How to replace crankshaft on MC-54-250B By robert1c (Read 1,811 times)

[robert1c]

Hi Guys,
I need your expertise again. On my Linhai we had an issue where the locking nut for the variator fan worked itself loose and chewed up the fan. I bought a new fan and when I went to replace it I noticed the crankshaft that the fan slides on to is chewed up. I tried to file the teeth back so that the fan could slide back on to it the best I could. I put it back together and it seemed to be working for a while but today when we checked the fan has begun to work itself loose and is rubbing against the variator cover. I even used red lock-tite!! ;D
I think I’m going to need to replace the crankshaft. Is this something doable… worth doing? Or is there a way to permanently affix the nut to the shaft so that it doesn’t work itself loose again?
Any guidance would be greatly appreciated.
Robert

[alleyoop]

What is causeing the nut to unscrew is the FAN is not holding onto the Splines on the Crank. Look at the FAN TEETH they may be rounded off which they would be because the metal is softer than the crank metal. So if the Work you did on the Crank Splines look hafway Descent get a new FAN PULLEY. If the Fan turns on the Crank it will unscrew the nut.
Alleyoop

[robert1c]

Hi Alleyoop, the fan is a new one. i just bought it about a month ago. but the teeth on the fan are now gone again because the fan spun on the spline. i may have to to buy another fan and work on the spline some more. the fan should slide pretty far back on to the spline right? i think i remember being able to see the teeth of the spline past the fan before they got chewed up.
Robert

[alleyoop]

Yea you need a new Fan there is nothing you can do to fix the fan teeth. Now when you put the fan on and you can SEE OR FEEL the CRANK SPLINE out side of the FAN THEN YOU NEED a washer to go over the SPLINES AGAINST the Fan so NO SPLINES from the crank stick out. THE NUT HAS TO TIGHTEN on the FAN NOT the spline OTHERWISE the FAN will move out and LOOSEN the NUT. So maybe that has been your problem and that is that you need a WASHER.
Alleyoop

[robert1c]

Thanks, I do have the washer on there and a new nut. I can get a fan for about 20.00 here locally. I guess I will need to work on the spline a little more. I did notice that if I look between the fan and the variator underneath the belt when the nut is fully seated there is a little gap between the boss and the fan.

[alleyoop]

There should not any gaps between the fan and the BOSS, the Fan should fit tight against the boss. That means the FAN is not going back all the way. When you put the Belt on ALWAYS OPEN the CLUTCH PULLEY and push the BELT down in the CLUTCH pulley some. Then you will have some slack in the Belt. Then Put the Variator and grab the belt and squeeze it together top and bottom that will move the BELT UP higher so that the FAN can be pushed in up against the BOSS and hold it there. With your other hand put the washer and nut on and tighten it up by hand against the fan. Then you can give the Nut 3 1 second raps with the IMPACT Wrench. Start it up and goose it several times and then take a spin putting a load on it to make sure it does not come loose.
Alleyoop

[robert1c]

Here is a pic of the inside of the fan. the BOSS is actually up against the fan. the gap you see is between the variator and the fan. is this normal?

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[alleyoop]

Something does not look right to me, What is that bigger Shinny cylinder and what is the next smaller shinny cylinder?
Take take the Variator FAN off and take take picture.
Alleyoop

[robert1c]

the shinnier one is the end of the variator. the deeper/smaller is the boss.

ill take it apart now and take a pic.

[alleyoop]

NO that cannot be, the bigger shinny one that I have labeled should be the BOSS that is the CYLINDER about 3 inchs long that goes into the VARIATOR PLATE and sticks out of the VARIATOR PULLEY. The BOSS GOES OVER THE CRANKSHAFT.
Alleyoop

[robert1c]

ive uploaded 3 new pics of the fan and the outside of the variator.

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[robert1c]

here

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[robert1c]

and here

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[robert1c]

yeah that the boss sitting over the crankshaft and sticking out just past the variator

[alleyoop]