Well, I took the 396 out of the Chevelle yesterday. The rear seal has been leaking pretty bad recently. So, now that it's out, is there a trick to getting the seal out and the new one in? Does the crank have to come out?
A good repair manual should have some pictures of the process for changing the mail seal. It can be done with the crankshaft in the engine. People sometimes change these with the engine in the car, provided that the oil pan can be removed from the engine while it is in the car.
Basically you are just pulling out the old seals and sliding one part in around the crank while placing the other part in the main cap.
Inspect the crank and make sure it doesn't have a groove where the seal rides. If it does it will probably leak again after putting a new seal in the engine. On some engines I have seen an offset seal offered that moves the lip to get it back to a flat and undamaged part of the crank.
If the seal area on the crank is worn/damaged and an ofset seal is not avail i would use crcus paper (avail at machine shops/good auto parts stores) to by hand/manually polish nthe main seal area of the crank. You can do it with crank in the motor but be carfull to clean any debries when done and be consistant about how mush you rub the corcus paper on each parts of the crank. You should do approx 1/4 of the sealing surface on the crank at a time then rotate the crank a 1/4 turn and do the same amount of rubbing/buffinf there.The crocus paper is very fine and bascially polishes the metal and really doesnt remove much if any material un;less you go nut with pressure and running in one area for a long time.
Also,make sure to put some rtv/silicone on the leading edge of where the main cap meets the rear of the block and also along the sides of the captoo. Not too much,just a little rtv is required. Also put a little dab of rtv on ends of seal halves to ensure they seal too.
I'm just piling on this question as I need to do this too. Was about to start on auto to stick conversion and noticed oil from rear of engine, so I need to get that fixed first. My shop manual says to pull the crank, but that opens a whole can of worms for me, so I want to replace the rear seal with crank installed, oil pan removed on an engine stand. Thanks for any advice guys. Dave.
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