Weird noise and vibration... Need help..

[69Gulfstream]

Hi,
I've got a 69' Glastron V204 Gulfstream with a 160hp mercruiser I/O. The problem is when I first start the engine.. I'll start it, speed the engine up to a fast idle out of gear, and it will sit there and run really nice and then all of a sudden theres this grinding noise and a vibration through the boat.. I'll slow the engine down and the noise and vibration goes away.. I'll speed the engine back up and it will be find for maybe 10-15 seconds and it will do it again.. Anybody know what this could be??? It doesn't make any weird noises when its in gear that sounds really nice.. Its only when its in nutral and I'm at a fast idle..

thanks,
Chris

 

[QC]

Re: Weird noise and vibration... Need help..

Have you observed this with the engine cover open? I had a similar issue once, not a vibration, but a hellacious racket only at a specific RPM. Turned out it was an alternator mounting bracket that was loose, but only made noise at a specific RPM.

I'd open the cover and watch until I Heard the noise and try and pinpoint it. Could be something very simple although the vibration has me concerned . . .

 

[Bt Doctur]

Re: Weird noise and vibration... Need help..

gimbal bearing, no /low oil in drive, if it`s rpm specific it might be the flywheel dust cover

 

[69Gulfstream]

Re: Weird noise and vibration... Need help..

I have the engine cover pulled open when I start the engine and hear the noise.. Its very deep sounding what ever it is.. The alternator is tight.. the lower unit is full of oil.. It kinda sounds like if you slightly put it in gear and just let the gears grind and bump eachother... Its the same sound I hear when I put it in gear.. Only its louder and a hell of a lot worse.. And not momentary like when it goes in gear. did that help describe it?

 

[69Gulfstream]

Re: Weird noise and vibration... Need help..

Is there any way to check the gimbal bearing without takeing everything apart?

 

[bruceb58]

Re: Weird noise and vibration... Need help..

If you are outside the boat and listening or putting your hand on the drive do you notice it there?

 

[69Gulfstream]

Re: Weird noise and vibration... Need help..

I'll try running it on a garden hose this after noon and see if it does it in the yard here and feel it... But you can feel it through the entire boat.. Its a very deep harsh vibration.

 

[bruceb58]

Re: Weird noise and vibration... Need help..

I suppose it could be a worn coupler too. You pull your drive every year and inspect the gimbal bearing, u-joints and grease the shaft that goes into the coupler?

You could also pull the drive and run the engine without the drive on to isolate the problem.

 

[QC]

Re: Weird noise and vibration... Need help..

Edit: Redundant after seeing post above ^^^^^

 

[69Gulfstream]

Re: Weird noise and vibration... Need help..

I've never had the drive off the boat.. I just baught the boat about 2 months ago.. So I've never had it apart. I spose it probly wouldn't be a bad thing to do? Other than this problem the boat works great.. No noises of any other kind really.. Everything is all original and works great. A 75 year old man had it for 30 years.. Everything seems really nice..

 

[69Gulfstream]

Re: Weird noise and vibration... Need help..

How do you know what drive that I have??? I'm lookin through the manual but it sayst theres differnt ones.. Theres a mercruiser 1, 2, and 3. I think its older than a Alpha drive. But how do I tell what I got?

 

[HT32BSX115]

Re: Weird noise and vibration... Need help..

I would say that you have a #1 drive.

You do need to pull the drive and have a look at the U-joints. If they come apart, you'll be replacing the drive & gimbal. (or it won't be worth it and you'll be parting everything out!)

The coupler in my previous boat (66 Marktwain 150 Merc/#1) lasted 39 years before it spun. The gimbal bearing was original too...



Cheers,


Rick

 

[69Gulfstream]

Re: Weird noise and vibration... Need help..

Just wanted to say thanks for the help guys. I'm going to start takin the drive off first chance I get.. Won't take it in the water till its fully checked out.. Thanks..

Chris