May have hit something submerged today. Prop looks ok. Minor low speed thumping?

[insttech1]

Came back to the dock today about 20mph. Felt two sharp thumps by the prop. Throttle down and put it in neutral; RPM OK. Can't see anything. Trim goes fully up and down. Throttle and steering feel fine.

While actually at the dock (100 yards away), I hear a tick or thump about every 3rd rotation of prop. In both forward and reverse. No noise in neutral. looks like one or two minor dings in prop, but nothing major.

Drivetrain is Regal LSR 1700 99 volvo penta gs and sx outboard, 135hp 4cylinder.
Ran great yesterday and today until that noise. Ran it up to speed after I assumed all was OK; acted normal; just hear dinging at the dock.

any ideas where to start looking? maybe sinker/fish line wrapped in there? It didn't stop the boat, it was jsut kinda loud.

Maybe it coul've been something running in the drivetrain that made the noise, but the boat shuttered a bit like a small collision (i thought i might have hit a large turtle...)

Thanks for any advice.

 

[reddogg]

Re: May have hit something submerged today. Prop looks ok. Minor low speed thumping

Pull the prop off and give it a good inspection for damage, also look at the shaft behind the prop for damage or fishing line. You may also want to pull the lower plug on your gearbox to check for water in your gear oil that would indicate leaking seals. Make sure to replace the oil you let out. If prop is damaged, get it fixed or buy a new one, don't run a damaged prop as it can cause damage to your gearbox thru vibration from being unbalanced.

red

 

[insttech1]

Re: May have hit something submerged today. Prop looks ok. Minor low speed thumping

Thanks Red! I'll take a look tomorrow. Saw some weeds, but it was getting dark. Didn't feel like I'd hit weeds though. For very minor prop strikes on an aluminum prop, is it OK to bend back over with vise grips and gently file contour back? I'm talking minor enough that there is no stress fracture in the prop. Thanks Again!

 

[insttech1]

Re: May have hit something submerged today. Prop looks ok. Minor low speed thumping

Hey Red--about the oil. I've read about 5 different things, including volvo's documentation (but european version) about this sx drive. What oil would you recommend? Thanks!

 

[reddogg]

Re: May have hit something submerged today. Prop looks ok. Minor low speed thumping

If prop is damaged, it needs to be taken to a shop for repairs. It's not just about fixing dings/bent, it has allot to do with balancing it. As far as the gear oil I recomend going with the mfg recomendations.

red

 

[insttech1]

Re: May have hit something submerged today. Prop looks ok. Minor low speed thumping

I'll try and pull the prop tonight and check the fluids. After that, I was thinking about putting muffs on and running in gear for 30 seconds to try and isolate general location of the noise. Any thoughts?

 

[insttech1]

Re: May have hit something submerged today. Prop looks ok. Minor low speed thumping

OK checked fluids; looks good; no water. Pulled prop. Nothing looks wrong there. Installed muffs and ran forward, neutral, and reverse. No funny noises. Re-installed prop and ran again; little vibration present, but no odd "thunk" noise at all.....

I guess next test is back in the water under load, and I assume that I had something wrapped around the prop....?