Engine Bearings

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Mike Betke

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Aug 31, 2004
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947
Hello Mike:

I made an attempt to change the bearings on my Rossi R65 marine engine. Wasn’t as easy as I’d hoped.

I heated the front housing in my oven (350 degrees) for 20 minutes. The front bearing barely came out. The rear wouldn’t move.
So I re-heated oven (to 400 degrees) for additional 15 minutes, rear bearing would not move.

This method worked for me in the past. Usually both bearings practically fall out without doing too much (maybe tapping the case with a wooden spoon a little).

What is best method? (I don’t want to screw it up)
Hi David,
I pretty much do as Rick has described here. I hold on to the housing by grabbing it with a vice grip on the cast web while heating it. If the bearings have been in for a long time there could be some residue or corrosion that makes them difficult to get out. A little extra heat can help with that. Shocking it as Rick describe will help as well. Make sure you let it air cool completely before cleaning and install new bearing.
 

David Bryant

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Sep 7, 2011
Messages
2,302
Hi David,
I pretty much do as Rick has described here. I hold on to the housing by grabbing it with a vice grip on the cast web while heating it. If the bearings have been in for a long time there could be some residue or corrosion that makes them difficult to get out. A little extra heat can help with that. Shocking it as Rick describe will help as well. Make sure you let it air cool completely before cleaning and install new bearing.
Thanks Mike & Rick for your input, that gives me a good idea.

What about installing new bearings? Do you attempt to heat the complete housing? Then quickly insert front bearing, rear bearing; slide crankshaft into position; install flywheel, and tighten collet to properly align and seat bearings?

Also what is a good propane torch example? Something like this:
 
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FloridaScaleBoater

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Oct 2, 2005
Messages
6,940
Perfect torch for your needs.
My bearing install procedure.
1: clean new bearings crank & housing with break clean
2: slide big bearing onto crank,
Pace in freezer with small bearing.
3: let freeze at least overnight.
4: I use a small toaster oven.
Heat housing/case for about 1/2 hour at 350*
5: quickly, remove from oven, slide big bearing & crank into housing/case. Slide small bearing on. Install flywheel sweadge piece, flywheel and snug up the shaft collet.
Wrap on the 4 sides with a brass hammer. Saturate with your after run oil & let set/cool to room temp.
My procedure, right, wrong!?!?
Works for me.
 

David Bryant

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Joined
Sep 7, 2011
Messages
2,302
Perfect torch for your needs.
My bearing install procedure.
1: clean new bearings crank & housing with break clean
2: slide big bearing onto crank,
Pace in freezer with small bearing.
3: let freeze at least overnight.
4: I use a small toaster oven.
Heat housing/case for about 1/2 hour at 350*
5: quickly, remove from oven, slide big bearing & crank into housing/case. Slide small bearing on. Install flywheel sweadge piece, flywheel and snug up the shaft collet.
Wrap on the 4 sides with a brass hammer. Saturate with your after run oil & let set/cool to room temp.
My procedure, right, wrong!?!?
Works for me.
Thanks Rick.

I made another attempt this morning to remove big rear bearing. This time I placed the front housing into conventional gas home oven @375 degrees, for 30 minutes-plus. Removed housing from oven, gave it a whack with my wooden spoon, bearing fell right out, no problem (I was using my convection oven last time. It just doesn’t put out the BTU’s as the conventional gas home oven).

I will clean internal surfaces of front housing, then make an attempt to install new bearings.

I’m purposely re-building this vintage (34 year old) Rossi engine as a way of “re-learning” all this stuff, before I work on (screw-up) my new engines.
 

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David Bryant

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okay, cleaned-up crank housing, placed into oven (375 degrees, 40 minutes). Inserted crankshaft w/bearings (both slid into housing with ease). Installed flywheel w/cone. Firmly hand-tightened cable collet

(I do notice a very small amount of end-play within bearings. I can visually see the front bearing inner race float, fore and aft)
 

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Mike Betke

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okay, cleaned-up crank housing, placed into oven (375 degrees, 40 minutes). Inserted crankshaft w/bearings (both slid into housing with ease). Installed flywheel w/cone. Firmly hand-tightened cable collet

(I do notice a very small amount of end-play within bearings. I can visually see the front bearing inner race float, fore and aft)
Looks like you got it. When you tighten up your crank / flywheel the bearing should spin smoothly. If bearings do not spin freely after tightening up the flywheel, the big bearing is probably not in all the way. You should be able to see a small gap (.005) between the bearing and the crank when installed.

The bearings typically have some end play in them. It has not been an issue on any motors that I run.
 

Jeff Lutz

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Jan 2, 2005
Messages
842
okay, cleaned-up crank housing, placed into oven (375 degrees, 40 minutes). Inserted crankshaft w/bearings (both slid into housing with ease). Installed flywheel w/cone. Firmly hand-tightened cable collet

(I do notice a very small amount of end-play within bearings. I can visually see the front bearing inner race float, fore and aft)
Don’t ever go over 250 degrees when installing bearings. It causes damage. I’m certified by SKF as a machinist and pump rebuilder. We use 235 degrees actually. Do some research on this and you will see Iam correct. Jeff Lutz
 

David Bryant

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Sep 7, 2011
Messages
2,302
Looks like you got it. When you tighten up your crank / flywheel the bearing should spin smoothly. If bearings do not spin freely after tightening up the flywheel, the big bearing is probably not in all the way. You should be able to see a small gap (.005) between the bearing and the crank when installed.

The bearings typically have some end play in them. It has not been an issue on any motors that I run.
thanks, that's exactly what I needed to know
 

David Bryant

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Joined
Sep 7, 2011
Messages
2,302
Don’t ever go over 250 degrees when installing bearings. It causes damage. I’m certified by SKF as a machinist and pump rebuilder. We use 235 degrees actually. Do some research on this and you will see Iam correct. Jeff Lutz
thanks Jeff. I was curious about that (thermal limits). I checked the spec sheet, it's showing like -40F to 220F degrees. So I will definitely try to never exceed 250F. Hopefully the "plastic" (polyamide) retainers were'nt compromised?
 
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