# Replacing Sump Gasket on B&S Twin cylinder



## northcountry (Sep 9, 2005)

My B&S Twin (vertical shaft, splash lubricated) recently developed an oil leak that grew worse after I tried the time-honored method of tightening the bolts in hopes of sealing the gasket between the oil sump and the engine block. 
I'm 99% sure it's the gasket between the two that's gone bad. 
After looking at the B&S repair manual, I note that there is no process for just changing the gasket, but only to disassemble the engine for the purpose of repair or replacement of the governeor, crankshaft, etc. 
It appears from looking at this that you can't just pull the engine block off the oil sump by removing the bolts that connect the two and what's worse, the replacement gasket set includes different thicknesses because there is a clearance tolerance with the crankshaft end. 

Is this job more complicated than just pulling the block off, replacing the gasket and reassembling it? All this is connected to an MTD Yard Mahine, about 6 yrs old, so I'm not inclined to do much more for it at this point.
Any advice much appreciated.


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## bugman (Aug 12, 2004)

if your worried, have a shop do it, they would check the specs out....the different thickness'es make up for slack.... if you do it yourself, most likely it won't be outta spec and you can just install the regular one and be off with it, though the engine has to come out...pulley stack taken off ( there's a bolt in that hole ) and the sump removed. and the old gasket completely removed.


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## northcountry (Sep 9, 2005)

I got the pulley stack and all the wires, linkages etc. off already - all that remains is to separate the block from the sump - which in my attempt to avoid unnecessary work I have attempted to do while leaving the sump mounted to the tractor frame.
The block of course is stuck to the sump pretty good - I just didn't want to go trying to crack it if the crankshaft wasn't going to pull out through the bottom of the sump itself. I also wasn't sure if the crankshaft gaskets at the sump would also need to be replaced - B&S calls for a special tool to replace them.

I guess it will take a bit of percussive maintenance and some elbow grease to separate the two.
If you know any tricks to make that task easier, please share.
I usually find this kind of stuff to be the hardest part of any repair...


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## scrench (Dec 8, 2004)

you will have to take the engine off , the crank shaft seal and pan gasket should both be replaced , there are more bolts under there you will have to take the engine off and turn it upsidedown , also look at the pan verry close make sure there are no cracks in it i have seen a few crack also be careful and line up the governor gear when you put the pan back on its simple you can do the work yourself


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## bugman (Aug 12, 2004)

yeah, the engine has to come out.....no other way around it


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## northcountry (Sep 9, 2005)

I'm going to finish pulling it out today - any tricks to cracking the seal between the sump and the engine?
I don't need to press the shaft out from the bottom?

My most specialized tools for separating engine parts are a rubber mallet and a pry bar


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## scrench (Dec 8, 2004)

take all the bolts out and tap on it it will come apart no need to pry or get rough with it , it will come apart , tap one side then the other ,the crank shaft ownt come out unless you take the rods , the cam , and the flywheel off , you will see when you get the pan off , dont forget to put the governor back in simple mistake have seen a few guys do ,,, good luck , oops you dont need luck you have hobby talk


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## northcountry (Sep 9, 2005)

OK, I've got the pan off - very easy once you get ALL the bolts off...

about that governor - is it as simple as lining up the gears? - I figure as long as the pan slides into place after I've finagled the gears to mesh(as near as i can tell) that it's a done deal.

I'm ordering the engine gasket set (after I check CAREFULLY for any cracks in the block or pan), so it's probably be a week or so before I finish this job up.
The gasket set includes three different thicknesses, so I'm thinking I should retain some of the old gasket and attempt to replace with the one closest in thickness??

thanks for the guidance - this place RULES!!


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## bugman (Aug 12, 2004)

yep, just compare thicknesses, and replace it with the same thickness gasket.


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## scrench (Dec 8, 2004)

I figure as long as the pan slides into place after I've finagled the gears to mesh(as near as i can tell) that it's a done deal.
yes just dont force anything ,, 

closest in thickness??
just use the darkest colored one in the kit that should be the .15 you will be ok i dont really think its going to be that critical , dont know if you know what the slack bugman was telling you about in his post is but its called endshaft play in the crankshaft if you grab the crankshaft and work it up and down that small ammount of slack is called endshaft play all engines have it you can mesure it with a straight edge if you want and do the math but if the engine hasnt been ran out of oil or a crank shaft or sump had to be changed or rod journal resizeing new rods ect, ect. you should be ok just use the dark colored gasket ,,, one other thing you might check for is crank case pressure might have caused it to blow the pan gasket make sure your crankcase breather is hooked up and is good .. and the 0-ring on the dipstick tube is good ,,


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## northcountry (Sep 9, 2005)

I intend to use the .15 gasket - in fact, after I realized that the gasket kit inluded EVERY single gasket the engine uses (and after reading these useful posts) , I simply ordered the .15 gasket and PTO side oil seal.
Crankcase breather? that rubber hose between the air cleaner and the block? I remember having that cover off once- isn't there some kind of fabric-type element in there I should check?
I'll give it a look...


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## bugman (Aug 12, 2004)

no,the breather is what that hooks into, serves as the valve spring cover as well, if its bad, replace it, if its good keep it. actually it wouldn't be all that bad of a thing to replace it anyway, also make sure that gasket is good, do you'll have a oil leak there as well. that and make sure the holes there are clear. i forget the measurement the valve should be on the breather ( orange kinda in color )


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## changetires (Sep 12, 2005)

Make sure the round end of the governor is sitting on the flat side of the governor arm or you will have to take it back out after you finish everything. You wont know it slipped off until you crank it and the engine will not govern itself down.


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## northcountry (Sep 9, 2005)

OK - going to get my gaskets today and put it back together tomorrow - I took off the breather - how do you tell if its bad? I am going to clean it out - there is a fabric mesh element behind what looks like a bakelite shield in front of the hole that the hose connects to. The element is a bit oily - I figure shaking a little carb cleaner won't hurt. Oil never leaked from it and gasket is OK.

Will check the governor carefully when I reassemble.


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## bugman (Aug 12, 2004)

don't clean it out....its supposed to be oily, if the breather tube that connects from the breather to the carb isn't dry, its oily then yeah that would show it one way, i forget the way you check the little valve on it, but don't take it apart or spray anything in it.


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## bsman (Jan 22, 2006)

I know what your talkin about. I have the same setup. Easy to pull the engine off the tractor and work on it there. I just did the same thing you need to to tonight. There is 4-5 bolts holding the two together. Pull it apart and replace the gasket. The old one will brake, so clean up the two parts real well, and stick on the new one!!


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