Johnson 175 outboard decel chatter?

[trxxx250r]

Hi, I have a 1995 - 19.5 ft Stratos with 175 fast strike.

All transom and T&T bolts are tight and installed properly. However, When I'm cruising (at variable different speeds) and trimmed out and drop off the gas I get a bit of a chatter or rattle from the motor. I don't know if this is normal or acceptable. Doesn't seem right to me.

Question is, what's causing it? My take is it might be the tilt arm having a little play in it.... I don't know.

I do know the boat sat for 10 years and the t&t haven't been serviced in at least that long, however there are no leaks and the system works perfectly

What do you think may be causing this and what do I need to do to fix it?

Thanks!

Btw - By visual inspection and lifting and tweaking on the motor, all the bushings seem to be tight, but, I could be wrong...

 

[Bosunsmate]

Re: Johnson 175 outboard decel chatter?

Mine rattles, but seems you think yours may be more than that.
Could be engine or fitting related.
Check for anything thats lose as that will rattle, you have probably done that. If its noisy enough post a video

You can also get someone at the back of the boat to poke it with a stick with a jesey or something tied on the end to try and locate where the rattle may be from

 

[racerone]

Re: Johnson 175 outboard decel chatter?

It may be the prop rotating because the boat is going fast.---------Do not slow down suddenly.

 

[Faztbullet]

Re: Johnson 175 outboard decel chatter?

Make sure the trim rollers are free, check upper motor mount bolts as they like to fall out.....

 

[trxxx250r]

Re: Johnson 175 outboard decel chatter?

delete

 

[trxxx250r]

Re: Johnson 175 outboard decel chatter?

Mine rattles, but seems you think yours may be more than that.
Could be engine or fitting related.
Check for anything thats lose as that will rattle, you have probably done that. If its noisy enough post a video

You can also get someone at the back of the boat to poke it with a stick with a jesey or something tied on the end to try and locate where the rattle may be from

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Join Date:Jun 2013Posts:54




Default Re: Johnson 175 outboard decel chatter?



No, I don't think it's more than that. It's a slight chatter on decel when I chop the throttle. I have checked all mounting points from the transom to the T&T, everything is good. The only thing I can figure is worn bushings or the hydraulic tilt arm witch controls the motors axis has some play? I don't know enough about that system to know if that is a common issue and if it is, how to correct it.

 

[trxxx250r]

Re: Johnson 175 outboard decel chatter?

Make sure the trim rollers are free, check upper motor mount bolts as they like to fall out.....

The rollers are in great shape.

I just went out and tried a few things. Like I said, everything is tight and sano. However, check this out. I tilted the motor up a bit and then lifted up on that pig with all I had, arrgg! Sure enough, it was pulling the tilt arm out maybe an 1/8 - 1/4 inch. Then I dropped it down to normal trim and did it again and same thing. The motor is coming off the trim rams and has about 3/8 - 1/2 total play. The reason for this is the tilt arm is allowing itself to be pulled out slightly but translates into almost 1/2" of free play in the motor. That explains why the motor is chattering on decal. The same force is applied by the water that I just applied with my arms in the garage.

Now, is this normal for the tilt arm to have outward play in it when a small force is applied? Unless this can be corrected then I will just have to live with the chatter but that can't be good for any of the mounting components or the hull.

Note: The T&T works fine but you can hear some kind of gurgling sounds coming from it in certain ranges of its motions. Possibly air in the system? Maybe that could be contributing to the play in that arm?

 

[Bosunsmate]

Re: Johnson 175 outboard decel chatter?

yes give it a bleed, check fluid level and that it isnt contaminated

 

[trxxx250r]

Re: Johnson 175 outboard decel chatter?

How do I go about bleeding it? I don't have a service manual & I searched around a little and couldn't find anything on it.

 

[Bosunsmate]

Re: Johnson 175 outboard decel chatter?

Boatinfo - The library, containing manuals, brochures and other technical documents from the last hundred years!

 

[trxxx250r]

Re: Johnson 175 outboard decel chatter?

Boatinfo - The library, containing manuals, brochures and other technical documents from the last hundred years!

THANKS Bosunsmate! That's awesome! Is that 92-2001 65-300 HP an actual OEM manual?

 

[Bosunsmate]

Re: Johnson 175 outboard decel chatter?

not sure , i use them and never had any problems

 

[trxxx250r]

Re: Johnson 175 outboard decel chatter?

OK, As it turns out it IS the motor making the noise and not the midsection or T&T. I wedged myself right at the motor and had my friend drive it. I wrapped my hands around the mid section and had full view of everything and had him nail the throttle and chop it off, coming out of the hole and at speed. Sure enough when the throttle was backed off the mid section was not rattling but I could hear the sound out of the motor above my head. The thing is, When I was at speed and then backed the throttle off slowly, it was worse than when I chopped it off. It would happen in the 5000-4000 range.

So, credit is due to those of you who obviously know your sh!t and have been around awhile. Thank you for your knowledge! Now, what do I do about it? Is it a problem or just a nuisance noise? This is a stock motor with about 500 hrs on it but I could be wrong. No way I'm rebuilding the motor so if this is terminal I will just sell the boat.

Your thoughts, thanks!

 

[Bosunsmate]

Re: Johnson 175 outboard decel chatter?

Do a compression check, if nothing is out there then i wouldnt be too concerned.
You could also grab the flywheel and see if it has any lateral or forward and back play.

Hard to say with any conviction without being there to hear it
I suppose it wouldnt be heard properly on a video.....

 

[Faztbullet]

Re: Johnson 175 outboard decel chatter?

If you running and chop throttle to idle the clutch dog in lower unit will override the gear ramps as prop is spinning faster than gears and make a chattering noise....

 

[trxxx250r]

Re: Johnson 175 outboard decel chatter?

Do a compression check, if nothing is out there then i wouldnt be too concerned.
You could also grab the flywheel and see if it has any lateral or forward and back play.

Hard to say with any conviction without being there to hear it
I suppose it wouldnt be heard properly on a video.....

I checked the compression awhile back and if I remember right it was right at 105 and all cylinders were very close within 5 points.

I'll try moving the flywheel. video probably wouldn't work as the wind really screws up the sound, but maybe.

 

[boobie]

Re: Johnson 175 outboard decel chatter?

I think what you have is called a de-cell knock where the motor leans out on deceleration from being to lean on fuel. Try hitting the choke once and see what happens.

 

[trxxx250r]

Re: Johnson 175 outboard decel chatter?

Yeah, that's what some others have said. So next time out I will hit the primer while hearing the noise and see what happens. It doesn't really matter though because from what I've been told there's nothing I can do about it short of a rebuild which isn't going to happen. I would sell the boat first.

 

[racerone]

Re: Johnson 175 outboard decel chatter?

Put the motor in forward gear.-------Then try and turn the prop clockwise what happens ?-----Now try and turn it counterclock wise.

 

[boobie]

Re: Johnson 175 outboard decel chatter?

What's that going to do ??