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Author Topic:   Loud screeching at idle on '04 Merc 90 4-stroke
Camuyano posted 07-24-2004 05:14 PM ET (US)   Profile for Camuyano   Send Email to Camuyano  
Friday we were fishing near the mouth of the Upper Machaddock creek. I decided to start the engine and let it idle while we reeled our lines in since I was worried about running down the battery. The engine ran perfectly for a few minutes but then stared making this awful screeching sound like when you try to start a motor while its already running.

I turned the motor off and checked it but everything look normal. I started it up again and the sound was gone. We quickly headed for the ramp and the motor ran perfectly. Later, when I flushed the motor the same thing happened. It ran well for a few minutes and then the noise started. I have a wave file of the sound and will try to find somewhere to post it.

I remember a post a while back about someone’s ignition switch getting stuck on the start position but don’t think this is the same thing because mine starts making the noise after it has already started. I did notice that the key doesn’t line up with the “Off”, “Run” and “Start” but I figured that maybe the switch had shifted slightly inside the bezel. Any ideas as what the problem could be?


Jkcam posted 07-24-2004 08:11 PM ET (US)     Profile for Jkcam  Send Email to Jkcam     
Don't know about your Merc, but on my Yamaha F90 I was getting what sounded like a belt sqweak at idle. I did my research and determined that it is the drive shaft inside the forward lower cowling. The drive shaft needs to be flushed carefully and given a silicone/wd40 type spray once in awhile. I am in the salt and brackish areas of So. Florida and apparently the salt build up on the shaft contributes to the sqweaking. Since I started a more careful flush and an occassional spray, the sqeak is history.
Dick posted 07-24-2004 08:41 PM ET (US)     Profile for Dick  Send Email to Dick     
Since it is a 2004 motor and under warranty take to your dealer and have it checked. Let a qualified Tech diagnose the problem rather than taking the risk of voiding your warranty.


Chuck Tribolet posted 07-25-2004 10:03 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
There have been at least two reports here of recent Merc
starter switches failing closed. It may well have been trying
to start the motor while it was already running.

If that's it, and you let it go on, it will toast the starter.


Maximus posted 07-25-2004 12:52 PM ET (US)     Profile for Maximus  Send Email to Maximus     
I reported my 03 4stroke making a noise. It was definitely the starter engaging on the flywheel while the engine was at idle. I never had anyone look at it, but will at the end of the season.

I take great care when starting as to release the key to the run position and make sure is springs back.

whale tauk posted 07-25-2004 01:34 PM ET (US)     Profile for whale tauk  Send Email to whale tauk     
While this likely has nothing to do with your screeching, while out in the bay I ran out of gas, switched tanks, try to re-start and nothing. The key just spun around. It was the lock nut that had come loose. I managed to finger tighten it enough to start it again but I now carry a small tool kit at all times. If for some reason your starter re-engages after it's started I'd definitely have the dealer fix it. The teeth on the flywheel are supposed to be harder than the starter gear but I'd want to be sure no damage had been done.
JohnJ80 posted 07-25-2004 06:57 PM ET (US)     Profile for JohnJ80  Send Email to JohnJ80     
I always carry a multitool (Swisstool RS or Leatherman WAVE) when boating. I have done some pretty major repairs on the water with just this. Indispensible.


Camuyano posted 07-26-2004 11:41 AM ET (US)     Profile for Camuyano  Send Email to Camuyano     
Well, I called the dealer today. They said I could drop it off but couldn't tell me when they would be able to get to it. They said they were swamped and that I had to wait for the same guy who hasn't returned my emails or calls about my prop corrosion problem in the last couple of weeks.

I also called a couple of Mercury shops around here since the dealer is an hour+ drive for me. The soonest they could get to it was 2 weeks! I am truly disappointed with the service I've been getting from the dealer. It seems that while they were trying to make the sale it was all smiles but when I'm having problems or need to get parts, they are less than responsive.

I thought that a high-end product like this was supposed to come with quality service but I guess I was wrong. Looks like the same story as my VW: superbly engineered but good luck getting it serviced!


andygere posted 07-27-2004 11:31 AM ET (US)     Profile for andygere  Send Email to andygere     
The starter keyswitch on my dad's '99 Dautless 16/Mercury 90 has caused similar problems as those described here. In my opinion it is a poorly made part, and not cheap to replace. Check it carefully to see that it is not spinning in the bezel, and that the key returns from the "start" position to the "run" position automatically. Also looke at the bendix unit on top of your starter motor. This should be lubed with a light grease (white lithium) so that it spins down easily after each start.

See if your dealer will get you on the waiting list for service while the boat is in your driveway, then bring it in when they are actually ready to work on it (using it the meantime if one of the two above solutions work). It is a frustrating thing trying to get outboard service in the summer. It seems like there is never enough capacity and one breakdown can cost you most of the boating season. I have lived on both coasts and it's the same thing everywhere. You'd think that minor warranty service on a new boat would somehow move you to the front of the waiting list after dropping some big coin on the dealership just months ago...

Camuyano posted 07-27-2004 02:50 PM ET (US)     Profile for Camuyano  Send Email to Camuyano     

I must take back some of what I said about my dealer. I finally received a call from the owner and he hooked me up. I took the boat down to Richmond today and, when they ran it with the flywheel cover off, it was obvious that the starter was engaging itself while the engine was running. They suspected that it was the switch (as we all did) and took one from a boat in the lot since they didn’t have the part in stock. Hopefully that will take care of it.

They listened to all my concerns about the boat and even installed a pair of eye straps for free so that I could tie down my bimini while folded back on the support poles to keep it from swaying so much.


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