GX390 balance shaft bearings

When the engine heats up when ran they will eventually fall out and cause big trouble. It is easy to break the block and/or side cover trying to get them out if not careful. Yes, heating the block helps. A very small puller can be used. I have seen bread used to remove them. Yes, bread. Bread pushed into the center hole until full and then a dowel the size of the hole beat into the bearing. Repack and redo. repack and redo. It will eventually drive the bearing out. Been told you could use thick grease also. I have also seen them staked in. Take a sharp punch and dimple the aluminum quite hard around the bearing thus causing them to be tight enough to stay in. the aluminum behind the bearings is quit thin. If you do bust the block behind the bearing you can use a freeze plug of the right diameter to fill the hole.
 

manyfunnies

New member
When the engine heats up when ran they will eventually fall out and cause big trouble. It is easy to break the block and/or side cover trying to get them out if not careful. Yes, heating the block helps. A very small puller can be used. I have seen bread used to remove them. Yes, bread. Bread pushed into the center hole until full and then a dowel the size of the hole beat into the bearing. Repack and redo. repack and redo. It will eventually drive the bearing out. Been told you could use thick grease also. I have also seen them staked in. Take a sharp punch and dimple the aluminum quite hard around the bearing thus causing them to be tight enough to stay in. the aluminum behind the bearings is quit thin. If you do bust the block behind the bearing you can use a freeze plug of the right diameter to fill the hole.
how did you remove them. i tried news paper and a dowel but the bearing didn't seem to want to budge. maybe i just need to pack more. it was thicker paper so maybe it wasn't pliable enough.
 
go to habor freight an buy a bearing removing kit 30 bucks that how I got mine out
Probably the best idea^.

But if you want to try again, Wet the newspaper and keep on packing. And repacking and repacking. problem is this puts pressure on the aluminum behind the bearing and could break it.
 

manyfunnies

New member
Warm up the block and sidecover in an oven (toaster oven works fine) and they all but drop out on their own. Light tap and they fall out -- watch, they'll be hot. ;)


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Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
28 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
what temp? I know aluminum's max temp is typically around 460f... i dont want to warp anything either. I think this might be my best option since the engine is already stripped down.
 

manyfunnies

New member
Aluminum melt temp is 1200 degrees, 3-350 wion't hurt it.
Melt temp might be 1200 but aluminum loses all of its strength after 400f.

Going to try the news paper again then going to put the block and side cover in the oven if it doesnt work
 

manyfunnies

New member
bearings fell out while in the oven at 300F. Very happy i removed the bearings. no doubt they would have fell out on track.
 

Oman

Member
Not really, the block would never get that hot when the motor is in use. If you block is anywhere that temp in the bearing pocket area the bearing falling out is the least of your problems.
 

manyfunnies

New member
Not really, the block would never get that hot when the motor is in use. If you block is anywhere that temp in the bearing pocket area the bearing falling out is the least of your problems.
i would assume the oil gets to over 200F. if the bearings fell out easily at 300F then its not a stretch to think they will at 200-220F.

Maybe i am thinking the oil gets hotter than it does.
 
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