If it is, can it be removed from the rear, after removing the transmission?

View attachment 1460545

I would be looking real close along the back side of that intake area.

 

[BeepBeepRR]

LOOK at the seal, you cannot rotate it on A small block Mopar.

and the rotation is not why it is leaking anyway.

the factory built how many thousands of BB mopars and they never rotated the rear main seal. They didn’t le

In the initial post It was not mentioned that it was a small block. I did not notice it was a small block until you mentioned it. And yes I agree that they were produced without being clocked different. I do see the wings that come off of the tips. So I see what you mean. Like I said didn't notice it was a small block.

 

[69Bee]

I have not checked it. I did some work on the engine about two years ago and it looked good, so I left it alone. Maybe I should have changed it, but nothing was leaking at the time so I did not think it should be changed. Attached is a picture during that work. What looks like oil around the camshaft plug is aviation sealant. I also added that sealant to the galley plugs which I did replace. I will see if I can find a small camera that I can snake up there to see if its leaking. If it is, can it be removed from the rear, after removing the transmission?

View attachment 1460545

Not saying that this is your problem, but that cam plug is installed incorrectly. The center is punched in, but around the edges is still concave meaning it is not really sealing well, and could be prone to leaking under higher oil pressure like you are experiencing. While I do not see indications on your plug (a blue hot spot), the center being pushed in too far could result in contact with the cam. The proper cam plug to use is EPC-203. It is installed with the numbered side in so it cannot contact the cam and has more sealing area like a regular core plug, and not a disc plug.

 

[StayTrue]

Are you running a PCV? Maybe you have too much crankcase pressure hence leaking over 2k rpm and not at idle.

 

[Huicho417]

Are you running a PCV? Maybe you have too much crankcase pressure hence leaking over 2k rpm and not at idle.

Yes, I actually installed a me Wagner dual flow adjustable pcv. Which works gret.

 

[Huicho417]

Ok update on the oil pan / rms leak saga. I purchased an inspection camera earlier that allowed me to snake it between transmission and engine. Happy to report the cam plug looked dry and no evidence of leaks. I also checked the galley plugs and no leak on them either.


I also purchased a four piece cork and rubber pan gasket, cleaned up the pan and reinstalled. It was much easier to install and had no issues in making sure the rubber end gaskets did not squeeze out. I started to torque the bolts down but only got to 7 foot pounds before I noticed the cork gasket start to squeeze out. The service manual states 15 foot pounds but that seems excessive. Maybe once the sealant dries I can tighten more.

 

[Huicho417]

Feeling defeated!!!

I installed my stock pan and gasket and voila no more pan leaks. Last time I deviate from using my original parts.

Bad news is, I can now tell the rear main seal is leaking. I had replaced it but must have done something incorrectly. I made sure to install the large lip towards the engine and added sealant to the outside edges. My rms does not allow me to clock it at an angle because the bottom half has the “ears”

After I installed it it cut the portion that stuck out past the cap. Should I have left it?

 

[snakeoil24]

I have not checked it. I did some work on the engine about two years ago and it looked good, so I left it alone. Maybe I should have changed it, but nothing was leaking at the time so I did not think it should be changed. Attached is a picture during that work. What looks like oil around the camshaft plug is aviation sealant. I also added that sealant to the galley plugs which I did replace. I will see if I can find a small camera that I can snake up there to see if its leaking. If it is, can it be removed from the rear, after removing the transmission?

View attachment 1460545

That looked normal

 

[73LemonTwist]

Check your oil pressure sender for a leak. I was convinced I had a rear main seal leak on my 340, but not the case. The sender was leaking oil and it was running down and dripping off the bell housing at the inspection plate. Replaced the sender and the drips are gone.