Changing Bearings

[Anonymous]

Hi Guys,
I picked up a OSMAX .25VFDF engine and I’m putting on a new front housing and bearing. I have never done this before and I don’t want to break the housing or ruin the bearing when I push it in.

What I plan to do is put the bearing in the freezer overnight, heat the housing with a heat gun and attempt to just slip the bearing into the housing. Am I on the right track? I don’t have access to an arbor press.
TIA!
Steve

[Anonymous]

Here is the information I was looking for… Quite simple! 🙄
Steve

http://www.airfieldmodels.com/information_source/model_aircraft_engines/disassemble_an_engine.htm

[JLorbiecki]

I didn’t read what was sent here, but here is how I do it…

You need a propane torch. This is the secret. Remove everything off the engine, including the crank. Fire up he torch and start heating the case. Some have loose fits on the bearings and others are pretty tight. So, heat the case (oh yeah, have a wooden dowel available that will slide into the case from the rear) and, after a short time, try lightly pushing aaginst the front bearing from the inside. If the bearing plops out, great. If not, heat it some more. It will then fall out. Now, grab onto the case with a rag and continue heating the rear bearing housing. Tap the back of the case against a wooden bench top and shortly it too should fall out. If not, heat some more…

The installation is done with everything clean. I take the crank and slide the new bearing (rear) onto it. I then slide the crank in place and gently tap the back of the crank with a dowel to somewhat place the bearing into the case. I then place the front bearing into the case and either lightly tap it in or else use a square faced vice and press it in.

After these are in, slide the crank into the bearings. Put on the collet and prop back plate along with a “bad” prop. I then tighten the prop nut, slightly. Heat the case with your torch and you will feel the bearings wiggle into place. I like to then push and pull on the prop to help setle the bearings. When this is done properly, there may be a small amount of free play front to rear, and the shaft should turn freely. If not, try reheating the case and tightening the prop. Many times you will actually hear or feel the bearings settle into place.

It is alot easier than it sounds!!!

[Author]

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