1998 mercury EFI 200 hp chattering at idle??? Help please!

[lippreaper]

My 1998 Mercury EFI 200 HP outboard started making a chattering noise when its at idle. Its not a constant noise, it goes in and out of this randomly. Sometimes it doesn't do it for a while and then it will for a few seconds. Other times it just goes in and out of this noise quite frequently. Before my last time out on the water I checked my flywheel nut and only got about 1 turn out of it, but I didn't wrench down on it to hard cause I didn't want to cause any issues if thats not it. It didn't help... The best way I can explain the noise it makes is chattering/rattle not an engine knock. I can't hear it when I have it out of the water with the ears and hose because the motor is to loud. Other than this noise the thing runs like a top, any suggestions?? Oh and new water pump and prop hub kit was installed 2 months ago... Any info would be much appreciated. Thanks in advance!

 

[Dukedog]

Re: 1998 mercury EFI 200 hp chattering at idle??? Help please!

In neutral? In gear? Make any difference?

That nut torques ta 120 ft. lbs. Dont think your gonna over do it without a holder and loooong break over! We have a "special" 1/2" drive impact that gets 'em real close. Lots easier on tha knuckels..............

 

[lippreaper]

Re: 1998 mercury EFI 200 hp chattering at idle??? Help please!

I could only notice it in neutral... If it does it in gear it is at low speed and not as noticeable. So are you thinking it is the flywheel being loose?

 

[Dukedog]

Re: 1998 mercury EFI 200 hp chattering at idle??? Help please!

Hard ta say without being able ta hear it. But you should not have been able to tighten (unless you turn green when your mad) it very much at all with just a ratchet and socket.
With tha motor off wiggle tha shifter back n forth from tha neutral position till you know for a fact that tha shifter is in neutral. Look at tha position slide on tha motor. Make sure tha "guide block" is exactly in tha marked neutral spot marked on tha anchor bracket......Try tha same thing with tha motor runnin'. When ya wiggle tha shifter it doesn't have ta be enough to go into either gear. Your just makin' sure that its as good as its gonna get in tha neutral slot.................

 

[floatnisalliwanado]

Re: 1998 mercury EFI 200 hp chattering at idle??? Help please!

did you fix your problem or is it still there. if so could it be your lower unit?

 

[Maxz695]

Re: 1998 mercury EFI 200 hp chattering at idle??? Help please!

Over torque of the waterpump housing will cause binding on the impellor this will restrict the driveshaft and cause chattering of the wedged driveshaft on the splines. The shaft shoud be turnable by hand before instalation of the LU

 

[Faztbullet]

Re: 1998 mercury EFI 200 hp chattering at idle??? Help please!

Over torque of the waterpump housing will cause binding on the impellor this will restrict the driveshaft and cause chattering of the wedged driveshaft on the splines

Nah.....
Check the upper crankshaft seal as I have seen several of these here lately that are loose/spun in the housing and chatter and pop.

 

[Maxz695]

Re: 1998 mercury EFI 200 hp chattering at idle??? Help please!

Did it make the noise before the water pump was installed???

 

[Maxz695]

Re: 1998 mercury EFI 200 hp chattering at idle??? Help please!

View attachment 175173 Also I discovered today that my engine (still testing it after the rebuild) makes a clickering noise through the prop on muffs. When I cover the prop it sounds fine. The engine is running smooth and quiet but when I let go of the prop i hear the clankering. I am assuming it is the exhaust tube. I replaced the 70 HP with the one from My 40 HP it may have a bit more wear up top. It may be possible that the exhaust tube seal PLATE, SUPPORT broke letting the tube rattle or the EXHAUST TUBE SEAL melted and exhaust tube has play without it,s presence also allowing the exhaust tube to rattle. Dropping the LU and inspecting these parts might be an easy fix to the problem. Also check to see if the water pick up tube may have gotten slightly bent it mat be sporatically hitting against the exhast tube.

 

[Faztbullet]

Re: 1998 mercury EFI 200 hp chattering at idle??? Help please!

Max..... a V-6 does not have a exhaust tube extension that extends into lower unit, its up in the midsection. The inline motors are a different breed , totally different than the stuff your used to.