Have 2 questions about removing and installing 2 piece Neoprene rear main seal in 1st Gen 392 Hemi? 1. Do you recommend installing seal flus with the end caps, or have 1 in of top and bottom of seal pretruding? 2. Best pre lube when installing the seal? Thank You for your opinions. Jack
I’ll try To give a little info,,,,,at least it worked for me . 1 . Yes,,,and yes . I’ve done them both ways,,,,flush and protruding opposite ways ,,,,,6 of one,,,half a dozen the other,,,,Mopar doesn’t seem to care . 2. Yes,,,,,I prelube,,,,,about 80 % of the perimeter . The crank will smear it the rest of the way ,, after tightening and rotating . I keep the lube away from the ends,,,,then I put a very slight dab on the mating ends . It’s not really necessary,,,,but I do it for peace of mind,,,,lol . I also usually put a minuscule amount around the o.d. Of the seal in the cap and block,,,so it can’t possibly ooze any around the outside. Completely not necessary,,,,but,,,,then again,,,the peace of mind part . Tommy
Tommy, That is the info I have heard most. I am going to install the seal flush with the bearing cap. This makes my 4th attempt to stop that seal leak. I think where I went wrong the other times, did not use any sealant, failed to pre lube, and just tightened. Did not torque properly. I will borrow a torque wrench. Ever where I have read, says torque to 75lbs, using 25lbs per tighten. 25+25+25=75? JJackheard
@moparjack44 Does any machining need to be done to the block and rear main cap to use a neoprene seal? What about the serrations on the crank? Thanks!
Will not know for sure until tomorrow when oil pan gasket arrives from Hot Heads. The other 3 times, crank was smooth, so hope no machining needs to be done, as the engine is in the car. If I find any perfections on the crank, I'm just going to put it back together and let 'er leak.
??? Never heard of it. Give me more info please. Is this something I can get at my local parts store?
Anaerobic sealer should be readily available anywhere that has a good selection of Loctite products. OEM dealer parts departments should have it as well. GM dealers in particular used it frequently to seal machined mating surfaces on things like transmission cases and differential carrier housings.
You don't lose anything by rotating the seal slightly during installation, but you may gain something. Less chance of a leak. I always put a small amount of sealer on the ends of the seal. I would not worry about lubricating the seal as that will prevent the sealer from doing its job. Once everything is bolted in place and torqued you can squirt a little oil or dap a little grease on the external part of the seal, but it should be fine. I definitely wouldn't take the approach that you will just install it and let it leak if the crank needs polishing .
I don't think the mating surface between the rear main cap and the block is the best place to use RTV sealant. RTV (Room Temperature Vulcanizing) is better suited to seal larger gaps between irregular mating surfaces, like a stamped steel valve cover to the cast mating surface on a cylinder head. RTV cures in the presence of oxygen. Anaerobic sealer is used to seal smaller gaps between machined mating surfaces and to fill minor surface imperfections like fine machine tool marks. As mentioned a few posts back, anaerobic sealers cure in the absence of oxygen and in the presence of metal. Since you've been having problems getting things to seal properly, I've also got to ask if the crankcase is properly vented on this engine. Either with a stock road draft tube and a breather, or preferably a functioning PCV system. If the engine is building any pressure in the crankcase it will try to vent itself anywhere it can and push out a bit of oil in the process.
Well vented K&N filler cap. Did have PCV, but when I went back to original valve covers, no breather, but it was leaking with the PCV. Defiently not using the RTV sealant.
If you had a cast oil pan with a flat, machined mating surface (like many later model engines use) that mounted to a flat machined surface on the block, the anaerobic sealer should work well. If that same pan uses a separate rubber seal or cork gasket for sealing at the front and/or rear of the pan you might use a little smear of RTV on those seals or gaskets. Or see if there is a specific molded rubber 1-piece gasket made for that application. With a stamped steel oil pan you need to make sure that the pan isn't warped and that the sealing flanges aren't distorted from over-torquing or other abuse. The pan needs to fit flat and squarely against the block. Anaerobic sealer isn't intended to seal the wider gaps and tolerances that you'll have even with a new or good used stamped steel pan. I've seen some stamped pans attached with RTV only that seemed to seal up good. But the mating surfaces need to be near surgically clean and dry for the best sealing. In less than ideal conditions (like replacing the pan with the engine installed) I'd rather use gaskets and molded rubber seals, maybe with just enough RTV to hold things in place during assembly. But then I tend to be a "belt and suspenders" kind of guy.
Me too. Great info, RTV it is. The gasket is cork, and it's 4 pieces. Could not find a 1 piece rubber gasket for the 1st Gen 392 Hemi, or a 1 piece period. Had to settle with what I got from Hot Heads. GREAT Info. Thank you. I'm the kinda guy that needs "belt and suspenders" info.
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