Can any one give me advice on changing a rear main seal on my 66 327-350? I have been told you can slip the upper half in place after removing the oil pan and brg half. Has any one else out there done this? Thanks in advance for any help. Dave
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Re: Rear main seal- Mid year
Hi Dave!
Your information is correct & 'tis not that difficult a job. In order:
1. Jack/support car safely, etc.
2. Drop the steering gear down. Can't remember if unbolting the idler & tilting down gives sufficient clearance (don't think so) in which case drop the idler & carefully remove the steering shaft from the pitman arm. Don't ound this off because the load will be indirectly transferred to the steering gearbox. Autozone will lend you a puller.
3. Drop the oil pan. Are the drainplug threads good? If not no time like now to fix/weld in new nut. The pan itself was only recently discontinued. You'll also have to remove the oil cannister. Oh, I forgot to mention drain the oil. If you haven't already, you will have by now...
4. Remove the rear main bearing cap, being VERY careful about the bearing. The seal is composed of two semicircular pieces of rubber. The edge has a lip that I believe is angled towards the block (not the transmission). Using wooden popsicle sticks (being VERY carfull not to scratch the journal) you can push the upper seal around the circumference far enough to ghrasp the other end and remove with piers. I haven't broken one yet but I suppose if it's quite deteriorated this could occur. Lubricate the new seal (National/Fel-Pro - don't save money here!) and push the upper half around. Install the lower half in the lower main bearing cap, lighly coat the bearing with engine oil, reinstall and EVENLY torque - is it 65 ft-lbs? Your manual wll have the spec value.
5. Remove any debris from the oil pan pickup. Paint/reinstall the pan. I have seen some companies selling "one-piece" oil pan gaskets nowadays which may be easier to install. Again, use only high-quality gaskets here (& I use the Ultra-copper sealant) 'cause you don't want to come back!
6. Oil filter, etc..rebolt everything back in. Don't forget to put oil in before starting.
I also highly reccomend: How to Rebuild Your Chevrolet Small-Block by HP books - will walk you through a rebuild but more importantly show you exactly what the peices look like before you get there.
Good luck!
Carl -
Re: Rear main seal- Mid year
there should be a piece of plastic with the seal kit that you use as a protector to prevent the sharp edge of the block from gougeing the back side of the seal when you push it around the crank into the block. if one does not come with the seal kit you can make one from a piece of brass shim stock.
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Re: Rear main seal- Mid year
Dave-----
I agree with all of the above and I will add a few extra pointers:
1) When you replace the rear main seal halves, be extremely careful to keep any oil from contacting the parting line of the seal halves(i.e. the ends where the two halves come together). This area is treated with an adhesive.
2) Be ABSOLUTELY CERTAIN that you apply sealer to the areas on the rear main cap shown in in the diagram/photo in your Chevrolet Service Manual. If you don't apply sealer or apply it improperly, your rear main seal WILL LEAK FOR SURE. I like Permatex non-hardening sealer for this application, but other sealers like high temp silicone will also work well.
3) Use a GM rear main seal, currently GM #10121044. This is a high vacuum, hi-performance Viton seal. You can also purchase this same seal under Fel-Pro #2918.
4) If you can get one (they're currently back-ordered and hard to get your hands on) use a Fel Pro one piece oil pan gasket for 55-74 small blocks. This is part number OS-34509T. This is THE ONLY WAY TO GO and borrows on the technology which GM used to help control oil leakage on later small blocks such as those used in 1986-96 Corvettes.In Appreciation of John HinckleyComment
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Re: Rear main seal- Mid year
Thanks for the info! Iam going to give it a goComment
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