busted diffuser ring

biggjimm

Chief Petty Officer
Joined
Jul 15, 2015
Messages
403
I've got a prop that i'm gonna try on my boat & it has a broken diffuser ring. Split down one side & popped clear off.

My boat is a 79 mercruiser 260 with MC-1 drive. I have an exhaust tube on it so the exhaust doesn't exit out thru the prop. Is the diffuser rings only job to keep the exhaust gasses from rolling back into the prop at low speeds? Will it work OK since my exhaust is not going thru the prop?

Thanks.
Jim
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Mercury props do not normally have diffuser rings on them. The trailing edge is flared a bit to help suck out the exhaust.

The only diffuser rings I have seen were on older OMC outboards. I think you will be fine. What make of prop do you have? Maybe it is time for a newer prop?
 

H20Rat

Vice Admiral
Joined
Mar 8, 2009
Messages
5,199
If your exhaust tube is installed correctly, your exhaust is still going out the prop...

In any case, as chris mentioned, diffuser rings only existed on old OMC stuff (I had one of those outboards), and even on those, they didn't make one difference. I've seen some merc props that had a plastic flared ring, which again, don't really seem to make any difference.

You won't have a problem.
 

biggjimm

Chief Petty Officer
Joined
Jul 15, 2015
Messages
403
Maybe diffuser ring is not the correct term? It's an extension that is kind of snapped on the hub where the exhaust comes out thru the prop only my exhaust doesn't come out thru the prop.

The piece my buddy leveraged a big screwdriver against trying to get the lock ring tabs pried up to remove the prop nut.

I've got like 5 oem mercruiser props & 3 or 4 Michigan wheel props & everyone of them have this ring thing on them. They are older props, late 70's to early 80's.

I'm going to get a new prop as soon as I figure out which size works best on this boat.
 
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