Diffuser ring on Johnson Prop?

[Chris1956]

I am purchasing a '98 150HP 60 degree V6 Johnson OB. It currently has an aluminum prop with one of those diffuser rings on the exhaust outlet. Since I was a Mercury owner, I need to ask:

Can I use props without the diffuser ring? Am I getting the correct prop with this motor?

I have a SS Rapture from my Mercruiser Alpha 1. Can I use the Merc thrust washer and Rapture prop on the Johnson OB?

 

[Ron G]

Re: Diffuser ring on Johnson Prop?

The splines will probably have to be drilled down.which costs about 35.00 bucks.the difusser ring is used on certain props i beleive to funnel the exhaust thru the hub,i needed one on one of my props but not the rest.what kind of pitch is it and what hull are you putting it on and what do ya want to do?

 

[walleyehed]

Re: Diffuser ring on Johnson Prop?

The Merc (Rapture by michigan wheel) will not go on the Johnrude shaft without reaming 3/4" of the splines out of the prop hub.
The diffuser ring is used on certain blade designs to help exhaust flow and help keep the air out of the blade area...
Is it the right prop??? Max RPM will tell us that...is this a Ficht or is it the Carbed model?

 

[walleyehed]

Re: Diffuser ring on Johnson Prop?

Sorry, Ron...we were pecking at the same time...8)

 

[Boomyal]

Re: Diffuser ring on Johnson Prop?

My OMC stringer came with a prop with a plastic diffuser ring. One day it broke off. It was as if the prop hub was slipping. I finally had to put on a spare prop to get home. The prop shop reinstalled the diffuser and all was well.

Later props that I have purchased had the integral aluminum flared outlet. Those worked as well.

 

[Chris1956]

Re: Diffuser ring on Johnson Prop?

Ken, It is the carbed model. Would a prop shop be able to "ream" the Rapture's spline down? What thrust hub would I use? I assume a standard Johnson one?

 

[Ron G]

Re: Diffuser ring on Johnson Prop?

Sorry, Ron...we were pecking at the same time...8)

ddddddi think we was on the same page.

 

[Ron G]

Re: Diffuser ring on Johnson Prop?

Any prop shop can do the reaming really all your buying is the bit for dueing it.i use the johnson one.

 

[walleyehed]

Re: Diffuser ring on Johnson Prop?

Yes, the Johnrude thrust washer will be the correct one after reaming the hub.

 

[walleyehed]

Re: Diffuser ring on Johnson Prop?

Let me back up on that....the correct thrust washer will be the one used on the Merc, beings the prop is for merc....it may require 1 extra spacer before the nut though....

 

[Chris1956]

Re: Diffuser ring on Johnson Prop?

OK Ken, Let me see if I have it. To use the Mercrusier prop on the Johnson V-6 OB, ream the Mercruiser prop's hub 3/4". Install the Mercruiser thrust washer, and one extra spacer. Is that correct? What is the extra spacer? Another thrust washer?

 

[walleyehed]

Re: Diffuser ring on Johnson Prop?

The spacer (extra) is the one AFTER you put the prop on......Just like you would do with an OMC prop, but the threads may stick out farther and require an extra spacer (2 total) before the nut so the key-way lines up when you snug it down....
Order of events.....Merc thrust washer on shaft, then prop, then 2 bronze spacers, then the nut.......you'll know if you need a another spacer if you put the first on, screw the nut on and the key-hole is aft of the nut..the second spacer is just to position the nut so you can properly lock the nut with a cotter pin.

 

[Chris1956]

Re: Diffuser ring on Johnson Prop?

Ken, Thanks for the update. I did the reaming, and installed a Alpha 1 prop on the Johnson's prop shaft. I do need the spacer under the nut, but the real issue is that the Johnson Thrust washer is too thick to allow the prop to recess into the gearhousing. It has a 1/8" gap. The Mercruiser Thrust Hub's hole is too small for it to seat at the base of the prop shaft, which causes it to hold the prop 1" away from the gearcase.

Is there a remedy?

 

[Chris1956]

Re: Diffuser ring on Johnson Prop?

Bump

 

[Ron G]

Re: Diffuser ring on Johnson Prop?

have you tried the other washer?

 

[Chris1956]

Re: Diffuser ring on Johnson Prop?

Ron, I tried both the Mer and the Johnson thrust washers. The merc thrust washer doesn't slide all the way the the "shoulder" of the prop shaft, and the Johnson thrust washer is 1/8" too thick to allow the hub of the Merc prop to recess into the gearcase, as it is supposed.

Do you thing the solution is to either drill out the merc thrust washer, or sand down the Johnson thrust washer? Do you have a better idea?

 

[Ron G]

Re: Diffuser ring on Johnson Prop?

see if ya can find a different thrust washer,if a propshop is close they may have one or they can mill one down a little for ya.i dont quite understand why its not going all the way down,on mine i used the omc washer and just drilled out the prop and it fit fine.

 

[Chris1956]

Re: Diffuser ring on Johnson Prop?

Ron, My Mercruiser props seem to be of two kinds. On one kind, you can see the rubber hub, and it looks as though the Merc thrusthub should recess into the opening in the prop hub to cover the rubber. The other kind has a brass cover over the rubber hub.

I also have two kinds of Merc thrust hubs. The old one looks like a thick washer, basically just flat on both sides. The other has a shoulder cut in the prop side face, that recesses into the hub. Maybe I can play some mix and match, and find some combination to work.

 

[Ron G]

Re: Diffuser ring on Johnson Prop?

Yea one of them should work.just wondering what pitch are running and what kind of boat do you have?

 

[Chris1956]

Re: Diffuser ring on Johnson Prop?

Ron, the boat is a '98 21' SeaSwirl Dual Console, that I just acquired. The Johnson prop I have is 17" pitch aluminum, installed on a '98 150 Ocean Runner. Currently the Tacho doesn't work (Voltage regulator problems??), so I have been unwilling to open the throttle. I traded in a 19' SeaRay bowrider with a Mercruiser Alpha 1, so I am hoping to use some of the props I have acquired over the years, on the Johnson.