Jack_K

How do I get the rear bearing out of an OS 46FX? It was totally frozen up and I soaked it in glow fuel for 5 days. Then in Evaporust overnight. I got it all apart except for the rear bearing.

blw

My Feedback: (3)

Heat.

Try heating the crankcase first. Then start in an oven at something like 300°F and work carefully up to 350° if you have to go that high.

Jack_K

I don't think my wife would let me use "her" oven.

1QwkSport2.5r

Then use a heat gun or propane torch. The latter must be used with extreme caution as to not melt or distort the crankcase. I've used the oven, but I cleaned the case very heavily to remove as much funk as possible and then heated in the oven when the wife isn't home. I've had to heat a case to 400F once to get a very suck bearing out. I wouldn't start any colder than 350F and bake the case for 15-20min. This really is the best way, but a heat gun will do the trick if it will get hot enough.

Try soaking in acetone for awhile (maybe an hour) and try re-heating the case. Acetone works significantly better than glow fuel for dissolving old oil.

Jack_K

Then I just bang it on the work bench and the bearing falls out?

blw

My Feedback: (3)

I mean using a Monokote heat gun when I said heat and then try the oven, but slipped up on the advice. You would be surprised what all will pop free using the heat gun.

Tim, I think starting at 350°F is too high. Again, a lot of bearings pop free at 300. I've used 350F but I'm not comfortable with my aluminum getting that hot.

1QwkSport2.5r

If the bearing doesn't just fall out, then yes, bang it on the bench smartly and squarely.

1QwkSport2.5r

Considering aluminum doesn't even think about melting until at least 700F (and that's pretty low), I think you're pretty safe at 350-400F. That is of course we're dealing with a high quality casting made of a quality alloy. I usually start at 325F for 20 minutes and try getting the bearing out. If that doesn't do the trick, I go up 350F, and raise 25 degrees and go 20 minutes again. I have had to go up to 400F on one of my buggy engines (made in Taiwan) to get the rear bearing out. It was a little stuck. New one went in with a little effort at 375F. The engine has had 2 gallons of fuel run at 25,000-30,000rpm (average) since then with no discernible change in performance or longevity yet.

I feel that if you're gonna stink the house up, might as well try getting it with the first shot. I think 350F is a safe bet, but do what you're comfortable with.

1QwkSport2.5r

I can't edit my last post - what I meant was start at 325 and heat for 20min, if needed raise 25 degrees and cook 20 more minutes. If needed raise 25 more for 20min with 400F being the max. On an OS, it should fall out at 375F I'd think.

blw

My Feedback: (3)

You mentioned stinking up the house and that reminded me of Power Blaster. Never use that stuff indoors.

franklin_m

Cheap toaster oven might be an option -- thrift store to cut cost even further?

Dealspeed

My Feedback: (17)

I just didn't tell my wife when I use the oven, I've used it twice lately to remove some of the worst bearings I've ever seen.

J330

My Feedback: (3)

How did those pop tarts taste the next day?

Propworn

My Feedback: (3)

I have a 1/4 steel plate I put in the BBQ turn it on and adjust the temp then place the crankcase on the steel plate and leave for 10 to 15 min. Tap it on a block of wood and it should drop right out. I you clean the crankcase before putting it in the BBQ there will be no smell or contamination. The oven or BBQ heats the whole crankcase up evenly and does a much better job than a heat gun or propane torch. I just pick it up with my welding glove and tap it on the wood and the outer race just falls out.

Dennis

1QwkSport2.5r

Another great idea and one thing pointed out that I forgot to point out - evenly heating the case. This is ideal, but a heat gun or torch can be used if careful.

jaka

Hi!
I always use a propane torch! -It's so easy! Just hold the engine in one of the engine lugs with a pair of wise grips and warm the whole crank case evenly and then bang it into a piece of wood ...and the bearing will fall out.
If it does not...cool it in water and then start the warming up process once more! Picture nr 2 shows a new open C4 WIB bearing being mounted (crank is heated before doing this).

Propworn

My Feedback: (3)

Quenching the crankcase may cause the thing to shrink unevenly and induce a warp better to let cool naturally/evenly. Heating the crankcase will heat the steel bearing race at the same temperature its the difference that aluminium expands at a greater rate than steel that allows the bearing race to literally fall out with a few taps. There is no advantage to allowing the case to cool just up the temp a few degrees until the race falls out. Heating the crank before insertion heats the bearing as well creating a tighter press fit. I believe you meant "heat the crankcase not the crank". This to is not required instead install the front bearing making sure it is fully seated in the crankcase. Be sure to use something like a socket or metal tube that presses only on the outer race so you do not put undue stress on the balls and races. This can cause brinelling and lead to early bearing failure. Press the rear bearing on the crankshaft using the inner bearing race to press in place. I have a small metal plate that just clears the crankshaft and presses against the inner race. I put this down on the drill press table over the through hole. Slide the crankshaft into the crankcase using the front bearing to line up the crank. Place nose down so the threaded end of the crankshaft passes through the hole in the plate. Use a 1/4 dowel or steel rod in the chuck and using the drill press to press the rear bearing and crank into position. The front bearing will keep everything in line and allow you to press the rear bearing into the crankcase cold.

Dennis

blw

My Feedback: (3)

Been there a few times too. It works.

jaka

Hi!
Oops! Meant heating the crank case...

706jim

Why not press it out from the front of the case? I've done this with several engines.

Jack_K

Can't contact the bearing face from the front.

fizzwater2

My Feedback: (61)

I second the toaster oven idea. I bought one at a garage sale, it works for heating engine cases. That way I don't have to use the "food oven"...

earlwb

Well for a recalcitrant rear bearing or the occasional front bearing too, I use a brass rod that fits down the hole in the case where the crankshaft used to be. The edge of the brass rod has a lip on it that is formed when whacking on it with a hammer. The lip on the brass rod can catch on the inner race of the bearing. I first heat the crankcase up good, then with the crankcase on something like a piece of 2x4, I use the brass rod to work the bearing out, but going around the inner race and tapping on the rod with a hammer. Now sometimes one could use a blind hole bearing puller, but usually there isn't a gap in there for the bearing puller to catch on the inner race inside the crankcase.

706jim

Same idea from me. You could even use a large nail with the head pushing against the bearing. Might not even need any heat. Just tap it with a hammer. Or buy a cheap press from Harbour Freight like I did.

blw

My Feedback: (3)

I want to buy a decently priced arbor press from Harbor Freight for pressing bearings back in.