installing a rear main seal in a gen I chevy v8



installing a rear main seal in a gen I chevy v8

Postby grumpyvette » May 22nd, 2009, 8:59 am

these links and this article below gives you some good info
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chevy swapped to one piece rear seals around the 1988 year range in the sbc engines

viewtopic.php?f=53&t=301&p=1815&hilit=+one+piece+crank#p1815

http://www.corvettehacks.com/article5.html

viewtopic.php?f=54&t=473

viewtopic.php?f=54&t=2725&p=7076#p7076

http://www.neow.org/rms1.html

http://www.summitracing.com/parts/FPP-2912/

http://www.summitracing.com/parts/FPP-2900/

viewtopic.php?f=32&t=474&p=585&hilit=+synthetic#p585

rear seals come in, rubber, silicon rubber,.Fluoroelastomer, and Viton , durability vary,s between brands but roughly in that order,they all work if properly installed but VITON usually lasts the longest
keep in mind the seal lip must be properly installed and the seal lip must ride on a mirror smooth lubricated crank journal, if its to last, no seal will last long on a rough or out of round crank that wears that seal lip


http://www.summitracing.com/parts/FEL-BS118291/.. rubber usually GOOD

http://www.summitracing.com/parts/FEL-2900/... Silicone VERY GOOD

http://www.summitracing.com/parts/FEL-2909/ Fluoroelastomer, SLIGHTLY BETTER

http://www.summitracing.com/parts/FEL-2918/..viton SLIGHTLY BETTER STILL IN SOME DESIGNS

Top Seal Install ---
IVE installed some rear seals with the ends offset and some flush, Ive never had one leak in 40 plus years, if you have the seal leak its been my experience looking at engines Ive repaired that about 80% of the leaks are due to improper installation and 20% due to rarely if ever doing oil changes so wear was the root cause of the leak due to sludge in the oil
Be sure the lip seal is positioned leaning inward towards the front of the engine, and the rear seals off-set from the main cap parting line by about 1/4" to reduce the tendency to leak oil

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don't forget the rear surface of the rear seal to block and main cap needs to be sealed, oil tight
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this seal CAN easily be installed backwards - all mating surfaces should be clean and free of oil, but the cranks surface should be lightly oiled to prevent the lip sticking to its surface, a mini- finger tip worth of Vaseline smeared on the crank surface will prevent that

(NOTICE THE DESIGN, and LOCATION,: theres no direct oil pressure, being applied to the rear seal, only oil, mist and blow bye pressure in the oil pan, will exert minimal pressure against the forward facing lip pushing against the lip forcing it to seal against the crank, and lubing the contact point, of the lip so wear is minimized, having a properly functioning PVC and breather combo, helps and having deck plate honed the cylinders and correctly installed the rings limits the crank case pressures)

Use a 1/4 inch offset so the bearing cap parting line does not line up with the main cap seal parting line

simply push seal up in cylinder case on one end so the other end sticks out 1/4"" and match the other seal half in the rear main cap offset by 1/4 inch - this offset will be on the bearing cap as well, and YES,the pictures below show the ends of the seals installed matching the main cap parting line which IS NOT CORRECTLY DONE, off setting the seal slightly helps prevent leaks
I use a light coat of brush on gasket sealer on the back of the seal in the main cap and block as its an extra precaution limiting leaks, applied just prior to installing them so slight movement has no effect on the sealant sealing the seal to the main cap or block


Roll the seal around crankshaft using the tool as a "shoehorn"
Install the other seal half in the bearing cap
Apply sealant (we like Permatex Ultra Copper High Temp RTV Silicone Part No. 81878)
to the bearing cap to case interface, keep the RTV off the seal split line (only on the cap mating surface next to the seal)
Install the rear main cap and torque to specs.
keep in mind theres NO DIRECT OIL PRESSURE ON THE REAR MAIN SEAL, the DRAIN AREA LOCATED BETWEEN the BEARING AND REAR SEAL AT THE REAR OF THE MAIN CAP BEARING (CLEARLY SHOWN IN THE PICTURE )SEPARATES & DRAINS ANY PRESSURIZED OIL INTO THE OIL PAN, the rear main seal forms part of the oil pan gasket perimeter seal, many leaks blamed on the rear main seal are caused by improper rear seal installation (having the lip face to the rear) or failure to place a thin layer of sealant under the rear main cap between the block and main cap, excessive piston ring leakage of compression in the cylinders can cause high crank case pressure that in more extreme cases can cause leaks but the PVC and valve cover breathers should prevent moderate to low leakage from causing problems

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don,t forget a very thin line of sealant under the main cap/block bearing surface or you may have a very slow oil drip from what you think is the rear main seal but its really seeping under the main cap
http://www.pitstopusa.com/detail.aspx?ID=60256

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theres always those guys that worry about the rear main seal leaking if the blocks been line honed as that moves the crank location in the block a couple thousands of an inch, the movement is never a problem, if the rear seal is installed correctly AND the surface it seals to is POLISHED to a MIRROR SMOOTH, surface so the seal won,t wear,, the rear crank journals CONCENTRIC, and ROUND, and the seals installed correctly, its un-fortunate but its possible to install the rear seal facing 180 degrees out with the lip facing to the rear which will cause leaks.
when blocks are align honed its very rare for the crank to be moved more than .005 deeper into the block, as IM sure you know there are slightly shorter timing chains available to compensate,
cloyes is my supplier of choice

tips ?

make sure your using the correct seal design for the journal diam.

use the correct seal with the lip facing to the engine front

use silicone sealant on the ends and off set the ends from the blocks main cap slightly

use the brush on sealant on the contact area between the main cap and block and the rear outward surface on the seal

make sure you degrease the seal mounting surface before snapping it into place with the wet brush on sealant on the back outer surface

lube the lip of the seal that touches the rotating crank with a finger tip of Vaseline

always use a one piece synthetic oil pan gasket, as some oil leaks blamed on rear seals are really faulty rear oil pan gaskets or improperly installed rear oil pan gaskets

LINK
viewtopic.php?f=54&t=206&p=1154&hilit=+synthetic+gasket#p1154
when your trying to prevent oil leaks , on a new engine ,I prefer to do the timing cover first but theres no reason not to install the oil pan gasket immediately after the timing cover


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viewtopic.php?f=54&t=206&p=1154&hilit=+synthetic+gasket#p1154

viewtopic.php?f=51&t=1718&p=4257&hilit=rear+seal#p4257

viewtopic.php?f=54&t=2725&p=7076&hilit=gasket+synthetic#p7076

one piece synthetic oil pan gaskets seals are superior to the older separate end piece and side piece design
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here you can see the thin line of sealant under the rear main cap, thats sometimes overlooked resulting in a slow drip near the rear main seal
http://www.cloyes.com/Default.aspx?TabI ... uage=en-US

now too answer your question, the rear seal must be installed with the inside lip that rides on the crank surface, facing toward the front of the block and the ends of the seal slightly off set from the main cap parting line with a small dab of high heat silicone on both ends of each seal, and the lip covered with moly lube, the slight difference in the block measurement is MEANINGLESS to the seal.
the back of the seal where it snaps onto the block and main cap are usually lightly coated with a non hardening liquid gasket cement (HIGHLY RECOMMENDED) but can be left dry, with a very low risk of leaking, why risk it

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remember between about 1955-1958 a rope seal was used after about 1986 a one piece rear seal design was used on the SBC, to replace the previous two piece rear main seal
read this also

viewtopic.php?f=53&t=301
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Lip orientation

The lip on the rear main seal should point toward the crankshaft and not towards the back of the engine. The lip on the seal is designed to allow oil pressure to force the seal against the crankshaft, improving its sealing capability. When the seal is pointed the wrong way, it allows oil pressure to force oil past the seal, resulting in a leak.

One piece-Two piece seals

Prior to 1986, Chevy engines used a two-piece rear main seal that was prone to occasional leaks. After 1986, Chevy switched to a one-piece seal design to reduce the chances of a leak occurring. One-piece seals are more effective than two-piece seals but are more difficult to service with the engine in the car.These later engines can be converted to use a two-piece seal by using an adapter kit that can be purchased from General Motors and most performance parts stores.

Rope seals

Prior to 1956, Chevy motors used a rope style rear main seal instead of neoprene rubber. These seals were made with asbestos and because this material is no longer available, replacements are made with modern materials that mimic the properties of the old asbestos seals. Chevy engines that use rope style seals cannot be easily converted to use modern neoprene seals and require machining to make the conversion possible.

Lubrication

Rear main seals should not be soaked in oil before installation. Once installed in their seats, and before the cranks is installed, a light coat of engine oil should be wiped across the seal's surfaces where it contacts the crankshaft. This will reduce the chances of seal failure at initial startup by providing lubrication for the new seal until oil pressure builds and begins properly lubricating the seal.
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: installing a rear main seal in a gen I chevy v8

Postby grumpyvette » January 31st, 2011, 4:18 pm

when installing an oil pan gasket its always preferable to install the front timing cover first if possible, as it makes sealing the oil pan to the block with the current one piece synthetic gaskets far easier

read these


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sources for oil leaks
Oil filter not tight
Oil drain plug seal bad
Oil cooler fitting loose
Faulty oil pressure switch
leaking valve cover gaskets
Oil pan gasket bad, or installed incorrectly
Rear seal failure, or installed incorrectly
Front seal bad,worn, or installed incorrectly
loose dip stick or installed incorrectly
rear cam freeze plug loose or installed incorrectly
rear oil passages plugs loose or installed incorrectly

viewtopic.php?f=54&t=2725&p=7076&hilit=synthetic+gasket#p7076

viewtopic.php?f=54&t=206&p=1154&hilit=+synthetic+gasket#p1154

the front timing cover seal, that provides the oil seal on the damper as it slides into the cover on the crank snout is pressed in from the front, most guys tap it in with a plastic mallet,after carefully cleaning and repainting the stock cover or buying a new chrome timing chain cover as they are fairly cheap,youll want to be coating the outside edge of the seal with a liquid sealant while the timing cover is supported from the rear on a block of wood,the seals knocked out from the rear with a flat blade screw driver and a small hammer , used at an angle on the inside lip, replace it so the inner seals lip angles in towards the crank not out toward the front damper
BUT most guys simply buy a new cover since they are cheap and don,t bother cleaning the old one if it looks damaged, at $8-$10, for a new cover its hardly worth taking a chance, with the old one if its damaged

http://www.summitracing.com/parts/SUM-G3200/

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youll want to leave the timing cover alignment studs sticking out of the block about 5/16"
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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: installing a rear main seal in a gen I chevy v8

Postby grumpyvette » October 5th, 2012, 5:44 pm

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: installing a rear main seal in a gen I chevy v8

Postby bytor » May 31st, 2013, 11:40 am

the back of the seal where it snaps onto the block and main cap are usually lightly coated with a non hardening liquid gasket cement (HIGHLY RECOMMENDED) but can be left dry, with a very low risk of leaking, why risk it


So Grumpy, when you talk about applying a non-hardening sealer on the back of the rear main seal, are you talking about the groove on the seal itself where it slides into the cap and block?

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Re: installing a rear main seal in a gen I chevy v8

Postby grumpyvette » May 31st, 2013, 12:34 pm

bytor wrote:
the back of the seal where it snaps onto the block and main cap are usually lightly coated with a non hardening liquid gasket cement (HIGHLY RECOMMENDED) but can be left dry, with a very low risk of leaking, why risk it
So Grumpy, when you talk about applying a non-hardening sealer on the back of the rear main seal, are you talking about the groove on the seal itself where it slides into the cap and block?


yes I usually wipe the block and main cap with a lint free rag soaked in acetone to DE-grease the metal then apply a thing coat of flexible sealant in the rear seal grove on the rear of the seal where it mates to the block and main cap, surfaces.a thin coat in that groove, in the back side of that seal tends to reduce the rear seal having anything leak and the picture shows the ends having sealant and a slight offset,also
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this stuff is pretty much interchangeable
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with this stuff used in THAT APPLICATION
recommended operational temp range is just a tiny bit different from what Ive seen, one has about a 30F higher recommended temp, youll never get close in a properly operating engine to either

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I can,t remember using this stuff but it appears to be similar

you need to use a sealant on that seal remains semi flexible,
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: installing a rear main seal in a gen I chevy v8

Postby elisalvador » November 25th, 2013, 8:53 am

hy grumpy. question for those engines that do use the rope seal , pontiac 400. how would you install the rear roper seal ? ive never used rope seals, and i have to install one on a rebuild 400 thanks
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Re: installing a rear main seal in a gen I chevy v8

Postby grumpyvette » November 25th, 2013, 11:08 am


rope rear main seals can be used and they work reasonably well, but there are vitron seals available that tend to last longer and seal better

obviously you first need access to the rear main seal, and its a whole lot easier if the engines out of the car, on an engine stand , during the instal process, but in any case youll remove the old rear main seal, carefully clean and degrease the area in the block and main cap where the seal you selected to use is installed.
if your using the vitron/rubber style rear main seal , the process duplicated the chevy rear seal info posted earlier,the surface facing the block or cap is lightly coated with a good flexible sealant, the seal installed with the flexible lip facing the front of the block, the ends of each seal get a dab of silicone sealant and a bit of MOLY grease on the inner surface the crank journal rests against, once the caps installed, hot oil from the running engine expands the rope seal, in theory sealing the rear main, in most cases it does a decent job.

if your using a rope/graphite seal the groove in the block and main caps carefully cleaned and degreased with brake cleaner and a brush. IF access is available ,the rope seals placed in the groove,with a bead of silicone on the outer edge facing the bottom of the groove in both the block and rear main cap , and its forced into the groove by rolling a large socket over its inner surface, compressing it into the groove,and a razors used on the ends to cut them flush then a dab of silicone applied to each end of the seal where they mate, the seal expands when soaked with hot oil from the running engine, the moly grease tends to prevent wear until the rope seal absorbs oil, in theory applying a low pressure contact seal, that prevents oil leaks.....the vitron seals tend to work a bit better.

the pictures below show a filthy block that needs to be cleaned and the guy trying to install obviously the larger and longer rear main seal from the larger crank diameter that must be cut and modified to fit but the process is nearly identical
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Kit says to use a smooth cylindrical object to pack seal in groove. big deep-socket worked fine.
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the rope seal below looks correctly seated but it must be coated with a mix of oil and moly assembly lube before the cranks installed
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http://www.ehow.co.uk/how_8000662_insta ... ntiac.html
http://www.jbp-pontiac.com/products/gas ... seals.html


http://www.tinindianperformance.com/Pon ... 0Seals.htm

http://www.allpontiac.com/rearmain_seal.html

http://www.bopengineering.com/viton_compare.shtml

http://www.bopengineering.com/seal_instructions.pdf

Which Pontiac rear main seal do I need?
At Tin Indian Performance, we sell / advertise our seals according to the main journal size of the appropriate engine that uses them.



Pontiac engines / blocks that have 3 inch mains are 326 / 350 / 389 / 400. Keep in mind that when I say this, it means the cid of the original block casting. Pontiac engines / blocks that have 3.25 inch mains are the 428 and 455 blocks. The most common main journal size for aftermarket blocks is 3"; however, 3.25" mains are also available as well. Now for those who are into measuring things and have the crankshaft available to them, the 3 inch main blocks have a crank sealing surface of approximately 3.188 inches. This would require the TIP-RM300 seal The 3.25 inch main bearing cranks have a sealing surface of 3.436 which would use the TIP-RM325.

So when ordering your seal, know what main bearing journal size you have.
If it is a 3" main you will need a TIP-RM300.
If it's a 3.25" rear main journal, then it is a TIP-RM325.

http://www.wallaceracing.com/torque-engine-specs.html
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VERIFY THE EDGE OF THE MAIN CAP BEARINGS IS NOT BINDING ON THE JOURNAL SIDE BEVEL RADIAS (BLUE /GREEN AREAS)
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VERIFY THE MAIN CAPS FACE THE CORRECT DIRECTION AND ARE IN THE CORRECT LOCATION, SEATED CORRECTLY AND TORQUED IN STAGES TO CORRECT TORQUE, BEARING TABS IN CORRECT PLACE
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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: installing a rear main seal in a gen I chevy v8

Postby elisalvador » November 26th, 2013, 2:46 pm

thanks grumpy for the information.
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Re: installing a rear main seal in a gen I chevy v8

Postby 87vette81big » November 27th, 2013, 12:00 am

The original GM Pontiac V8 Rope Rear Main Seals worked best.
They had a Center core of Asbestos Fibers.
They lasted near indefinate as long as the car was driven regular.
Aftermarket Viton rear seals are Ok. I have used the BOP Viton seals. No problem with engineered design.
Its the Factory tolerance used in the cut groove of the #5 Main cap & Block.
Measured with a Brown & Sharp inside Barrel Micrometer its all over the place.
Can vary + - .020".
Never mattered original because packing rope seal filled in low spots.
Be sure to read directions that come with the BOP Seal.
Measure & check as directions state.
At best no leaks when driving.
After nightly shutdown, couple of drips always from BOP Rear main seal. Consider it normal.
VITON BOP REAR MAIN SEAL RIDES DIRECT ON CRANKSHAFT OIL SHREDDER SERATION GROOVES ALSO.
NOT 100% smooth as SBC & BBC.
Last edited by 87vette81big on November 27th, 2013, 7:14 am, edited 3 times in total.
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Re: installing a rear main seal in a gen I chevy v8

Postby 87vette81big » November 27th, 2013, 12:04 am

1970'S & 1980's Fel Pro Vintage NOS Pontiac V8 Rear main seals are made with a 100% Asbestos core.
Hard to find today.
Oil shredder serations on Crankshaft rear main seal surface kept Rope seal from glazing up.
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