rattling sound when reving up

[imraan47]

Hey.
so i am getting this rattling sound or basically tin to tin hitting each other.
its only when i rev the engine or go over 2000rpm. runs like crap this way and its making me concerned.
could it just be the plate behind the engine coupler or is this something more serious?

1988 merc alpha 1,gen 1.
120hp 4cyl

 

[Bt Doctur]

Re: rattling sound when reving up

check the flywheel dust cover for cracks.the tin part just behind the oil pan. almost positive you`ll see the crack. annoying but not destructive.

 

[produceguy]

Re: rattling sound when reving up

Hey.
so i am getting this rattling sound or basically tin to tin hitting each other.
its only when i rev the engine or go over 2000rpm. runs like crap this way and its making me concerned.
could it just be the plate behind the engine coupler or is this something more serious?

1988 merc alpha 1,gen 1.
120hp 4cyl

I had that issue before. Mine was lower shift cable not meshed together right with the lower unit.
Have you had your lower unit off lately?
If so check were the gears mesh together on the back of the drive, you might be off a little.

 

[timfives]

Re: rattling sound when reving up

If it is affecting the engine performance. Then it maybe an engine issue. Check your oil, plugs and compression.

If engine performance is okay then it could be a cracked dust cover or maybe exhaust shutters.

Just my two cents

T

Hey.
so i am getting this rattling sound or basically tin to tin hitting each other.
its only when i rev the engine or go over 2000rpm. runs like crap this way and its making me concerned.
could it just be the plate behind the engine coupler or is this something more serious?

1988 merc alpha 1,gen 1.
120hp 4cyl

 

[JetBote]

Re: rattling sound when reving up

Sounds like timing is off, or bad gas, especially if this occurs under load, not in neutral.

 

[180shabah]

Re: rattling sound when reving up

Is this on the trailer in neutral or in the water under load?

I had a swim platform the resonated through the transom - sounded t
like the dam boat was coming apart - didn't do it in the water though - left a bungee on the trailer and hooked the ladder with it - problem solved.

Bigger concern - you might be running lean and detonating - yes it is as bad as it sounds - could cost you a new engine.

Do you have any history on this engine - tune up - condition of fuel, filters etc????

 

[imraan47]

Re: rattling sound when reving up

I had that issue before. Mine was lower shift cable not meshed together right with the lower unit.
Have you had your lower unit off lately?
If so check were the gears mesh together on the back of the drive, you might be off a little.

If it is this then i am going to blast the damn mechanic that keeps giving me attitude when i drop the boat to him. He took the lower unit and serviced it by replacing water pump impeller. I then installed the outrdive back on to save on labour.
This sound just started the last time i went out but before that there wasn't this issue except rough idle and engine ran alittle too rough. i mean just standing on the boat you could hear vibration and didn't feel like normal.
Anyhow i have given the boat to the mechanic so lets see what he comes up with. He was saying it will cost me abit but he had no clue. I tried to look around where the coupler is and the flywheel but no sign of cracks or anything that is obvious.

Is it true that if the engine starts and runs fine the compression is normal?

I dont have much history of the boat's engine although i dont think its rebuilt at all for a 1988. I praying it doesn't need a rebuild because if it does i am going to just part it/sell it or toss it out if i am too pissed.

 

[Bondo]

Re: rattling sound when reving up

Is it true that if the engine starts and runs fine the compression is normal?

Nope.....


I'm guessin' yer Fuel System is boogered up....

Have ya changed the fuel Filters,..??

 

[produceguy]

Re: rattling sound when reving up

http://forums.iboats.com/showthread.php?t=480696&highlight=rattling+noise+lower+unit

Check this one out.

 

[imraan47]

Re: rattling sound when reving up

http://forums.iboats.com/showthread.php?t=480696&highlight=rattling+noise+lower+unit

Check this one out.

no mine is when its in water (havent tested on muffs)
plus is not from outdrive but from engine side.

mechanic told me its some springs on flybridge? ? ?
i think thats what i heard.
but either way he said some springs and engine has to be taken out. apparently though its not a big deal so i can still run the boat like that
however i want to see if i can fix it myself.

oh also i posted another thread 'alternator'
so i need an alternator since he said mine is seized,.
so whats the right one to get?

 

[imraan47]

Re: rattling sound when reving up

no mine is when its in water (havent tested on muffs)
plus is not from outdrive but from engine side.

mechanic told me its some springs on flybridge? ? ?
i think thats what i heard.
but either way he said some springs and engine has to be taken out. apparently though its not a big deal so i can still run the boat like that
however i want to see if i can fix it myself.

oh also i posted another thread 'alternator'
so i need an alternator since he said mine is seized,.
so whats the right one to get?

any idea what is wrong exactly so that i can fix this? the sound is just not nice and makes me too scared to go anywhere.