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tobski

crank bearings on 325431

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tobski
A briggs 325431 engine was recently disassembled. while disassembling, one of the bearings fell off crankshaft, crankshaft was taken out, (without the other remaining bearing on it as well), (bearing stayed in bearing retainer)..so what I'm saying is this engines crankshaft has/had no bearings "pressed" on to it...are the bearings wore down.. or is this how it's supposed to be...according to briggs manual I thought this crank should have 2 bearings "hot pressed" on to it..I guess I dont know what to think of it..sounds like I might need new bearings maybe, my crankpin journal diameter is good and above reject spec.... In anyones experiences, Does this crank normally have two bearings on it when removed from engine?,.are they just placed on there in reassembly?..is this a sign of excessive engine wear? and what type of oil should be used to heat bearing up in to put back onto crank? ( whats a good method of heating oil hot enough to do this?) Thanks in advance...since the 243431 engine has some issues I'm just wondering which one I want to try to use to power b-10..

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DanD
I had the same issue on the 326431 engine in my 7016 that I overhauled several years ago. The engine was completely worn out. The old bearings were loose on the crankshaft, and new bearings just slid on and fell off the old shaft as well. Don't ask me how the crankshaft main bearing journals wore when the bearings are a tight fit. Perhaps years of pounding and shaking eventually wore it out anyway. I don't know. I bought a new crankshaft, and of course, the new bearings wouldn't go on (which is correct). I heated the bearings in hot oil according to the Briggs shop manual. I used an old electric deep fryer and heated the bearings to about 250F in vegetable oil. When heated, the bearings almost fell into place..I just tapped them a little bit with a brass drift and they went right into place. When cooled, they were TIGHT. Engine has been running great ever since I overhauled it. I bored the cylinder, put in a new piston and rings, rod, crankshaft and bearings, points plunger and bushing, and correctly set the end play on the crankshaft and camshaft. See it running here! [url][/url]http://www.youtube.com/watch?v=Pg2Gmq2EjLA

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powerking_one
Tobin, Do you see signs of the bearings wearing on the crankshaft pilot ends due to them possibly seizing/spinning? If not then I would submit that this crank was mis-machined with the O.D. out of spec by a few thousandths too small. Since Briggs never provided a spec for these diameters, it is hard to know without mic'ing a known good crankshaft. I'll ping my brother to mic one since he has a few "on the bench". Also, as DanD notes, they should be an interference fit and heating them up in oil should allow them slide on. Tom (PK)

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tobski
the diameter where bearing sits is around 1.378 (if I'm reading mic right)and is tapered very slightly. From what I see nothing looks worn or wrong, maybe a small little scuff here or there, nothing big it seems, crankpin journal is above reject spec, it also has syncro balance gear(s) on it. I just tried sliding a bearing on, it went on with a little fight, came off with a little fight...dont know wha I'll do.....anyone have a crankshaft for 325431 engine? Thanks

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steve-wis
The bearings have a metric size bore, and 35 MM is 1.3779, so the crank should be a bit bigger than that. They will wear over many years from the stressing of the engine running. The crank can be reworked if the rest is good by grinding down the main bearing areas, chroming them oversize, then grinding back to size. Might be cheaper to buy a new crank tho. Steve

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DanD
Most suppliers I found online including the Briggs and Stratton website itself lists the crankshaft at $266.15. The old part number of 261131 has been changed to 691797. Here is a link to the best price I found after searching a few minutes. [url][/url]http://www.smallenginesuppliers.com/shop/html/pages/products/Briggs_Stratton_Crankshafts3376.html Here is a link to a place that lists a supposedly good crankshaft. Don't know anything about the place though. [url][/url]http://www.vendio.com/stores/GreenSwampMowers/item/yard-garden-outdoor-living-par/briggs-stratton-15hp-325431-cr/lid=3235577

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lgtbrown
do not be afraid of using loctite in this application it is amazing the different products & applications available if you should choose this option get with a loctite supplier and ask for an application guide book to make yhe proper selection. (i was told by a loctite rep. onetime that one of the auto manufactures uses loctite to install individual lobes on a straight shaft instead of a cast componet) just a thought good luck

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powerking_one
Tobin, Here's my brother's response on measuring some cranks: Tom: I measured all of the cranks that I have and the largest main bearing journal is about 1.379". Tom (PK)

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Al
HI, I think you could get by using 620 Loctite. I believe this is the number. It is designed for this purpose. Once you put on, disassembly is an issue. This is from memory, but as I remember it is good for about 33,000 lbs per square inch and it takes 500 degree to soften it. I think it is good to about .010 or 020. You are probably looking at less than .001 clearance. I have to look it up and recommend you research it first. I have a bottle and it was about 40.00. I use it with the Loctite primer. When you use the primer, you spray it on and let it dry for 5 minutes. At this point you can not tell it is on the surface. when you put the Loctite on and assemble, it starts setting up in about 2 minutes. Before I put the primer on, I spray carb or brake cleaner on and blow it off with air to remove all oil etc. I can assure you that the bearings WILL NOT come loose. You have little to lose because if you were to use new bearings they would probably last a couple of engine bore jobs and by then the block would either be scrap or need sleeved. If you use the old bearings and run it that way, when you tear it apart in the future you can heat the bearing inner race with a torch and pull them off and clean up and repeat with new bearings or look at the problem as you are now replacing the crank, etc. If you focus the torch heat on the inner race a neutral flame will be about 7000 degrees and the race will heat quickly and the joint between the race and crank will be a thermal barrier and the crank temps will lag if you work quickly and do not direct the heat at the crank. My thoughts and they are free, value accordingly. Al Eden

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