Connecting shaft - trueness problem

[nreed]

The connecting shaft between the intermediate shaft and the oil pump is not running as true as I would like. No matter what I do, it seems to cause a 1/16" (or so) wobble. Before tightening down the pump, it makes the pump move slightly.

Things I have checked:

1. The intermediate shaft itself is true. I had a machinist check it.
2. I have tried two different connecting shafts, both are the same.
3. I have tried moving the shaft around on different splines, still the same.
4. New pump and without the pump attached I can still see the connecting shaft is not running true.

Has anyone seen this before?

Is this amount of runout normal? Maybe I am too paranoid...

Thanks in advance

[MBEngineering]

HI nreed
the oil pump is sat in the seal in the crank case,

you need to tighten down the oil pump on all 3 nuts and you will find the shaft will then run true,

to check the shaft is OK, tighten down all 3 nuts and then see if the shaft will slide freely on the pump and the inter-gear splines, if not you need to find out why?

regards mike

[chris_seven]

Its a splined shaft and it will find its centre when it runs.

It won't tolerate much misalignment but measuring when stationary can be misleading.

[turbo nut]

I have also been told not to tighten the pump too tight. Just snug down good and the Locking tabs will hold the nuts from coming loose then it can kind of find it Center. I have seen turbo pumps gal and burn up the gear shafts. I was told it was because the pump was too tight and could not find it Center

[Henry Schmidt]

Some run-out is acceptable.
What you want is to see the shaft move freely when the pump and intermediate gear are installed.
What I mean by "freely" is the shaft should slide from snap ring on the pump to snap ring on the intermediate shaft. If it slides easily you're good to go. If it binds, there's something wrong.

If the run-out is excessive it's possible that the spline end of the intermediate shaft is bent. This happens when a failed connecting rod bearing allows the rod to contact the shaft.

[nreed]

Originally Posted by Henry Schmidt

Some run-out is acceptable.
What you want is to see the shaft move freely when the pump and intermediate gear are installed.
What I mean by "freely" is the shaft should slide from snap ring on the pump to snap ring on the intermediate shaft. If it slides easily you're good to go. If it binds, there's something wrong.

If the run-out is excessive it's possible that the spline end of the intermediate shaft is bent. This happens when a failed connecting rod bearing allows the rod to contact the shaft.

Thanks henry et al... I feel much better to know that a slight runout is acceptable and that the spline will self center.

Thanks again!