08 Mobius LSV Noise

[d10ward]

Hi Everyone,

I'm new to the forum, but from what I have read so far, this is a great resource.

I'm currently looking to buy my first inboard (have had an I/O for about 6 years now). I tested out an 08 Mobius LSV tonight and really liked it. However, about 5 minutes after putting the boat in the water I noticed a noise coming from the engine bay but wasn't able to pinpoint where it was coming from. The best way that I can describe it is a "wahhh wahhh" type sound. At first the owner said he hadn't noticed that noise before, but then after a few minutes of listening to the noise and closing the engine cover, he said he felt like the sound was normal. He seems like an honest guy, but I would prefer to get some of your opinions and probably have a mechanic check this out before I purchase. I've posted a short video clip at the link below. If anyone has any suggestions on what might be causing this noise, I'd really appreciate it. The noise didn't seem to change much when in gear or with higher RPMs, except that the engine noise seemed to drown out the whine a little bit with the elevated RPMs.


Thanks for your help!

https://youtu.be/x75DVMnU-vE



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[moombahighrider]

That sounds like a ballast pump sound, maybe? Or a bilge pump? I never had that sort of sound on my 08 lsv. Purred like a kitten

[supra790]

I thought it sounded like a pump as well..

2016 Supra SG 450

[kaneboats]

Sounds like a bilge pump running but without enough water to make it run consistently. So, I would be looking for a stuck float switch on the bilge pump.

[chawkphil]

Check the bilge pump to see if it's still attached to the bottom of the boat. Mine came loose and was sitting on it's side which kept the float switch on so it was running all the time

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[d10ward]

Thanks for the responses. The bilge and ballast pumps were off. The owner agreed to have the boat inspected by a mechanic so hope to have that done soon.


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[brad460]

Not an engine noise at all..you can hear the engine purring just fine. In fact you can easily hear the injectors firing.

Like the others said, this is one of the pumps. Either the ballast pump and the bilge. On the auto bilge you don't need to turn it on, it's auto via float switch..

Surprised you guys didn't just look under the rear seat?! Could have diagnosed it in 30 seconds...hard to believe a guy needs to take it to a mechanic...

[kaneboats]

The bilge and ballast pumps were off.

Yea, the bilge pump has a switch on the dash to turn it on manually. However, it also has an auto "on" switch with a float so that it will turn on automatically when water level in bilge gets high enough to activate the switch. That is the switch we are talking about. It is attached to the bilge pump and is NOT the one you see on the dash. Good luck!

[JesseC]

You should be able to shut the engine off and the sound should NOT go away if it is pump related. All the pumps on the boat can run with the engine off. If you shut the engine down and the sound goes away it could be the fuel pump. Do you remember hearing it with the engine off?


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[d10ward]

Jesse - you are correct, the noise stopped when the boat was shut off. I did initially do a quick search for symptoms of a bad fuel pump the other day, but didn't look too much into it because the boat ran fine. Maybe I should do some more reading on this. Thanks for the suggestion.


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[kaneboats]

Points for Jesse. This could be an interesting one. Let us know what you find out.

[supra790]

I listened to it again. It still sounds like a bilge pump to me. If it's not wired correctly the bilge pump could shut off when the engine is shut off.

2016 Supra SG 450

[chawkphil]

Ever get an answer on this?

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[d10ward]

The boat is a little less than 3 hours away from where I live so I haven't been back over to look at it again. It is scheduled to go in at the end of this week for an inspection and the owner agreed to have whatever the issue is corrected. Hopefully it's a quick and easy fix. I'll be sure to let you guys know what I find out. Thanks for all of the suggestions.


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[KT Mobius]

Did you ever find out what the noise was? I have the similar sound, I have an 08 lbs. I changed my fuel filter to no avail. It's definitely not the bridge or ballast pumps.