Engine Bearings

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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.
 
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:
https://www.grainger.com/product/BERNZOMATIC-Hand-Torch-w-Cylinder-Webbed-52RM88
 
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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.
 
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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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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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.
 
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
 
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
 
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?
 
I have a good stock of bearings available now if you're looking to do a winter refresh on an engine.

Prices are still the same. $25 for a .21 size set and $30 for everything else.
 
I just restocked on all bearing sizes again if anyone is looking to refresh those motors for next season.

Prices are the same for now. $25 for a .21 size set and $30 for everything else.
 
Merry Christmas Doug.

Yes, I have those. They are $30 a set plus $5 for shipping.

Check the first page of the thread and it has all the different sets of bearings that I have.
Hi Mike I need a #5 set please. Please let me know total and PP. Thanks.
 
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.


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)

[/QUOTE]
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

He was talking about case heating temperature not heating the bearing up.

That is when heating a bearing for it's inner race to slide over a shaft.

Heating a bearing your pressing in a housing would be working against yourself. You would heat the housing of course. The temperature you use to heat a aluminum housing has no relation to the temp the bearing can withstand. The bearing is not heated to that high a temp anywhere it matters by pressing in extra hot aluminum bore.

Because this has nothing to do with heating a aluminum case you are about to put a bearing in. If you were heating bearing to get crank into it that is different. Heating the aluminum case to install the bearing you can go hotter so it opens up more to freely accept the bearing with minimal insertion force.

Those are bearing heating temps for going over steel. Not aluminum temps for opening it up to accept the bearing. That can be hotter and it is never going to affect the bearing if you cool it following insertion of bearing especially.

That heat is dissipated by the outer race and the atmosphere so fast if you merrily press it in and if you just blow it cool immediately with compressed air you are golden. 250° is not hot enough and you will remove aluminum pressing the old out as well as the new one back in.

You want case at high temp so it lasts a long time and you retain your fit indefinitely. Some aluminum engines can operate up to 250° so surely that isn't hot enough to fully release a properly fitted bearing. The interference fit is altered when you use a lot of force to remove or install a bearing in aluminum bore.

I heat aluminum cases to 350° and I can guarantee the bearing is not getting affected. Most of the bearings I use are phenolic plastic type high speed retainer. No heat makes it there whatsoever. That 100° too much for bearing is gone by the time the bearing hits home.

250° is not opening up the case and releasing or accepting the bearing like it could if heated more like you should.

And for sure NEVER FREEZE the bearing. The reason being is it does very little to shrink it versus heating the aluminum ONLY and will suck your heat out before it goes in.

What can happen is if you do not get the new frozen bearing fully seated in the bore in one quick fast motion the frozen bearing will suck the heat out of the aluminum so fast it will lock the case up on the bearing where ever it is. Now you are 100% screwed. Now you got to reheat the case with your brand new bearing in it and you have created a real problem you could have avoided by leaving the bearing room temperature always. Beside it fills your brand new bearing with water when it warms up. Bad idea. Repeat NEVER FREEZE the bearing. If anything you can actually warm it just slightly so as to ensure it doesn't suck the heat out of your case going in. A cold bearing is for sure detrimental to this bearing going in aluminum bore process.

Installed many hundreds of bearings in aluminum cases and have learned a bit along the way. Do not believe most of how the internet seems to think it should be done as they are just frigging clueless.

A good high temp heat gun is better for heating cases than the torch. You get much more even heating with the heat gun.
 
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