Crankshaft Play

[mgre2643]

Hello

just finished doing a bottom end rebuild on my EC 300 2002 new main bearings seals and conrod installed all went together well and spins freely and selects gears well.

This engine does use the roller type bearing on one side the bearings where with c3 cleareance.

The question is there appears to be quite a lot of play side to side in the crank as in moves about in the cases but no vertical play i haven't attached anything onto the crank yet like the primary nut or flywheel would this and refitting the piston and cylinder solve this problem ?

First time doing this so didn't want to go any further in case i have done something majorly wrong ?

Any help appreciated

Matt

 

[(F5)]

Forget your fears. Zip it up and enjoy.

 

[mgre2643]

Okay i will try.

Its just that this thing does seem to have a lot of end play and the cases went together like a dream which makes me think the actual diameter of the crankshaft is worn away which is allowing that in and out movement i describe.

Am i on the right track..or is this just a normal thing for an old gas gas ?

 

[Neil E.]

Normally the crank would be a snug fit in the bearing and would not move back and forth. In reality some movement is not a big deal. Other machines that have roller bearings on both sides of the crank always have some end play. This would be .005 to .010 inches. Have you measured the actual play?

 

[Doc Brown]

If I understood everything right the crank moves from side to side not back and forth.

 

[mgre2643]

Yes you are correct the movement is 1mm it moves fully from one side of the case to the other.

It is definitely the crank moving and not the bearing moving in the case the more i think about it the less issues i think this could cause but I'm a novice at this.

 

[mgre2643]

Picture of the crank it moves from side to side till.it hits the case

 

[Neil E.]

Movement is not an issue but it should not actually be able to rub on the case while it rotates.

 

[Neil E.]

Is the rod big end narrower than normal? Does the crank pin project out each side of the flywheels? 1mm (.040") movement is large. Is there any change a shim was missed on reassembly? Meaning a shim between the flywheel and inner bearing race. It is normal to shim the crank bearings to reach a nominal reference width.

 

[Doc Brown]

From what I see from the picture the crank touches the case and that is a no-no. 1mm, as Neil already said seems to be too much imo.

Did you change any parts? Casings or crank? Have the bearings the same width as the old ones?

 

[mgre2643]

Yeah all the bearings where the same although I did source them all locally due to delivery reasons but did double check the widths and dimensions with a set of calipers.

The crank pin doesnt project out the side of the webs and I have got a reference dimension which is 54.70 for the distance between not sure how correct this is though the rod has movement of .9 with a feeler gauge so can I assume that reference dimension is correct ??

Looking at the parts fiche I literally have only the bearings and seals installed so when I install everything onto the crank could it correct this issue because item 17 is a spacer and when I do the primary nut up would it pull the crank into the bearing and therefore sit where it wants to be ??

I.cant see off any shims missing from the diagram and didnt notice any when I took the bearings out...although that does sound like a solution but the question is how thick should the shins be to correct this alignment?

An idea I was also toying with is maybe get a thin feeler like .01mm if its possible and wrap it around the crank therefore giving it .02mm more on diameter and that should therefore create a very tight fit of the crank on the bearing.....but from my very limited knowledge these could cause all.sorts of problems with clearances when things get hot.

Thanks for the help and advice really appreciate it I'm.just a novice trying to learn new things.

 

[Neil E.]

Shimming around the shaft does not work. Use loctite to keep the race from spinning on the crank. If the pinion nut draws the crank away from the case (no rubbing) and positions the crank against the bearing, that would be a solution. Does the pinion gear push against a spacer that contacts the bearing race or does the spacer contact a crank shoulder?

 

[mgre2643]

From my understanding how it works the spacer pushes against the crank and when you do the nut up it must force the crank to sit into the bearing.

I done this today and all my end play problems disappeared so you where correct when you said something was missing half the engine in my case you have been a great help.

I put this down as a learning curve I thought there was something a lot more serious going on.

 

[Doc Brown]

That sounds great. My next idea would have been to torque the nut to specs and then measure again, but that is not necessary anymore

Glad you got it fixed!