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Author Topic:   Mercury 90-HP 2-stroke Squeal
1stwhaler posted 07-11-2004 03:05 AM ET (US)   Profile for 1stwhaler   Send Email to 1stwhaler  
After running my Montauk 170 with a 90-HP Mercury 2-stroke at wide open throttle, then backing down to no-wake speed, my motor makes a squeal (which sound like it is coming form the flywheel area). Then, after a few minutes, the noise goes away. But now the noise is not going away. Anybody else have this problem or may know what is causing it. Thanks
Jimm posted 07-11-2004 02:02 PM ET (US)     Profile for Jimm  Send Email to Jimm     
Saw a topic discussing this here or on "thehulltruth". The consensus was it only happens when you to idle from WOT too quickly. You throw a monkey wrench into that notion when you say "But now the noise is not going away."
cmarques posted 07-12-2004 08:02 PM ET (US)     Profile for cmarques  Send Email to cmarques     
I've had the same noise on mine at times. Mercury 90 2-stroke sounds like a loose belt. The noise will go away after a minute or so and might not be heard again for weeks.


erik selis posted 07-13-2004 05:06 AM ET (US)     Profile for erik selis  Send Email to erik selis     
I have heard it once on mine. It also went away quickly but it caused me some concern at the time.


newt posted 07-13-2004 12:48 PM ET (US)     Profile for newt  Send Email to newt     
I have never heard such a noise from my 2003 Mercury 90 2-stroke.
fredfizzle posted 07-13-2004 03:49 PM ET (US)     Profile for fredfizzle  Send Email to fredfizzle     
Mine squaled several times the way you described in the first 100hrs back in 2002. Did not do it again until the other day. Went away after about 1 min not to do it again. My motor has 300 hrs on it. ??????
1stwhaler posted 07-21-2004 08:35 PM ET (US)     Profile for 1stwhaler  Send Email to 1stwhaler     
Well I think I found the problem,dropped lower unit and found that the water pump housing rubber seal was out of place (rode up on shaft 3 inches) and the shaft was rubbing against the water pump housing,need to buy some lower unit oil and will repost what happened.
jimh posted 07-22-2004 08:35 AM ET (US)     Profile for jimh  Send Email to jimh     
Thanks for the follow up report on the source of this noise. If an engine suddenly starts making a strange noise, it is a good idea to investigate. Your experience demonstrates that.
1stwhaler posted 07-23-2004 02:44 AM ET (US)     Profile for 1stwhaler  Send Email to 1stwhaler     
The mystery is solved, and the noise is gone. It was the water pump housing rubbing on the drive shaft.
Divedog posted 08-02-2004 04:48 PM ET (US)     Profile for Divedog  Send Email to Divedog     
I'm on about my fifth tank of fuel and my 2-stroke 90-HP started making the same noise after running WOT. How hard is the repair you described? I'm not really set up for making repairs on a brand new engine and I'm considering asking the dealer to have a look. I'm assuming the cost of the repair of this problem would be covered by the warranty . Any advice would be greatly appreciated.
jimh posted 08-02-2004 08:14 PM ET (US)     Profile for jimh  Send Email to jimh     
If the motor is still under warranty coverage, and the warranty provides for this type of repair, you ought to let the dealer solve it for you at his or Mercury's expense.

Generally the warranty coverage is limited by time, not by amount of usage, so "five tanks" of gas may or may not put the motor under warranty.

jimh posted 08-02-2004 08:16 PM ET (US)     Profile for jimh  Send Email to jimh     
The repair described by 1st whaler is rather vague. Could you please elaborate on exactly what you did to cure this.
Divedog posted 08-02-2004 11:34 PM ET (US)     Profile for Divedog  Send Email to Divedog     
The dealer agrees with you Jimh. I described the problem over the phone and they said to bring it right in. Hopefully they can duplicate the noise. The engine needs to be pretty hot to make the noise. When I say 'hot' I'm not referring to an overheating problem. The air temp was in the 90's and the lake water was probably in the upper 60s - low 70s.
As far as the warrantee period is concerned. I'm well within the time line. I've only had the boat a few months and I have a 3 year warrantee period.
I'll be out of town for a few weeks (on someone else's boat) but I'll let you know what the dealer's mechanics say when I get back.
erik selis posted 08-03-2004 04:46 AM ET (US)     Profile for erik selis  Send Email to erik selis     
I was out yesterday and I did a lot of fast boating. I usually fish for a while and shut the main engine off. Yesterday I just left the fishing rods at home and did some fast cruising. I wanted to see how my motor performed after 150 hours of use and what the fuel consumption was. (My motor seems to be getting faster and more fuel efficient)One thing though: I heard that squealing sound again but it was not as loud as the first time. It also lasted longer. I heard it when going into the harbour on the way to the ramp and it lasted until I shut off the engine. Again, it wasn't nearly as loud as the first time.

It was also very hot outside yesterday(35°C). The first time I heard it was in Spain where it was also very hot.


Divedog posted 08-03-2004 10:07 AM ET (US)     Profile for Divedog  Send Email to Divedog     
Sounds a lot like the situation I have. I'll be sure to post an update in a couple of weeks. I am concerned the mechanics won't be able to duplicate the sound since you really need to push the motor to get the sound to appear. Anyway, I'll report back.
Divedog posted 08-20-2004 03:40 PM ET (US)     Profile for Divedog  Send Email to Divedog     
Well the dealer just called and after 2-1/2 hours of hard running they couldn't get the engine to make the same noise. So, I'm picking it up today and hoping it was just a 'break-in' noise. The good news is, I have a 3-year warranty so if it dies in the next couple of years it's still on their nickel.
erik selis posted 08-21-2004 03:37 AM ET (US)     Profile for erik selis  Send Email to erik selis     

The weather has cooled off quite a bit the last couple of weeks and when I was out last week I couldn't reproduce the squeal either. It must have something to do with ambient temp. or water temp. I am waiting to discuss it with my Merc. mechanic when I see him.

Thanks for reporting back.


1stwhaler posted 08-27-2004 09:49 AM ET (US)     Profile for 1stwhaler  Send Email to 1stwhaler     
The repair was very simple,removed lower unit,4 nuts plus one under the trim zinc,then I noticed the problem right away.The rubber seal on the water pump housing was not in place and rode up drive shaft and the water pump housing was rubbing against shaft,I then removed the 4 bolts on the water pump housing and removed housing,put rubber seal back in position and bolted down water pump housing,re-installed lower unit.The job took approx.45 minutes and right back at slip. It has been about 30 hours since I did this and problem has not been back,easy back yard mechanic job.If your motor is under warranty have the dealer repair unless you do not want to wait.I have 330 hours on the motor(2003) and this has been the only problem.
Divedog posted 08-27-2004 03:56 PM ET (US)     Profile for Divedog  Send Email to Divedog     
Thanks for the detailed description.
BritSti posted 07-30-2007 02:31 PM ET (US)     Profile for BritSti  Send Email to BritSti     
I believe I have just noticed the same sound on my 04 Merc 90 2 stroke on a 170 montauk. Basically, after say 20 min of sustained 3k rpm + running, at idle the motor sounds like it has a squealing fan belt. This sound goes away once the motor has run at idle for a while.

I did drop the lower unit, and the rubber seal at the top of the impeller housing was indeed not seated. I reseated it and lubed the inside diameter, however, this thing grips the top of the impeller housing so lightly, there is no way it will not come off again. The sound did go away, but is back after a day or two of higher rpm usage.

Any suggestions on a more permanent fix, it is not a mechanical issue, just an annoying one.


Divedog posted 08-03-2007 11:12 AM ET (US)     Profile for Divedog  Send Email to Divedog     
I don't have any suggestions, but after 3 years my motor is still going strong and it doesn't make the noise any more.

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