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Discussion Starter #1
Hey guys I need some advise.

1. When installing the rear main bearing do I need sealant (RTV) under the rear main bearing cap. If so what kind, where does it go and is there a specific set up time for the gasket sealer? Pics would be great showing where to put the sealer if needed.

2. Should I install the one piece rear main seal while the rear main cap is off which seems really easy or wait until the rear main cap is on and then press it in. I am really leaning toward installing while the cap is off.

3. I have been using ARP assembly lube on the main bearing cap bolts. Is this correct?

Thanks, Eric
 

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1. When installing the rear main bearing do I need sealant (RTV) under the rear main bearing cap. If so what kind, where does it go and is there a specific set up time for the gasket sealer? Pics would be great showing where to put the sealer if needed.
I dont use any sealant on the cap at all.

2. Should I install the one piece rear main seal while the rear main cap is off which seems really easy or wait until the rear main cap is on and then press it in. I am really leaning toward installing while the cap is off.
Put the seal in afterwards with a little RTV around the outside circumference and if you want you can put a little on the face once its installed, cheap insurance.

3. I have been using ARP assembly lube on the main bearing cap bolts. Is this correct?
ARP fasteners usually come with moly lube for the threads, I use that in combination with a light oil under the head where it contacts the beveled washer. (bevel up)

HTH


Mike
 

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FFCobra Craftsman
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Can't remember where but i read that it is standard procedure to put a thin coat of silicone on the block and then install the cap.have the area perfectly dry (use brake clean or alcohol) and then put a tiny bit of sealer on your fingertip.Wipe it into the recess in the block around the bolt hole and up the vertical surface so the corner gets sealed. key is thin-enough so you can see it but no more.
 

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Actually putting a very thin coat of silicone betwwen block and bearing cap. Was done when useing blocks that used the 2 peice seals.
I still do this regaurdless of seal used.
Smear a very,very little amount of silicone under the ends of the bearing cap.
It helps to keep oil from seeping between the cap and block.
Seal must be installed after crack is in and motor buttoned up.
Assembly lube on all bolts,nuts used in bottom end. Tq specs will be different for assembly lube compared to regular oil on threads if used.:)
 

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Discussion Starter #5
I will smear a light film of RTV on the bearing surface.

Any reasoning on why it is better to put the seal in last. I thought it would be good to put the seal in after the bearing cap is installed but before the main bearing bolts are torqued down. Perhaps when they are hand tight. This would allow the seal to go in easy and then torquing the bolts would compress the seal. I'm just curios why this would not be better.
 

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DO NOT put silicone of the bearing surface itself.
It goes on the rear of block's surface so to seal the cap to the block at the point where seal will go.
Nothing can be on the bearing surface aside from assembly lube.
If in doupt just leave it dry. There's no garentee it will elak if not doing this when useing a one piece seal.
This is just a cautionary proceedure some(myself included) still carry over fromm the blocks useing two piece seals.
More importand nothing gets onto the bearing surface then add this step:)

Seal could effect the actual torque reading if installed before caps tq'ed down. Wait till assembled then install.
 

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Too much silicone is never a good thing as it will end up in the pan. This can clog your oil pump pickup and restrict flow ,or end up inside the pump and damage it.
 

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Have to admit i installed the seal while the cap was still loose. Made it real easy to get the seal over the crank and then into position.i didn't think about it's affecting torque since the spec is about 100 lbs(351).
 

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Discussion Starter #9
My comment about putting RTV on the bearing surface was a typo. I was meaning to type on the main bearing cap surface.

I think the benefits of sliding the seal in prior to torquing the cap outweigh the negative of having the seal interfere with the torque value. I can almost collapse the bearing if I squeeze it so I don't thing the seal will affect the bearing torque. I could always torque to the higher end of the range. I typically shoot for the middle of the torque range.

BTW what is the torque range for the 5.0 bearing caps with ARP Assembly Lube.
 

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60-70 foot pounds on the main caps with arp assembly lube and stock fasteners.
Not sure you want to go higher. The torque spec is choosen to give the proper holding force along with making sure bearing has it's proper crush pattern. Too hi things can distort causeing too much bearing crush and premature failure.
Too little tq will also cause problem.
Personal opinion and not to preach. But making certain bearing and cap recieve the proper tq rateing is much more importand then the small effort required to install the rear seal. Useing a seal installer is almost fool prove and very easy. Even if useing a block of wood it's a very simple task.:)
 

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I've had good luck installing the one piece rear main seal right before I install the # 5 (rear) bearing cap. Before final installation of the caps and RMS, I've already confirmed proper clearances for the main bearings. During final cap assembly, I tighten caps 1 through 4 (finger tight or a tad more) and clean cap # 5 and the rear of the block with paint thinner or acetone. Next, put black RTV around 60% of the out side of the rear main seal. Remember the spring side of the RMS goes toward the inside of the engine. Next I slide the RMS over the rear of the crank and push it firmly into place. Then I add black RTV to the other 40% of the RMS that is still exposed, making sure now that 100% of the RMS has near equal coverage of RTV sealant. I put a very thin coat of RTV between the block and # 5 cap, hoping to seal any abnormalities in the casting to prevent leaks. Finally and quickly, I install cap # 5, install hardware (bolts or stud-nuts) and torque 1 through 5 down in sequence to proper values. I refrain from spinning the crank until I've given the RTV some time to dry, so I don't spin the RMS around the crank.

Here's what it looks like when done, it's not pretty, but it doesn't leak! :)




Side note, if your using a used crank, consider using a RMS sleeve ($7) to give the RMS something meatier to ride on...this will reduce chances of a leak.

-dan
 

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Discussion Starter #12
I am planning on using the correct torque specs and a light coat of RTV on the rear main bearing cap surface. I was not planning on putting RTV on the outside of the seal itself. It does not come like this from the factory. Does anyone else put the seal in without RTV on the outer circumference. It will make removing the seal a pain and then the cleanup of the RTV on the surfaces will be almost impossible. If this was the last rear main seal it might be okay but since this is a serviceable part I was thinking of keeping the surfaces clean. If you have to clean the surfaces later you will have to pull the crank.
 
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