Merc 3.0 still chirping

[rcarden711]

Hello-
I have a 1999 3.0 Mercruiser that has begun to chirp when I increase the throttle and continues at cruise speed sounding like crickets. There is no chirping at idle.
As read in previous posts, I disconnected the belts temporarily to rule out the alternator and circulating pump. Still chirped with belts off. Put new belts on tight as always and still no change.

Any help would be appreciated.

First time poster, but iBoats has saved me so many times before. Thanks!!!

 

[zbnutcase]

Re: Merc 3.0 still chirping

Pull the drive and check the alignment or have it checked.

 

[rcarden711]

Re: Merc 3.0 still chirping

Thanks ZB...

I can get the drive off, but checking the alignment doesn't sound like a job I can do myself. Looks like I'll have to take it in.

Thanks again!

 

[JaseBosto]

Re: Merc 3.0 still chirping

If you download the manual from this site it, and get an alignment tool you can do it. I brought mine in last spring but I will do it myself next time.

 

[Bondo]

Re: Merc 3.0 still chirping

Ayuh,... My 1st Guess is, the head to exhaust manifold gasket is Failin' at 1 of the exhaust ports....

Just a Guess....

At idle,... Run yer fingers along the gasket line,... If it's leakin', it'll feel Hot when it Chirps....

 

[nitrosteve]

Re: Merc 3.0 still chirping

Could it be spark knocking. I could see how that could sound a little like chirping. But thats a stretch. Does it do it worse under a heavy load such as accelerating?

 

[rcarden711]

Re: Merc 3.0 still chirping

Thanks Bond-o...I will replace the manifold gasket today and see if that clears it up.

Nitrosteve, The chirping does worsen when I accelerate. I hope it's not spark knocking...that sounds serious.

 

[dpoff]

Re: Merc 3.0 still chirping

My gimbal bearing sounded like that when it started to go.

 

[Bondo]

Re: Merc 3.0 still chirping

Thanks Bond-o...I will replace the manifold gasket today and see if that clears it up.

Ayuh,... I'd Check it before I bought the gasket kit myself....

 

[nitrosteve]

Re: Merc 3.0 still chirping

Its also known as detonation or pinging that sounds a little better but it can tear a perfectly good motor up in a hurry. Just pretend you are smacking a hammer on top of the piston. In short its firing in the cylinder before its time and it makes an audible noise. Similar to change rattling I guess. You tube has some videos of it check it out and see if it sounds similar.

 

[rcarden711]

Re: Merc 3.0 still chirping

Just replaced all gaskets...manifold to block, manifold to elbow, and manifold to carb. Still got the chirping. I ca't distinguish where the chirp is coming from but my wife listened and said it seems to be coming from the rear. Perhaps it's the gimbal bearing. Hopefully that will fix it...I'm still dreading the spark knocking possibity.

 

[rcarden711]

Re: Merc 3.0 still chirping

Looking back at nitrosteve's comments and after more research from this site, I think I have found where the chirping noise is coming from. I tried disconnecting one sparkplug at a time and ran the engine. I disconnected rear sparkplug and let it run on the other 3. No change...connected the rear plug back up and then disconnected the # 3 plug...still chirping. #2 plug...same. But when I disconnected the first sparkplug in the front, I cranked it up and chirping sound was gone. Connected it back up and started chirping again, disconnected it and it stopped. I think it's the cylinder but this is way out of my league. Any ideas?

Thanks again for everyone's help!

 

[dubs283]

Re: Merc 3.0 still chirping

could upload a video to youtube and link it here??

that would be the best way to start, sometimes it works well, other times its hard to tell what the sound is that way

what is the timing set at??

 

[dingdongs]

Re: Merc 3.0 still chirping

are the manifold bolts tight.if someone had changed head or manifold and left some of the old gasket on when the new one was torqued down may be leaking slightly.sounds as if you found what cylinder its at anyway.may have to get yourself a gasket set and give head a look over too!

 

[daydreamer1252]

Re: Merc 3.0 still chirping

Loose spark plug??? When plug fires the escaping gasses make a chirp? Had an old Kawasaki (40 years ago) with mostly stripped spark plug threads so couldn't properly tighten the plug :redface: and when the inevitable looseness returned it would start to chirp.....just saying.....

 

[rcarden711]

Re: Merc 3.0 still chirping

Thanks again for everyone's input and ideas!! I really appreciate it.

It would be great if the chirp noise was from a loose spark plug. I was hoping to be able to look at them this afternoon but ran out of time. I will get to it tomorrow and send an update.

I know the manifold bolts are torqued down pretty good. I just changed the manifold gasket and I made sure it was 100% clean and free of any remaining gasket material. I'm afraid that both manifolds and both elbows are due for replacement, but that's for another day.

If the spark plug isn't the culprit, I will make a video and pass it along.

 

[Brew411]

Re: Merc 3.0 still chirping

A chirp sounds like a high compression "whistle" (except with a much shorter attack and a quick decay of sound)) If you her a chirp its likely, that on the compression stroke as the air excapes quickly, (through its outlet) you hear a "chirp", like a pulse of breath on a whistle, again, as the piston comes up on its compression stroke. It then quickly returns to its bottom posistion and then returns up again to it's top dead center within the cylinder. Chirp, Chirp, Chirp as the motor is running is what you hear. Can you also hear (over the noise of the engine) an inhale sucking noise as it draws it's breath of air as the piston pulls it's air in to the bottom intake stoke? Not so easy to hear, but if you blow smoke at the suspected leak area you may be able to "see" the back or intake draft. Don't light a cigerette near the engine.

 

[rcarden711]

Re: Merc 3.0 still chirping

Well.....I replaced the sparkplugs with the hopes that it would fix the chirping noise. Made sure they were good and tight...I cranked her up and the chirping was still there.

I have made a video and put it on YouTube. Link is below. You can definitely hear it if the video is played at the 480p hi-def setting. At 360p, the chirping does not come through on video.

http://www.youtube.com/watch?v=Je1RZ4wovBI

Thanks again!

 

[Fishermark]

Re: Merc 3.0 still chirping

I watched it at 480p but didn't hear a "chirp". I heard what sounds like a miss, but no chirping.

I guess I'm missing something.

Have you tried a tune up - new wires, plugs, etc.?

 

[Fishermark]

Re: Merc 3.0 still chirping

Also would suggest a compression check and leak down test. Maybe a valve is sticking.