Help with rear main seal

[Nickaru]

I'm replacing the rear main seal in my M1008. I found information on it and I'm at the point of putting the main bearing cap back on, but I have a question on this procedure. On the Fel-Pro instructions, it states "apply RTV sealer to the outside edges of the cap recess in the block". I don't know where exactly they mean and don't want to place RTV in the wrong place.

On another document I have, it states"Following the TM, use anaerobic sealing compound on the rear main cap as specified, install rear main cap and torque to spec". Isn't this thread locker? If so, wouldn't they specify placing it on the threads of the bolt instead of the main cap.

I'm lost

Any guidance would be greatly appreciated.

 

[camogriz]

I'm not sure if the anaerobic sealing compound is thread locker, but I would refer to the Fel-Pro instructions. I replaced the rear main seal in my M1009 using the instructions provided by Fel-Pro and have no leaks. The RTV sealer goes in the two corners (one on either side of the crankshaft) where the rear main seal, main cap and ultimately the oil pan meet up. The RTV will basically be on the outer edge of the motor, not inside, and will create a silicone membrane between the two halves of the new rear main seal. I hope this helps. Please ask if this isn't clear enough.

 

[Nickaru]

added pictures

I've attached the pictures of the main cap and crank area. I just don't want to place the RTV in the wrong place.

 

[doghead]

Replacing the rear main seal in a 350 small block Chevy | 350 Tech Article | 4x4 Tech Articles & Off Road Locations | 4x4 Mecca

 

[txmytx_catahoula]

Just did this to my M1009. Fel-Pro's instructions make it really easy, they even print "outside" on the side of the seal that goes toward the outside. Make sure you follow what "camogriz" says, put the RTV in the groove toward the outside(air side). Good luck!!

 

[camogriz]

I was just looking at the photos you provided. Basically put the RTV in the vicinity of the new seal as depicted in your second photo, on that side of the motor and main cap. The RTV should cover the ends of the new seal, creating a silicone membrane between the two new halves. It is critical that both surfaces be completely free of grease, oil and grime when applying the RTV in order to ensure a leak-free seal. Also refer to the instructions provided with the new seal regarding possible trimming of the excess rear main seal protruding past the mating surface of the main cap to provide for flush mounting.

 

[lavarok]

Per the TM,

CAUTION
Contact points of rear main seal
halves (5 and 6) should be at
4 o’clock and 10 o’clock positions
or 8 o’clock and 2 o’clock
positions. Failure to follow this
caution may result in oil leakage
and damage to rear main seal.

Also, it does call for Anaerobic sealer, not RTV. I've used both before, not together but separately, and prefer the anaerobic sealer.

In the -34 tm, page 3/113 shows clearly where to put the sealant.

 

[Nickaru]

Doghead, thanks for the link. At first I saw 350 small block and thought "what does this have to do with the diesel engine?" I didn't even know the 350 small block has a split seal also.

Camogriz, thanks for your info. I did know about the "OUTSIDE" label on the seal. I was just nervous on where to place the RTV because I figured if placed in the wrong location, it can affect the clearances on the main bearing and crank if RTV increases the space.

Lavarok, I did read about off setting the seal as you mention and it makes sense.

Should I add rtv to the end of the seals where they but together? off set or not?

 

[lavarok]

Should I add rtv to the end of the seals where they but together? off set or not?

I have not in the past and wouldn't in the future.