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5 HP Nissan 2-stroke crankcase torque specs - bad bearing replacement

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code1p36

Regular Contributor
I have a NS5B 5 HP 2-stroke that had a bad lower bearing so I am replacing it along with the top bearing and top and bottom seals. Does anyone know the torque specs for the crankcase bolts and in which order for when I put it back together?

I believe I should use a thin bead of Loctite 518 on one side of the crankcase but would like confirmation.

I took the old bearing and put in toaster oven at 250 deg for 10 minutes and it slipped right over the crankshaft for a test, could that much heat hurt the new bearing?

Last questions, the top seal the lip faces down which I know but what about the bottom seal? It looks like on the diagrams that faces down too, is that right? Should I use a little Permatex Aviation Form-A-Gasket around the top and bottom seals and then seat it?

Thank you, I appreciate it!
 
Of course the data is in the Factory service manual, but may be difficult to glean, unless you read everything. Standard torques apply unless that section of the manual supercedes the standard torques. Standard torque for 6 mm bolts is 44-53 inch pounds. Start with the bolts closest to the center and work outward.

Yes, some anaerobic sealer/gasket maker, such as Loctite 518, is a good idea on the mating surfaces of the block.

Most people just drive the new bearings on, as the press is not too much. However, since they are just ball bearings, that heat level shouldn't hurt them; However, it would toast seals.

The lower main seal is actually two seals with a spacer (new design), and the lips do point down. There will probably be some sealer on the outside of the new seals, but you can add a tiny bit if that makes you feel better. The press fit is what actually does the job.
 
Paul, thanks for the info! I double checked the diagram and I don't see the double seal on the bottom nor did two come off either so maybe that is a newer model than mine.

I don't have a press therefore the heat for the bearings.
 
Dunno what diagram you are using; Here is the appropriate page from the parts catalog:
002-21005-6_FIG01.JPG

Most people just use a socket and a hammer to tap the bearings on. I have never seen a press used.
 
I used to use an " induction " type bearing heater all the time.----Heats the bearing to about 250F without a chance to get the bearing contaminated.-----Then they fall in place usually.-------Used boiling hot water on $10,000 stainless bearings too.
 
Paul, the lower seal I was referencing is on the crankshaft/lower part of crankcase, not the part you are referencing.

Thanks again for the help.
 
The lower crank seal is now superceded by two seals and a spacer. Back around 1992, it was a single seal.
 
Paul, I am referring to part number 301001220 bottom oil seal and only one will fit between the bottom crank pin and crankcase head 369012100. I got both bearings on and now need to confirm a couple things; which way does bottom oil seal face? Does the lip face down towards propeller? The below picture shows what I am talking about where it will seat. There is a small groove, is that an oil path? Also, the crank pins 369000610 seem to be a little loose in there, do the oil seals press against them tightening them up? When I dropped the crankshaft I set the very little bit of play the same on the crank pins and am hoping the oil seals press against them making them snug otherwise it seems they would rattle. Thanks.
lowerbearing.jpg
 
Part 301001220 was superceded to 369001220M
The
369001220MOIL SEAL B

... Has the lip pointing down, both at the top and bottom of the crank.

002-21005-6_FIG02.JPG
 
Thanks Paul for confirming down. When I seat those seals all the way down should they snug up the crank pins so they dont rattle? I am kind of wondering if that was part of the noise coming out of the area below the flywheel since that seal was about flush with the top when removed and looks like it could have went down further to snug up crank pins. I am obviously new to Nissan. Thanks for your patience and assistance..
 
Just seat them all the way in the bore. They are not thrust washers. Probably was just a loud bearing.
 
I got both bearings on and now need to confirm a couple things; which way does bottom oil seal face? Does the lip face down towards propeller? The below picture shows what I am talking about where it will seat. There is a small groove, is that an oil path [FONT=&quot][/FONT][FONT=&quot]best home safe[/FONT][FONT=&quot][/FONT]? Also, the crank pins 369000610 seem to be a little loose in there, do the oil seals press against them tightening them up? When I dropped the crankshaft
 
If you look at the diagram in #9, you will see that the lip of the lower seal faces down. What groove? The crank shaft is pressed, so the pin should not be loose.
 
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