Mercruiser 140 Prop Thrust Washer

[jackball42]

1977 Mercruiser 140. I noticed this weekend that my prop was a little loose so I took it off and found the thrust washer had spun on the shaft. The thrust washer is the old stainless part and not the new brass design. I am using a Michigan Wheel prop.

I assume that because the washer spun on the shaft it made the hole bigger and is causing the washer to sit lower on the taper. Will a new washer fix my issue? There is about 1/16 to 1/8 inch of play in the prop. Should I replace with a Michigan Wheel washer or will the Sierra part from IBoats work fine?

What causes the washer to spin independently of the shaft?

 

[Bt Doctur]

Re: Mercruiser 140 Prop Thrust Washer

There is about 1/16 to 1/8 inch of play in the prop. Should I replace with a Michigan Wheel washer or will the Sierra part from IBoats work fine?

if the shaft is moving with the prop its normal, if the prop is moving and the shaft is not, time to investigate.

 

[jackball42]

Re: Mercruiser 140 Prop Thrust Washer

The prop is moving on the shaft.

 

[jestor68]

Re: Mercruiser 140 Prop Thrust Washer

If you torque the nut to 55 ft lbs, there should be no movement of the prop on the shaft, and the prop should not contact the lower unit housing.

The thrust washer can vibrate and "spin" on the prop shaft if the prop nut is not torqued down properly. Just sorta tight is not enough. That's why we use a torque wrench.

 

[QC]

Re: Mercruiser 140 Prop Thrust Washer

Help me here. There is nothing except interference (taper) to keep the thrust washer from spinning. Why do we care about the thrust washer spinning? What is the actual complaint? Prop loose? Or thrust washer spins on shaft? With no prop on the shaft all thrust washers spin unless they are stuck due to corrosion. I am confused here

 

[jestor68]

Re: Mercruiser 140 Prop Thrust Washer

1977 Mercruiser 140. I noticed this weekend that my prop was a little loose.

I think he said that the prop was loose on the shaft.

 

[QC]

Re: Mercruiser 140 Prop Thrust Washer

OK a little clearer when I reread. Sorry :redface:

Ok, so real issue is loose prop. How do you know that the thrust washer hole is "bigger"? The answer to your question is that the hole in the washer and/or the shaft wearing will allow the prop to drive down on the shaft further.

To follow up on jestor's question. Does the prop move (wobble) when the nut is torqued?

I guess my confusion is why are we discussing the thrust washer? How do you know it spun, and how do you know the prop goes down further on the shaft?

 

[jestor68]

Re: Mercruiser 140 Prop Thrust Washer

It sounds as if the OP thought something was wrong with the thrust washer when he noticed that the prop was "loose". When he removed the prop, he noticed what appeared to be unusual wear on the thrust washer. If the nut was not properly torqued, it could allow the washer to vibrate(and spin on the shaft). This could eventually wear the thrust washer and caused the prop to become loose.

That's why I suggested he torque it down and check the prop to hub clearance. At this point, it would be best to go ahead and replace the thrust washer since it appears there may be some wear on it. And always use a torque wrench to tighten the prop nut to the specs for that particular motor/drive.

 

[jackball42]

Re: Mercruiser 140 Prop Thrust Washer

Yes, the washer shows signs of wear and I am going to replace it. I will be sure to torque the nut to 55 ft lbs when I install the new washer. I will let you know what i find.