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Old 04-26-2010, 12:07 PM   #1
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Join Date: Mar 2010
Location: MelbourneFL/AtwaterCA
Default What is the best rear main seal and where to get?

I read on brickboards that there are 2 types. "There are two rear seals available: one is 10mm thick (red: silicone) and the other (grey or brown: Viton) is 7mm. The more expensive Viton will last much longer than the silicone rubber material.The 10mm is stock and the 7mm is replacement. Why? Because the original 10mm seal wore a tiny groove in the crankshaft after thousands of miles of driving."
I can only find the "Elring" brand from both IPD and fcp groton, which appears to be a "rust" color. Is elring the "viton" kind? Anyone?

-And just to be 100% positive, I do NOT have a flame trap on my 92 940 turbo, correct? I cant afford to go through another seal due to a crankcase pressure issue.
1992 940 turbo wagon
Let em Eat!
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Old 04-26-2010, 12:14 PM   #2
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Join Date: Aug 2004
Location: The Netherlands, Europe

I got the grey one from the dealer. I think that is the Viton kind.

No flametrap, but here is a box under the intake manifold, that can get clogged. replace it if it is still original, same with the small T-piece and hose to the pre-turbo pipe. Replace or clean thoroughly.
240 | 1991 | 326 KKm | B230F+T | Cossie T3 60/63 | M90 | TrueTrack
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Don't forget about properly seasoning it on HF jackstands for a couple years whilst dreaming about big powah 'goals'.
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Old 04-26-2010, 12:19 PM   #3
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Join Date: Feb 2005
Location: Land of Enchantment

Any crank seal left for many miles can groove the crankshaft. Dirt can get between the crank and seal and grind away the metal. When this happens, the seal can be placed ahead or behind the grooved postion of the crankshaft where it is smooth and will seal better.

Not to argue about silicone or Viton, the real reason why a seal will last longer is whether it has some long wear lubricant on it, not as much a property of the material. When you buy the seal from Volvo, it is the gray Viton and has a sticky black paste lubricant on it (or at least they came that way at some point) I haven't seen this lube anywhere else, and know it stays put to lubricate the seal during it's life, whereas a plain grease will eventually migrate away or wash away with engine oil.

Also Viton is a supreior elastomer for oil seals compared to silicone (red, rust). Viton can come in many different colors, black, gray, brown. Viton is a perflouro-elastomer, meaning it is a teflon containing carbon polymer and has great temperature stability as well as chemical resistance. It's worth the cost.
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Old 04-26-2010, 02:01 PM   #4
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Location: MelbourneFL/AtwaterCA

okay, so where is the cheapest place to purchase this part? Is there a cheap volvo parts place out there? I know they exist in the honda a subbie world. Best volvo dealer to deal with?
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Old 04-26-2010, 03:59 PM   #5

Believe it or not, a old type VW Beetle, aircooled,pancake motor rear main seal works!! VWs had a DOUBLE LIPPED SEAL for thier rear main. I used one in my 79 245, for a loooooonnnggg time.Never leaked, even when over heated clutch. I changed clutch, installed Volvo RMS, it leaked.

I imagine this would be a good alterantive for a very hi milaige crank, with not many unused seal places left(like mine, 500,000 miles)

Don't laugh, it WORKS!!!!!
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