Another prop question.

I am changing the old prop on my 87 regal 18' open bow. I was in the boat for the first time and I may have hit a log or something in the water but the belts on the 4.3 smoked and the engine revved out. The next thing I know the boat does not move. The engine runs and when I got it out of the water I was told the "jets" may be clogged. Well I hooked up the "ears" and flushed it, the boat goes into gear and the prop spins well in both directions, I was told i spun the hub. I did the test of marking the hub and prop but while I was installing prop back on the shaft it spun. The marks were a little out of line. I just want to make sure I am not having my leg pulled. I was told that if the boat goes in gear and the prop spins I have not torn the coupler. I will be doing the right thing by replacing the prop and hub. I know the belts on the engine smoked because they are glossy now. does this sound right?

Re: Another prop question.

Welcome aboard!

If the marks do not align and have moved, then yes, you need a new prop and/or hub. Do you have a spare you can try?

Re: Another prop question.

Just as a follow up - I don't know what "jets" your friends are referring to. I guess I also don't know what drive, engine, etc you have. Time for a few more details!

Re: Another prop question.

Sorry, 4.3 v6 Mercruiser/ alpha 1? outdrive/ 18.5' regal open bow. Not sure of the HP but it is a brand new engine. engine runs like a top. I just don't want to be stranded again. I looked under the out drive and the exhaust hose is old and dryrotted but the upper hose is brand new. I think he was talking about the water intakes on the sides of the lower unit as jets.

Re: Another prop question.

Well, whoever told you the "jets" may be clogged either doesn't know what he is talking about, or is pulling your leg.

The prop thing is right on the mark however.

Also, just to "stay on the same page" with those who will provide help - you might want to get used to calling the "exhaust hose" a bellows, instead of a hose. Same with the upper - it is called a drive bellows.

The bottom exhaust bellows is not important - the upper, drive bellows is.

One last thing - your belt slipping would have nothing to do with the boat not moving. When you spin the hub on the prop the engine will rev like yours did.

Re: Another prop question.

Thanks for the info! I really appreciate it and am the way to get the new bellows for the exhaust.

Re: Another prop question.

You may find it quite a challenge to install a new exhaust bellows. I would recommend replacing the bellows with an exhaust tube.


The tube mounts on the transom side and not on the bell housing side: (MUCH easier to install).

Re: Another prop question.

The exhaust piece i am referring to is actually a corrugated rubber hose that attaches at the transom? on one side and to the back of the drive with hose clamps. Once again apologies I am new to the boating world but have thoroughly enjoyed what little I have been able to do. The pic showed in above reply is what the "hose" attaches to.

Re: Another prop question.

wetbehindtheears said:

The pic showed in above reply is what the "hose" attaches to.

Click to expand...

It may look like it, but no.

It replaces the bellows - the "corrugated rubber hose."

Instead of buying a new rubber exhaust bellows, it is common to replace the bellows with the tube pictured above. It only attaches to the transom side. When the outdrive is lowered, it slips into the tube. When raised it slides out.

It's just a LOT easier to install.

Re: Another prop question.

but the belts on the 4.3 smoked and the engine revved out.

Click to expand...

That small statement about the smoked belts makes me wonder if you seen the belts smoke, or just assumed that was the cause for a smell of burned rubber.
If you aren't sure about the belts, my guess is you have a spun coupler and not a prop. Similar to a prop hub spinning, but when it happens the rpms go up and the coupler smokes and smells like burned rubber.
Another question I have is you mentioned you have a new engine. Was it aligned properly? My guess is NO, and that would take out a coupler in a hurry if it was very far off.

Re: Another prop question.

It could be your prop, if you're lucky it is, but...

If your coupler is spun, it will not have enough power to drive the propeller in the water, but will usually still spin the prop when on the muffs. There is no resistance when spinning the prop on the muffs. You don't sound like you're very familiar with these drive systems. On the back of the flywheel there is a piece that has a metal ring that bolts to the flywheel, then a rubber membrane, then in the center a metal ring with splines in it that the driveshaft through the transom slides into. When the propeller is in gear and the outdrive shaft stops, the prop stops, but the engine keeps trying to turn it. The driveshaft won't turn because the prop is stopped. What happens is the metal ring on the driveshaft spins inside the rubber membrane. Creates lots of "rubber belt" smelling smoke. Afterwards, anytime the prop has a significant load on it, the metal ring spins inside the rubber again.

If the engine is not properly aligned with the outdrive, friction is created that can make the same thing happen. So you may be looking at pulling the outdrive, pulling the engine, replacing the coupling, making sure the alignment between the engine and outdrive is correct, then reinstalling the outdrive.

Re: Another prop question.

The engine was replaced by a very reputable mechanic and only had about 35 hours when I got the boat and as I said the engine belts themselves are glossy like they have been slipped, However not discounting any advise I am going to try a used, good prop to hopefully fix this and if not does anyone want to buy a cheap nice boat with a small issue?