1996 gt-40 with 270 hours

[NAVYFLYER]

Well I ran the boat this weekenf for the first time this season. I changed the oil and the boat was run in the driveway with no noticable issues. I started it when I got to the lake on Saturday and I was picking up a ticking sound at first on the left rear side of the motor. It seemed to increase in frequency with an increase in speed. I had good oil pressure and the engine ran great. I had no noticable power loss. The oil looked new as I only put about 10 hours on it all last season. But I changed it anyway as I always do at the beginning of the season. I had the manifolds and risers media blasted about three years ago and replaced with new gaskets. I did not have any audible or visible external exhaust leaks. It sounds like it could be an exhaust leak but is that something that could cause sound from the inside of the manifold? I have not done a compression test yet but that is on my to do list. I put five hours on the engine from skiing the slalom course the past two days and like I said the engine ran fine but I had this noise. Any ideas?

[Polar Express]

Did it sound like a lifter tick? Would it be the approx. frequency of a lifter tick? As the engine ran, throughout the weekend, did the noise volume change? Does it happen in your driveway now? (no load) does it happen at idle when on the water?

You can buy a mechanic's stethoscope at most Major auto parts stores, it looks like a stethoscope, but no little 'cup' thinggy on the end, but rather a metal wand. You touch the tip of the wand to various parts, and it really is amazing how the noise will change, and you can do a nice job isolating where the noise is coming from.

If you don't have a mechanics stethoscope, you CAN use a very long shafted screwdriver, and just put the handle end up to your ear, and gently push that little nubbin' at the center-front of your ear, until it closes off the ear canal, This works very well too.. but not as flexible as the proper tool.

The better you can find out where (location) its strongest, the better one can determine what it causing it.

PE

[NAVYFLYER]

The lifter tick was a thought but I have never heard one of those before. Another one I was told it could be by fellow skiers was a wrist pin but again never heard one of those either.

It does it at idle in neutral no load and picks up in frequency once in gear and accelerating.

I have the mechanics stethoscope so I will get after that when I get home.

[Polar Express]

what oil did you use? did you change viscosity? I've known a couple engine designs that if you used too thick an oil, it would forever cause a lifter tick.

Hydraulic lifters are far more likely to make a noise than a wrist pin. They can still run for a long time, but the noise is rather maddening sometimes.....

And... the lifter tick would be 1/2 the frequency of a wrist pin tick. (2:1 cycle ratio of a 4-stroke motor, wrist pin:valve)

PE

[NAVYFLYER]

same oil since day 1.

[rcsmith727]

same oil since day 1.

Navy, did you ever solve this? I've got a similar problem. My buddy thinks it's the exhaust manifold but I haven't solved it yet

[kmarine]

Just a quick note, this is more common with boats that sit in storage. The oil passages dry out and gunk up and starve the lifters for oil, I used marvel mystery oil in mine which helped, but took a while to work. My other friend uses lucas oil additives in the engines with this issue and has success too. I like to let engine idle for a hour and at least use twice a week to let the oil detergents work into the sludge. sometimes we still have to replace lifters anyway.

[rcsmith727]

Just a quick note, this is more common with boats that sit in storage. The oil passages dry out and gunk up and starve the lifters for oil, I used marvel mystery oil in mine which helped, but took a while to work. My other friend uses lucas oil additives in the engines with this issue and has success too. I like to let engine idle for a hour and at least use twice a week to let the oil detergents work into the sludge. sometimes we still have to replace lifters anyway.

My boat apparently sat in storage for 6 yrs before we bought this year, so I like your feedback. I'll put some additives in before changing anything out on it. My tick sounds more like a lifter problem at this point. I've heard Seafoam works well at getting carbon deposits out, but I'll see if I can find some marvel mystery since it worked for you.

[DW SD]

some use ATF - 1 quart - to free up stuck lifters. I'd probably go there before seafoam, since it does have lubricating properties. ATF is heavy in detergent. Just run for 1 day and then change the oil.