Oil Seal or Muffler leak? - Page 2 - MyTractorForum.com - The Friendliest Tractor Forum and Best Place for Tractor Information
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post #16 of 20 Old 06-07-2019, 02:17 AM
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Talking Re: Oil Seal or Muffler leak?

A lot of good information in this thread and as always everyone is entitled to their opinions. I would like to add a couple of points here. There are basically two types of fail regarding the oil seals. The rubber seal itself that rides against the crankshaft fails and allows weeping of the oil past the seal and down the crank. The other failure is the seal working it's way completely out. The first type of failure could be caused by a number of things such as old age, (the seal has been on the mower for a long time), when the seal was installed the crankshaft had a burr or rust which may have damaged the seal, and I supposed just like most everything there is a shelf life for oil seals as they are a rubber compound and will, over time, get hard and brittle. How long this will take is anyone's guess but how they are stored may have an adverse affect on the rubber. Lawnboy used the green coated seals for a long time such as the ones Mike is referring to. Whichever seal you choose, proper installation is important to make sure the seal stays in. Clean the crankcase thoroughly and remove all traces of oil before driving in the seal. Only oil the crankshaft lightly to aid sliding the seal on. I have not had any seal that I installed this way, either the metal green coated ones or the rubber ones work their way out of the crankcase. As far as oil in the muffler goes, there will be unburned oil in the exhaust and when you remove the muffler on these old pre F series "Boys" you will more than likely see carbon and unburned oil in the bottom of the muffler if you are using standard dino 2 cycle oil. Some of this may come out the exhaust during operation. The muffler seals are pretty much all compressed in the groove on these old mowers and they are rarely replaced. There should not be oil coming from the seam between the muffler halves. Replacing seals on these old "Boys" can be a good preventative maintenance if you know they have been in there a long time. Otherwise just wait until they show a bit of leaking onto the crankshaft and then replace as needed. Bill

1968 Lawnboy Model 3054******1973 Lawnboy Model 8231******1974 Lawnboy Model 5023
1975 Lawnboy Model 5024******1975 Lawnboy Model 5273******1976 Lawnboy Model 5274
1976 Lawnboy Model 8234EX****1977 Lawnboy Model 5024******1978 Lawnboy Model 5269G
1979 Lawnboy Model 7268******1980 Lawnboy Model 5247******1982 Lawnboy Model 5247
1982 Lawnboy Model 5247*******1972 Lawnboy Model 1015******1972 Lawnboy Model 1015
1987 Lawnboy Model 1400CL****1995 Lawnboy Model 61638

Where there's a will, there's Mr. Bill!***They don't call me MacGyver for nothing!***I have LBAD and DCAD!
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post #17 of 20 Old 06-07-2019, 10:18 AM
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Re: Oil Seal or Muffler leak?

Quote:
Originally Posted by LawnBoy90 View Post
They do require a service every once in a while and most mechanics don't like messing with them. Lawn Boys are great mowers and have powerful engines but two cycle mowers seem to have fallen largely out of favor with most of the public. On the subject of straight gassing, its sad to think of the large amount of these machines sent to the scrapper from being straight gassed. Probably some nice desirable/rare models too,
Yes, I've seen real good 4 cycle mechanic's that just hate 2 cycle engines. When a 4 cycle engine seal leaks oil, not really a big deal engine running wise, but a 2 cycle seal leak and no visible evidence of such usually, the engine gets, erratic, people go to work adjusting the carb, replacing the carb, etc, then to the scrap yard due to a little wimpy seal bad and or the engine gets ruined due to running lean.:tango_f ace_sad:
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post #18 of 20 Old 06-08-2019, 02:03 PM
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Re: Oil Seal or Muffler leak?

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Originally Posted by Lawnboy77 View Post
I respectfully disagree. There is no miracle rubber that doesn’t age. The shelf life program is taken very seriously in the commercial aviation world, and with good reason. Obviously we are not dealing with airplanes here, but the principle is the same. Good luck with those 30 year old rubber o-rings and seals in general. If I do that at my job I run the risk of jail time. We, as certified mechanics, turn in certification documents on every seal that we install on an aircraft that states, when it was produced, lot numbers and FAA approval, manufacturer and most importantly, the expiration date. You guys do what you want, there is no safety risk here, it’s just a lawn mower right. I would be laughed out of the courtroom for stating something like, “shelf life doesn’t apply to quality rubber”.
Many of the rubber compounds used today in o rings and seals are rated for unlimited shelf life. The finite nature of the aviation industry requires everything be dated and given a life time which is fine, but it doesn't mean the O rings and seals that are past an arbitrary date are no longer good. That being said, the oil seals used by Lawn Boy are made from a compound called nitrile NBR rubber and the company that makes them does not give a shelf life, but does say to store them away from heat and in packaging. I have seen charts that give a 10 year shelf live for nitrile NBR rubber, but I know from experience it will last much longer and retain its sealing qualities. I have quite a few C/R 8624 oil seals that I acquired from a closed dealership about 15 years ago. I do not know how long he had them, but they are in excellent condition and I use them at teardowns only since I never had a seal leak or fall out. They are stored in a plastic bag in a parts cabinet.
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post #19 of 20 Old 06-08-2019, 06:27 PM
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Talking Re: Oil Seal or Muffler leak?

Mike, thanks for that additional information on the compound of rubber used in the seals and info regarding the shelf life. I am sure we would all agree that the aviation industry has much higher standards and accountability than the mower industry. With that being said, any rubber item that is stored in less than ideal conditions will age faster than a similar one stored in optimal conditions. I would be one of the guilty ones that has seals in a plastic cabinet drawer in a garage that has no climate control. I have not found this to be a detriment to the seals, and I have not noticed any problems with premature aging. As always, the older anything gets the more it is subject to aging and the possibility of failing whether on the mower or in a drawer. As I stated before, proper installation in itself will assure the seals stay in place and not pop out. Bill

1968 Lawnboy Model 3054******1973 Lawnboy Model 8231******1974 Lawnboy Model 5023
1975 Lawnboy Model 5024******1975 Lawnboy Model 5273******1976 Lawnboy Model 5274
1976 Lawnboy Model 8234EX****1977 Lawnboy Model 5024******1978 Lawnboy Model 5269G
1979 Lawnboy Model 7268******1980 Lawnboy Model 5247******1982 Lawnboy Model 5247
1982 Lawnboy Model 5247*******1972 Lawnboy Model 1015******1972 Lawnboy Model 1015
1987 Lawnboy Model 1400CL****1995 Lawnboy Model 61638

Where there's a will, there's Mr. Bill!***They don't call me MacGyver for nothing!***I have LBAD and DCAD!
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post #20 of 20 Old 06-08-2019, 08:51 PM
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Re: Oil Seal or Muffler leak?

My first restore a few years ago on a 1977 model 5024 I used an NOS dual bushing crankcase. The green metal seal looked and felt good, so I took a chance and used it. Well I suppose I guessed wrong because it leaked bad right out the gate. The engine ran good though with those dual bushings and close tolerance of the new bushings, and it was an easy fix since the extended snout was down there at easy access below the muffler. Ever since then I don't even give the NOS seals a chance to do that to me. I do try to use the original primers on the NOS D-400 carbs since they are so dang expensive. Those have about a 50% success rate out of the box for me, both of the NOS for the 1960's models required new plunger seals. The two from the 70's were good to go. Unfortunately those primer seals aren't really replaceable, so it's at least a new plunger.

The correct storage is vital to maintaining these items. So much of these items on ebay, or wherever, have more than likely been abused by storage in uncontrolled climates, so that is why I advise to buy new OEM. I'm fairly certain that Toro is pretty strict about proper storage and shelf life principles. It's not going to be a safety issue if there is premature failure, but who wants the extra equipment down time and hassle of changing them out more frequently? I enjoy tinkering, but not that kind of tinkering. LOL
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