Miss Delmarva

[RickK]

Looking very nice Scott - gotta be proud.  Only way to be more proud is if you did it all yourself.

[fitz73222]

Scotty,
In the grand scheme of things, your little 75s will be happy at 26", will give you many long years of service.  This ain't a Fountain, YF, or what ever, if you know what I mean...  

Not trying to derail this thread but this twin engine alignment discussion leads me into a problem I've had with my 115's. My port engine experiences an obnoxious rattle at cruise almost sounding like detonation.
it comes and goes but in all cases is most prevalent on deceleration. A complete check of the powerhead reveals nothing, timing,spark plugs, carbon build up, gearcase bearing carrier side play, no bent prop shaft, rolling the powerhead over by hand to feel any bearing issues; everything checks out OK. The strange thing is; if I run the port engine by itself with the starboard tilted up, no noise at all from idle to WOT. Propellers are 4 blade Turbo M 13 1/4 X 18 non counter rotating. So I pulled the props and noticed a high degree of wear and what looks like galling on the thrust washer face where it contacts the prop. Port side being mush worse than the starboard engine. So doing some research I found that this can be caused by inadequate torque on the prop nuts. I've honestly never torqued propeller nuts but Mercury say's 55 foot pounds which is tight compared to just snugging them like I've always done. Additionally, I have an engine synchronizer on the flow scan so I can dial them in but it seems that if a push the port engine a 100 rpms faster than the starboard the noise diminishes. When I stuff the throttles down the noise goes away; this is a cruise issue between 3200-4000 rpm The port engine does not like to trail to the starboard from an RPM standpoint; the racket gets worse.  I can also manipulate the rattle with trim position. I have the engines set at neutral toe, previously they were 3/4 inch toe in. So I'm not sure if this is a propeller issue, thrust washer torque issue or an alignment issue. I ordered new thrust washers and will torque the props correctly and give it a try. The previous owner said it always had the issue and they chalked it up to turbulence interference but I don't buy it. So Bob or anyone ever heard of this condition?

[slvrlng]

I too have a Turbo prop on mine and it too was "rattling". Mine uses the insert for my Johnson. In talking to Dhadley about the noise, some of the noise comes from the fact they are ventilated props. He recommended 55 ft lbs and this seemed to help. I also changed the lower unit oil and went with Lucas synthetic. No more noise and it shifts a thousand percent better.

[fitz73222]

I understand an idle rattle issue because of prop inertia relative to powerhead idle speed where the prop wants to out run the idle speed and clanks and bangs, that's somewhat normal and even more prevalent on four strokes because of the interrupted rotation due to the nature of a 4 cycle engine. I'm not hearing the noise when the engine is running by itself or under acceleration load.  It's a light loading cruise noise. My gut tells me it's the torque of the prop nut and the damaged thrust washer that's causing this rattle and slight vibration and the fact that the rattle can change when crossing a wake that this is a downstairs issue and not a powerhead issue. Just looking for opinions or conjecture in a similar installation.

[seabob4]

You know Farley, if you were to strap yourself onto the back side of your port motor, armed with a mechanics stethescope, and have your buddy run the boat, why, you'd find the source of that rattle in a heartbeat!

On a more serious note, when I install props, I really lean on the prop nuts, every bit of 55 ft-lbs if not a bit more.  Just the way I've always done it, Merc, Yam, OMC, Zuke, Honda.  Same deal on all makes.  So put the new thrust washers in, and put some muscle on those nuts.  As an example of how much I tighten, when I need to either back off the nut or tighten it a smidge to get the cotter pin hole to line up with the castle nut, I really have to lean on my 1/2" drive ratchet...

[gran398]

Farl, no derail bro, keep the discussion right here. Sounds like you're close to figuring it out.

Rick, thanks. There is absolutely no way I could have produced that kind of work. First I'm incapable, and secondly, don't have anywhere near that kind of time.

I'm better off sticking around the store and selling something.

It always gets me when folks dive into something in which they have no skill set or knowledge. If you're sick...you go to the doctor. If you have legal needs, you go to an attorney. Taxes, CPA. And so forth.

You can't beat a man at his own game, and you never will. Many more times than we care to admit, we should have paid the money straight off and get it right the first time, rather than fix it, paint it, alter it, etc.

[seabob4]

Now Scott, that was certainly a de-rail...but a quite enjoyable one!

[fitz73222]

You know Farley, if you were to strap yourself onto the back side of your port motor, armed with a mechanics stethescope, and have your buddy run the boat, why, you'd find the source of that rattle in a heartbeat!

On a more serious note, when I install props, I really lean on the prop nuts, every bit of 55 ft-lbs if not a bit more.  Just the way I've always done it, Merc, Yam, OMC, Zuke, Honda.  Same deal on all makes.  So put the new thrust washers in, and put some muscle on those nuts.  As an example of how much I tighten, when I need to either back off the nut or tighten it a smidge to get the cotter pin hole to line up with the castle nut, I really have to lean on my 1/2" drive ratchet...

I'll tighten those nuts good-n-tight @55 ft # or better and see or hear the effects. All that I've read before posting this complaint that this is quite common in surface running cleavers and chopper style props because of the vibration associated with running in air and water at high engine heights. So maybe the added surface area of the four blade makes it sensitive to nut torque and subsequent vibration/rattle. This sled ain't no 2.5 powered Allison and the gearcases are plenty deep and cozy from surface air! As usual Bob, thanks for the input! I'll report back in my normal expanded version of "Devil in the Details!"

[seabob4]

Farley,
Fernando runs a 4-blade on his 200 Opti, haven't heard him mention any vibration and/or rattling.  Armstrong bracket mounted, no jack plate...

[fitz73222]

Farley,
Fernando runs a 4-blade on his 200 Opti, haven't heard him mention any vibration and/or rattling.  Armstrong bracket mounted, no jack plate...

I'm always been guilty of trying to put to much "head" towards solving simple problems and my ADD comes to mind; hopefully this will bode well for me during my senile years when I'm trying remember that the toilet is to pee in and not drink out of like the bulldog does!  The stump I keep running into is why the hell is the port engine quiet when running by itself? It steers me back into alignment or some kind of sinister thrust wave or harmonics between the engines. Is it because they are not counter rotating? Once again, I'm trying understand the dynamic events that are occurring. Fernando just has a tighter nut than I do; some guys get all the luck!

[seabob4]

Farley,
It very well may be unwanted harmonics that are set up by the 2 standard rotating props.  Obviously, the port engine is being affected by the starboard, as when you take the starboard out of the equation, all is well.

Soooo, a question.  Has this "issue" always been there since day one?  If not, what changed just prior to the issue raising it's ugly head?

[Blue Agave]

Farley,
It very well may be unwanted harmonics that are set up by the 2 standard rotating props.  Obviously, the port engine is being affected by the starboard, as when you take the starboard out of the equation, all is well.

Ding, ding, ding!  I think you are on to something Bob.

Soooo, a question.  Has this "issue" always been there since day one?  If not, what changed just prior to the issue raising it's ugly head?

I believe that would be once Farley's port nut got loose.

[fitz73222]

Farley,
It very well may be unwanted harmonics that are set up by the 2 standard rotating props.  Obviously, the port engine is being affected by the starboard, as when you take the starboard out of the equation, all is well.

Soooo, a question.  Has this "issue" always been there since day one?  If not, what changed just prior to the issue raising it's ugly head?

Yep, as far as I can remember this has always been an issue. The PO who I've known since '75, bought the boat in '84 with original 70 Johnson's and replaced them in '95 with the current 115 Mercs and these propellers. I actually helped rig these engines out of the boxes back then. So the brain trust dealer at the time had surmised that this was an interference related issue (not sure how this was validated) but to my knowledge, no other props were ever tried and the PO just lived with the rattle. So I can still switch propellers and even gearcases if the thrust washers and nut torquing doesn't solve the complaint. I thought about changing props and number of blades but finding a pair of stainless 19" or 20" pitch loner props can be a challenge. These engines were only 250 hours each when I bought the boat and were very babied in their early years.

[seabob4]

Well, obviously, do the easy chit first.  If that solves the problem, drink some beer.  If not, contact Ken at Prop Gods (http://propgods.com/content2/Default.aspx), he may be able to help out with loaner props.  A gear case swap?  Don't think it's gonna help, unless you're talking about swapping the port LU for a CR LU.  Kinda pricey there.

All sorts of fun, huh Farley?  

[fitz73222]

Yea Bob, lucky me; it's what I live for! No CR gearcase ever made for this engine. The swap option would be just to see if the noise follows the gearcase. The great thing about having twins is that you always have a donor engine available for this kind of chit. So we'll let this sleeping dog lay until I get back from the Southport jamboree starring Monte Rhodes and the AS Tabernacle choir where it is OK to drink during confession!