Hamonic noise in the 2520XL cabin???

Classic Parker Boat Forum

Help Support Classic Parker Boat Forum:

Ludicrous40

Well-known member
Joined
May 13, 2013
Messages
208
Reaction score
3
Location
Newburyport, MA
Repowered my 2003 2520XL with a 2021 Suzuki DF300AP, the engine is on a bracket. Got it in the water late October, only have 50 hours on it, so still getting familiar with it. It is completely different than the Evinrude 300 that I removed, the Evinrude wanted to go fast, the Suzuki is a power plant. The power, torque, noise, economy, all are better than the E-Tec. To the point: At some conditions now ( I think a following sea was the worse ), I get harmonics in the cabin of the boat that I would compare to the sounds that you get when you put a rear window down in your truck. If you go out into the cockpit there is no evidence of this, just the motor sounding awesome. If you come back into the cabin, there is a definite harmonic noise. Just curious if anyone has experienced this and found ways to improve the situation. If you close the cabin door, it is better, but when at the helm, you can just move your head in various distances from the front window, and you get different noise levels. It seems like the harmonics or frequency of the motor are being magnified in the hull/cabin, but the engine isn't vibrating. The Evinrude was loud but didn't do this, but the engines are dramatically different.
 

PKS1801

Well-known member
Joined
Feb 5, 2016
Messages
282
Reaction score
16
Location
Chapel Hill and Pine Knoll Shores NC
In my experience, I always thought the truck noise(2 Subs, 3 Pickups) came from roof oscillations, and had nothing to do with the motor. I can't put any window down, would hate to think you have to lock yourself in the cabin.
 

Ludicrous40

Well-known member
Joined
May 13, 2013
Messages
208
Reaction score
3
Location
Newburyport, MA
That makes sense with respect to a truck, but this is new with the motor. My roof is loaded with stuff (life raft, radar tower, roof rack with tuna bag on it, telescoping davit for the anchor hauler. I doubt it's the roof, but I'll put someone up there as a dampener to test.
 

TimC2520

Well-known member
Joined
Feb 22, 2006
Messages
1,154
Reaction score
10
Location
Media, PA and Brigantine. NJ
I noticed it also when I repowered my 2520 with a DF300 (transom mount). When I first noticed it, I thought, man that doesn't sound right (the motor), then I'd have someone take the wheel while I stepped out on deck to find the noise was only in the cabin. If I crack a window, it seems to go away.
 

got_em_on

Well-known member
Joined
Jan 11, 2007
Messages
283
Reaction score
15
Location
Point Pleasant, NJ
I think something in the cabin or attached to the hardtop/cabin is vibrating at certain RPMs. Im not saying the engine is running rough or vibrating-being a brand new engine it is probably purring right along.

But something is vibrating at just the right way to cause those harmonics. Sort of the way you can run your finger over a wine glass and get different tones out of it depending how full it is. Those tones are caused by just the right vibration.

If it is attached to the hardtop/pilot house the inside of the pilot house can be acting almost like a speaker and amplifying it which is why you don't hear it on the back deck. Take a friend out for ride and cruise at the speed you hear it. Then have them start grabbing and holding things and see if that changes it.

You said when you are driving you can just move your head around and it changes so start in that area. On our boat the horns are right over our head so have you buddy go out and hold the horns. Does the sound change or stop? Then work around anything else outside-antennae, rocket launcher, anything in the rocket launcher, windshield wiper, grab rails, bow rail, window frames, etc. if nothing repeat on interior of pilot house seat posts, foot rests, stuff in storage, etc.

I dont think it is wind related like in a truck since that is due from increased air pressure at the front of the car unevenly pushing back in on the rear window area causing that flub flub flub noise-easily solved by opening a front window to even out the air pressure. This same issue would have been going on with your old motor as well since wind is wind and does not care about what motor you are running. If you want to take air pressure of the list of possibilities run with the windows open. You should still hear it. If you don't i think you are getting closer to finding out what is vibrating.

Good luck.
 

HOTPURSUIT

Well-known member
Joined
Apr 8, 2011
Messages
594
Reaction score
16
Location
Edgemere, Maryland
i have the same year 2520. It is so hard to figure out where a noise is coming from when in the cabin. Like GOT EM ON check everything storage compartments etc. I often hear the unusual noise the mono on my rods make when the wind blows thru them underway. the window screens do it when open all the way, a little vibration from the door hook that holds the door open if not in place. Go over everything they may have touched installing the new motor. There maybe cable along the gunnel that’s rubbing. Does it sound like a bilge pump sticking on? Just my thoughts, I could not even imagine you would be hearing the electric fuel pump
 

Ludicrous40

Well-known member
Joined
May 13, 2013
Messages
208
Reaction score
3
Location
Newburyport, MA
Again thanks for the replies. The reference to truck noise was just a way to describe it. I think the motor comparison is like apples and oranges as we are comparing a 2 stroke and a 4 stroke. I'm sure that the 4-stroke is running fine but is at a different vibration frequency, the motor sounds great. I like the suggestions by got_em_on, that really gives me a methodical way to try to narrow it down...
 

Andy

Well-known member
Joined
Jan 17, 2017
Messages
936
Reaction score
458
Location
Pungo Creek, NC
I think something in the cabin or attached to the hardtop/cabin is vibrating at certain RPMs. Im not saying the engine is running rough or vibrating-being a brand new engine it is probably purring right along.

But something is vibrating at just the right way to cause those harmonics. Sort of the way you can run your finger over a wine glass and get different tones out of it depending how full it is. Those tones are caused by just the right vibration.

If it is attached to the hardtop/pilot house the inside of the pilot house can be acting almost like a speaker and amplifying it which is why you don't hear it on the back deck. Take a friend out for ride and cruise at the speed you hear it. Then have them start grabbing and holding things and see if that changes it.

You said when you are driving you can just move your head around and it changes so start in that area. On our boat the horns are right over our head so have you buddy go out and hold the horns. Does the sound change or stop? Then work around anything else outside-antennae, rocket launcher, anything in the rocket launcher, windshield wiper, grab rails, bow rail, window frames, etc. if nothing repeat on interior of pilot house seat posts, foot rests, stuff in storage, etc.

I dont think it is wind related like in a truck since that is due from increased air pressure at the front of the car unevenly pushing back in on the rear window area causing that flub flub flub noise-easily solved by opening a front window to even out the air pressure. This same issue would have been going on with your old motor as well since wind is wind and does not care about what motor you are running. If you want to take air pressure of the list of possibilities run with the windows open. You should still hear it. If you don't i think you are getting closer to finding out what is vibrating.

Good luck.
I was going to chime in here, then I read what 'got-em-on' wrote, and he said most of what I was going to suggest.... We had a similar issue on our 2520 (300 Yamaha). In our case it was the harmonics/vibration coming from the engine (I know this of course, because it as not happening when the engine was off! ☺) vibrating a wooden storage/catch-all shelf that I had built and installed with through-bolts to the side of the pilot house wall; I could feel, and hear, it vibrating when running.... I added nylon washes and tightened the ny-lock nuts, and the noise went away.... it was a small noise, and a small vibration but enough to bother me. It happened at idle (about 800 RPM) and also at 'cruise' (about 4200 RPM)... The noise is gone now....
On other boats it could be most any item in, and/or around, botted to, screwed on and/or touching the pilothouse.... We had very similar issues on our past two boats. (Diesel engines; more vibration)... The noises and rattles happened at particular RPMS... We were able to search them down, tighten stuff, add rubber padding etc, and stopped the noises...
By the way; I have been laid up with a serious/bad case of Covid since around December 19. I am back to normal (or as close to 'normal' as I can be!).... I have not been very active on CP for the past month or so, .... It's nice to be back...
 
Last edited:

mark

Well-known member
Joined
Mar 3, 2008
Messages
83
Reaction score
2
Location
tacoma washington
I have had this same issue since repowering my 2530 with twin 200 Suzukis in 2016.
Mine is the worst at about 4000 RPM and the sound reverb would give me a headache.
Had it in the shop multiple times trying different things to make it better.
The biggest improvement came from changing the rotation of both motors to spin opposite of typical.
It still is there but its about half of what it was. Bearable but still very noticeable.
Something about the exhaust note of my motors that just does not agree with my boat.
Good luck with yours and if you figure it out I would appreciate learning what you found was the cause.
 

Ludicrous40

Well-known member
Joined
May 13, 2013
Messages
208
Reaction score
3
Location
Newburyport, MA
Appreciate all the feedback. Back on the water soon and will start trying to isolate the problem. I also might change my prop to get this dialed in perfect. Thinking the prop will also play a role as the cruise rpms will likely change slightly. Target WOT for the Suzuki 300 is 5700-6300. I can just barely hit 5700 in absolute perfect conditions, so I'm slightly overpropped. Suzuki doesn't make a smaller prop (3x16x17R watergrip), so have to go aftermarket.
 

Miker1234

Active member
Joined
Aug 5, 2021
Messages
29
Reaction score
12
Mine turned out to be the Westcoat bow rail vibrating in drive at low RPMs. Try holding it and see if it goes away. I also heard it can be the step ladder on the outboard bracket vibrating. That is not the case with mine.
 
Top