Magnum 18 - horizontal shaft - oil seal

wildbill59

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Looking for info about Magnum oil seals, and reading the last thread about the vertical shaft 20. Mine's a horizontal shaft, doesn't sound as scary. What seems like an oil pan - bottom sump cover on a V looks more like just a cover on an H. Seems like I should be able to pull the front cover, pull out and replace the bearing, new gasket for the cover, and carefully slide it, with its new seal, over the crank. I read the manual, but they really just do a full assembly and reassembly. I don't want to tear down the whole engine, everything else is good, so I want to do as little teardown as possible. Hey, I'm for an easy life! Any advice would be great, thanks in advance.
 

cashman

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If your just going to replace the seal, it is pressed into the cover or closure plate as it is called. To replace the bearing, you will have to disassemble the engine and split the crankcase on the Magnum horizontal as the bearing has a lip that is held in place on the inside of the crankcase. Also don't lose the little ball and spring when you remove the closure plate as the ball and spring is the oil pressure regulator and if it's not in place, you won't have any oil pressure when started up. The closure plate on the Magnum doesn't have a gasket behind it. You use a 1/16" bead of RTV sealant.
 

wildbill59

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Excellent - thanks for the advice, cashman. Looks like I'll be pulling the closure plate, I don't have a seal tool long enough to drive over the crank - almost 6" long from the closure plate. The bearing seems good enough, I just think the seal has gone from sitting. As far as the RTV goes - I've heard that from someone else too, I think even the manual says that. But as I was looking up the part # for the seal, it also had a listing for the closure plate gasket. It said something about applications with serial #s under 18000### (how ever many digits after the 18), mine starts with 16. Also, the manual said that above 18 had alignment pins in the block, and to use RTV, but under 18 had no pins, and to use a gasket. As much as I love my Kohler manuals, they've had some pretty big mistakes a few times over the years :mad: . Any thoughts about that? Sounds like you definitely know what you're talking about, and appreciate your advice!
 

cashman

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I don't remember seeing a closure plate gasket on a Magnum twin horizontal, but some applications could have? The KT twins had one. But if yours has a gasket behind the closure plate then definitely use one. As far as oil goes, if your under freezing conditions you can use 10W30 oil. Otherwise use a 30Wt. oil. And I would use a good oil made for air-cooled engines if it was mine. Those engines get pretty warm when they are running. Regular automotive oils are not designed for the amount of heat generated buy that type of air-cooled engine. Good luck!!!
 

wildbill59

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Thanks, cashman. Gonna tear into it next week, I'll post how everything works out. Thanks for your advice!
 
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