Rear main seal & case half seal - '98 Deville
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Northstar Engines and System Technical Discussion Discussion, Rear main seal & case half seal - '98 Deville in Cadillac Engine Technical Discussion; I am working on a '98 Deville enigne - replacing the rear main seal, Timeserting, new rings, re-sealing case half, ...
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    KHE
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    Rear main seal & case half seal - '98 Deville

    I am working on a '98 Deville enigne - replacing the rear main seal, Timeserting, new rings, re-sealing case half, re-sealing oil pan, etc. and apparently, there was a change to the rear main seal for 1997+ and the installation tool is different than the 1996 model year. For the price of the special tool (even on ebay...), It would be cheaper to haul the engine and my parts down to my local dealer and have them do it for 1/2 hour of labor.

    The '96 Shop manual I have for my Seville doesn't mention replacing the oil distribution plate but that seems to be part of the procedure per the bulletin. Anyone know why the existing plate can't be reused? Was there an engineering change to the plate?


    Thanks!

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    tateos's Avatar
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    Re: Rear main seal & case half seal - '98 Deville

    I don't know to much about the plate, but there was a change. The rear main seal did definitely change - I had to buy that special tool - nearly $300 for 30 seconds use, but you really do need that tool. I did see it since then, maybe a year ago, for under $20 on e-bay, so that may be worth a try. The previous seal was a simple lip type seal - the new design is called a cartridge. The best way I can describe it is I think it's like holding your hands in front of you with your fingers curled and interlocked, as if you are trying to pull them apart. The one side of the seal is pressed onto the crankshaft flange - the other half into the block cavity. Make sure you either change the torque converter to crankshaft flange bolts per the service manual, or clean the threads on both the flange and the bolt and then apply a little RTV sealer to the threads during re-assembly (that's what I did).

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    Re: Rear main seal & case half seal - '98 Deville

    still having that same question, whats with the oil dist plate? I cant seem to find one anywhere, and why is it not to be re used?

    Hmm....just called the dealer, this same TSB # on GM's computer doesnt read "oil distrubution plate" it says "engine manifold" .........everything else in the bullletin reads the same.

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    97EldoCoupe's Avatar
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    Re: Rear main seal & case half seal - '98 Deville

    The reason it can't (or shouldn't in most cases) be re-used is because it has a formed-in-place silicone seal. If it gets re-used it will leak. Unless you're really good at cleaning and spreading RTV silicone.

    It is called an "oil manifold" plate (by GM). It basically keeps pressurized oil in it's passages in the lower part of the engine block, as well as provides a mount/pick-up hole for the oil pick-up tube.

    They actually CAN be re-used. There's a trick I use with these that involves removing the original silicone out of the grooves and spreading a nice even bead of the AC-Delco RTV in the grooves. If anyone attempts this, it has to be done very carefully. Any mistake will cause a drop in oil pressure as well as potential external leaks. And the aluminum has to be 100% free of grease/oil residues. Lay the plate back in place with the RTV in it. Start the M6 bolts and finger snug them, but wait about 15-20 minutes before you go ahead and torque them to specs.

    RTV silicone is not supposed to shrink as easily/as much as the original gaskets. There's a TSB on this. Just make sure you use the GM / AC-Delco RTV silicone. I've seen poor results in the past with other silicones, even the Permatex brands.

    The ring of silicone around the oil pick-up tube needs to be left in place, there's no way to substitute that with an O-ring or RTV. If that ring is damaged, chuck it and use a new plate. Oil pressure rides on this being done right. A small bead of RTV around the pick-up tube never hurts either.

    Usually there will be still some oil in the pistons (with the engine upside down) so when you have the whole bottom end together, allow the RTV to dry as long as you possibly can to prevent oil contamination and weakening of the RTV. Once it has had adequate time to set up/cure, flip the engine over and proceed with the heads or installation of the engine.

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    Re: Rear main seal & case half seal - '98 Deville

    Also- washing that plate with any type of solvents WILL destroy the silicone seal for the oil pick-up tube. Soap and water on this one.

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    Re: Rear main seal & case half seal - '98 Deville

    And the rear-main seal changed for the 2000 model year. I've seen some 99's that came factory with the upgraded steel sleeve seal but very few. 95-96-97-98- most 99's should all be the same.

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    Re: Rear main seal & case half seal - '98 Deville

    I just found another one of these damned inserts that let go in the block. So KHE - It's totally up to you whether you choose to go with but please don't use these time serts. I'll be posting a pic in a new thread in one sec...

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    KHE
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    Re: Rear main seal & case half seal - '98 Deville

    Thanks for the detailed information on the oil manifold plate. I can't wait to see how much that costs at the stealership.

    I thought there was a difference between the 1996 rear main seal and the 1997-1999 rear main seal.

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    buggin123 is offline Cadillac Owners Member
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    Re: Rear main seal & case half seal - '98 Deville

    If you really need to replace the oil dist plate, this is an auction on E-Bay right now for one. auction #330385943451 Just so you know.

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    Re: Rear main seal & case half seal - '98 Deville

    I just found the plate at the dealer for $110, so ill skip the ebay thing.

    So is this plate and seal something that will cause the external leak again?? or is this only internal and the gm rtv used on the case and oil pan?

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    Re: Rear main seal & case half seal - '98 Deville

    I never use just RTV on the oil pan. I use this in between the block halves and for the oil manifold plate, but for the oil pan, the groove is so deep that I use a new Fel-Pro seal as well as running a bead of RTV along the outside edge of the seal for an added measure of leak prevention.

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    Re: Rear main seal & case half seal - '98 Deville

    tell me more about this plate, is it in between the pan and the half case?? or completely inside?

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    KHE
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    Re: Rear main seal & case half seal - '98 Deville

    Quote Originally Posted by 97EldoCoupe View Post
    I never use just RTV on the oil pan. I use this in between the block halves and for the oil manifold plate, but for the oil pan, the groove is so deep that I use a new Fel-Pro seal as well as running a bead of RTV along the outside edge of the seal for an added measure of leak prevention.
    But it is OK to use the GM part no. 88861417 sealant on the case half with no seal correct? gmotors.com (Braisingtons/Palm Motors) said the seal is now just the 88861417 sealant.

    I'll probably bite the bullet and buy a oil manifold plate from the dealer rather than attempting to salvage the old one.

    Also, back to the oil pan - can Permatex Ultra Grey be used for the bead outside of the Fel-Pro seal or does the GM 88861417 sealer need to be used there too?

    One last thing, when I removed the bolts from the oil pan, the threads appeared to have teflon pipe thread sealant (teflon pipe dope) on them. Do you use such a sealant on the oil pan bolts?

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    Re: Rear main seal & case half seal - '98 Deville

    The oil pan bolts go into blind holes. You shouldn't need any sealant there whatsoever. The factory never put sealant on these so I think yours might have been done by someone before. The bolts are on the outside of the sealing edge as well.

    Ultra Grey is garbage when it comes to oil. So is ultra black. Use the GM sealant as well there if you can. It's expensive (I get a discount from the dealership) but worth every cent. That Ultra black stuff is OK but only when it comes to stuff involving coolant or other things where oil is not in contact with it.

    I've seen a number of cars done with this thread sealant on the bolts. Are you located in Ohio or anywhere near south of the Great Lakes KHE?

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    Re: Rear main seal & case half seal - '98 Deville

    One more thing- the flexplate (flywheel) bolts need sealant put on the threads (FSM says to use new bolts; unnecessary) because these are not blind holes and go right into the crankcase. As well with the 3 camshaft seal screws(by the water pump drive)- these need sealant too.

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